Feeds:
Posts
Comments

Posts Tagged ‘Coronary artery disease’


Icelandic Population Genomic Study Results by deCODE Genetics come to Fruition: Curation of Current genomic studies

Reporter/Curator: Stephen J. Williams, Ph.D.

 

UPDATED on 9/6/2017

On 9/6/2017, Aviva Lev-Ari, PhD, RN had attend a talk by Paul Nioi, PhD, Amgen, at HMS, Harvard BioTechnology Club (GSAS).

Nioi discussed his 2016 paper in NEJM, 2016, 374:2131-2141

Variant ASGR1 Associated with a Reduced Risk of Coronary Artery Disease

Paul Nioi, Ph.D., Asgeir Sigurdsson, B.Sc., Gudmar Thorleifsson, Ph.D., Hannes Helgason, Ph.D., Arna B. Agustsdottir, B.Sc., Gudmundur L. Norddahl, Ph.D., Anna Helgadottir, M.D., Audur Magnusdottir, Ph.D., Aslaug Jonasdottir, M.Sc., Solveig Gretarsdottir, Ph.D., Ingileif Jonsdottir, Ph.D., Valgerdur Steinthorsdottir, Ph.D., Thorunn Rafnar, Ph.D., Dorine W. Swinkels, M.D., Ph.D., Tessel E. Galesloot, Ph.D., Niels Grarup, Ph.D., Torben Jørgensen, D.M.Sc., Henrik Vestergaard, D.M.Sc., Torben Hansen, Ph.D., Torsten Lauritzen, D.M.Sc., Allan Linneberg, Ph.D., Nele Friedrich, Ph.D., Nikolaj T. Krarup, Ph.D., Mogens Fenger, Ph.D., Ulrik Abildgaard, D.M.Sc., Peter R. Hansen, D.M.Sc., Anders M. Galløe, Ph.D., Peter S. Braund, Ph.D., Christopher P. Nelson, Ph.D., Alistair S. Hall, F.R.C.P., Michael J.A. Williams, M.D., Andre M. van Rij, M.D., Gregory T. Jones, Ph.D., Riyaz S. Patel, M.D., Allan I. Levey, M.D., Ph.D., Salim Hayek, M.D., Svati H. Shah, M.D., Muredach Reilly, M.B., B.Ch., Gudmundur I. Eyjolfsson, M.D., Olof Sigurdardottir, M.D., Ph.D., Isleifur Olafsson, M.D., Ph.D., Lambertus A. Kiemeney, Ph.D., Arshed A. Quyyumi, F.R.C.P., Daniel J. Rader, M.D., William E. Kraus, M.D., Nilesh J. Samani, F.R.C.P., Oluf Pedersen, D.M.Sc., Gudmundur Thorgeirsson, M.D., Ph.D., Gisli Masson, Ph.D., Hilma Holm, M.D., Daniel Gudbjartsson, Ph.D., Patrick Sulem, M.D., Unnur Thorsteinsdottir, Ph.D., and Kari Stefansson, M.D., Ph.D.

N Engl J Med 2016; 374:2131-2141June 2, 2016DOI: 10.1056/NEJMoa1508419

Abstract
Article
References
Citing Articles (22)
Metrics

BACKGROUND

Several sequence variants are known to have effects on serum levels of non–high-density lipoprotein (HDL) cholesterol that alter the risk of coronary artery disease.

METHODS

We sequenced the genomes of 2636 Icelanders and found variants that we then imputed into the genomes of approximately 398,000 Icelanders. We tested for association between these imputed variants and non-HDL cholesterol levels in 119,146 samples. We then performed replication testing in two populations of European descent. We assessed the effects of an implicated loss-of-function variant on the risk of coronary artery disease in 42,524 case patients and 249,414 controls from five European ancestry populations. An augmented set of genomes was screened for additional loss-of-function variants in a target gene. We evaluated the effect of an implicated variant on protein stability.

RESULTS

We found a rare noncoding 12-base-pair (bp) deletion (del12) in intron 4 of ASGR1, which encodes a subunit of the asialoglycoprotein receptor, a lectin that plays a role in the homeostasis of circulating glycoproteins. The del12 mutation activates a cryptic splice site, leading to a frameshift mutation and a premature stop codon that renders a truncated protein prone to degradation. Heterozygous carriers of the mutation (1 in 120 persons in our study population) had a lower level of non-HDL cholesterol than noncarriers, a difference of 15.3 mg per deciliter (0.40 mmol per liter) (P=1.0×10−16), and a lower risk of coronary artery disease (by 34%; 95% confidence interval, 21 to 45; P=4.0×10−6). In a larger set of sequenced samples from Icelanders, we found another loss-of-function ASGR1 variant (p.W158X, carried by 1 in 1850 persons) that was also associated with lower levels of non-HDL cholesterol (P=1.8×10−3).

CONCLUSIONS

ASGR1 haploinsufficiency was associated with reduced levels of non-HDL cholesterol and a reduced risk of coronary artery disease. (Funded by the National Institutes of Health and others.)

 

Amgen’s deCODE Genetics Publishes Largest Human Genome Population Study to Date

Mark Terry, BioSpace.com Breaking News Staff reported on results of one of the largest genome sequencing efforts to date, sequencing of the genomes of 2,636 people from Iceland by deCODE genetics, Inc., a division of Thousand Oaks, Calif.-based Amgen (AMGN).

Amgen had bought deCODE genetics Inc. in 2012, saving the company from bankruptcy.

There were a total of four studies, published on March 25, 2015 on the online version of Nature Genetics; titled “Large-scale whole-genome sequencing of the Icelandic population[1],” “Identification of a large set of rare complete human knockouts[2],” “The Y-chromosome point mutation rate in humans[3]” and “Loss-of-function variants in ABCA7 confer risk of Alzheimer’s disease[4].”

The project identified some new genetic variants which increase risk of Alzheimer’s disease and confirmed some variants known to increase risk of diabetes and atrial fibrillation. A more in-depth post will curate these findings but there was an interesting discrete geographic distribution of certain rare variants located around Iceland. The dataset offers a treasure trove of meaningful genetic information not only about the Icelandic population but offers numerous new targets for breast, ovarian cancer as well as Alzheimer’s disease.

View Mark Terry’s article here on Biospace.com.

“This work is a demonstration of the unique power sequencing gives us for learning more about the history of our species,” said Kari Stefansson, founder and chief executive officer of deCode and one of the lead authors in a statement, “and for contributing to new means of diagnosing, treating and preventing disease.”

The scale and ambition of the study is impressive, but perhaps more important, the research identified a new genetic variant that increases the risk of Alzheimer’s disease and already had identified an APP variant that is associated with decreased risk of Alzheimer’s Disease. It also confirmed variants that increase the risk of diabetes and a variant that results in atrial fibrillation.
The database of human genetic variation (dbSNP) contained over 50 million unique sequence variants yet this database only represents a small proportion of single nucleotide variants which is thought to exist. These “private” or rare variants undoubtedly contribute to important phenotypes, such as disease susceptibility. Non-SNV variants, like indels and structural variants, are also under-represented in public databases. The only way to fully elucidate the genetic basis of a trait is to consider all of these types of variants, and the only way to find them is by large-scale sequencing.

Curation of Population Genomic Sequencing Programs/Corporate Partnerships

Click on “Curation of genomic studies” below for full Table

Curation of genomic studies
Study Partners Population Enrolled Disease areas Analysis
Icelandic Genome

Project

deCODE/Amgen Icelandic 2,636 Variants related to: Alzheimer’s, cardiovascular, diabetes WES + EMR; blood samples
Genome Sequencing Study Geisinger Health System/Regeneron Northeast PA, USA 100,000 Variants related to hypercholestemia, autism, obesity, other diseases WES +EMR +MyCode;

– Blood samples

The 100,000 Genomes Project National Health Service/NHS Genome Centers/ 10 companies forming Gene Consortium including Abbvie, Alexion, AstraZeneca, Biogen, Dimension, GSK, Helomics, Roche,   Takeda, UCB Rare disorders population UK Starting to recruit 100,000 Initially rare diseases, cancer, infectious diseases WES of blood, saliva and tissue samples

Ref paper

Saudi Human Genome Program 7 centers across Saudi Arabia in conjunction with King Abdulaziz City Science & Tech., King Faisal Hospital & Research Centre/Life Technologies General population Saudi Arabia 20,000 genomes over three years First focus on rare severe early onset diseases: diabetes, deafness, cardiovascular, skeletal deformation Whole genome sequence blood samples + EMR
Genome of the Netherlands (GoNL) Consortium consortium of the UMCG,LUMCErasmus MCVU university and UMCU. Samples where contributed by LifeLinesThe Leiden Longevity StudyThe Netherlands Twin Registry (NTR), The Rotterdam studies, and The Genetic Research in Isolated Populations program. All the sequencing work is done by BGI Hong Kong. Families in Netherlands 769 Variants, SNV, indels, deletions from apparently healthy individuals, family trios Whole genome NGS of whole blood no EMR

Ref paper in Nat. Genetics

Ref paper describing project

Faroese FarGen project Privately funded Faroe Islands Faroese population 50,000 Small population allows for family analysis Combine NGS with EMR and genealogy reports
Personal Genome Project Canada $4000.00 fee from participants; collaboration with University of Toronto and SickKids Organization; technical assistance with Harvard Canadian Health System Goal: 100,000 ? just started no defined analysis goals yet Whole exome and medical records
Singapore Sequencing Malay Project (SSMP) Singapore Genome Variation Project

Singapore Pharmacogenomics Project

Malaysian 100 healthy Malays from Singapore Pop. Health Study Variant analysis Deep whole genome sequencing
GenomeDenmark four Danish universities (KU, AU, DTU and AAU), two hospitals (Herlev and Vendsyssel) and two private firms (Bavarian Nordic and BGI-Europe). 150 complete genomes; first 30 published in Nature Comm. ? See link
Neuromics Consortium University of Tübingen and 18 academic and industrial partners (see link for description) European and Australian 1,100 patients with neuro-

degenerative and neuro-

muscular disease

Moved from SNP to whole exome analysis Whole Exome, RNASeq

References

  1. Gudbjartsson DF, Helgason H, Gudjonsson SA, Zink F, Oddson A, Gylfason A, Besenbacher S, Magnusson G, Halldorsson BV, Hjartarson E et al: Large-scale whole-genome sequencing of the Icelandic population. Nature genetics 2015, advance online publication.
  2. Sulem P, Helgason H, Oddson A, Stefansson H, Gudjonsson SA, Zink F, Hjartarson E, Sigurdsson GT, Jonasdottir A, Jonasdottir A et al: Identification of a large set of rare complete human knockouts. Nature genetics 2015, advance online publication.
  3. Helgason A, Einarsson AW, Gumundsdottir VB, Sigursson A, Gunnarsdottir ED, Jagadeesan A, Ebenesersdottir SS, Kong A, Stefansson K: The Y-chromosome point mutation rate in humans. Nature genetics 2015, advance online publication.
  4. Steinberg S, Stefansson H, Jonsson T, Johannsdottir H, Ingason A, Helgason H, Sulem P, Magnusson OT, Gudjonsson SA, Unnsteinsdottir U et al: Loss-of-function variants in ABCA7 confer risk of Alzheimer’s disease. Nature genetics 2015, advance online publication.

Other post related to DECODE, population genomics, and NGS on this site include:

Illumina Says 228,000 Human Genomes Will Be Sequenced in 2014

CRACKING THE CODE OF HUMAN LIFE: The Birth of BioInformatics & Computational Genomics

CRACKING THE CODE OF HUMAN LIFE: The Birth of BioInformatics and Computational Genomics – Part IIB

Human genome: UK to become world number 1 in DNA testing

Synthetic Biology: On Advanced Genome Interpretation for Gene Variants and Pathways: What is the Genetic Base of Atherosclerosis and Loss of Arterial Elasticity with Aging

Genomic Promise for Neurodegenerative Diseases, Dementias, Autism Spectrum, Schizophrenia, and Serious Depression

Sequencing the exomes of 1,100 patients with neurodegenerative and neuromuscular diseases: A consortium of 18 European and Australian institutions

University of California Santa Cruz’s Genomics Institute will create a Map of Human Genetic Variations

Three Ancestral Populations Contributed to Modern-day Europeans: Ancient Genome Analysis

Impact of evolutionary selection on functional regions: The imprint of evolutionary selection on ENCODE regulatory elements is manifested between species and within human populations

Read Full Post »

Summary – Volume 4, Part 2: Translational Medicine in Cardiovascular Diseases


Summary – Volume 4, Part 2:  Translational Medicine in Cardiovascular Diseases

Author and Curator: Larry H Bernstein, MD, FCAP

 

We have covered a large amount of material that involves

  • the development,
  • application, and
  • validation of outcomes of medical and surgical procedures

that are based on translation of science from the laboratory to the bedside, improving the standards of medical practice at an accelerated pace in the last quarter century, and in the last decade.  Encouraging enabling developments have been:

1. The establishment of national and international outcomes databases for procedures by specialist medical societies

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

On Devices and On Algorithms: Prediction of Arrhythmia after Cardiac Surgery and ECG Prediction of an Onset of Paroxysmal Atrial Fibrillation
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC
https://pharmaceuticalintelligence.com/2013/05/07/on-devices-and-on-algorithms-arrhythmia-after-cardiac-surgery-prediction-and-ecg-prediction-of-paroxysmal-atrial-fibrillation-onset/

Mitral Valve Repair: Who is a Patient Candidate for a Non-Ablative Fully Non-Invasive Procedure?
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/04/mitral-valve-repair-who-is-a-candidate-for-a-non-ablative-fully-non-invasive-procedure/

Cardiovascular Complications: Death from Reoperative Sternotomy after prior CABG, MVR, AVR, or Radiation; Complications of PCI; Sepsis from Cardiovascular Interventions
Author, Introduction and Summary: Justin D Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/07/23/cardiovascular-complications-of-multiple-etiologies-repeat-sternotomy-post-cabg-or-avr-post-pci-pad-endoscopy-andor-resultant-of-systemic-sepsis/

Survivals Comparison of Coronary Artery Bypass Graft (CABG) and Percutaneous Coronary Intervention (PCI) /Coronary Angioplasty
Larry H. Bernstein, MD, Writer And Aviva Lev-Ari, PhD, RN, Curator
https://pharmaceuticalintelligence.com/2013/06/23/comparison-of-cardiothoracic-bypass-and-percutaneous-interventional-catheterization-survivals/

Revascularization: PCI, Prior History of PCI vs CABG
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/04/25/revascularization-pci-prior-history-of-pci-vs-cabg/

Outcomes in High Cardiovascular Risk Patients: Prasugrel (Effient) vs. Clopidogrel (Plavix); Aliskiren (Tekturna) added to ACE or added to ARB
Reporter and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/27/outcomes-in-high-cardiovascular-risk-patients-prasugrel-effient-vs-clopidogrel-plavix-aliskiren-tekturna-added-to-ace-or-added-to-arb/

Endovascular Lower-extremity Revascularization Effectiveness: Vascular Surgeons (VSs), Interventional Cardiologists (ICs) and Interventional Radiologists (IRs)
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/13/coronary-artery-disease-medical-devices-solutions-from-first-in-man-stent-implantation-via-medical-ethical-dilemmas-to-drug-eluting-stents/

and more

2. The identification of problem areas, particularly in activation of the prothrombotic pathways, infection control to an extent, and targeting of pathways leading to progression or to arrythmogenic complications.

Cardiovascular Complications: Death from Reoperative Sternotomy after prior CABG, MVR, AVR, or Radiation; Complications of PCI; Sepsis from Cardiovascular Interventions Author, Introduction and Summary: Justin D Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/07/23/cardiovascular-complications-of-multiple-etiologies-repeat-sternotomy-post-cabg-or-avr-post-pci-pad-endoscopy-andor-resultant-of-systemic-sepsis/

Anticoagulation genotype guided dosing
Larry H. Bernstein, MD, FCAP, Author and Curator
https://pharmaceuticalintelligence.com/2013/12/08/anticoagulation-genotype-guided-dosing/

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

The Effects of Aprotinin on Endothelial Cell Coagulant Biology
Co-Author (Kamran Baig, MBBS, James Jaggers, MD, Jeffrey H. Lawson, MD, PhD) and Curator
https://pharmaceuticalintelligence.com/2013/07/20/the-effects-of-aprotinin-on-endothelial-cell-coagulant-biology/

Outcomes in High Cardiovascular Risk Patients: Prasugrel (Effient) vs. Clopidogrel (Plavix); Aliskiren (Tekturna) added to ACE or added to ARB
Reporter and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/27/outcomes-in-high-cardiovascular-risk-patients-prasugrel-effient-vs-clopidogrel-plavix-aliskiren-tekturna-added-to-ace-or-added-to-arb/

Pharmacogenomics – A New Method for Druggability  Author and Curator: Demet Sag, PhD
https://pharmaceuticalintelligence.com/2014/04/28/pharmacogenomics-a-new-method-for-druggability/

Advanced Topics in Sepsis and the Cardiovascular System at its End Stage    Author: Larry H Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2013/08/18/advanced-topics-in-Sepsis-and-the-Cardiovascular-System-at-its-End-Stage/

3. Development of procedures that use a safer materials in vascular management.

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

Biomaterials Technology: Models of Tissue Engineering for Reperfusion and Implantable Devices for Revascularization
Author and Curator: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/05/05/bioengineering-of-vascular-and-tissue-models/

Vascular Repair: Stents and Biologically Active Implants
Author and Curator: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, RN, PhD
https://pharmaceuticalintelligence.com/2013/05/04/stents-biologically-active-implants-and-vascular-repair/

Drug Eluting Stents: On MIT’s Edelman Lab’s Contributions to Vascular Biology and its Pioneering Research on DES
Author: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, PhD, RN
http://PharmaceuticalIntelligence.com/2013/04/25/Contributions-to-vascular-biology/

MedTech & Medical Devices for Cardiovascular Repair – Curations by Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/04/17/medtech-medical-devices-for-cardiovascular-repair-curation-by-aviva-lev-ari-phd-rn/

4. Discrimination of cases presenting for treatment based on qualifications for medical versus surgical intervention.

Treatment Options for Left Ventricular Failure – Temporary Circulatory Support: Intra-aortic balloon pump (IABP) – Impella Recover LD/LP 5.0 and 2.5, Pump Catheters (Non-surgical) vs Bridge Therapy: Percutaneous Left Ventricular Assist Devices (pLVADs) and LVADs (Surgical)
Author: Larry H Bernstein, MD, FCAP And Curator: Justin D Pearlman, MD, PhD, FACC
https://pharmaceuticalintelligence.com/2013/07/17/treatment-options-for-left-ventricular-failure-temporary-circulatory-support-intra-aortic-balloon-pump-iabp-impella-recover-ldlp-5-0-and-2-5-pump-catheters-non-surgical-vs-bridge-therapy/

Coronary Reperfusion Therapies: CABG vs PCI – Mayo Clinic preprocedure Risk Score (MCRS) for Prediction of in-Hospital Mortality after CABG or PCI
Writer and Curator: Larry H. Bernstein, MD, FCAP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/06/30/mayo-risk-score-for-percutaneous-coronary-intervention/

ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery Reporter: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/05/accaha-guidelines-for-coronary-artery-bypass-graft-surgery/

Mitral Valve Repair: Who is a Patient Candidate for a Non-Ablative Fully Non-Invasive Procedure?
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/04/mitral-valve-repair-who-is-a-candidate-for-a-non-ablative-fully-non-invasive-procedure/ 

5.  This has become possible because of the advances in our knowledge of key related pathogenetic mechanisms involving gene expression and cellular regulation of complex mechanisms.

What is the key method to harness Inflammation to close the doors for many complex diseases?
Author and Curator: Larry H Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2014/03/21/what-is-the-key-method-to-harness-inflammation-to-close-the-doors-for-many-complex-diseases/

CVD Prevention and Evaluation of Cardiovascular Imaging Modalities: Coronary Calcium Score by CT Scan Screening to justify or not the Use of Statin
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/03/03/cvd-prevention-and-evaluation-of-cardiovascular-imaging-modalities-coronary-calcium-score-by-ct-scan-screening-to-justify-or-not-the-use-of-statin/

Richard Lifton, MD, PhD of Yale University and Howard Hughes Medical Institute: Recipient of 2014 Breakthrough Prizes Awarded in Life Sciences for the Discovery of Genes and Biochemical Mechanisms that cause Hypertension
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/03/03/richard-lifton-md-phd-of-yale-university-and-howard-hughes-medical-institute-recipient-of-2014-breakthrough-prizes-awarded-in-life-sciences-for-the-discovery-of-genes-and-biochemical-mechanisms-tha/

Pathophysiological Effects of Diabetes on Ischemic-Cardiovascular Disease and on Chronic Obstructive Pulmonary Disease (COPD)
Curator:  Larry H. Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2014/01/15/pathophysiological-effects-of-diabetes-on-ischemic-cardiovascular-disease-and-on-chronic-obstructive-pulmonary-disease-copd/

Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))
Reviewer and Co-Curator: Larry H Bernstein, MD, CAP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

Notable Contributions to Regenerative Cardiology  Author and Curator: Larry H Bernstein, MD, FCAP and Article Commissioner: Aviva Lev-Ari, PhD, RD
https://pharmaceuticalintelligence.com/2013/10/20/notable-contributions-to-regenerative-cardiology/

As noted in the introduction, any of the material can be found and reviewed by content, and the eTOC is identified in attached:

http://wp.me/p2xfv8-1W

 

This completes what has been presented in Part 2, Vol 4 , and supporting references for the main points that are found in the Leaders in Pharmaceutical Intelligence Cardiovascular book.  Part 1 was concerned with Posttranslational Modification of Proteins, vital for understanding cellular regulation and dysregulation.  Part 2 was concerned with Translational Medical Therapeutics, the efficacy of medical and surgical decisions based on bringing the knowledge gained from the laboratory, and from clinical trials into the realm opf best practice.  The time for this to occur in practice in the past has been through roughly a generation of physicians.  That was in part related to the busy workload of physicians, and inability to easily access specialty literature as the volume and complexity increased.  This had an effect of making access of a family to a primary care provider through a lifetime less likely than the period post WWII into the 1980s.

However, the growth of knowledge has accelerated in the specialties since the 1980’s so that the use of physician referral in time became a concern about the cost of medical care.  This is not the place for or a matter for discussion here.  It is also true that the scientific advances and improvements in available technology have had a great impact on medical outcomes.  The only unrelated issue is that of healthcare delivery, which is not up to the standard set by serial advances in therapeutics, accompanied by high cost due to development costs, marketing costs, and development of drug resistance.

I shall identify continuing developments in cardiovascular diagnostics, therapeutics, and bioengineering that is and has been emerging.

1. Mechanisms of disease

REPORT: Mapping the Cellular Response to Small Molecules Using Chemogenomic Fitness Signatures 

Science 11 April 2014:
Vol. 344 no. 6180 pp. 208-211
http://dx.doi.org/10.1126/science.1250217

Abstract: Genome-wide characterization of the in vivo cellular response to perturbation is fundamental to understanding how cells survive stress. Identifying the proteins and pathways perturbed by small molecules affects biology and medicine by revealing the mechanisms of drug action. We used a yeast chemogenomics platform that quantifies the requirement for each gene for resistance to a compound in vivo to profile 3250 small molecules in a systematic and unbiased manner. We identified 317 compounds that specifically perturb the function of 121 genes and characterized the mechanism of specific compounds. Global analysis revealed that the cellular response to small molecules is limited and described by a network of 45 major chemogenomic signatures. Our results provide a resource for the discovery of functional interactions among genes, chemicals, and biological processes.

Yeasty HIPHOP

Laura Zahn
Sci. Signal. 15 April 2014; 7(321): ec103.   http://dx.doi.org/10.1126/scisignal.2005362

In order to identify how chemical compounds target genes and affect the physiology of the cell, tests of the perturbations that occur when treated with a range of pharmacological chemicals are required. By examining the haploinsufficiency profiling (HIP) and homozygous profiling (HOP) chemogenomic platforms, Lee et al.(p. 208) analyzed the response of yeast to thousands of different small molecules, with genetic, proteomic, and bioinformatic analyses. Over 300 compounds were identified that targeted 121 genes within 45 cellular response signature networks. These networks were used to extrapolate the likely effects of related chemicals, their impact upon genetic pathways, and to identify putative gene functions

Key Heart Failure Culprit Discovered

A team of cardiovascular researchers from the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai, Sanford-Burnham Medical Research Institute, and University of California, San Diego have identified a small, but powerful, new player in thIe onset and progression of heart failure. Their findings, published in the journal Nature  on March 12, also show how they successfully blocked the newly discovered culprit.
Investigators identified a tiny piece of RNA called miR-25 that blocks a gene known as SERCA2a, which regulates the flow of calcium within heart muscle cells. Decreased SERCA2a activity is one of the main causes of poor contraction of the heart and enlargement of heart muscle cells leading to heart failure.

Using a functional screening system developed by researchers at Sanford-Burnham, the research team discovered miR-25 acts pathologically in patients suffering from heart failure, delaying proper calcium uptake in heart muscle cells. According to co-lead study authors Christine Wahlquist and Dr. Agustin Rojas Muñoz, developers of the approach and researchers in Mercola’s lab at Sanford-Burnham, they used high-throughput robotics to sift through the entire genome for microRNAs involved in heart muscle dysfunction.

Subsequently, the researchers at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai found that injecting a small piece of RNA to inhibit the effects of miR-25 dramatically halted heart failure progression in mice. In addition, it also improved their cardiac function and survival.

“In this study, we have not only identified one of the key cellular processes leading to heart failure, but have also demonstrated the therapeutic potential of blocking this process,” says co-lead study author Dr. Dongtak Jeong, a post-doctoral fellow at the Cardiovascular Research Center at Icahn School of  Medicine at Mount Sinai in the laboratory of the study’s co-senior author Dr. Roger J. Hajjar.

Publication: Inhibition of miR-25 improves cardiac contractility in the failing heart.Christine Wahlquist, Dongtak Jeong, Agustin Rojas-Muñoz, Changwon Kho, Ahyoung Lee, Shinichi Mitsuyama, Alain Van Mil, Woo Jin Park, Joost P. G. Sluijter, Pieter A. F. Doevendans, Roger J. :  Hajjar & Mark Mercola.     Nature (March 2014)    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13073.html

 

“Junk” DNA Tied to Heart Failure

Deep RNA Sequencing Reveals Dynamic Regulation of Myocardial Noncoding RNAs in Failing Human Heart and Remodeling With Mechanical Circulatory Support

Yang KC, Yamada KA, Patel AY, Topkara VK, George I, et al.
Circulation 2014;  129(9):1009-21.
http://dx.doi.org/10.1161/CIRCULATIONAHA.113.003863              http://circ.ahajournals.org/…/CIRCULATIONAHA.113.003863.full

The myocardial transcriptome is dynamically regulated in advanced heart failure and after LVAD support. The expression profiles of lncRNAs, but not mRNAs or miRNAs, can discriminate failing hearts of different pathologies and are markedly altered in response to LVAD support. These results suggest an important role for lncRNAs in the pathogenesis of heart failure and in reverse remodeling observed with mechanical support.

Junk DNA was long thought to have no important role in heredity or disease because it doesn’t code for proteins. But emerging research in recent years has revealed that many of these sections of the genome produce noncoding RNA molecules that still have important functions in the body. They come in a variety of forms, some more widely studied than others. Of these, about 90% are called long noncoding RNAs (lncRNAs), and exploration of their roles in health and disease is just beginning.

The Washington University group performed a comprehensive analysis of all RNA molecules expressed in the human heart. The researchers studied nonfailing hearts and failing hearts before and after patients received pump support from left ventricular assist devices (LVAD). The LVADs increased each heart’s pumping capacity while patients waited for heart transplants.

In their study, the researchers found that unlike other RNA molecules, expression patterns of long noncoding RNAs could distinguish between two major types of heart failure and between failing hearts before and after they received LVAD support.

“The myocardial transcriptome is dynamically regulated in advanced heart failure and after LVAD support. The expression profiles of lncRNAs, but not mRNAs or miRNAs, can discriminate failing hearts of different pathologies and are markedly altered in response to LVAD support,” wrote the researchers. “These results suggest an important role for lncRNAs in the pathogenesis of heart failure and in reverse remodeling observed with mechanical support.”

‘Junk’ Genome Regions Linked to Heart Failure

In a recent issue of the journal Circulation, Washington University investigators report results from the first comprehensive analysis of all RNA molecules expressed in the human heart. The researchers studied nonfailing hearts and failing hearts before and after patients received pump support from left ventricular assist devices (LVAD). The LVADs increased each heart’s pumping capacity while patients waited for heart transplants.

“We took an unbiased approach to investigating which types of RNA might be linked to heart failure,” said senior author Jeanne Nerbonne, the Alumni Endowed Professor of Molecular Biology and Pharmacology. “We were surprised to find that long noncoding RNAs stood out.

In the new study, the investigators found that unlike other RNA molecules, expression patterns of long noncoding RNAs could distinguish between two major types of heart failure and between failing hearts before and after they received LVAD support.

“We don’t know whether these changes in long noncoding RNAs are a cause or an effect of heart failure,” Nerbonne said. “But it seems likely they play some role in coordinating the regulation of multiple genes involved in heart function.”

Nerbonne pointed out that all types of RNA molecules they examined could make the obvious distinction: telling the difference between failing and nonfailing hearts. But only expression of the long noncoding RNAs was measurably different between heart failure associated with a heart attack (ischemic) and heart failure without the obvious trigger of blocked arteries (nonischemic). Similarly, only long noncoding RNAs significantly changed expression patterns after implantation of left ventricular assist devices.

Comment

Decoding the noncoding transcripts in human heart failure

Xiao XG, Touma M, Wang Y
Circulation. 2014; 129(9): 958960,  http://dx.doi.org/10.1161/CIRCULATIONAHA.114.007548 

Heart failure is a complex disease with a broad spectrum of pathological features. Despite significant advancement in clinical diagnosis through improved imaging modalities and hemodynamic approaches, reliable molecular signatures for better differential diagnosis and better monitoring of heart failure progression remain elusive. The few known clinical biomarkers for heart failure, such as plasma brain natriuretic peptide and troponin, have been shown to have limited use in defining the cause or prognosis of the disease.1,2 Consequently, current clinical identification and classification of heart failure remain descriptive, mostly based on functional and morphological parameters. Therefore, defining the pathogenic mechanisms for hypertrophic versus dilated or ischemic versus nonischemic cardiomyopathies in the failing heart remain a major challenge to both basic science and clinic researchers. In recent years, mechanical circulatory support using left ventricular assist devices (LVADs) has assumed a growing role in the care of patients with end-stage heart failure.3 During the earlier years of LVAD application as a bridge to transplant, it became evident that some patients exhibit substantial recovery of ventricular function, structure, and electric properties.4 This led to the recognition that reverse remodeling is potentially an achievable therapeutic goal using LVADs. However, the underlying mechanism for the reverse remodeling in the LVAD-treated hearts is unclear, and its discovery would likely hold great promise to halt or even reverse the progression of heart failure.

 

Efficacy and Safety of Dabigatran Compared With Warfarin in Relation to Baseline Renal Function in Patients With Atrial Fibrillation: A RE-LY (Randomized Evaluation of Long-term Anticoagulation Therapy) Trial Analysis

Circulation. 2014; 129: 951-952     http://dx.doi.org/10.1161/​CIR.0000000000000022

In patients with atrial fibrillation, impaired renal function is associated with a higher risk of thromboembolic events and major bleeding. Oral anticoagulation with vitamin K antagonists reduces thromboembolic events but raises the risk of bleeding. The new oral anticoagulant dabigatran has 80% renal elimination, and its efficacy and safety might, therefore, be related to renal function. In this prespecified analysis from the Randomized Evaluation of Long-Term Anticoagulant Therapy (RELY) trial, outcomes with dabigatran versus warfarin were evaluated in relation to 4 estimates of renal function, that is, equations based on creatinine levels (Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]) and cystatin C. The rates of stroke or systemic embolism were lower with dabigatran 150 mg and similar with 110 mg twice daily irrespective of renal function. Rates of major bleeding were lower with dabigatran 110 mg and similar with 150 mg twice daily across the entire range of renal function. However, when the CKD-EPI or MDRD equations were used, there was a significantly greater relative reduction in major bleeding with both doses of dabigatran than with warfarin in patients with estimated glomerular filtration rate ≥80 mL/min. These findings show that dabigatran can be used with the same efficacy and adequate safety in patients with a wide range of renal function and that a more accurate estimate of renal function might be useful for improved tailoring of anticoagulant treatment in patients with atrial fibrillation and an increased risk of stroke.

Aldosterone Regulates MicroRNAs in the Cortical Collecting Duct to Alter Sodium Transport.

Robert S Edinger, Claudia Coronnello, Andrew J Bodnar, William A Laframboise, Panayiotis V Benos, Jacqueline Ho, John P Johnson, Michael B Butterworth

Journal of the American Society of Nephrology (Impact Factor: 8.99). 04/2014;     http://dx. DO.org/I:10.1681/ASN.2013090931

Source: PubMed

ABSTRACT A role for microRNAs (miRs) in the physiologic regulation of sodium transport in the kidney has not been established. In this study, we investigated the potential of aldosterone to alter miR expression in mouse cortical collecting duct (mCCD) epithelial cells. Microarray studies demonstrated the regulation of miR expression by aldosterone in both cultured mCCD and isolated primary distal nephron principal cells.

Aldosterone regulation of the most significantly downregulated miRs, mmu-miR-335-3p, mmu-miR-290-5p, and mmu-miR-1983 was confirmed by quantitative RT-PCR. Reducing the expression of these miRs separately or in combination increased epithelial sodium channel (ENaC)-mediated sodium transport in mCCD cells, without mineralocorticoid supplementation. Artificially increasing the expression of these miRs by transfection with plasmid precursors or miR mimic constructs blunted aldosterone stimulation of ENaC transport.

Using a newly developed computational approach, termed ComiR, we predicted potential gene targets for the aldosterone-regulated miRs and confirmed ankyrin 3 (Ank3) as a novel aldosterone and miR-regulated protein.

A dual-luciferase assay demonstrated direct binding of the miRs with the Ank3-3′ untranslated region. Overexpression of Ank3 increased and depletion of Ank3 decreased ENaC-mediated sodium transport in mCCD cells. These findings implicate miRs as intermediaries in aldosterone signaling in principal cells of the distal kidney nephron.

 

2. Diagnostic Biomarker Status

A prospective study of the impact of serial troponin measurements on the diagnosis of myocardial infarction and hospital and 6-month mortality in patients admitted to ICU with non-cardiac diagnoses.

Marlies Ostermann, Jessica Lo, Michael Toolan, Emma Tuddenham, Barnaby Sanderson, Katie Lei, John Smith, Anna Griffiths, Ian Webb, James Coutts, John hambers, Paul Collinson, Janet Peacock, David Bennett, David Treacher

Critical care (London, England) (Impact Factor: 4.72). 04/2014; 18(2):R62.   http://dx.doi.org/:10.1186/cc13818

Source: PubMed

ABSTRACT Troponin T (cTnT) elevation is common in patients in the Intensive Care Unit (ICU) and associated with morbidity and mortality. Our aim was to determine the epidemiology of raised cTnT levels and contemporaneous electrocardiogram (ECG) changes suggesting myocardial infarction (MI) in ICU patients admitted for non-cardiac reasons.
cTnT and ECGs were recorded daily during week 1 and on alternate days during week 2 until discharge from ICU or death. ECGs were interpreted independently for the presence of ischaemic changes. Patients were classified into 4 groups: (i) definite MI (cTnT >=15 ng/L and contemporaneous changes of MI on ECG), (ii) possible MI (cTnT >=15 ng/L and contemporaneous ischaemic changes on ECG), (iii) troponin rise alone (cTnT >=15 ng/L), or (iv) normal. Medical notes were screened independently by two ICU clinicians for evidence that the clinical teams had considered a cardiac event.
Data from 144 patients were analysed [42% female; mean age 61.9 (SD 16.9)]. 121 patients (84%) had at least one cTnT level >=15 ng/L. A total of 20 patients (14%) had a definite MI, 27% had a possible MI, 43% had a cTNT rise without contemporaneous ECG changes, and 16% had no cTNT rise. ICU, hospital and 180 day mortality were significantly higher in patients with a definite or possible MI.Only 20% of definite MIs were recognised by the clinical team. There was no significant difference in mortality between recognised and non-recognised events.At time of cTNT rise, 100 patients (70%) were septic and 58% were on vasopressors. Patients who were septic when cTNT was elevated had an ICU mortality of 28% compared to 9% in patients without sepsis. ICU mortality of patients who were on vasopressors at time of cTNT elevation was 37% compared to 1.7% in patients not on vasopressors.
The majority of critically ill patients (84%) had a cTnT rise and 41% met criteria for a possible or definite MI of whom only 20% were recognised clinically. Mortality up to 180 days was higher in patients with a cTnT rise.

 

Prognostic performance of high-sensitivity cardiac troponin T kinetic changes adjusted for elevated admission values and the GRACE score in an unselected emergency department population.

Moritz BienerMatthias MuellerMehrshad VafaieAllan S JaffeHugo A Katus,Evangelos Giannitsis

Clinica chimica acta; international journal of clinical chemistry (Impact Factor: 2.54). 04/2014;   http://dx.doi.org/10.1016/j.cca.2014.04.007

Source: PubMed

ABSTRACT To test the prognostic performance of rising and falling kinetic changes of high-sensitivity cardiac troponin T (hs-cTnT) and the GRACE score.
Rising and falling hs-cTnT changes in an unselected emergency department population were compared.
635 patients with a hs-cTnT >99th percentile admission value were enrolled. Of these, 572 patients qualified for evaluation with rising patterns (n=254, 44.4%), falling patterns (n=224, 39.2%), or falling patterns following an initial rise (n=94, 16.4%). During 407days of follow-up, we observed 74 deaths, 17 recurrent AMI, and 79 subjects with a composite of death/AMI. Admission values >14ng/L were associated with a higher rate of adverse outcomes (OR, 95%CI:death:12.6, 1.8-92.1, p=0.01, death/AMI:6.7, 1.6-27.9, p=0.01). Neither rising nor falling changes increased the AUC of baseline values (AUC: rising 0.562 vs 0.561, p=ns, falling: 0.533 vs 0.575, p=ns). A GRACE score ≥140 points indicated a higher risk of death (OR, 95%CI: 3.14, 1.84-5.36), AMI (OR,95%CI: 1.56, 0.59-4.17), or death/AMI (OR, 95%CI: 2.49, 1.51-4.11). Hs-cTnT changes did not improve prognostic performance of a GRACE score ≥140 points (AUC, 95%CI: death: 0.635, 0.570-0.701 vs. 0.560, 0.470-0.649 p=ns, AMI: 0.555, 0.418-0.693 vs. 0.603, 0.424-0.782, p=ns, death/AMI: 0.610, 0.545-0.676 vs. 0.538, 0.454-0.622, p=ns). Coronary angiography was performed earlier in patients with rising than with falling kinetics (median, IQR [hours]:13.7, 5.5-28.0 vs. 20.8, 6.3-59.0, p=0.01).
Neither rising nor falling hs-cTnT changes improve prognostic performance of elevated hs-cTnT admission values or the GRACE score. However, rising values are more likely associated with the decision for earlier invasive strategy.

 

Troponin assays for the diagnosis of myocardial infarction and acute coronary syndrome: where do we stand?

Arie Eisenman

ABSTRACT: Under normal circumstances, most intracellular troponin is part of the muscle contractile apparatus, and only a small percentage (< 2-8%) is free in the cytoplasm. The presence of a cardiac-specific troponin in the circulation at levels above normal is good evidence of damage to cardiac muscle cells, such as myocardial infarction, myocarditis, trauma, unstable angina, cardiac surgery or other cardiac procedures. Troponins are released as complexes leading to various cut-off values depending on the assay used. This makes them very sensitive and specific indicators of cardiac injury. As with other cardiac markers, observation of a rise and fall in troponin levels in the appropriate time-frame increases the diagnostic specificity for acute myocardial infarction. They start to rise approximately 4-6 h after the onset of acute myocardial infarction and peak at approximately 24 h, as is the case with creatine kinase-MB. They remain elevated for 7-10 days giving a longer diagnostic window than creatine kinase. Although the diagnosis of various types of acute coronary syndrome remains a clinical-based diagnosis, the use of troponin levels contributes to their classification. This Editorial elaborates on the nature of troponin, its classification, clinical use and importance, as well as comparing it with other currently available cardiac markers.

Expert Review of Cardiovascular Therapy 07/2006; 4(4):509-14.   http://dx.doi.org/:10.1586/14779072.4.4.509 

 

Impact of redefining acute myocardial infarction on incidence, management and reimbursement rate of acute coronary syndromes.

Carísi A Polanczyk, Samir Schneid, Betina V Imhof, Mariana Furtado, Carolina Pithan, Luis E Rohde, Jorge P Ribeiro

ABSTRACT: Although redefinition for acute myocardial infarction (AMI) has been proposed few years ago, to date it has not been universally adopted by many institutions. The purpose of this study is to evaluate the diagnostic, prognostic and economical impact of the new diagnostic criteria for AMI. Patients consecutively admitted to the emergency department with suspected acute coronary syndromes were enrolled in this study. Troponin T (cTnT) was measured in samples collected for routine CK-MB analyses and results were not available to physicians. Patients without AMI by traditional criteria and cTnT > or = 0.035 ng/mL were coded as redefined AMI. Clinical outcomes were hospital death, major cardiac events and revascularization procedures. In-hospital management and reimbursement rates were also analyzed. Among 363 patients, 59 (16%) patients had AMI by conventional criteria, whereas additional 75 (21%) had redefined AMI, an increase of 127% in the incidence. Patients with redefined AMI were significantly older, more frequently male, with atypical chest pain and more risk factors. In multivariate analysis, redefined AMI was associated with 3.1 fold higher hospital death (95% CI: 0.6-14) and a 5.6 fold more cardiac events (95% CI: 2.1-15) compared to those without AMI. From hospital perspective, based on DRGs payment system, adoption of AMI redefinition would increase 12% the reimbursement rate [3552 Int dollars per 100 patients evaluated]. The redefined criteria result in a substantial increase in AMI cases, and allow identification of high-risk patients. Efforts should be made to reinforce the adoption of AMI redefinition, which may result in more qualified and efficient management of ACS.

International Journal of Cardiology 03/2006; 107(2):180-7. · 5.51 Impact Factor   http://www.sciencedirect.com/science/article/pii/S0167527305005279

 

3. Biomedical Engineerin3g

Safety and Efficacy of an Injectable Extracellular Matrix Hydrogel for Treating Myocardial Infarction 

Sonya B. Seif-Naraghi, Jennifer M. Singelyn, Michael A. Salvatore,  et al.
Sci Transl Med 20 February 2013 5:173ra25  http://dx.doi.org/10.1126/scitranslmed.3005503

Acellular biomaterials can stimulate the local environment to repair tissues without the regulatory and scientific challenges of cell-based therapies. A greater understanding of the mechanisms of such endogenous tissue repair is furthering the design and application of these biomaterials. We discuss recent progress in acellular materials for tissue repair, using cartilage and cardiac tissues as examples of application with substantial intrinsic hurdles, but where human translation is now occurring.

 Acellular Biomaterials: An Evolving Alternative to Cell-Based Therapies

J. A. Burdick, R. L. Mauck, J. H. Gorman, R. C. Gorman,
Sci. Transl. Med. 2013; 5, (176): 176 ps4    http://stm.sciencemag.org/content/5/176/176ps4

Acellular biomaterials can stimulate the local environment to repair tissues without the regulatory and scientific challenges of cell-based therapies. A greater understanding of the mechanisms of such endogenous tissue repair is furthering the design and application of these biomaterials. We discuss recent progress in acellular materials for tissue repair, using cartilage and cardiac tissues as examples of applications with substantial intrinsic hurdles, but where human translation is now occurring.


Instructive Nanofiber Scaffolds with VEGF Create a Microenvironment for Arteriogenesis and Cardiac Repair

Yi-Dong Lin, Chwan-Yau Luo, Yu-Ning Hu, Ming-Long Yeh, Ying-Chang Hsueh, Min-Yao Chang, et al.
Sci Transl Med 8 August 2012; 4(146):ra109.   http://dx.doi.org/ 10.1126/scitranslmed.3003841

Angiogenic therapy is a promising approach for tissue repair and regeneration. However, recent clinical trials with protein delivery or gene therapy to promote angiogenesis have failed to provide therapeutic effects. A key factor for achieving effective revascularization is the durability of the microvasculature and the formation of new arterial vessels. Accordingly, we carried out experiments to test whether intramyocardial injection of self-assembling peptide nanofibers (NFs) combined with vascular endothelial growth factor (VEGF) could create an intramyocardial microenvironment with prolonged VEGF release to improve post-infarct neovascularization in rats. Our data showed that when injected with NF, VEGF delivery was sustained within the myocardium for up to 14 days, and the side effects of systemic edema and proteinuria were significantly reduced to the same level as that of control. NF/VEGF injection significantly improved angiogenesis, arteriogenesis, and cardiac performance 28 days after myocardial infarction. NF/VEGF injection not only allowed controlled local delivery but also transformed the injected site into a favorable microenvironment that recruited endogenous myofibroblasts and helped achieve effective revascularization. The engineered vascular niche further attracted a new population of cardiomyocyte-like cells to home to the injected sites, suggesting cardiomyocyte regeneration. Follow-up studies in pigs also revealed healing benefits consistent with observations in rats. In summary, this study demonstrates a new strategy for cardiovascular repair with potential for future clinical translation.

Manufacturing Challenges in Regenerative Medicine

I. Martin, P. J. Simmons, D. F. Williams.
Sci. Transl. Med. 2014; 6(232): fs16.   http://dx.doi.org/10.1126/scitranslmed.3008558

Along with scientific and regulatory issues, the translation of cell and tissue therapies in the routine clinical practice needs to address standardization and cost-effectiveness through the definition of suitable manufacturing paradigms.

 

 

 

Read Full Post »

Summary of Translational Medicine – e-Series A: Cardiovascular Diseases, Volume Four – Part 1


Summary of Translational Medicine – e-Series A: Cardiovascular Diseases, Volume Four – Part 1

Author and Curator: Larry H Bernstein, MD, FCAP

and

Curator: Aviva Lev-Ari, PhD, RN

 

Part 1 of Volume 4 in the e-series A: Cardiovascular Diseases and Translational Medicine, provides a foundation for grasping a rapidly developing surging scientific endeavor that is transcending laboratory hypothesis testing and providing guidelines to:

  • Target genomes and multiple nucleotide sequences involved in either coding or in regulation that might have an impact on complex diseases, not necessarily genetic in nature.
  • Target signaling pathways that are demonstrably maladjusted, activated or suppressed in many common and complex diseases, or in their progression.
  • Enable a reduction in failure due to toxicities in the later stages of clinical drug trials as a result of this science-based understanding.
  • Enable a reduction in complications from the improvement of machanical devices that have already had an impact on the practice of interventional procedures in cardiology, cardiac surgery, and radiological imaging, as well as improving laboratory diagnostics at the molecular level.
  • Enable the discovery of new drugs in the continuing emergence of drug resistance.
  • Enable the construction of critical pathways and better guidelines for patient management based on population outcomes data, that will be critically dependent on computational methods and large data-bases.

What has been presented can be essentially viewed in the following Table:

 

Summary Table for TM - Part 1

Summary Table for TM – Part 1

 

 

 

There are some developments that deserve additional development:

1. The importance of mitochondrial function in the activity state of the mitochondria in cellular work (combustion) is understood, and impairments of function are identified in diseases of muscle, cardiac contraction, nerve conduction, ion transport, water balance, and the cytoskeleton – beyond the disordered metabolism in cancer.  A more detailed explanation of the energetics that was elucidated based on the electron transport chain might also be in order.

2. The processes that are enabling a more full application of technology to a host of problems in the environment we live in and in disease modification is growing rapidly, and will change the face of medicine and its allied health sciences.

 

Electron Transport and Bioenergetics

Deferred for metabolomics topic

Synthetic Biology

Introduction to Synthetic Biology and Metabolic Engineering

Kristala L. J. Prather: Part-1    <iBiology > iBioSeminars > Biophysics & Chemical Biology >

http://www.ibiology.org Lecturers generously donate their time to prepare these lectures. The project is funded by NSF and NIGMS, and is supported by the ASCB and HHMI.
Dr. Prather explains that synthetic biology involves applying engineering principles to biological systems to build “biological machines”.

Dr. Prather has received numerous awards both for her innovative research and for excellence in teaching.  Learn more about how Kris became a scientist at
Prather 1: Synthetic Biology and Metabolic Engineering  2/6/14IntroductionLecture Overview In the first part of her lecture, Dr. Prather explains that synthetic biology involves applying engineering principles to biological systems to build “biological machines”. The key material in building these machines is synthetic DNA. Synthetic DNA can be added in different combinations to biological hosts, such as bacteria, turning them into chemical factories that can produce small molecules of choice. In Part 2, Prather describes how her lab used design principles to engineer E. coli that produce glucaric acid from glucose. Glucaric acid is not naturally produced in bacteria, so Prather and her colleagues “bioprospected” enzymes from other organisms and expressed them in E. coli to build the needed enzymatic pathway. Prather walks us through the many steps of optimizing the timing, localization and levels of enzyme expression to produce the greatest yield. Speaker Bio: Kristala Jones Prather received her S.B. degree from the Massachusetts Institute of Technology and her PhD at the University of California, Berkeley both in chemical engineering. Upon graduation, Prather joined the Merck Research Labs for 4 years before returning to academia. Prather is now an Associate Professor of Chemical Engineering at MIT and an investigator with the multi-university Synthetic Biology Engineering Reseach Center (SynBERC). Her lab designs and constructs novel synthetic pathways in microorganisms converting them into tiny factories for the production of small molecules. Dr. Prather has received numerous awards both for her innovative research and for excellence in teaching.

VIEW VIDEOS

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk#t=0

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk#t=12

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk#t=74

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk#t=129

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk#t=168

https://www.youtube.com/watch?feature=player_embedded&v=ndThuqVumAk

 

II. Regulatory Effects of Mammalian microRNAs

Calcium Cycling in Synthetic and Contractile Phasic or Tonic Vascular Smooth Muscle Cells

in INTECH
Current Basic and Pathological Approaches to
the Function of Muscle Cells and Tissues – From Molecules to HumansLarissa Lipskaia, Isabelle Limon, Regis Bobe and Roger Hajjar
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/48240
1. Introduction
Calcium ions (Ca ) are present in low concentrations in the cytosol (~100 nM) and in high concentrations (in mM range) in both the extracellular medium and intracellular stores (mainly sarco/endo/plasmic reticulum, SR). This differential allows the calcium ion messenger that carries information
as diverse as contraction, metabolism, apoptosis, proliferation and/or hypertrophic growth. The mechanisms responsible for generating a Ca signal greatly differ from one cell type to another.
In the different types of vascular smooth muscle cells (VSMC), enormous variations do exist with regard to the mechanisms responsible for generating Ca signal. In each VSMC phenotype (synthetic/proliferating and contractile [1], tonic or phasic), the Ca signaling system is adapted to its particular function and is due to the specific patterns of expression and regulation of Ca.
For instance, in contractile VSMCs, the initiation of contractile events is driven by mem- brane depolarization; and the principal entry-point for extracellular Ca is the voltage-operated L-type calcium channel (LTCC). In contrast, in synthetic/proliferating VSMCs, the principal way-in for extracellular Ca is the store-operated calcium (SOC) channel.
Whatever the cell type, the calcium signal consists of  limited elevations of cytosolic free calcium ions in time and space. The calcium pump, sarco/endoplasmic reticulum Ca ATPase (SERCA), has a critical role in determining the frequency of SR Ca release by upload into the sarcoplasmic
sensitivity of  SR calcium channels, Ryanodin Receptor, RyR and Inositol tri-Phosphate Receptor, IP3R.
Synthetic VSMCs have a fibroblast appearance, proliferate readily, and synthesize increased levels of various extracellular matrix components, particularly fibronectin, collagen types I and III, and tropoelastin [1].
Contractile VSMCs have a muscle-like or spindle-shaped appearance and well-developed contractile apparatus resulting from the expression and intracellular accumulation of thick and thin muscle filaments [1].
Schematic representation of Calcium Cycling in Contractile and Proliferating VSMCs

Schematic representation of Calcium Cycling in Contractile and Proliferating VSMCs

 

Figure 1. Schematic representation of Calcium Cycling in Contractile and Proliferating VSMCs.

Left panel: schematic representation of calcium cycling in quiescent /contractile VSMCs. Contractile re-sponse is initiated by extracellular Ca influx due to activation of Receptor Operated Ca (through phosphoinositol-coupled receptor) or to activation of L-Type Calcium channels (through an increase in luminal pressure). Small increase of cytosolic due IP3 binding to IP3R (puff) or RyR activation by LTCC or ROC-dependent Ca influx leads to large SR Ca IP3R or RyR clusters (“Ca -induced Ca SR calcium pumps (both SERCA2a and SERCA2b are expressed in quiescent VSMCs), maintaining high concentration of cytosolic Ca and setting the sensitivity of RyR or IP3R for the next spike.
Contraction of VSMCs occurs during oscillatory Ca transient.
Middle panel: schematic representa tion of atherosclerotic vessel wall. Contractile VSMC are located in the media layer, synthetic VSMC are located in sub-endothelial intima.
Right panel: schematic representation of calcium cycling in quiescent /contractile VSMCs. Agonist binding to phosphoinositol-coupled receptor leads to the activation of IP3R resulting in large increase in cytosolic Ca calcium pumps (only SERCA2b, having low turnover and low affinity to Ca depletion leads to translocation of SR Ca sensor STIM1 towards PM, resulting in extracellular Ca influx though opening of Store Operated Channel (CRAC). Resulted steady state Ca transient is critical for activation of proliferation-related transcription factors ‘NFAT).
Abbreviations: PLC – phospholipase C; PM – plasma membrane; PP2B – Ca /calmodulin-activated protein phosphatase 2B (calcineurin); ROC- receptor activated channel; IP3 – inositol-1,4,5-trisphosphate, IP3R – inositol-1,4,5- trisphosphate receptor; RyR – ryanodine receptor; NFAT – nuclear factor of activated T-lymphocytes; VSMC – vascular smooth muscle cells; SERCA – sarco(endo)plasmic reticulum Ca sarcoplasmic reticulum.

 

Time for New DNA Synthesis and Sequencing Cost Curves

By Rob Carlson

I’ll start with the productivity plot, as this one isn’t new. For a discussion of the substantial performance increase in sequencing compared to Moore’s Law, as well as the difficulty of finding this data, please see this post. If nothing else, keep two features of the plot in mind: 1) the consistency of the pace of Moore’s Law and 2) the inconsistency and pace of sequencing productivity. Illumina appears to be the primary driver, and beneficiary, of improvements in productivity at the moment, especially if you are looking at share prices. It looks like the recently announced NextSeq and Hiseq instruments will provide substantially higher productivities (hand waving, I would say the next datum will come in another order of magnitude higher), but I think I need a bit more data before officially putting another point on the plot.

 

cost-of-oligo-and-gene-synthesis

cost-of-oligo-and-gene-synthesis

Illumina’s instruments are now responsible for such a high percentage of sequencing output that the company is effectively setting prices for the entire industry. Illumina is being pushed by competition to increase performance, but this does not necessarily translate into lower prices. It doesn’t behoove Illumina to drop prices at this point, and we won’t see any substantial decrease until a serious competitor shows up and starts threatening Illumina’s market share. The absence of real competition is the primary reason sequencing prices have flattened out over the last couple of data points.

Note that the oligo prices above are for column-based synthesis, and that oligos synthesized on arrays are much less expensive. However, array synthesis comes with the usual caveat that the quality is generally lower, unless you are getting your DNA from Agilent, which probably means you are getting your dsDNA from Gen9.

Note also that the distinction between the price of oligos and the price of double-stranded sDNA is becoming less useful. Whether you are ordering from Life/Thermo or from your local academic facility, the cost of producing oligos is now, in most cases, independent of their length. That’s because the cost of capital (including rent, insurance, labor, etc) is now more significant than the cost of goods. Consequently, the price reflects the cost of capital rather than the cost of goods. Moreover, the cost of the columns, reagents, and shipping tubes is certainly more than the cost of the atoms in the sDNA you are ostensibly paying for. Once you get into longer oligos (substantially larger than 50-mers) this relationship breaks down and the sDNA is more expensive. But, at this point in time, most people aren’t going to use longer oligos to assemble genes unless they have a tricky job that doesn’t work using short oligos.

Looking forward, I suspect oligos aren’t going to get much cheaper unless someone sorts out how to either 1) replace the requisite human labor and thereby reduce the cost of capital, or 2) finally replace the phosphoramidite chemistry that the industry relies upon.

IDT’s gBlocks come at prices that are constant across quite substantial ranges in length. Moreover, part of the decrease in price for these products is embedded in the fact that you are buying smaller chunks of DNA that you then must assemble and integrate into your organism of choice.

Someone who has purchased and assembled an absolutely enormous amount of sDNA over the last decade, suggested that if prices fell by another order of magnitude, he could switch completely to outsourced assembly. This is a potentially interesting “tipping point”. However, what this person really needs is sDNA integrated in a particular way into a particular genome operating in a particular host. The integration and testing of the new genome in the host organism is where most of the cost is. Given the wide variety of emerging applications, and the growing array of hosts/chassis, it isn’t clear that any given technology or firm will be able to provide arbitrary synthetic sequences incorporated into arbitrary hosts.

 TrackBack URL: http://www.synthesis.cc/cgi-bin/mt/mt-t.cgi/397

 

Startup to Strengthen Synthetic Biology and Regenerative Medicine Industries with Cutting Edge Cell Products

28 Nov 2013 | PR Web

Dr. Jon Rowley and Dr. Uplaksh Kumar, Co-Founders of RoosterBio, Inc., a newly formed biotech startup located in Frederick, are paving the way for even more innovation in the rapidly growing fields of Synthetic Biology and Regenerative Medicine. Synthetic Biology combines engineering principles with basic science to build biological products, including regenerative medicines and cellular therapies. Regenerative medicine is a broad definition for innovative medical therapies that will enable the body to repair, replace, restore and regenerate damaged or diseased cells, tissues and organs. Regenerative therapies that are in clinical trials today may enable repair of damaged heart muscle following heart attack, replacement of skin for burn victims, restoration of movement after spinal cord injury, regeneration of pancreatic tissue for insulin production in diabetics and provide new treatments for Parkinson’s and Alzheimer’s diseases, to name just a few applications.

While the potential of the field is promising, the pace of development has been slow. One main reason for this is that the living cells required for these therapies are cost-prohibitive and not supplied at volumes that support many research and product development efforts. RoosterBio will manufacture large quantities of standardized primary cells at high quality and low cost, which will quicken the pace of scientific discovery and translation to the clinic. “Our goal is to accelerate the development of products that incorporate living cells by providing abundant, affordable and high quality materials to researchers that are developing and commercializing these regenerative technologies” says Dr. Rowley

 

Life at the Speed of Light

http://kcpw.org/?powerpress_pinw=92027-podcast

NHMU Lecture featuring – J. Craig Venter, Ph.D.
Founder, Chairman, and CEO – J. Craig Venter Institute; Co-Founder and CEO, Synthetic Genomics Inc.

J. Craig Venter, Ph.D., is Founder, Chairman, and CEO of the J. Craig Venter Institute (JVCI), a not-for-profit, research organization dedicated to human, microbial, plant, synthetic and environmental research. He is also Co-Founder and CEO of Synthetic Genomics Inc. (SGI), a privately-held company dedicated to commercializing genomic-driven solutions to address global needs.

In 1998, Dr. Venter founded Celera Genomics to sequence the human genome using new tools and techniques he and his team developed.  This research culminated with the February 2001 publication of the human genome in the journal, Science. Dr. Venter and his team at JVCI continue to blaze new trails in genomics.  They have sequenced and a created a bacterial cell constructed with synthetic DNA,  putting humankind at the threshold of a new phase of biological research.  Whereas, we could  previously read the genetic code (sequencing genomes), we can now write the genetic code for designing new species.

The science of synthetic genomics will have a profound impact on society, including new methods for chemical and energy production, human health and medical advances, clean water, and new food and nutritional products. One of the most prolific scientists of the 21st century for his numerous pioneering advances in genomics,  he  guides us through this emerging field, detailing its origins, current challenges, and the potential positive advances.

His work on synthetic biology truly embodies the theme of “pushing the boundaries of life.”  Essentially, Venter is seeking to “write the software of life” to create microbes designed by humans rather than only through evolution. The potential benefits and risks of this new technology are enormous. It also requires us to examine, both scientifically and philosophically, the question of “What is life?”

J Craig Venter wants to digitize DNA and transmit the signal to teleport organisms

https://pharmaceuticalintelligence.com/2013/11/01/j-craig-venter-wants-to-digitize-dna-and-transmit-the-signal-to-teleport-organisms/

2013 Genomics: The Era Beyond the Sequencing of the Human Genome: Francis Collins, Craig Venter, Eric Lander, et al.

https://pharmaceuticalintelligence.com/2013/02/11/2013-genomics-the-era-beyond-the-sequencing-human-genome-francis-collins-craig-venter-eric-lander-et-al/

Human Longevity Inc (HLI) – $70M in Financing of Venter’s New Integrative Omics and Clinical Bioinformatics

https://pharmaceuticalintelligence.com/2014/03/05/human-longevity-inc-hli-70m-in-financing-of-venters-new-integrative-omics-and-clinical-bioinformatics/

 

 

Where Will the Century of Biology Lead Us?

By Randall Mayes

A technology trend analyst offers an overview of synthetic biology, its potential applications, obstacles to its development, and prospects for public approval.

  • In addition to boosting the economy, synthetic biology projects currently in development could have profound implications for the future of manufacturing, sustainability, and medicine.
  • Before society can fully reap the benefits of synthetic biology, however, the field requires development and faces a series of hurdles in the process. Do researchers have the scientific know-how and technical capabilities to develop the field?

Biology + Engineering = Synthetic Biology

Bioengineers aim to build synthetic biological systems using compatible standardized parts that behave predictably. Bioengineers synthesize DNA parts—oligonucleotides composed of 50–100 base pairs—which make specialized components that ultimately make a biological system. As biology becomes a true engineering discipline, bioengineers will create genomes using mass-produced modular units similar to the microelectronics and computer industries.

Currently, bioengineering projects cost millions of dollars and take years to develop products. For synthetic biology to become a Schumpeterian revolution, smaller companies will need to be able to afford to use bioengineering concepts for industrial applications. This will require standardized and automated processes.

A major challenge to developing synthetic biology is the complexity of biological systems. When bioengineers assemble synthetic parts, they must prevent cross talk between signals in other biological pathways. Until researchers better understand these undesired interactions that nature has already worked out, applications such as gene therapy will have unwanted side effects. Scientists do not fully understand the effects of environmental and developmental interaction on gene expression. Currently, bioengineers must repeatedly use trial and error to create predictable systems.

Similar to physics, synthetic biology requires the ability to model systems and quantify relationships between variables in biological systems at the molecular level.

The second major challenge to ensuring the success of synthetic biology is the development of enabling technologies. With genomes having billions of nucleotides, this requires fast, powerful, and cost-efficient computers. Moore’s law, named for Intel co-founder Gordon Moore, posits that computing power progresses at a predictable rate and that the number of components in integrated circuits doubles each year until its limits are reached. Since Moore’s prediction, computer power has increased at an exponential rate while pricing has declined.

DNA sequencers and synthesizers are necessary to identify genes and make synthetic DNA sequences. Bioengineer Robert Carlson calculated that the capabilities of DNA sequencers and synthesizers have followed a pattern similar to computing. This pattern, referred to as the Carlson Curve, projects that scientists are approaching the ability to sequence a human genome for $1,000, perhaps in 2020. Carlson calculated that the costs of reading and writing new genes and genomes are falling by a factor of two every 18–24 months. (see recent Carlson comment on requirement to read and write for a variety of limiting  conditions).

Startup to Strengthen Synthetic Biology and Regenerative Medicine Industries with Cutting Edge Cell Products

https://pharmaceuticalintelligence.com/2013/11/28/startup-to-strengthen-synthetic-biology-and-regenerative-medicine-industries-with-cutting-edge-cell-products/

Synthetic Biology: On Advanced Genome Interpretation for Gene Variants and Pathways: What is the Genetic Base of Atherosclerosis and Loss of Arterial Elasticity with Aging

https://pharmaceuticalintelligence.com/2013/05/17/synthetic-biology-on-advanced-genome-interpretation-for-gene-variants-and-pathways-what-is-the-genetic-base-of-atherosclerosis-and-loss-of-arterial-elasticity-with-aging/

Synthesizing Synthetic Biology: PLOS Collections

https://pharmaceuticalintelligence.com/2012/08/17/synthesizing-synthetic-biology-plos-collections/

Capturing ten-color ultrasharp images of synthetic DNA structures resembling numerals 0 to 9

https://pharmaceuticalintelligence.com/2014/02/05/capturing-ten-color-ultrasharp-images-of-synthetic-dna-structures-resembling-numerals-0-to-9/

Silencing Cancers with Synthetic siRNAs

https://pharmaceuticalintelligence.com/2013/12/09/silencing-cancers-with-synthetic-sirnas/

Genomics Now—and Beyond the Bubble

Futurists have touted the twenty-first century as the century of biology based primarily on the promise of genomics. Medical researchers aim to use variations within genes as biomarkers for diseases, personalized treatments, and drug responses. Currently, we are experiencing a genomics bubble, but with advances in understanding biological complexity and the development of enabling technologies, synthetic biology is reviving optimism in many fields, particularly medicine.

BY MICHAEL BROOKS    17 APR, 2014     http://www.newstatesman.com/

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is The Secret Anarchy of Science.

The basic idea is that we take an organism – a bacterium, say – and re-engineer its genome so that it does something different. You might, for instance, make it ingest carbon dioxide from the atmosphere, process it and excrete crude oil.

That project is still under construction, but others, such as using synthesised DNA for data storage, have already been achieved. As evolution has proved, DNA is an extraordinarily stable medium that can preserve information for millions of years. In 2012, the Harvard geneticist George Church proved its potential by taking a book he had written, encoding it in a synthesised strand of DNA, and then making DNA sequencing machines read it back to him.

When we first started achieving such things it was costly and time-consuming and demanded extraordinary resources, such as those available to the millionaire biologist Craig Venter. Venter’s team spent most of the past two decades and tens of millions of dollars creating the first artificial organism, nicknamed “Synthia”. Using computer programs and robots that process the necessary chemicals, the team rebuilt the genome of the bacterium Mycoplasma mycoides from scratch. They also inserted a few watermarks and puzzles into the DNA sequence, partly as an identifying measure for safety’s sake, but mostly as a publicity stunt.

What they didn’t do was redesign the genome to do anything interesting. When the synthetic genome was inserted into an eviscerated bacterial cell, the new organism behaved exactly the same as its natural counterpart. Nevertheless, that Synthia, as Venter put it at the press conference to announce the research in 2010, was “the first self-replicating species we’ve had on the planet whose parent is a computer” made it a standout achievement.

Today, however, we have entered another era in synthetic biology and Venter faces stiff competition. The Steve Jobs to Venter’s Bill Gates is Jef Boeke, who researches yeast genetics at New York University.

Boeke wanted to redesign the yeast genome so that he could strip out various parts to see what they did. Because it took a private company a year to complete just a small part of the task, at a cost of $50,000, he realised he should go open-source. By teaching an undergraduate course on how to build a genome and teaming up with institutions all over the world, he has assembled a skilled workforce that, tinkering together, has made a synthetic chromosome for baker’s yeast.

 

Stepping into DIYbio and Synthetic Biology at ScienceHack

Posted April 22, 2014 by Heather McGaw and Kyrie Vala-Webb

We got a crash course on genetics and protein pathways, and then set out to design and build our own pathways using both the “Genomikon: Violacein Factory” kit and Synbiota platform. With Synbiota’s software, we dragged and dropped the enzymes to create the sequence that we were then going to build out. After a process of sketching ideas, mocking up pathways, and writing hypotheses, we were ready to start building!

The night stretched long, and at midnight we were forced to vacate the school. Not quite finished, we loaded our delicate bacteria, incubator, and boxes of gloves onto the bus and headed back to complete our bacterial transformation in one of our hotel rooms. Jammed in between the beds and the mini-fridge, we heat-shocked our bacteria in the hotel ice bucket. It was a surreal moment.

While waiting for our bacteria, we held an “unconference” where we explored bioethics, security and risk related to synthetic biology, 3D printing on Mars, patterns in juggling (with live demonstration!), and even did a Google Hangout with Rob Carlson. Every few hours, we would excitedly check in on our bacteria, looking for bacterial colonies and the purple hue characteristic of violacein.

Most impressive was the wildly successful and seamless integration of a diverse set of people: in a matter of hours, we were transformed from individual experts and practitioners in assorted fields into cohesive and passionate teams of DIY biologists and science hackers. The ability of everyone to connect and learn was a powerful experience, and over the course of just one weekend we were able to challenge each other and grow.

Returning to work on Monday, we were hungry for more. We wanted to find a way to bring the excitement and energy from the weekend into the studio and into the projects we’re working on. It struck us that there are strong parallels between design and DIYbio, and we knew there was an opportunity to bring some of the scientific approaches and curiosity into our studio.

 

 

Read Full Post »


Regeneration: Cardiac System (cardiomyogenesis) and Vasculature (angiogenesis)

Author and Curator: Aviva Lev-Ari, PhD, RN

 

UPDATED on 4/8/2014

Stem-Cell Therapy for Ischemic Heart Failure: Clinical Trial MSC Demonstrates Efficacy

https://pharmaceuticalintelligence.com/2014/04/08/stem-cell-therapy-for-ischemic-heart-failure-clinical-trial-msc-demonstrates-efficacy/ 

This article represents the FRONTIER on Cardiac Regeneration as developed by Anthony Rosenzweig in Science 338, 1549 (2012).

Point #1: Current Pharmacotherapy for Cardiovascular Diseases and Heart Failure

Point #2: Dynamic model for the Adult heart capacity for cardiomyogenesis to compensate for losses occurring in heart failure: recognition of even limited regenerative capacity in the heart 

Point #3: Results of Multiple Cell Therapy Clinical Trials

Point #4:  The Endogenous Regeneration Potential

Point #5: On pathways regulating cardiomyocyte regeneration in animal models

Point #6: Prof. A. Rosenzweig’s Summary and His Future Outlook of Cardiac Regeneration

This article represents a continuation of the following articles on this topic that were published in this Open Access Online Scientific Journal:

Bernstein HL and A. Lev-Ari 1/14/2014 Circulating Endothelial Progenitors Cells (cEPCs) as Biomarkers

https://pharmaceuticalintelligence.com/2014/01/14/circulating-endothelial-progenitors-cells-as-biomarkers/

Lev-Ari, A. 2/28/2013 The Heart: Vasculature Protection – A Concept-based Pharmacological Therapy including THYMOSIN

https://pharmaceuticalintelligence.com/2013/02/28/the-heart-vasculature-protection-a-concept-based-pharmacological-therapy-including-thymosin/

Lev-Ari, A. 2/27/2013 Arteriogenesis and Cardiac Repair: Two Biomaterials – Injectable Thymosin beta4 and Myocardial Matrix Hydrogel

https://pharmaceuticalintelligence.com/2013/02/27/arteriogenesis-and-cardiac-repair-two-biomaterials-injectable-thymosin-beta4-and-myocardial-matrix-hydrogel/

Lev-Ari, A. 11/13/2012 Peroxisome proliferator-activated receptor (PPAR-gamma) Receptors Activation: PPARγ transrepression for Angiogenesis in Cardiovascular Disease and PPARγ transactivation for Treatment of Diabetes

https://pharmaceuticalintelligence.com/2012/11/13/peroxisome-proliferator-activated-receptor-ppar-gamma-receptors-activation-pparγ-transrepression-for-angiogenesis-in-cardiovascular-disease-and-pparγ-transactivation-for-treatment-of-dia/

Lev-Ari, A. 8/29/2012 Positioning a Therapeutic Concept for Endogenous Augmentation of cEPCs — Therapeutic Indications for Macrovascular Disease: Coronary, Cerebrovascular and Peripheral

https://pharmaceuticalintelligence.com/2012/08/29/positioning-a-therapeutic-concept-for-endogenous-augmentation-of-cepcs-therapeutic-indications-for-macrovascular-disease-coronary-cerebrovascular-and-peripheral/

Lev-Ari, A. 8/28/2012 Cardiovascular Outcomes: Function of circulating Endothelial Progenitor Cells (cEPCs): Exploring Pharmaco-therapy targeted at Endogenous Augmentation of cEPCs

https://pharmaceuticalintelligence.com/2012/08/28/cardiovascular-outcomes-function-of-circulating-endothelial-progenitor-cells-cepcs-exploring-pharmaco-therapy-targeted-at-endogenous-augmentation-of-cepcs/

Lev-Ari, A. 8/27/2012 Endothelial Dysfunction, Diminished Availability of cEPCs, Increasing CVD Risk for Macrovascular Disease – Therapeutic Potential of cEPCs

https://pharmaceuticalintelligence.com/2012/08/27/endothelial-dysfunction-diminished-availability-of-cepcs-increasing-cvd-risk-for-macrovascular-disease-therapeutic-potential-of-cepcs/

Lev-Ari, A. 8/24/2012 Vascular Medicine and Biology: CLASSIFICATION OF FAST ACTING THERAPY FOR PATIENTS AT HIGH RISK FOR MACROVASCULAR EVENTS Macrovascular Disease – Therapeutic Potential of cEPCs

https://pharmaceuticalintelligence.com/2012/08/24/vascular-medicine-and-biology-classification-of-fast-acting-therapy-for-patients-at-high-risk-for-macrovascular-events-macrovascular-disease-therapeutic-potential-of-cepcs/

Lev-Ari, A. 7/19/2012 Cardiovascular Disease (CVD) and the Role of agent alternatives in endothelial Nitric Oxide Synthase (eNOS) Activation and Nitric Oxide Production

https://pharmaceuticalintelligence.com/2012/07/19/cardiovascular-disease-cvd-and-the-role-of-agent-alternatives-in-endothelial-nitric-oxide-synthase-enos-activation-and-nitric-oxide-production/

Lev-Ari, A. 4/30/2012 Resident-cell-based Therapy in Human Ischaemic Heart Disease: Evolution in the PROMISE of Thymosin beta4 for Cardiac Repair

https://pharmaceuticalintelligence.com/2012/04/30/93/

Lev-Ari, A. 7/2/2012 Macrovascular Disease – Therapeutic Potential of cEPCs: Reduction Methods for CV Risk

https://pharmaceuticalintelligence.com/2012/07/02/macrovascular-disease-therapeutic-potential-of-cepcs-reduction-methods-for-cv-risk/

This article represent the FRONTIER on Cardiac Regeneration as developed by Anthony Rosenzweig in Science 338, 1549 (2012).

Prof. A. Rosenzweig is with the Cardiovascular Division at Beth Israel Deaconess Medical Center, Harvard Medical School, and the Harvard Stem Cell Institute, Boston, MA 02215, USA. E-mail: arosenzw@bidmc.harvard.edu

In the United States, heart failure afflicts about 6 million people (1), costs $34.4 billion each year (2), and is now the single most common discharge diagnosis in those over 65 (3). Although enormous progress has been made in managing acute cardiovascular illnesses such as heart attacks, many patients go on to develop late sequelae of their disease, including heart failure and arrhythmia. Thus, the growing number of these patients in some ways represents a burden of our success. It also reflects the incomplete success of most current therapies, which mitigate and manage but do not cure the disease.

Point #1: Current Pharmacotherapy for Cardiovascular Diseases and Heart Failure include:

  • Beta-blockers
  • Angiotensin-converting enzyme inhibitors, and
  • Mineralocorticoid antagonists – in congestive heart failure, they are used in addition to other drugs for additive diuretic effect, which reduces edema and the cardiac workload, and Potassium-sparing diuretics are diuretic drugs that do not promote the secretion of potassium into the urine

These medicines block pathways that are likely compensatory initially but become progressively more maladaptive, thus, prognosis and quality of life remain poor for many heart failure patients.

Point #2: Dynamic model for the Adult heart capacity for cardiomyogenesis to compensate for losses occurring in heart failure: recognition of even limited regenerative capacity in the heart

  • The heart has some endogenous regenerative potential
  • New cardiomyocytes may arise from existing cardiomyocytes  and from
  • Progenitor or stem cells

Point #3: Results of Multiple Cell Therapy Clinical Trials

  • the largest randomized trial thus far— the REPAIR-AMI trial which delivered unfractionated bone marrow cells (BMCs) to patients after a heart attack—as well as
  • a recent meta-analysis of 50 similar trials enrolling 2625 patients (16) suggest that adverse clinical events may actually be less common in BMC-treated patients
  • Autologous BMCs are by far the most common cells used to date but have yielded mixed results. Two recent trials report results with heart-derived donor cells are summariezed, below.  Although both of these studies break new conceptual ground, it is still too early to know how these approaches will hold up in larger studies or impact clinical outcomes, and whether heart-derived cells will have demonstrable advantages over other cell types.

1. The SCIPIO trial targeted patients with cardiac dysfunction undergoing bypass surgery for subsequent delivery of c-kit–positive cells derived from heart tissue harvested at surgery. In interim analyses, cardiac function was substantially better at 4 months in the 14 cell-treated patients available for comparison to seven control patients.

2. In CADUCEUS, autologous cells derived from cardiospheres grown from cardiac biopsies (CDCs) were delivered to patients randomized after myocardial infarction to receive CDCs or usual care. In this trial, although overall heart function was not significantly improved by cell treatment, scar (determined by magnetic resonance imaging) was reduced at 6 and 12 months in the 17 CDC-treated patients but unchanged in the eight control patients.

Point #4:  The Endogenous Regeneration Potential

  • Donor cells have often been selected for their apparent ability to form new cardiomyocytes, the limited clinical data available suggest that relatively few of the donor cells may remain in the heart (20).
  • Other benefits of the cells or molecules delivered with them could include enhanced angiogenesis, cardiomyocyte survival, or endogenous regeneration.
  • The success or failure of cardiovascular cell therapy will ultimately depend on its ability to improve clinical outcomes whatever the mechanisms, and advocates argue that
  • the donor cells may provide a particularly potent mixture of salutary effects. However,
  • the complex and sometimes heterogeneous cell preparations being infused make standardization and reconciling discrepant results particularly challenging. It seems likely that
  • identification and purification of the essential cellular and molecular components mediating any observed benefits will ultimately provide the most effective, safe, and consistent approach.

Point #5: On pathways regulating cardiomyocyte regeneration in animal models

  • Recent work has begun to elucidate the settings and pathways regulating cardiomyocyte regeneration in animal models. Porrello et al. demonstrated a remarkable though transient regenerative capacity of the neonatal murine heart (14), and
  • related studies have begun to define the signaling mechanisms leading to withdrawal of cardiomyocytes from the cell cycle (21).
  • The Hippo pathway is a potent negative regulator of Wnt signaling and cardiomyocyte proliferation (22), which also intersects via Yap with insulin growth factor I (IGF-I) signaling (23).
  • How effectively these pathways can be coopted to promote regeneration after injury is of great interest.
  • Individual pathways may also have multiple effects.
  • Huang et al. ( 24) demonstrate that C/EBP inhibition, previously implicated in exercise-induced cardiac growth and possible cardiomyogenesis (25), also reduces ischemic injury by mitigating inflammation. In addition to
  • Endogenous pathways, reprogramming resident nonprogenitor cells such as fibroblasts through gene delivery has generated contractile cardiomyocyte-like cells (26, 27) that mitigate scar formation and improve function after heart attacks in mice (28).
  • These promising developments have yet to be translated clinically but could provide a path to cardiac repair that obviates the need for exogenous cells.

Point #6: Prof. A. Rosenzweig’s Summary and His Future Outlook of Cardiac Regeneration

  • We are still relatively early in the development of new approaches to cardiovascular disease. It will be some time before we know the conclusion of what will likely be a long and challenging road ahead.
  • Almost as challenging is conveying to patients and policymakers an appropriate perspective that balances unmitigated enthusiasm for the scientific discoveries, cautious optimism for the broader implications, and humble acknowledgment that though even the most appealing ideas may fail, there is only one way to find out.

REFERENCES and NOTES in  Science 338, 1549 (2012).

1. V. L. Roger et al., Circulation 125, e2 (2012).

2. CDC (2012), http://www.cdc.gov/dhdsp/data_statistics/fact_

sheets/docs/fs_heart_failure.pdf

3. C. J. DeFrances, M. N. Podgornik, Adv. Data 371, 1

(2006).

4. T. E. Owan et al., N. Engl. J. Med. 355, 251 (2006).

5. R. S. Bhatia et al., N. Engl. J. Med. 355, 260 (2006).

6. J. Narula et al., N. Engl. J. Med. 335, 1182 (1996).

7. G. Olivetti et al., N. Engl. J. Med. 336, 1131 (1997).

8. A. P. Beltrami et al., Cell 114, 763 (2003).

9. K. Bersell, S. Arab, B. Haring, B. Kühn, Cell 138, 257

(2009).

10. P. C. H. Hsieh et al., Nat. Med. 13, 970 (2007).

11. O. Bergmann et al., Science 324, 98 (2009).

12. J. Kajstura et al., Circ. Res. 107, 305 (2010).

13. K. Kikuchi et al., Nature 464, 601 (2010).

14. E. R. Porrello et al., Science 331, 1078 (2011).

15. V. Schächinger et al., N. Engl. J. Med. 355, 1210 (2006).

16. V. Jeevanantham et al., Circulation 126, 551 (2012).

17. A. Rosenzweig, N. Engl. J. Med. 355, 1274 (2006).

18. R. Bolli et al., Lancet 378, 1847 (2011).

19. R. R. Makkar et al., Lancet 379, 895 (2012).

20. M. Hofmann et al., Circulation 111, 2198 (2005).

21. E. R. Porrello et al., Circ. Res. 109, 670 (2011).

22. T. Heallen et al., Science 332, 458 (2011).

23. M. Xin et al., Sci. Signal. 4, ra70 (2011).

24. G. N. Huang et al., Science 338, 1599 (2012);

10.1126/science.1229765.

25. P. Boström et al., Cell 143, 1072 (2010).

26. M. Ieda et al., Cell 142, 375 (2010).

27. L. Qian et al., Nature 485, 593 (2012).

28. K. Song et al., Nature 485, 599 (2012).

 

Read Full Post »

Curation, HealthCare System in the US, and Calcium Signaling Effects on Cardiac Contraction, Heart Failure, and Atrial Fibrillation, and the Relationship of Calcium Release at the Myoneural Junction to Beta Adrenergic Release


Curation, HealthCare System in the US, and Calcium Signaling Effects on Cardiac Contraction, Heart Failure, and Atrial Fibrillation, and the Relationship of Calcium Release at the Myoneural Junction to Beta Adrenergic Release

Curator and e-book Contributor: Larry H. Bernstein, MD, FCAP
Curator and BioMedicine e-Series Editor-in-Chief: Aviva Lev Ari, PhD, RN

and 

Content Consultant to Six-Volume e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC

This portion summarises what we have covered and is now familiar to the reader.  There are three related topics, and an extension of this embraces other volumes and chapters before and after this reading.  This approach to the document has advantages over the multiple authored textbooks that are and have been pervasive as a result of the traditional publication technology.  It has been stated by the founder of ScoopIt, that amount of time involved is considerably less than required for the original publications used, but the organization and construction is a separate creative process.  In these curations we amassed on average five articles in one curation, to which, two or three curators contributed their views.  There were surprises, and there were unfulfilled answers along the way.  The greatest problem that is being envisioned is the building a vision that bridges and unmasks the hidden “dark matter” between the now declared “OMICS”, to get a more real perspective on what is conjecture and what is actionable.  This is in some respects unavoidable because the genome is an alphabet that is matched to the mino acid sequences of proteins, which themselves are three dimensional drivers of sequences of metabolic reactions that can be altered by the accumulation of substrates in critical placements, and in addition, the proteome has functional proteins whose activity is a regulatory function and not easily identified.  In the end, we have to have a practical conception, recognizing the breadth of evolutionary change, and make sense of what we have, while searching for more.

We introduced the content as follows:

1. We introduce the concept of curation in the digital context, and it’s application to medicine and related scientific discovery.

Topics were chosen were used to illustrate this process in the form of a pattern, which is mostly curation, but is significantly creative, as it emerges in the context of this e-book.

  • Alternative solutions in Treatment of Heart Failure (HF), medical devices, biomarkers and agent efficacy is handled all in one chapter.
  • PCI for valves vs Open heart Valve replacement
  • PDA and Complications of Surgery — only curation could create the picture of this unique combination of debate, as exemplified of Endarterectomy (CEA) vs Stenting the Carotid Artery (CAS), ischemic leg, renal artery stenosis.

2. The etiology, or causes, of cardiovascular diseases consist of mechanistic explanations for dysfunction relating to the heart or vascular system. Every one of a long list of abnormalities has a path that explains the deviation from normal. With the completion of the analysis of the human genome, in principle all of the genetic basis for function and dysfunction are delineated. While all genes are identified, and the genes code for all the gene products that constitute body functions, there remains more unknown than known.

3. Human genome, and in combination with improved imaging methods, genomics offers great promise in changing the course of disease and aging.

4. If we tie together Part 1 and Part 2, there is ample room for considering clinical outcomes based on individual and organizational factors for best performance. This can really only be realized with considerable improvement in information infrastructure, which has miles to go.

Curation

Curation is an active filtering of the web’s  and peer reviewed literature found by such means – immense amount of relevant and irrelevant content. As a result content may be disruptive. However, in doing good curation, one does more than simply assign value by presentation of creative work in any category. Great curators comment and share experience across content, authors and themes.
Great curators may see patterns others don’t, or may challenge or debate complex and apparently conflicting points of view.  Answers to specifically focused questions comes from the hard work of many in laboratory settings creatively establishing answers to definitive questions, each a part of the larger knowledge-base of reference. There are those rare “Einstein’s” who imagine a whole universe, unlike the three blindmen of the Sufi tale.  One held the tail, the other the trunk, the other the ear, and they all said this is an elephant!
In my reading, I learn that the optimal ratio of curation to creation may be as high as 90% curation to 10% creation. Creating content is expensive. Curation, by comparison, is much less expensive.  The same source says “Scoop.it is my content marketing testing “sandbox”. In sharing, he says that comments provide the framework for what and how content is shared.

Healthcare and Affordable Care Act

We enter year 2014 with the Affordable Care Act off to a slow start because of the implementation of the internet signup requiring a major repair, which is, unfortunately, as expected for such as complex job across the US, and with many states unwilling to participate.  But several states – California, Connecticut, and Kentucky – had very effective state designed signups, separate from the federal system.  There has been a very large rush and an extension to sign up. There are many features that we can take note of:

1. The healthcare system needed changes because we have the most costly system, are endowed with advanced technology, and we have inexcusable outcomes in several domains of care, including, infant mortality, and prenatal care – but not in cardiology.

2. These changes that are notable are:

  • The disparities in outcome are magnified by a large disparity in highest to lowest income bracket.
  • This is also reflected in educational status, and which plays out in childhood school lunches, and is also affected by larger class size and cutbacks in school programs.
  • This is not  helped by a large paralysis in the two party political system and the three legs of government unable to deal with work and distraction.
  • Unemployment is high, and the banking and home construction, home buying, and rental are in realignment, but interest rates are problematic.

3.  The  medical care system is affected by the issues above, but the complexity is not to be discounted.

  •  The medical schools are unable at this time to provide the influx of new physicians needed, so we depend on a major influx of physicians from other countries
  • The technology for laboratories, proteomic and genomic as well as applied medical research is rejuvenating the practice in cardiology more rapidly than any other field.
  • In fields that are imaging related the life cycle of instruments is shorter than the actual lifetime use of the instruments, which introduces a shortening of ROI.
  • Hospitals are consolidating into large consortia in order to maintain a more viable system for referral of specialty cases, and also is centralizing all terms of business related to billing.
  • There is reduction in independent physician practices that are being incorporated into the hospital enterprise with Part B billing under the Physician Organization – as in Partners in Greater Boston, with the exception of “concierge” medical practices.
  • There is consolidation of specialty laboratory services within state, with only the most specialized testing going out of state (Quest, LabCorp, etc.)
  • Medicaid is expanded substantially under the new ACA.
  • The federal government as provider of services is reducing the number of contractors for – medical devices, diabetes self-testing, etc.
  • The current rearrangements seeks to provide a balance between capital expenses and fixed labor costs that it can control, reduce variable costs (reagents, pharmaceutical), and to take in more patients with less delay and better performance – defined by outside agencies.

Cardiology, Genomics, and calcium ion signaling and ion-channels in cardiomyocyte function in health and disease – including heart failure, rhythm abnormalities, and the myoneural release of neurotransmitter at the vesicle junction.

This portion is outlined as follows:

2.1 Human Genome: Congenital Etiological Sources of Cardiovascular Disease

2.2 The Role of Calcium in Health and Disease

2.3 Vasculature and Myocardium: Diagnosing the Conditions of Disease

Genomics & Genetics of Cardiovascular Disease Diagnoses

actin cytoskeleton

wall stress, ventricular workload, contractile reserve

Genetic Base of Atherosclerosis and Loss of Arterial Elasticity with Aging

calcium and actin skeleton, signaling, cell motility

hypertension & vascular compliance

Genetics of Conduction Disease

Ca+ stimulated exostosis: calmodulin & PKC (neurotransmitter)

complications & MVR

disruption of Ca2+ homeostasis cardiac & vascular smooth muscle

synaptotagmin as Ca2+ sensor & vesicles

atherosclerosis & ion channels


It is increasingly clear that there are mutations that underlie many human diseases, and this is true of the cardiovascular system.  The mutations are mistakes in the insertion of a purine nucleotide, which may or may not have any consequence.  This is why the associations that are being discovered in research require careful validation, and even require demonstration in “models” before pursuing the design of pharmacological “target therapy”.  The genomics in cardiovascular disease involves very serious congenital disorders that are asserted early in life, but the effects of and development of atherosclerosis involving large and medium size arteries has a slow progression and is not dominated by genomic expression.  This is characterized by loss of arterial elasticity. In addition there is the development of heart failure, which involves the cardiomyocyte specifically.  The emergence of regenerative medical interventions, based on pleuripotent inducible stem cell therapy is developing rapidly as an intervention in this sector.

Finally, it is incumbent on me to call attention to the huge contribution that research on calcium (Ca2+) signaling has made toward the understanding of cardiac contraction and to the maintenance of the heart rhythm.  The heart is a syncytium, different than skeletal and smooth muscle, and the innervation is by the vagus nerve, which has terminal endings at vesicles which discharge at the myocyte junction.  The heart specifically has calmodulin kinase CaMK II, and it has been established that calmodulin is involved in the calcium spark that triggers contraction.  That is only part of the story.  Ion transport occurs into or out of the cell, the latter termed exostosis.  Exostosis involves CaMK II and pyruvate kinase (PKC), and they have independent roles.  This also involves K+-Na+-ATPase.  The cytoskeleton is also discussed, but the role of aquaporin in water transport appears elsewhere, as the transport of water between cells.  When we consider the Gibbs-Donnan equilibrium, which precedes the current work by a century, we recall that there is an essential balance between extracellular Na+ + Ca2+ and the intracellular K+ + Mg2+, and this has been superceded by an incompletely defined relationship between ions that are cytoplasmic and those that are mitochondrial.  The glass is half full!

 

Read Full Post »

The Cost to Value Conundrum in Cardiovascular Healthcare Provision


The Cost to Value Conundrum in Cardiovascular Healthcare Provision

Author: Larry H. Bernstein, MD, FCAP

I write this introduction to Volume 2 of the e-series on Cardiovascular Diseases, which curates the basic structure and physiology of the heart, the vasculature, and related structures, e.g., the kidney, with respect to:

1. Pathogenesis
2. Diagnosis
3. Treatment

Curation is an introductory portion to Volume Two, which is necessary to introduce the methodological design used to create the following articles. More needs not to be discussed about the methodology, which will become clear, if only that the content curated is changing based on success or failure of both diagnostic and treatment technology availability, as well as the systems needed to support the ongoing advances.  Curation requires:

  • meaningful selection,
  • enrichment, and
  • sharing combining sources and
  • creation of new synnthesis

Curators have to create a new perspective or idea on top of the existing media which supports the content in the original. The curator has to select from the myriad upon myriad options available, to re-share and critically view the work. A search can be overwhelming in size of the output, but the curator has to successfully pluck the best material straight out of that noise.

Part 1 is a highly important treatment that is not technological, but about the system now outdated to support our healthcare system, the most technolog-ically advanced in the world, with major problems in the availability of care related to economic disparities.  It is not about technology, per se, but about how we allocate healthcare resources, about individuals’ roles in a not full list of lifestyle maintenance options for self-care, and about the important advances emerging out of the Affordable Care Act (ACA), impacting enormously on Medicaid, which depends on state-level acceptance, on community hospital, ambulatory, and home-care or hospice restructuring, which includes the reduction of management overhead by the formation of regional healthcare alliances, the incorporation of physicians into hospital-based practices (with the hospital collecting and distributing the Part B reimbursement to the physician, with “performance-based” targets for privileges and payment – essential to the success of an Accountable Care Organization (AC)).  One problem that ACA has definitively address is the elimination of the exclusion of patients based on preconditions.  One problem that has been left unresolved is the continuing existence of private policies that meet financial capabilities of the contract to provide, but which provide little value to the “purchaser” of care.  This is a holdout that persists in for-profit managed care as an option.  A physician response to the new system of care, largely fostered by a refusal to accept Medicaid, is the formation of direct physician-patient contracted care without an intermediary.

In this respect, the problem is not simple, but is resolvable.  A proposal for improved economic stability has been prepared by Edward Ingram. A concern for American families and businesses is substantially addressed in a macroeconomic design concept, so that financial services like housing, government, and business finance, savings and pensions, boosting confidence at every level giving everyone a better chance of success in planning their personal savings and lifetime and business finances.

http://macro-economic-design.blogspot.com/p/book.html

Part 2 is a collection of scientific articles on the current advances in cardiac care by the best trained physicians the world has known, with mastery of the most advanced vascular instrumentation for medical or surgical interventions, the latest diagnostic ultrasound and imaging tools that are becoming outdated before the useful lifetime of the capital investment has been completed.  If we tie together Part 1 and Part 2, there is ample room for considering  clinical outcomes based on individual and organizational factors for best performance. This can really only be realized with considerable improvement in information infrastructure, which has miles to go.  Why should this be?  Because for generations of IT support systems, they are historically focused on billing and have made insignificant inroads into the front-end needs of the clinical staff.

Read Full Post »


Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))

Reviewer and Co-Curator: Larry H Bernstein, MD, FCAP

and

Curator: Aviva Lev-Ari, PhD, RN

The role of ion channels in Na(+)-K(+)-ATPase: regulation of ion
transport across the plasma membrane has been studied by our Team in 2012 and 2013. This is article TWELVE in a 13 article series listed at the end of this article.

Chiefly, our sources of inspiration were the following:

1.            2013 Nobel work on vesicles and calcium flux at the neuromuscular junction

Machinery Regulating Vesicle Traffic, A Major Transport System in our Cells 

The 2013 Nobel Prize in Physiology or Medicine is awarded to Dr. James E. Rothman, Dr. Randy W. Schekman and Dr. Thomas C. Südhof for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells. This represents a paradigm shift in our understanding of how the eukaryotic cell, with its complex internal compartmentalization, organizes the routing of molecules packaged in vesicles to various intracellular destinations, as well as to the outside of the cell. Specificity in the delivery of molecular cargo is essential for cell function and survival. 

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2013/advanced-medicineprize2013.pdf

Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

2. Perspectives on Nitric Oxide in Disease Mechanisms

available on Kindle Store @ Amazon.com

http://www.amazon.com/dp/B00DINFFYC

https://pharmaceuticalintelligence.com/biomed-e-books/series-a-e-books-on-cardiovascular-diseases/perspectives-on-nitric-oxide-in-disease-mechanisms-v2/

3.            Professor David Lichtstein, Hebrew University of Jerusalem, Dean, School of Medicine

Lichtstein’s main research focus is the regulation of ion transport across the plasma membrane of eukaryotic cells. His work led to the discovery that specific steroids that have crucial roles, as the regulation of cell viability, heart contractility, blood pressure and brain function. His research has implications for the fundamental understanding of body functions, as well as for several pathological states such as heart failure, hypertension and neurological and psychiatric diseases.

Physiologist, Professor Lichtstein, Chair in Heart Studies at The Hebrew University elected Dean of the Faculty of Medicine at The Hebrew University of Jerusalem

Reporter: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/12/18/physiologist-professor-lichtstein-chair-in-heart-studies-at-the-hebrew-university-elected-dean-of-the-faculty-of-medicine-at-the-hebrew-university-of-jerusalem/

4.            Professor Roger J. Hajjar, MD at Mount Sinai School of Medicine

Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/01/calcium-molecule-in-cardiac-gene-therapy-inhalable-gene-therapy-for-pulmonary-arterial-hypertension-and-percutaneous-intra-coronary-artery-infusion-for-heart-failure-contributions-by-roger-j-hajjar/

5.            Seminal Curations by Dr. Aviva Lev-Ari on Genetics and Genomics of Cardiovascular Diseases with a focus on Conduction and Cardiac Contractility

Aviva Lev-Ari, PhD, RN

Aviva Lev-Ari, PhD, RN

Aviva Lev-Ari, PhD, RN and Larry H. Bernstein, MD, FCAP

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

Other related research by the Team of Leaders in Pharmaceutical Business Intelligence published on the Open Access Online Scientific Journal

http://pharmaceuticalintelligence.com

See References to articles at the end of this article on

  • ION CHANNEL and Cardiovascular Diseases

https://pharmaceuticalintelligence.com/?s=Ion+Channel

  • Calcium Role in Cardiovascular Diseases – The Role of Calcium Calmodulin Kinase  (CKCaII) and Ca(2) flux
  • Mitochondria and Oxidative Stress Role in Cardiovascular Diseases

Thus, the following article follows a series of articles on ion-channels and cardiac contractility mentioned, above. The following article is closely related to the work of Prof. Lichtstein.

These investigators studied the possible correlation between

  • Myocardial Ischemia (Coronary Artery Disease (CAD)) aka Ischemic Heart Disease (IHD) and
  • single-nucleotide polymorphisms  (SNPs) genes encoding several regulators involved in Coronary Blood Flow Regulation (CBFR), including
  • ion channels acting in vascular smooth muscle and/or
  • endothelial cells of coronary arteries.

They completely analyzed exon 3 of both KCNJ8 and KCNJ11 genes (Kir6.1 and Kir6.2 subunit, respectively) as well as

  • the whole coding region of KCN5A gene (Kv1.5 channel).
The work suggests certain genetic polymorphisms may represent a non-modifiable protective factor that could be used
  • to identify individuals at relatively low-risk for cardiovascular disease
  • an independent protective role of the
    • rs5215_GG against developing CAD and
    • a trend for rs5219_AA to be associated with protection against coronary microvascular dysfunction

Their findings are a lead into further investigations on ion channels and IHD affecting the microvasculature.

Role of genetic polymorphisms of ion channels in the pathophysiology of coronary microvascular dysfunction and ischemic heart disease

BasicResCardiol(2013)108:387   http//dx.dio.org/10.1007/s00395-013-0387-4

F Fedele1•M Mancone1•WM Chilian2•P Severino2•E Canali•S Logan•ML DeMarchis3•M Volterrani4•R Palmirotta3•F Guadagni3

1Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences,Sapienza University of Rome, UmbertoI Policlinic, Rome, Italy  e-mail:francesco.fedele@uniroma1.it
2Department of Integrative Medical Sciences, Northeastern Ohio Universities College of Medicine, Rootstown,OH
3Department of Advanced Biotechnologies and Bioimaging, IRCCS San Raffaele Pisana,Rome,It
4Cardiovascular Research Unit, Department of Medical Sciences, Centre for Clinical and Basic Research, Raffaele Pisana, Rome, Italy (CBFR)

BasicResCardiol(2013)108:387   http//dx.dio.org/10.1007/s00395-013-0387-4
This article is published with open access at Springerlink.com

Abstract

Conventionally,ischemic heart disease (IHD) study is equated with large vessel coronary disease (CAD). However, recent evidence has suggested

  • a role of compromised microvascular regulation in the etiology of IHD.

Because regulation of coronary blood flow likely involves

  • activity of specific ion-channels, and
  • key factors involved in endothelium-dependent dilation,

genetic anomalies of ion-channels or specific endothelial-regulators may underlie coronary microvascular disease.

We aimed to evaluate the clinical impact of single-nucleotide polymorphisms in genes encoding for

  • ion-channels expressed in the coronary vasculature and the possible
  • correlation with IHD resulting from microvascular dysfunction.

242 consecutive patients who were candidates for coronary angiography were enrolled. A prospective, observational, single-center study was conducted, 

  • analyzing genetic polymorphisms relative to

(1) NOS3 encoding for endothelial nitric oxide synthase (eNOS);
(2) ATP2A2 encoding for the Ca/H-ATP-ase pump (SERCA);
(3) SCN5A encoding for the voltage-dependent Na channel (Nav1.5);
(4) KCNJ8 and in KCNJ11 encoding for the Kir6.1and Kir6.2 subunits
of genetic K-ATP channels, respectively;and
(5) KCN5A encoding for the voltage-gated K channel (Kv1.5).

No significant associations between clinical IHD manifestations and

  • polymorphisms for SERCA, Kir6.1, and Kv1.5. were observed (p[0.05),

whereas specific polymorphisms detected in eNOS, as well as in Kir6.2 and Nav1.5 were found to be correlated with

  • IHD and microvascular dysfunction.

 Interestingly, genetic polymorphisms of ion-channels  seem to have an important clinical impact

  • influencing the susceptibility for microvascular dysfunction and (IHD,
  • independent of the presence of classic cardiovascular risk factors: atherosclerosis   

http//dx.dio.org/10.1007/s00395-013-0387-4

Keywords: Ion-channels, Genetic polymorphisms, Coronary microcirculation, Endothelium, Atherosclerosis Ischemic heart disease

 Introduction

Historically, in the interrogation of altered vascular function in patientswith ischemic heart disease (IHD), scientists have focused their attention on the correlation between

  • endothelial dysfunction and
  • atherosclerosis [11, 53, 6567].

The endothelium-independent dysfunction in coronary microcirculation and its possible correlations with  

  • atherosclerotic disease and
  • myocardial ischemia has not been extensively investigated.

In normal conditions, coronary blood flow regulation (CBFR) is mediated by several different systems, including

  • endothelial,
  • nervous,
  • neurohumoral,
  • myogenic, and
  • metabolic mechanisms [2, 10, 14, 15, 63, 64, 69].

Physiologic CBFR depends also on several ion channels, such as

  • ATP-sensitive potassium (KATP) channels,
  • voltage-gated potassium (Kv) channels,
  • voltage-gated sodium (Nav) channels, and others.

Ion channels regulate the concentration of calcium in both

  • coronary smooth muscle and endothelial cells, which
  • modulates the degree of contractile tone in vascular muscle and
  • the amount of nitric oxide that is produced by the endothelium

Ion channels play a primary role in the rapid response of both

  • the endothelium and vascular smooth muscle cells of coronary arterioles
  • to the perpetually fluctuating demands of the myocardium for blood flow
    [5, 6, 13, 18, 33, 45, 46, 51, 52, 61, 73, 75].

Despite this knowledge, there still exists an important gap about 

  • the clinical relevance and 
  • causes of microvascular dysfunction in IHD

By altering the overall

  • regulation of blood flow in the coronary system,
  • microvascular dysfunction could alter the normal distribution of shear forces in large coronary arteries

Proximal coronary artery stenosis could

  • contribute to microvascular dysfunction [29, 60]. But
  • ion channels play a critical role in microvascular endothelial
  • and smooth muscle function.

Therefore, we hypothesized  that alterations of coronary ion  channels could be the primary cause in a chain of events leading to

  • microvascular dysfunction and 
  • myocardial ischemia

independent of the presence of atherosclerosis.

Therefore, the objective of our study was to evaluate the possible correlation between

  • IHD and single-nucleotide polymorphisms  (SNPs) for genes encoding several regulators involved in CBFR, including
  • ion channels acting in vascular smooth muscle and/or
  • endothelial cells of coronary arteries.

Discussion

Implications of the present work. This study describes the possible correlation of polymorphisms in genes encoding for CBFR effectors (i.e., ion channels, nitric oxide synthase, and SERCA) with the susceptibility for microcirculation dysfunction and IHD.

Our main findings are as follows: (Group 3 – Normal Patients – anatomically and functionally normal coronary arteries).

  • In Group 3, the genotype distribution of SNP rs5215 (Kir6.2/KCNJ11) moderately deviates from the HW equilibrium (p = 0.05).
  • In Group 1 (CAD), the polymorphism rs6599230 of Nav1.5/SCN5A showed deviation from HW equilibrium (p = 0.017).
  • The genotypic distribution of rs1799983 polymorphism for eNOS/NOS3 is inconsistent with the HW equilibrium in groups 1, 2, and 3 (p = 0.0001, p = 0.0012 and p = 0.0001, respectively).

Haplotype analyses revealed that there is no linkage disequilibrium between polymorphisms of the analyzed genes. There was no significant difference in the prevalence of T2DM (p = 0.185) or dyslipidemia (p = 0.271) between groups, as shown in Table2. In regards to genetic characteristics, no significant differences between the three.

1. A marked HW disequilibrium in the genotypic distribution of rs1799983 polymorphism for eNOS/NOS3 was observed in all three populations. Moreover, this SNP seems to be an independent risk factor for microvascular dysfunction, as evidenced by multivariate analysis;
2. The SNPs rs5215_GG, rs5218_CT, and rs5219_AA for Kir6.2/KCJ11 could reduce susceptibility to IHD, since they were present more frequently in patients with anatomically and functionally normal coronary arteries;
3. In particular, with regard to rs5215 for Kir6.2/KCJ11, we observed a moderate deviation from the HW equilibrium in the genotypic
distribution in the control group. In addition, this genotype appears to be an independent protective factor in the development of IHD, as evidenced by multivariate analysis;
4. Furthermore, the trend observed for the SNP  rs5219_AA of Kir6.2/KCNJ11 may suggest an independent protective factor  in the development of coronary microvascular dysfunction
5. The rs1805124_GG genotype of Nav1.5/SCN5A seems to play a role against CAD;
6. No association seems to exist between the polymorphisms of SERCA/ATP2A2, Kir6.1/KCNJ8, and Kv1.5/KCNA5 and the presence of IHD;
7. All groups are comparable regarding the cardiovascular risk factors of T2DM and dyslipidemia, illustrating a potentially important implication of genetic polymorphisms in the susceptibility to IHD.

It is important to underline that the control group (Group 3) is a high-risk population, because of their cardiovascular risk factors

  • hypertension = 17 %,
  • T2DM = 34.1 %,
  • dyslipidemia = 41.4 %,

with an appropriate indication for coronary angiography, in accordance with current guidelines. Nevertheless, these patients were demonstrated to have both anatomically and functionally normal coronary arteries. Moreover, as shown in Tables 2 and 3, we observed that

  • rs5215_GG, rs5218_CT and rs5219_AA for Kir6.2/KCNJ11 had a higher prevalence in this group,compared to patients with CAD
  • and patients with microvascular dysfunction.

Moreover, as shown in Table 4, the presence of the rs5215_GG polymorphism for the Kir6.2 subunit was

  • inversely correlated with the prevalence of cardiovascular risk factors and CAD,whereas
  • rs5219_AA of the Kir6.2 subunit trended towards an inverse correlation with coronary microvascular dysfunction.

On the other hand, the SNP rs1799983_GT of eNOS was

  • confirmed to be an independent risk factor for microvascular dysfunction.

Our data suggest that the presence of certain genetic polymorphisms may represent a non-modifiable protective factor that could be used

  • to identify individuals at relatively low-risk for cardiovascular disease,
  • regardless of the presence of T2DM and dyslipidemia.

Current Clinical and Research Context

In normal coronary arteries, particularly the coronary microcirculation, there are several different mechanisms of CBFR, including

  • endothelial, neural, myogenic, and metabolic mediators [2, 8, 10, 12, 14, 15, 37, 55, 63, 64, 69].

In particular, endothelium-dependent vasodilation acts mainly via eNOS-derived nitric oxide (NO) in response to acetylcholine and shear stress.

  • NO increases intracellular cyclic guanosine monophosphate. It also causes vasodilation via
  • activation of both K-Ca channels and K-ATP channels.

Recent data suggested a pathophysiologically relevant role for the polymorphisms of eNOS/NOS3 in human coronary vasomotion [40–43]. Our data suggest that rs1799983_GT at exon 7 (Glu298Asp, GAG-GAT) of eNOS/NOS3 represents

  • an independent risk factor for coronary micro-vascular dysfunction, which agrees with a recent meta-analysis reporting an
  • association of this SNP with CAD in Asian populations [74]. In addition,
  • this SNP has been associated with endothelial dysfunction, although the mechanisms are not well defined [30].

Consistently, a recent study performed on 60 Indian patients with documented history of CAD reported a significantly higher frequency of rs1799983 (p.05) compared to control subjects, indicating that

  • variations in NOS3 gene may be useful clinical markers of endothelial dysfunction in CAD [54].
Interestingly, another association between rs1799983_GT and impaired collateral development has been observed in patientswith a

  • high-grade coronary stenosis or occlusion [19].
As is well known, the significance of the mechanisms of CBFR is partly determined by the location within the coronary vasculature. For instance, for vessels with a diameter of < 200 µm—which comprise the coronary microcirculation—metabolic regulation of coronary blood flow is considered the most important mechanism [24, 63]. Importantly, many of these mediators of metabolic regulation act through specific ion channels. In particular, in both coronary artery smooth muscle cells and endothelial cells
  • potassium channels determine the resting membrane potential (Em) and serve as targets of endogenous and therapeutic vasodilators [9, 27].
Several types of K+ channels are expressed in the coronary tree.
  • The K-ATP channels couple cell metabolic demand to conductance, via pore-forming (Kir6.1 and/or Kir6.2) subunits and regulatory
    [sulphonylurea-binding (SUR 1, 2A, or 2B)] subunits.
  • Kir6.x allows for channel inhibition by ATP, while SURx is responsible for channel activation by ADP and Mg2+.
K-ATP channel activation results in an outward flux of potassium and

  • consequent hyperpolarization, resulting in
  • voltage-gated calcium channel closure,
  • decreased Ca2+ influx, and ultimately
  • vasodilation [1, 5, 18, 20, 21, 33, 61, 62, 73, 75].

Our data do not support any significant difference regarding the Kir6.1 subunit of the K-ATP channel. On the other hand, this study suggests

  • an important role of specific SNPs for the Kir6.2 subunit (Tables 2, 3)—i.e., rs5215, rs5219, and rs5218—

in the susceptibility to IHD and microvascular dysfunction. These SNPs are among the most studied K-ATP channel polymorphisms, especially in the context of diabetes mellitus. In fact, in both Caucasian and Asian populations, these three SNPs as well as other genetic polymorphisms for the KCNJ11 gene have been associated with diabetes mellitus [34, 35, 44, 50, 57, 58, 70].

Nevertheless, the precise

  • structure–function impacts of the various amino acid substitutions remain unclear.

The rs5215 and rs5219 polymorphisms, also known as I337V and E23K, respectively, are highly linked with reported

  • concordance rates between 72 and 100 % [22, 23, 56].

The high concordance between rs5219 and rs5215 suggests that these polymorphisms

  • may have originated in a common ancestor, further indicating a
  • possible evolutionary advantage to their maintenance in the general population [49].

In our study, multivariate analysis suggests both an independent protective role of the

  • rs5215_GG against developing CAD and
  • a trend for rs5219_AA to be associated with protection against coronary microvascular dysfunction (Table 4a, b).
  • The variant rs5215_GG is a missense SNP located in the gene KCNJ11 at exon 1009 (ATC-GTC) and results in
    the substitution of isoleucine (I) residue with valine (V) [23].

Future studies are necessary to better understand the influence of this single amino acid variant on the function of the channel.

In humans, vasodilation of the coronary microvasculature in response to hypoxia and K-ATP channel opening
  • are both impaired in diabetes mellitus [39].
It is also described that gain-of-function mutations of the KCNJ11 gene cause neonatal diabetes mellitus, and loss-of-function mutations lead to congenital hyperinsulinism [43]. Our study is not discordant with previous studies about the correlation of SNPs of the Kir6.2 subunit and diabetes mellitus. Rather, our findings show that these SNPs are correlated with anatomically and functionally normal coronary arteries,
  • independent of the presence of either diabetes mellitus or dyslipidemia.
These data suggest the possibility that these particular SNPs may identify individuals with decreased risk for coronary microcirculatory dysfunction and IHD,
  • regardless of the presence of T2DM and/or dyslipidemia.

However, further studies are necessary to confirm these findings. In this context, to better investigate the implications of genetic variation in the K-ATP channel,

  • future studies should include ion channel’s functional modification due to the SNPs and analysis of SUR subunits.

More than 40-kV channel subunits have been identified in the heart, and sections of human coronary smooth muscle cells demonstrate Kv1.5 immunoreactivity [16, 17, 27, 38]. Through constant regulation of smooth muscle tone, Kv channels contribute to the control of coronary microvascular resistance [4, 7]. Pharmacologic molecules that inhibit Kv1.5 channels such as

  • pergolide [25],
  • 4-amino-pyridine [32], and
  • correolide [17]

lead to coronary smooth muscle cell contraction and block the coupling between

  • cardiac metabolic demand and
  • coronary blood flow.

However, no significant differences were identified between the study groups in terms of the particular polymorphisms for Kv1.5 that were analyzed in this study. Expression of

  • the voltage-dependent Na+ channel (Nav) has been demonstrated in coronary microvascular endothelia cells [3, 66].

Our analysis reveals a possible implication of the polymorphism rs1805124_GG for Nav1.5 channel with the presence of anatomically and functionally normal coronary arteries. This SNP leads to a homozygous 1673A-G transition, resulting in a His558-to-Arg (H558R) substitution. It is important to underline that

  • our data are the first to correlate the polymorphism rs1805124_GG with IHD.

Further research is necessary to confirm the observed implication.

Finally, we have analyzed the sarco/endoplasmic reticulum calcium transporting Ca2+-ATPase (SERCA), which is fundamental in the regulation of intracellular Ca2+ concentration [6].

SERCA is an intracellular pump that

  • catalyzes the hydrolysis of ATP coupled with the
  • translocation of calcium from the cytosol into the lumen of the sarcoplasmic reticulum.

Although this pump plays a critical role in regulation of the contraction/relaxation cycle, our analysis did not reveal any apparent association between

  • genetic variants of SERCA and the
  • prevalence of microvascular dysfunction or IHD.

Conclusions

This pilot study is the first to compare the prevalence of SNPs in genes encoding coronary ion channels between patients
  • with CAD or microvascular dysfunction and those with both anatomically and functionally normal coronary arteries.
Taken together, these results suggest the possibility of associations between SNPs and IHD and microvascular dysfunction, although

  • the precise manners by which specific genetic polymorphisms affect ion channel function and expression
have to be clarified by further research involving larger cohorts.

Limitations and future perspectives

Notable limitations of this pilot study are as follows:

1. Due to the lack of pre-existing data, the power calculation was performed in advance on the basis of assumptions of allele frequencies and the population at risk.
2. The sample size for each group is small, mainly due to both the difficulty in enrolling patients with normal coronary arteries and normal microvascular function (group 3) and the elevated costs of the supplies such as Doppler flow wires.
3. There is a lack of ethnic diversity of our cohort.
4. Currently, there is an absence of supportive findings in another independent cohort or population. However, our pilot study included patients within a well-defined, specific population and was aimed to identify the presence of statistical associations between selected genetic polymorphisms and the prevalence of a specific disease.
5. There is a lack of functional characterization of the described genetic polymorphisms.
6. We have not identified any correlation between novel SNPs and IHD. Nevertheless, we completely analyzed exon 3 of both KCNJ8 and KCNJ11 genes (Kir6.1 and Kir6.2 subunit, respectively) as well as the whole coding region of KCN5A gene (Kv1.5 channel).  Moreover, we examined previously described SNPs since there are no data in the literature regarding the possible association of the prevalences of those polymorphisms in the examined population.More extensive studies are necessary to confirm our  findings, possibly with a larger number of patients. Future investigations are also required to confirm the roles of ion  channels in the pathogenesis of coronary microvascular dysfunction and IHD. These studies should involve analysis of both other subunits of the K-ATP channels

  • sulfonylurea receptor, SURx and further coronary ion channels (e.g., calcium-dependent K channels), as well as
  • in vitro evaluation of ion channel activity by patch clamp and analysis of channel expression in the human cardiac tissue.

Moreover, to better address the significance of microvascular dysfunction in IHD, it could be interesting to analyze

  • typical atherosclerosis susceptibility genes (e.g., PPAP2B, ICAM1, et al.).

Methods

In this prospective, observational, single-center study – 242 consecutive patients admitted to our department were enrolled with

  • the indication to undergo coronary angiography .

All patients matched inclusion criteria

  1. age [18];
  2. suspected or documented diagnosis of acute coronary syndrome or stable angina
  3. with indication(s) for coronary angiography, in accordance with current guidelines [36, 68], and
  4. the same ethno-geographic Caucasian origin) and

Exclusion Criteria

  1. previous allergic reaction to iodine contrast,
  2. renal failure,
  3. simultaneous genetic disease,
  4. cardiogenic shock,
  5. non- ischemic cardiomyopathy

All patients signed an informed consent document  –

prior to participation in the study, which included

  • acknowledgement of the testing procedures to be performed
    (i.e., coronary angiography; intracoronary tests; genetic analysis, and processing of personal data).

The study was approved by the Institution’s Ethics Committee.
All clinical and instrumental characteristics were collected in a dedicated  database.

 Study Design

(a)  Standard therapies were administered, according to current guidelines [36, 68].
(b) An echocardiography was performed before and after coronary angiography
(c)  Coronary angiography was performed using radial artery or femoral artery
Judkins approach via sheath insertion.
(d) In patients showing normal epicardial arteries, intracoronary functional tests
were performed through Doppler flow wire to evaluate

  1. both endothelium-dependent microvascular function
    [via intracoronary (IC) infusion of acetylcholine (2.5–10 lg)] and
  2. nonendothelium-dependent microvascular function
    [via IC infusion of adenosine (5 lg)] [31]. 

(e) In all enrolled patients, a peripheral blood sample for genetic analysis was taken. 

On the basis  of the  coronary angiography and the intracoronary functional tests, 

  • the 242 patients were divided into three groups (see also Fig. 1).
  1. Group 1: 155 patients with anatomic coronary alteration
    (comprising patients with acute coronary syndrome and chronic stable angina).

    • microvascular dysfunction defined as coronary flow reserve (CFR) \ 2.5
    • after IC infusion of acetylcholine and adenosine].
  2. Group 2: 46 patients with functional coronary alteration
    [normal coronary arteries as assessed by angiography, and

    • as assessed by angiography and with normal functional tests
      (CFR C 2.5 after intracoronary infusion of acetylcholine and adenosine) (Fig. 1).
  3. Group 3: 41 patients with anatomically and functionally normal coronary arteries


BRC 2013 fedele genetic polymorphisms of ion channels.pdf_page_2

Fig. 1 Study design: 242 consecutive not randomized patients matching inclusion and exclusion criteria were enrolled.
In all patients, coronary angiography was performed, according to current ESC/ACC/AHA guidelines. In patients with
angiographically normal coronary artery, intracoronary functional tests were performed. In 242 patients
(155 with coronary artery disease, 46 patients with micro-vascular dysfunction, endothelium and/or non-endothelium
dependent, and 41 patients with anatomically and functionally normal coronary arteries) genetic analysis was performed.

Genetic Analysis

In conformity with the study protocol, ethylenediaminetetraacetic acid (EDTA) whole blood samples were collected according
to the international guidelines reported in the literature [48]. Samples were transferred to the Interinstitutional Multidisciplinary
BioBank (BioBIM) of IRCCS San Raffaele Pisana (Rome) and stored at -80 C until DNA extraction. Bibliographic research by
PubMed and web tools OMIM (http://www.ncbi.nlm.nih.gov/omim), Entrez SNP (http://www.ncbi.nlm.nih.gov/snp), and
Ensembl (http://www.ensembl.org/index.html) were used to select variants of genes involved in signaling pathways

  • related to ion channels and/or reported to be associated with
  • microvascular dysfunction and/or myocardial ischemia and/or
  • diseases correlated to IHD, such as diabetes mellitus.
Polymorphisms for the following genes were analyzed:
  1. NOS3 (endothelial nitric oxide synthase, eNOS),
  2. ATP2A2 (Ca2+/H+-ATPase pump, SERCA2),
  3. SCN5A (voltage-dependent Na+ channel,
  4. Nav1.5),
  5. KCNJ11 (ATP-sensitive K+ channel, Kir6.2 subunit),
  6. KCNJ8 (ATP-sensitive K+ channel, Kir6.1 subunit) and
  7. KCNA5 (voltage-gated K+ channel, Kv1.5).

In particular, we completely analyzed by direct sequencing

  • exon 3 of KCNJ8 (Kir6.1 subunit), which includes eight SNPs, as well as
  • the whole coding region of KCNA5 (Kv1.5 channel), which includes 32 SNPs and
  • four previously described variants [26, 47, 71, 72].
We also examined
  • the whole coding region of KCNJ11 (Kir6.2 subunit), for which sequence variants are described [26, 28].

All SNPs and sequence variants analyzed—a total of 62 variants of 6 genes—are listed in Table 1.

BRC 2013 fedele genetic polymorphisms of ion channels_page_004
BRC 2013 fedele genetic polymorphisms of ion channels_page_005

DNA was isolated from EDTA anticoagulated whole blood using the MagNA Pure LC instrument and theMagNA Pure LC
total DNA isolation kit I (Roche Diagnostics, Mannheim, Germany) according to the manufacturer’s instructions. Standard
PCR was performed in a GeneAmp PCR System 9700 (Applied Biosystems, CA) using HotStarTaq Master Mix
(HotStarTaq Master Mix Kit, QIAGEN Inc, CA). PCR conditions and primer sequences are listed in Table 1.

In order to exclude preanalytical and analytical errors, all direct sequencing analyses were carried out on both
strands using Big Dye Terminator v3.1 Cycle Sequencing kit
(Applied Biosystems), run on an ABI 3130
Genetic Analyzer (Applied Biosystems), and repeated on PCR products obtained from new nucleic acid extractions.
All data analyses were performed in a blind fashion.

Statistical Analysis

This report, intended as pilot study, is the first to compare

  • the prevalence of SNPs in genes encoding  several effectors (including ion channels)
  • involved in CBFR between these groups of patients.

No definite sample size could be calculated to establish a power analysis. groups of patients. However, assuming

  • a 15 % prevalence of normal  macrovascular and microvascular coronary findings in unselected patients
    undergoing coronary angiography,

we estimated that

  • a sample size of at least 150 patients could enable the computation of two-sided 95 % confidence intervals for
    • such prevalence estimates ranging between -5.0 and + 5.0 %.

The significance of the differences of observed alleles and genotypes between groups, as well as

  • analysis of multiple inheritance models for SNPs were also tested
    (co-dominant, dominant, recessive, over-dominant and log-additive)
  • using a free web-based application (http://213. 151.99.166/index.php?module=Snpstats)
  • designed from a genetic epidemiology  point of view to analyze association studies.

Akaike Information Criterion (AIC) was used to determine the best-fitting inheritance model for analyzed SNPs,

  • with the model with the lowest AIC reflecting the best balance of  goodness-of-fit and parsimony.

Moreover,  the allelic frequencies were estimated by gene counting, and the genotypes were scored. For each gene,

  • the observed numbers of each genotype were compared with those expected for a population in Hardy–Weinberg (HW) equilibrium
  • using a free web-based application  (http://213.151.99.166/index.php?module=Snpstats) [59].

Linkage disequilibrium coefficient (D0) and  haplotype analyses were assessed using  the  Haploview 4.1 program.
Statistical analysis was performed using SPSS software package for Windows v.16.0 (SPSS Inc., Chicago, IL).

All categorical variables are expressed as percentages, and all continuous variables as mean ± standard deviation.
Differences between categorical variables

  • were analyzed by Pearson’s Chi-SQ test.

Given the presence of three groups, differences  between continuous variables, were calculated using
(including the number of SNPs tested),

  • one-way ANOVA; a post-hoc analysis with Bonferroni correction was made for multiple comparisons.

Univariate and multivariate logistic regression analyses

  • the independent impact of genetic polymorphisms on
    • coronary artery disease and microvascular dysfunction,

were performed to assess the independent impact of

  • genetic polymorphisms on coronary artery disease
    and microvascular dysfunction
    ,

while adjusting for other confounding variables.  The following parameters were entered into the model:

  • age,
  • male gender,
  • type 2 diabetes mellitus (T2DM),
  • systemic arterial hypertension,
  • dyslipidemia,
  • smoking status, and
  • family history of myocardial infarction (MI).

Only variables with a p value < 0.10 after univariate analysis were entered

  • into the multivariable model as covariates.

A two-tailed p < 0.05 was considered statistically significant.

Definition of Cardiovascular Risk Factors

Patients were classified as having T2DM if they had

  • fasting levels of glucose of >126 mg/dL in two separate measurements or
  • if they were taking hypoglycemic drugs.

Systemic arterial hypertension was defined as

  • systolic blood pressure  > 140 mmHg / diastolic blood pressure > 90 mmHg
  • in two separate measurements or
  • if the patient was currently taking antihypertensive drugs.

Dyslipidemia was considered to be present if

  • serum cholesterol levels were>220 mg/dL or
  • if the patient was being treated with cholesterol-lowering drugs.

Family history of MI was defined as a first-degree relative with MI before the age of 60 years.

Results

Sixty-two polymorphisms distributed among six genes coding for
  • nitric oxide synthase,
  • the SERCA pump, and
  • ion channels
    • were screened for sequence variations using PCR amplification and
    • direct DNA sequencing analysis

in the population of

  • 155 patients with CAD (group 1),
  • 46 patients with microvascular dysfunction (group 2), and
  • 41 patients with normal coronary arteries and
    • normal endothelium dependent and endothelium-independent vasodilation (group 3).
In Group 3, the genotype distribution of

  • SNP rs5215 (Kir6.2/KCNJ11) moderately deviates from the HW equilibrium (p = 0.05).
In Group 1 (CAD), the polymorphism

  • rs6599230 of Nav1.5/SCN5A showed deviation from HW equilibrium (p = 0.017).
The genotypic distribution of groups in terms of polymorphisms for
  • eNOS/NOS3, SERCA/ATP2A2, Nav1.5/SCN5A, Kir6.1/KCNJ8, or Kv1.5/KCNA5
were noticed. However, significant differences (p.05) for the SNPs
  • rs5215_GG, and
  • rs5219_AA of Kir6.2/KCNJ11 were observed,
as shown in Table 2. 

Table 3 displays 
significant differences between normal subjects (group 3) and
  • patients with either CAD (group 1) or microvascular dysfunction (group 2).

BRC 2013 fedele genetic polymorphisms of ion channels_page_006

When correcting for other covariates as risk factors, the rs5215_GG genotype of Kir6.2/KCNJ11 was found to be 

  • significantly associated with CAD after multivariate analysis (OR = 0.319, p = 0.047, 95 % CI = 0.100–0.991), evidencing
  • a ‘‘protective’’ role of this genotype, as shown in Table 4a.

Similarly, a trend that supports this role of Kir6.2/KCNJ11 was also observed

  • in microvascular dysfunction for rs5219 AA. In contrast,
  • rs1799983_GT for eNOS/NOS3 was identified as an independent risk factor

following multivariate analysis (Table 4b), which agrees with literature findings as described below. 

BRC 2013 fedele genetic polymorphisms of ion channels_page_007

SOURCE for TABLES

BasicResCardiol(2013)108:387   http//dx.dio.org/10.1007/s00395-013-0387-4

Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest.
Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

REFERENCES

1. Alekseev AE, Hodgson DM, Karger AB, Park S, Zingman LV, Terzic A (2005) ATP-sensitive K? channel channel/enzyme multimer: metabolic gating in the heart. J Mol
Cell Cardiol 38:895–905. doi:10.1016/j.yjmcc.2005.02.022
2. Baumgart D, Naber C, Haude M, Oldenburg O, Erbel R, Heusch G, Siffert W (1999) G protein beta3 subunit 825T allele and enhanced coronary vasoconstriction on
alpha(2)-adrenoceptor activation. Circ Res 85:965–969. doi:10.1161/01.RES.85.10.965
3. Belardinelli L, Shryock JC, Fraser H (2006) Inhibition of the late sodium current as a potential cardioprotective principle: effects of the late sodium current inhibitor
ranolazine. Heart 92:6–14. doi:10.1136/hrt.2005.078790
4. Berwick ZC, Moberly SP, Kohr MC, Morrical EB, Kurian MM, Dick GM, Tune JD (2012) Contribution of voltage-dependent K+ and Ca2+ channels to coronary pressure-
flow autoregulation. Basic Res Cardiol 107:264. doi:10.1007/s00395-012-0264-6
5. Brayden JE (2002) Functional roles of KATP channels in vascular smooth muscle. Clin Exp Pharmacol Physiol 29:312–316. doi:10.1046/j.1440-1681.2002.03650.x
6. Brini M, Carafoli E (2009) Calcium pumps in health and disease. Physiol Rev 89:1341–1378. doi:10.1152/physrev.00032.2008
7. Chen TT, Luykenaar KD, Walsh EJ, Walsh MP, Cole WC (2006) Key role of Kv1 channels in vasoregulation. Circ Res 99:53–60. doi:10.1161/01.RES.0000229654.45090.57
8. Cohen KD, Jackson WF (2005) Membrane hyperpolarization is not required for sustained muscarinic agonist-induced increases in intracellular Ca2+ in arteriolar endothelial
cells. Microcirculation 12:169–182. doi:10.1080/10739680590904973
9. Daut J, Maier-Rudolph W, von Beckerath N, Mehrke G, Gu¨nter K, Goedel-Meinen L (1990) Hypoxic dilation of coronary arteries is mediated by ATP-sensitive potassium
channels. Science 247:1341–1344. doi:10.1126/science.2107575
10. Davidson SM, Duchen MR (2007) Endothelial mitochondria: contributing to vascular function and disease. Circ Res 100:1128–1141. doi:10.1161/01.RES.0000261970.18328.1d
…. 75

SOURCE for References 1-75

Basic Res Cardiol (2013) 108:387   http://dx.doi.org/10.1007/s00395-013-0387-4

Other related articles published on this Open Access Online Scientific Journal include the following: 

ION CHANNEL and Cardiovascular Diseases

https://pharmaceuticalintelligence.com/?s=Ion+Channel

Calcium Role in Cardiovascular Diseases

Part I: Identification of Biomarkers that are Related to the Actin Cytoskeleton

Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/12/10/identification-of-biomarkers-that-are-related-to-the-actin-cytoskeleton/

Part II: Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility

Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/26/role-of-calcium-the-actin-skeleton-and-lipid-structures-in-signaling-and-cell-motility/

Part III: Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease

Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
 and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/02/renal-distal-tubular-ca2-exchange-mechanism-in-health-and-disease/

Part IV: The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure-arterial-smooth-muscle-post-ischemic-arrhythmia-similarities-and-differen/

Part V: Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter

Larry H Bernstein, MD, FCAP
and
Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/12/23/calmodulin-and-protein-kinase-c-drive-the-ca2-regulation-of-hormone-and-neurotransmitter-release-that-triggers-ca2-stimulated-exocytosis/

Part VI: Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/01/calcium-molecule-in-cardiac-gene-therapy-inhalable-gene-therapy-for-pulmonary-arterial-hypertension-and-percutaneous-intra-coronary-artery-infusion-for-heart-failure-contributions-by-roger-j-hajjar/

Part VII: Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure – Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

Part VIII: Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells: The Cardiac and Cardiovascular Calcium Signaling Mechanism

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/12/disruption-of-calcium-homeostasis-cardiomyocytes-and-vascular-smooth-muscle-cells-the-cardiac-and-cardiovascular-calcium-signaling-mechanism/

Part IX: Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction (Ryanopathy) and Calcium as Neurotransmitter Sensor

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/16/calcium-channel-blocker-calcium-as-neurotransmitter-sensor-and-calcium-release-related-contractile-dysfunction-ryanopathy/

Part X: Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

Part XI: Sensors and Signaling in Oxidative Stress

Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/11/01/sensors-and-signaling-in-oxidative-stress/

Part XII: Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

Mitochondria and Oxidative Stress Role in Cardiovascular Diseases

Reversal of Cardiac Mitochondrial Dysfunction

Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/04/14/reversal-of-cardiac-mitochondrial-dysfunction/

Calcium Signaling, Cardiac Mitochondria and Metabolic Syndrome

Larry H. Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/11/09/calcium-signaling-cardiac-mitochondria-and-metabolic-syndrome/

Mitochondrial Dysfunction and Cardiac Disorders

Larry H. Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2013/04/14/mitochondrial-dysfunction-and-cardiac-disorders/

Mitochondrial Metabolism and Cardiac Function

Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/04/14/mitochondrial-metabolism-and-cardiac-function/

Mitochondria and Cardiovascular Disease: A Tribute to Richard Bing

Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/04/14/chapter-5-mitochondria-and-cardiovascular-disease/

MIT Scientists on Proteomics: All the Proteins in the Mitochondrial Matrix Identified

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/02/03/mit-scientists-on-proteomics-all-the-proteins-in-the-mitochondrial-matrix-identified/

Mitochondrial Dynamics and Cardiovascular Diseases

Ritu Saxena, Ph.D.

https://pharmaceuticalintelligence.com/2012/11/14/mitochondrial-dynamics-and-cardiovascular-diseases/

Mitochondrial Damage and Repair under Oxidative Stress

Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/10/28/mitochondrial-damage-and-repair-under-oxidative-stress/

Nitric Oxide has a Ubiquitous Role in the Regulation of Glycolysis -with a Concomitant Influence on Mitochondrial Function

Larry H. Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2012/09/16/nitric-oxide-has-a-ubiquitous-role-in-the-regulation-of-glycolysis-with-a-concomitant-influence-on-mitochondrial-function/

Mitochondrial Mechanisms of Disease in Diabetes Mellitus

Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/08/01/mitochondrial-mechanisms-of-disease-in-diabetes-mellitus/

Mitochondria Dysfunction and Cardiovascular Disease – Mitochondria: More than just the “Powerhouse of the Cell”

Ritu Saxena, PhD

https://pharmaceuticalintelligence.com/2012/07/09/mitochondria-more-than-just-the-powerhouse-of-the-cell/

Read Full Post »


Ischemic Stable CAD: Medical Therapy and PCI no difference in End Point: Meta-Analysis of Contemporary Randomized Clinical Trials

Reporter: Aviva Lev-Ari, PhD, RN

 

SOURCE

Stergiopoulos K, Boden WE, Hartigan P, et al. Percutaneous coronary intervention outcomes in patients with stable obstructive coronary artery disease and myocardial ischemia: A collaborative meta-analysis of contemporary randomized clinical trialsJAMA Intern Med 2013; DOI:10.1001/jamainternmed.2013.12855. Available at:http://www.jamainternalmedicine.com.

 

PCI No Benefit Over Medical Therapy in Ischemic Stable CAD

December 02, 2013

NEW YORK, NY — A new analysis is calling into question the de facto rationale for many of the revascularization procedures taking place today, at least in patients with stable coronary artery disease[1]. In a meta-analysis of more than 5000 patients, PCI was no better than medical therapy in patients with documented ischemia by stress testing or fractional flow reserve (FFR).

“Cardiology has a long history of finding a marker of a bad outcome and treating that marker of that bad outcome as if it were the cause of the bad outcome,” senior author on the study, Dr David Brown (State University of New York [SUNY]–Stony Brook School of Medicine), told heartwire . In the case of proceeding to PCI on the basis of documented ischemia, that stems from evidence that patients with ischemia have a worse prognosis than patients who don’t.”It has gotten to the point that a positive stress test [is the gateway] to doing an intervention, even if the ischemia is not in the same ischemic territory as the vessel being treated,” he said. “The medical/industrial complex in cardiology is now focused on finding and treating ischemia, and I think that’s not justified, and these data suggest that that’s not justified.”

Brown and colleagues, with first author Dr Kathleen Stergiopoulus (SUNY–Stony Brook School of Medicine), reviewed the literature for randomized clinical trials of PCI and medical therapy for stable CAD conducted over the past 40 years, ultimately including five trials of 5286 patients. These were a small German trial published in 2004, plus MASS II COURAGE , BARI 2D , and FAME 2 . In all, 4064 patients had myocardial ischemia documented by exercise, nuclear or echo stress imaging, or FFR.

Over a median follow-up of five years, mortality, nonfatal MI, unplanned revascularization, and angina were no different between patients treated medically vs those treated with PCI.

Odds Ratio, PCI vs Medical Therapy

Outcome Odds ratio 95% CI
Death 0.90 0.71–1.16
Nonfatal MI 1.24 0.99–1.56
Unplanned revascularization 0.64 0.35–1.17
Angina 0.91 0.57–1.44

“These findings are unique in that this is the first meta-analysis to our knowledge limited to patients with documented, objective findings of myocardial ischemia, almost all of whom underwent treatment with intracoronary stents and disease-modifying secondary-prevention therapy,” Stergiopoulus et al write.

The findings, they continue, “strongly suggest that the relationship between ischemia and mortality is not altered or ameliorated by catheter-based revascularization of obstructive, flow-limiting coronary stenosis.”

To heartwire , Brown pointed out that their analysis could not separate out patients who had small amounts of ischemia from those with larger ischemic territories. “Maybe that’s where the differentiating factor will be,” he acknowledged, adding that the 8000-patient ISCHEMIA trial, still ongoing, will hopefully yield some insights.

Current practice, however, is to check for ischemia and to proceed with catheterization and, usually, revascularization when ischemia is confirmed by stress testing or during FFR. “But if that doesn’t improve outcomes, why are we doing it?” Brown asked. “We think that needs to be rethought.”

There’s never been a better time to take advantage of accredited nursing degree programs designed to fit your busy schedule.
Information from Industry

Commenting on the study for heartwire Dr Peter Berger(Geisinger Health System, Danville, PA) pointed out: “There is no question that PCI is more effective than medical therapy for relief of symptoms: the more severe the angina and the more active the patient, the greater the superiority of PCI.” And, as Berger noted, most of the studies included in this analysis documented ischemia but did not report on the frequency or severity of angina at baseline.

That said, “Patients with minimal angina—and certainly those with silent ischemia but no angina—are unlikely to have a significantly greater reduction of symptoms with PCI, and PCI is rarely beneficial in such patients.”

Moreover, Berger continued, it has been clearly established that PCI does not reduce the risk of death or MI in most such patients.

“I very much agree with the authors, however, that just because more severe ischemia has been shown to be associated with a worse long-term prognosis, reducing the ischemic burden ought not be assumed to reduce the likelihood of death or MI. In most such patients, it does not.”

Stergiopoulos and Brown had no disclosures. Disclosures for the coauthors are listed in the paper.

SOURCE 

Read Full Post »


Reporter: Aviva Lev-Ari, PhD, RN

We decided to include ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery in this Scientific Journal as a Reference resource to all our Experts, Authors, Writers.

Example of the Guidelines in use in this Journal:

Mitral Valve Repair: Who is a Patient Candidate for a Non-Ablative Fully Non-Invasive Procedure?

https://pharmaceuticalintelligence.com/2013/11/04/mitral-valve-repair-who-is-a-candidate-for-a-non-ablative-fully-non-invasive-procedure/

SOURCE

ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery

http://circ.ahajournals.org/content/100/13/1464.long

  • ACC/AHA Practice Guidelines

ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery: Executive Summary and Recommendations

A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1991 Guidelines for Coronary Artery Bypass Graft Surgery)

  1. Committee Members
  1. Kim A. Eagle, MD, FACC, Cochair;
  2. Robert A. Guyton, MD, FACC, Cochair;
  3. Ravin Davidoff, MB, BCh, FACC;
  4. Gordon A. Ewy, MD, FACC;
  5. James Fonger, MD;
  6. Timothy J. Gardner, MD, FACC;
  7. John Parker Gott, MD, FACC;
  8. Howard C. Herrmann, MD, FACC;
  9. Robert A. Marlow, MD, MA, FAAFP;
  10. William Nugent, MD;
  11. Gerald T. O’Connor, PhD, DSc;
  12. Thomas A. Orszulak, MD;
  13. Richard E. Rieselbach, MD, BS, FACP;
  14. William L. Winters, MD, FACC;
  15. Salim Yusuf, MB, BS, PhD
  1. Task Force Members
  1. Raymond J. Gibbons, MD, FACC, Chair;
  2. Joseph S. Alpert, MD, FACC;
  3. Kim A. Eagle, MD, FACC;
  4. Timothy J. Gardner, MD, FACC;
  5. Arthur Garson Jr, MD, MPH, FACC;
  6. Gabriel Gregoratos, MD, FACC;
  7. Richard O. Russell, MD, FACC;
  8. Thomas J. Ryan, MD, FACC;
  9. Sidney C. Smith Jr, MD, FACC

Key Words:

I. Introduction

The American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Practice Guidelines was formed to make recommendations regarding the appropriate use of diagnostic tests and therapies for patients with known or suspected cardiovascular disease. Coronary artery bypass graft (CABG) surgery is among the most common operations performed in the world and accounts for more resources expended in cardiovascular medicine than any other single procedure. Since the original Guidelines were published in 1991, there has been considerable evolution in the surgical approach to coronary disease, and at the same time there have been advances in preventive, medical, and percutaneous catheter approaches to therapy. These revised guidelines are based on a computerized search of the English literature since 1989, a manual search of final articles, and expert opinion.

As with other ACC/AHA guidelines, this document uses ACC/AHA classifications I, II, and III as summarized below:

Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective.

Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness or efficacy of a procedure.

Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy.

Class IIb: Usefulness/efficacy is less well established by evidence/opinion.

Class III: Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful.

II. Outcomes

A. Hospital Outcomes

Seven core variables (priority of operation, age, prior heart surgery, sex, left ventricular [LV] ejection fraction [EF], percent stenosis of the left main coronary artery, and number of major coronary arteries with significant stenoses) are the most consistent predictors of mortality after coronary artery surgery. The greatest risk is correlated with the urgency of operation, advanced age, and 1 or more prior coronary bypass surgeries. Additional variables that are related to mortality include coronary angioplasty during index admission; recent myocardial infarction (MI); history of angina, ventricular arrhythmias, congestive heart failure, or mitral regurgitation; and comorbidities such as diabetes, cerebrovascular disease, peripheral vascular disease, chronic obstructive pulmonary disease, and renal dysfunction. Table 1 shows a method by which key patient variables can be used to predict an individual patient’s operative risk of death, stroke, or mediastinitis.

B. Morbidity Associated With Bypass Surgery

1. Neurological Events

Neurological impairment after bypass surgery may be attributable to hypoxia, emboli, hemorrhage, and/or metabolic abnormalities. Postoperative neurological deficits have been divided into 2 types: type 1, associated with major, focal neurological deficits, stupor, or coma; and type 2, in which deterioration in intellectual function is evident. Adverse cerebral outcomes are observed in ≈6% of patients after bypass surgery and are equally divided between type 1 and type 2 deficits. Predictors of cerebral complications after bypass surgery include advanced age and a history of hypertension. Particular predictors of type 1 deficits include proximal aortic atherosclerosis as defined by the surgeon at operation, history of prior neurological disease, use of the intra-aortic balloon pump, diabetes, hypertension, unstable angina, and increased age. Predictors of type 2 deficits include a history of excess alcohol consumption; dysrhythmias, including atrial fibrillation; hypertension; prior bypass surgery; peripheral vascular disease; and congestive heart failure. Estimation of a patient’s risk for postoperative stroke can be calculated from Table 1.

2. Mediastinitis

Deep sternal wound infection occurs in 1% to 4% of patients after bypass surgery and carries a mortality of ≈25%. Predictors of this complication include obesity, reoperation, use of both internal mammary arteries at surgery, duration and complexity of surgery, and diabetes. An individual patient’s risk of postoperative mediastinitis can be estimated from Table 1.

3. Renal Dysfunction

Postoperative renal dysfunction occurs in as many as 8% of patients. Among patients who develop postoperative renal dysfunction (defined as a postoperative serum creatinine level >2.0 mg/dL or an increase in baseline creatinine level of >0.7 mg/dL), 18% require dialysis. Overall mortality among patients who develop postoperative renal dysfunction is 19% and approaches two thirds among patients requiring dialysis. Predictors of renal dysfunction include advanced age, a history of moderate or severe congestive heart failure, prior bypass surgery, type 1 diabetes, and prior renal disease. Table 2 can be used to estimate the risk for an individual patient. Patients with advanced preoperative renal dysfunction who undergo CABG surgery have an extraordinarily high rate of requiring postoperative dialysis. Among patients with a preoperative creatinine level >2.5 mg/dL, 40% to 50% require hemodialysis.

Table 2.

Risk of Postoperative Renal Dysfunction (PRD) After Coronary Artery Bypass Graft Surgery

C. Long-Term Outcomes

Predictors of poor long-term survival after bypass surgery include advanced age, poor LVEF, diabetes, number of diseased vessels, and female sex. In some studies, additional predictors include angina class, hypertension, prior MI, renal dysfunction, and clinical congestive heart failure. Predictors of the recurrence of angina, late MI, or any cardiac event also include obesity and lack of use of an internal mammary artery, as well as those factors identified above. Of these events, the return of angina is the most common and is primarily related to late vein-graft atherosclerosis and occlusion.

III. Comparison of Medical Therapy Versus Surgical Revascularization

The comparison of medical therapy with coronary surgical revascularization is primarily based on randomized, clinical trials and large registries. Although clinical trials have provided valuable insights, there are limitations to their interpretation in the current era. Patient selection had primarily included individuals ≤65 years of age, very few included large cohorts of women, and for the most part, the studies evaluated patients at low risk who were clinically stable. In addition, because the studies were done in the late 1970s and early 1980s, only 1 of the trials used arterial grafts, and even that trial had no arterial grafts in 86% of patients. Newer modalities of cardioprotection during cardiopulmonary bypass were not used, nor were minimally invasive or off-bypass techniques. Finally, medical therapy was not optimized in the trials. Lipid-lowering therapy had not yet become standard, aspirin was not widely used, and β-blockers were used in just half of the patients. Angiotensin-converting enzyme inhibitors were not being routinely used in patients with congestive heart failure or dilated cardiomyopathy. Accordingly, although the clinical trials have provided important insights, their interpretation must be viewed with caution, given the evolution in all types of coronary therapies.

For the most part, stratification of patients in the trials was based on the number of vessels with anatomically significant disease, whether or not the major epicardial obstruction was proximal, and the extent of LV dysfunction as determined by global EF. The end point of the trials was primarily survival.

Overview: Randomized Trials

There were 3 major, randomized trials and several smaller ones. A collaborative meta-analysis of 7 trials with a total enrollment of 2649 patients has allowed comparison of outcomes at 5 and 10 years (Tables 3, 4, and 5 and the Figure). Among all patients, the extension survival of CABG surgical patients compared with medically treated patients was 4.3 months at 10 years of follow-up. The benefit of CABG compared with medical therapy in various clinical subsets is presented below.

Figure 1.

Extension of survival after 10 years of follow-up in various subgroups of patients, from a meta-analysis of 7 randomized studies. LV indicates left ventricular; VA, Veterans Administration.

Table 3.

Total Mortality at 5 and 10 Years

Table 4.

Subgroup Results at 5 Years

Table 5.

Subgroup Analysis of 5-Year Mortality by Risk Stratum

1. Left Main Coronary Artery Disease

The trials defined significant left main coronary artery stenosis as a >50% reduction in lumen diameter. Median survival for surgically treated patients was 13.3 years versus 6.6 years in medically treated patients. Left main equivalent disease (≥70% stenosis in both the proximal left anterior descending [LAD] and proximal left circumflex arteries) appeared to behave similarly to true left main coronary artery disease. Median survival for surgical patients was 13.1 years versus 6.2 years for medically assigned patients. The benefit of surgery for left main coronary artery disease patients continued well beyond 10 years. By 15 years, it was estimated that two thirds of patients originally assigned to medical therapy and who survived would have had surgery. The 15-year cumulative survival for left main coronary artery disease patients having CABG surgery was 44% versus 31% for medical patients.

2. Three-Vessel Disease

If one defines 3-vessel disease as stenosis of 50% or more in all 3 major coronary territories, the overall extension of survival was 7 months in CABG patients compared with medically treated patients. Patients with class III or IV angina, those with more proximal and severe LAD stenosis, those with worse LV function, and/or those with more positive stress tests derived more benefit from surgery.

3. Proximal LAD Disease

In patients with severe, proximal LAD stenosis, the relative risk reduction due to bypass surgery compared with medical therapy was 42% at 5 years and 22% at 10 years. This was even more striking in patients with depressed LV function.

4. LV Function

In patients with mildly to moderately depressed LV function, the poorer the LV function, the greater was the potential advantage of CABG surgery. Although the relative benefit was similar, the absolute benefit was greater because of the high-risk profile of these patients.

5. Symptoms and Quality of Life

Improvement in symptoms and quality of life after bypass surgery parallels the outcome data regarding survival. Beyond survival, bypass surgery may be indicated to alleviate symptoms of angina above and beyond medical therapy or to reduce the incidence of nonfatal complications like MI, congestive heart failure, and hospitalization. Registry studies have shown a reduction in late MI among highest-risk patients, such as those with 3-vessel disease, and/or those with severe angina. In pooled analyses, a benefit on the incidence of MI was not evident. This result likely reflected an early increase in MI perioperatively after CABG, which was balanced by fewer MIs over the long term among CABG recipients. Antianginal medications were required less frequently after bypass surgery. At 5 years, two thirds of bypass patients were symptom-free compared with 38% of medically assigned patients. By 10 years, however, these differences were no longer significant. This result is related to the attrition of vein grafts in the bypass group as well as crossover of medically assigned patients to bypass surgery.

6. Loss of Benefit of Surgery

After 10 to 12 years of follow-up, there was a tendency for the bypass surgery and medical therapy curves to converge, in regard to both survival as well as nonfatal outcomes. This convergence is due to a number of factors. First, the reduced life expectancy of patients with coronary disease (regardless of treatment) leads to a steady attrition. Second, the increased event rate in the late follow-up period of surgically assigned patients was likely related to the progression of native coronary disease and graft disease over time. Finally, medically assigned patients crossed over to surgery late, thus allowing the highest-risk medically assigned patients to gain from the benefit of surgery later in the course of follow-up. By 10 years, 37% to 50% of medically assigned patients had crossed over to surgery. Tables 3, 4, and 5 and the Figure provide estimates of long-term outcomes among patients randomized in the trials. These tables and the Figure can be used to estimate the general survival expectations in various anatomic categories.

IV. Comparison of Bypass Surgery With Percutaneous Revascularization

The results of a number of randomized, clinical trials comparing angioplasty and bypass surgery have been published. The trials excluded patients in whom survival had already been shown to be longer with bypass surgery than with medical therapy. Also, none of the trials was sufficiently large to detect relatively modest differences in survival between the 2 techniques. Most of the trials did not have a long-term follow-up, ie, 5 to 10 years, and therefore were unable to provide clear inferences regarding long-term benefit of the 2 techniques in similar populations. Also, and perhaps most notably, only ≈5% of screened patients with multivessel disease at enrolling institutions were included in the trials. Half of the patients approached were ineligible owing to left main coronary artery disease, insufficient symptoms, or other reasons. Even among a large group of patients with multivessel disease suitable for enrollment, only half were actually randomized. It appeared that physicians elected not to enroll many patients with 3-vessel disease in the trials but rather refer them for bypass surgery, whereas patients with 2-vessel disease tended to be referred for angioplasty rather than be enrolled in the trials.

Overall, procedural complications were low for both procedures but tended to be higher with CABG surgery (Table 6). For patients randomized to angioplasty, CABG was needed in ≈6% during the index hospitalization and in nearly 20% by 1 year. The initial cost and length of stay were lower for angioplasty than for CABG. Patients having angioplasty returned to work sooner and were able to exercise more at 1 month. The extent of revascularization achieved by bypass surgery was generally higher than with angioplasty. Long-term survival was difficult to evaluate owing to the short period of follow-up and the small sample size of the trials. However, for the Bypass Angioplasty Revascularization Investigation (BARI) trial, bypass patients had a 5-year survival of 89.3% compared with 86.3% for angioplasty. Secondary analysis revealed that in treated diabetic patients in the BARI trials, CABG led to significantly superior survival compared with percutaneous transluminal coronary angioplasty (PTCA). However, this finding was not evident in other trials. In long-term follow-up, the most striking difference was the 4- to 10-fold-higher likelihood of reintervention after initial PTCA. Quality of life, physical activity, employment, and cost were similar by 3 to 5 years after both procedures. The BARI trial suggested higher mortality associated with PTCA in several high-risk groups, including those with diabetes, unstable angina, and/or non–Q wave MI, and in patients with heart failure.

Table 6.

CABG vs PTCA: Randomized Controlled Trials

An analysis of registries generally shows data similar to those of the trials. However, a recent analysis of ≈60 000 patients who were treated in New York State in the early 1990s provides a 3-year survival analysis of patients undergoing CABG and PTCA. After adjustment for various covariates, bypass surgery in the New York State registry experience was associated with longer survival in patients with severe proximal LAD stenosis and/or 3-vessel disease. Contrariwise, patients with 1-vessel disease not involving the proximal LAD had improved survival with PTCA. Table 7 summarizes survival data from the New York State registry with respect to various cohorts of patients undergoing angioplasty or bypass surgery. These data can be used to estimate 3-year survival expectations for patients with various anatomic features.

Table 7.

Three-Year Survival by Treatment in Each Anatomic Subgroup

V. Management Strategies

Reduction of Perioperative Mortality and Morbidity

1. Reducing the Risk of Type 1 Brain Injury After CABG

Postoperative neurological complications represent 1 of the most devastating consequences of CABG surgery. Type 1 injury, in which a significant, permanent, neurological injury is sustained, occurs in ≈3% of patients overall and is responsible for a 21% mortality.

Atherosclerotic Ascending Aorta

An important predictor of this complication is the surgeon’s identification of a severely atherosclerotic, ascending aorta before or during the bypass operation. Perioperative atheroembolism from aortic plaque is thought to be responsible for approximately one third of strokes after CABG. Atherosclerosis of the ascending aorta is strongly related to increased age. Thus, stroke risk is particularly increased in patients beyond 75 to 80 years of age. Preoperative, noninvasive testing to identify high-risk patients has variable accuracy. Computed tomography identifies the most severely involved aortas but underestimates mild or moderate involvement. Transesophageal echocardiography is useful for aortic arch examination, but examination of the ascending aorta may be limited by the intervening trachea. Intraoperative assessment with epiaortic imaging is superior to both methods. Intraoperative palpation underestimates the high-risk aorta. The highest-risk aortic pattern is a protruding or mobile aortic arch plaque. An aggressive approach to the management of patients with severely diseased ascending aortas identified by intraoperative echocardiographic imaging reduces the risk of postoperative stroke. For patients with aortic walls ≤3 mm thick, standard treatment is used. For aortas >3 mm thick, the cannulation, clamp, or proximal anastomotic sites may be changed, or a no-clamp, fibrillatory arrest strategy may be used. For high-risk patients with multiple or circumferential involvement or those with extensive middle ascending aortic involvement, replacement of the ascending aorta under hypothermic circulatory arrest may be indicated. Alternatively, a combined approach with off-bypass, in situ internal mammary grafting to the LAD and percutaneous coronary intervention to treat other vessel stenoses has conceptual merit.

Atrial Fibrillation and Stroke

Chronic atrial fibrillation is a hazard for perioperative stroke. Intraoperative surgical manipulation or spontaneous resumption of sinus rhythm during the early postoperative period may lead to embolism of a left atrial clot. One approach to reduce this risk is the performance of preoperative, transesophageal echocardiography. The absence of a left atrial clot would suggest that the operation may proceed with acceptable risk. For elective patients, if a left atrial clot is identified, 3 to 4 weeks of anticoagulation therapy followed by restudy and then subsequent surgery is reasonable. Few clinical trial data are available to assist clinicians in this circumstance.

New-onset postoperative atrial fibrillation occurs in ≈30% of post-CABG patients, particularly on the second and third postoperative days, and is associated with a 2- to 3-fold increased risk of postoperative stroke. Risk factors include advanced age, chronic obstructive pulmonary disease, proximal right coronary disease, prolonged operation, atrial ischemia, and withdrawal of β-blockers. The role of anticoagulants in patients who develop post-CABG atrial fibrillation is unclear. Aggressive anticoagulation and cardioversion may reduce the neurological complications associated with this arrhythmia. Early cardioversion within 24 hours of the onset of atrial fibrillation can probably be performed safely without anticoagulation. However, persistence of the arrhythmia beyond this time argues for the use of oral anticoagulants to reduce stroke risk in patients who remain in atrial fibrillation and/or in those for whom later cardioversion is planned.

Recent MI, LV Thrombus, and Stroke

Patients with a recent, anterior MI and residual wall-motion abnormality are at increased risk for the development of an LV mural thrombus and its potential for embolization. For patients undergoing surgical revascularization after sustaining an anterior MI, preoperative screening with echocardiography may be appropriate to identify the presence of a clot. Detection of an acute LV mural thrombus may call for long-term anticoagulation and reevaluation by echocardiography to ensure resolution or organization of the thrombus before coronary bypass surgery. Additionally, 3 to 6 months of anticoagulation therapy is appropriate for patients with persistent, anterior wall–motion abnormalities after coronary bypass surgery.

Recent, Antecedent Cerebrovascular Event

A recent, preoperative cerebrovascular accident represents a situation in which delaying surgery may reduce the perioperative neurological risk. In particular, evidence of a hemorrhagic component based on computed tomographic scan identifies high risk for the extension of neurological damage with cardiopulmonary bypass. It is generally believed that a delay of 4 weeks or more after a cerebrovascular accident is prudent, if coronary anatomy and symptoms permit, before proceeding with CABG.

Carotid Disease and Neurological Risk Reduction

Hemodynamically significant carotid stenoses are thought to be responsible for up to 30% of early postoperative strokes. The trend for coronary surgery to be performed in an increasingly elderly population and the increasing prevalence of carotid disease in this same group of patients underscore the importance of this issue. Perioperative stroke risk is thought to be <2% when carotid stenoses are <50%, 10% when stenoses are 50% to 80%, and 11% to 19% in patients with stenoses >80%. Patients with untreated, bilateral, high-grade stenoses and/or occlusions have a 20% chance of stroke. Carotid endarterectomy for patients with high-grade stenosis is generally done preceding or coincident with coronary bypass surgery and, with proper teamwork in high-volume centers, is associated with a low risk for both short- and long-term neurological sequelae. Carotid endarterectomy performed in this fashion carries a low mortality (3.5%) and reduces early postoperative stroke risk to <4%, with a concomitant 5-year freedom from stroke of 88% to 96%.

The decision about who should undergo preoperative carotid screening is controversial. Predictors of important carotid stenosis include advanced age, female sex, known peripheral vascular disease, previous transient ischemic attack or stroke, a history of smoking, and left main coronary artery disease. Many centers screen all patients >65 years old. Patients with left main coronary disease are often screened, as are those with a previous transient ischemic attack or stroke. Preoperative central nervous system symptoms suggestive of vertebral basilar insufficiency should lead to an evaluation before elective CABG.

When surgery of both carotid and coronary disease is planned, the most common approach is to perform the operation in a staged manner, in which the patient first has carotid surgery followed by coronary bypass in 1 to 5 days. Alternatively, especially if the patient has compelling cardiac symptoms or coronary anatomy, the operations may be performed during a single period of anesthesia, with the carotid endarterectomy immediately preceding coronary bypass. Neither strategy has been established as being superior. Stroke risk is increased if a reversed-stage procedure is used, in which the coronary bypass operation precedes the carotid endarterectomy by ≥1 day.

2. Reducing the Risk of Type 2 Brain Injury

Type 2 neurological complications are seen in ≈3% of patients and are correlated with a 10% risk of postoperative death, with 40% of patients requiring additional care in a transitional facility after hospital discharge. Microembolization is thought to be a major contributor to the postoperative cerebral dysfunction after CABG. The release of microemboli during extracorporeal circulation, involving small gaseous or lipid emboli, may be responsible. The use of a 40-μm arterial-line filter on the heart-lung machine circuit and routine use of membrane oxygenators rather than bubble oxygenators may reduce such neurological injury. Additional maneuvers to reduce type 2 neurological injury include the maintenance of steady, cerebral blood flow during cardiopulmonary bypass, avoidance of cerebral hyperthermia during and after cardiopulmonary bypass, meticulous control of perioperative hyperglycemia, and avoidance and limitation of postoperative cerebral edema.

3. Reducing the Risk of Perioperative Myocardial Dysfunction

Protection in Patients With Normal LV Function

There is no universally applicable myocardial protection technique. Among patients with preserved preoperative cardiac function, no strong argument can currently be made for warm versus cold and crystalloid versus blood cardioplegia. However, certain techniques may offer a wider margin of safety for special patient subsets.

Myocardial Protection for Acutely Depressed Cardiac Function

Several studies have suggested that blood cardioplegia (compared with crystalloid) may offer a greater margin of safety during CABG performed on patients with acute coronary occlusion, failed angioplasty, urgent revascularization for unstable angina, and/or chronically impaired LV function.

Protection for Chronically Depressed LV Function

The use of a prophylactic intra-aortic balloon pump as an adjunct to myocardial protection may reduce mortality in patients having CABG in the setting of severe LV dysfunction (eg, LVEF <0.25). Placement of the intra-aortic balloon pump immediately before operation appears to be as effective as placement on the day preceding bypass surgery.

Adjuncts to Myocardial Protection

Although it is widely appreciated that use of the internal mammary artery leads to improved long-term survival after coronary bypass surgery, it has also been documented that use of the internal mammary artery influences operative mortality itself. Thus, internal mammary artery use should be encouraged in the elderly, emergent, or acutely ischemic patient and other patient groups.

Inferior Infarct With Right Ventricular Involvement

An acutely infarcted right ventricle is at great risk for severe, postoperative dysfunction and predisposes the patient to a higher postoperative mortality. During operation, loss of the pericardial constraint may lead to acute dilatation of the dysfunctional right ventricle, which then fails to recover even with optimal myocardial protection and revascularization. The best defense against right ventricular dysfunction is its recognition during preoperative evaluation. When possible, CABG should be delayed for ≥4 weeks to allow the right ventricle to recover.

4. Reducing the Systemic Consequences of Cardiopulmonary Bypass

A variety of measures have been tried to reduce the systemic consequences of cardiopulmonary bypass, which elicits a diffuse inflammatory response that may cause transient or prolonged multisystem organ dysfunction. Administration of corticosteroids before cardiopulmonary bypass may reduce complement activation and release of proinflammatory cytokines. Proper timing and duration of corticosteroid application are incompletely resolved. The administration of the serine protease inhibitor aprotinin may attenuate complement activation and cytokine release during extracorporeal circulation. Unfortunately, aprotinin is relatively expensive. Another method to reduce the inflammatory response is perioperative leukocyte depletion through hematologic filtration.

5. Reducing the Risk of Perioperative Infections

Several methods exist to reduce the risk of wound infections in patients undergoing CABG. These begin with interval reporting to individual surgeons regarding their respective wound infection rates and adherence to sterile operative techniques. Additional strategies include skin preparation with topical antiseptics, clipping rather than shaving the skin, avoidance of hair removal, reduction of operating room traffic, laminar-flow ventilation, shorter operation, minimization of electrocautery, avoidance of bone wax, use of double-glove barrier techniques for the operating room team, and routine use of a pleural pericardial flap. Aggressive, perioperative glucose control in diabetics through the use of continuous, intravenous insulin infusion reduces perioperative hyperglycemia and its associated infection risk. Avoidance of homologous blood transfusions after CABG may reduce the risk of both viral and bacterial infections. This is due to an immunosuppressive effect of transfusion. Leukodepletion of transfused blood also reduces this effect. This can be accomplished by regional blood blanks at the time of donation or at the bedside by use of a transfusion filter.

Preoperative antibiotic administration reduces the risk of postoperative infection 5-fold. Efficacy is dependent on adequate drug tissue levels before microbial exposure. Cephalosporins are currently the agents of choice. Table 8 identifies appropriate choices, doses, and routes of therapy. A 1-day course of intravenous antimicrobials is as effective as 48 hours or more. Therapy should be administered within 30 minutes of incision and again in the operating room if the operation exceeds 3 hours. Many centers deliver antibiotics just before incision. One fail-safe method is to have the anesthesiologist administer the cephalosporin after induction but before skin incision. If deep sternal wound infection does occur, aggressive surgical debridement and early vascularized muscle flap coverage are the most effective methods for treatment, along with long-term systemic antibiotics.

Table 8.

Prophylactic Antimicrobials for Coronary Artery Bypass Graft Surgery

6. Prevention of Postoperative Dysrhythmias

Postoperative atrial fibrillation increases the length of stay, cost, and most important, the risk of stroke. Atrial fibrillation occurs in up to 30% of patients, usually on the second or third postoperative day. Methods to avoid atrial fibrillation are several. First, withdrawal of preoperative β-blockers in the postoperative period doubles the risk of atrial fibrillation after CABG. Thus, early reinitiation of β-blockers is critical for avoidance of this complication. Virtually every study of patients receiving β-blockers prophylactically has shown benefit in lowering the frequency of atrial fibrillation. Most have used the drug in the postoperative period, but greater benefit may occur if β-blockade is begun before the operation. More recently, small studies of propafenone, sotalol, and amiodarone have also shown effectiveness in reducing the risk of postoperative atrial fibrillation. Table 9provides a review of pharmacological approaches in the randomized trials. Digoxin and calcium channel blockers have no consistent benefit for preventing atrial fibrillation after CABG, although they are frequently used to control its rate after it does occur. Currently, the routine preoperative or early postoperative administration of β-blockers is considered standard therapy to reduce the risk of atrial fibrillation after CABG.

Table 9.

Pharmacological Strategies for Prevention of Atrial Fibrillation (AF) After Coronary Artery Bypass Graft Surgery

7. Strategies to Reduce Perioperative Bleeding and Transfusion Risk

Transfusion Risk

Despite the increasing safety of homologous blood transfusion, concerns surrounding viral transmission during transfusion remain. Currently, the risks are likely very low and have been estimated to be 1/493 000 for human immunodeficiency virus, 1/641 000 for human T-cell lymphotrophic virus, 1/103 000 for hepatitis C virus, and 1/63 000 for hepatitis B virus.

Perioperative Bleeding

Risk factors for blood transfusion after CABG include advanced age, low preoperative red blood cell volume, preoperative aspirin therapy, urgent operation, duration of cardiopulmonary bypass, recent thrombolytic therapy, reoperation, and differences in heparin management. Institutional protocols that establish minimum thresholds for transfusion lead to a reduced number of units transfused and the percentage of patients requiring blood. Additional strategies can reduce the transfusion requirement after CABG. For stable patients, aspirin and other antiplatelet drugs may be discontinued 7 days before elective CABG. Aprotinin, a serum protease inhibitor with antifibrinolytic activity, also decreases postoperative blood loss and transfusion requirements in high-risk patients. Although there has been some concern that aprotinin may reduce early graft patency, recent studies have failed to document this effect. Routine use of aprotinin is limited by its high cost. Multidisciplinary approaches to conserve blood in single institutions appear to be effective.

For patients without exclusions, such as low hemoglobin values, heart failure, unstable angina, left main coronary artery disease, or advanced anginal symptoms, self-donation of 1 to 3 units of red blood cells over 30 days before operation reduces the need for homologous transfusion during or after operation. Donation immediately before cardiopulmonary bypass yields a higher platelet and hemoglobin count compared with simple hemodilution without pre–cardiopulmonary bypass blood harvesting.

8. Antiplatelet Therapy for Saphenous Vein Graft Patency

Aspirin significantly reduces vein graft closure during the first postoperative year. The aspirin should be started within 24 hours after surgery because its benefit on saphenous vein graft patency is lost when begun later. Dosing regimens from as little as 100 mg/d to as much as 325 mg TID appear to be efficacious. Ticlopidine offers no advantage over aspirin but is an alternative in truly aspirin-allergic patients. Life-threatening neutropenia is a rare but recognized side effect. Clopidogrel offers the potential for fewer side effects compared with ticlopidine as an alternative in aspirin-allergic patients. Its incidence of severe leukopenia is rare.

9. Pharmacological Management of Hyperlipidemia

Aggressive treatment of hypercholesterolemia reduces progression of atherosclerotic vein graft disease in patients after bypass surgery. Statin therapy has been shown to reduce saphenous vein graft disease progression over the ensuing years after bypass. Patients with unknown low-density lipoprotein (LDL) cholesterol levels after bypass should have cholesterol levels determined and treated pharmacologically if the LDL exceeds 100 mg/dL. Patients with treated LDL cholesterol should have their low-fat diet and cholesterol-lowering medications continued after bypass surgery to reduce subsequent graft attrition. Data regarding the benefit of cholesterol lowering after bypass surgery are most supported by studies that have used HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors, particularly targeting LDL levels to <100 mg/dL.

10. Hormonal Manipulation

While observational studies have suggested that hormone replacement therapy in postmenopausal women leads to a reduction in all-cause mortality, a recent, randomized trial for secondary coronary prevention failed to show a beneficial effect on the overall rate of coronary events. Thus, hormone replacement therapy should be considered in postmenopausal women after bypass when, in the physician’s judgment, the potential coronary benefit is not offset by an increased risk of uterine or breast cancer.

11. Smoking Cessation

Smoking cessation is the single, most important risk-modification goal after CABG in patients who smoke. Smoking cessation leads to less recurrent angina, improved physical function, fewer admissions, maintenance of employment, and improved survival. Treatment individualized to the patient is crucial. Depression may be an important complicating factor and should be approached with behavioral and drug therapy. Nicotine replacement with a transdermal patch, nasal spray, gum, or inhaler is beneficial. A sustained-release form of bupropion, an antidepressant similar to selective serotonin reuptake inhibitors, reduces the nicotine craving and anxiety of smokers who quit. All smokers should receive educational counseling and be offered smoking cessation therapy after CABG (Table 10).

Table 10.

Proven Management Strategies to Reduce Perioperative and Late Morbidity and Mortality

Table 1.

12. Cardiac Rehabilitation

Cardiac rehabilitation, including early ambulation during hospitalization, outpatient prescriptive exercise, family education, and dietary and sexual counseling, has been shown to improve outcomes after CABG. The benefits include better physical mobility and perceived health. A higher proportion of rehabilitated patients are working at 3 years after CABG. The benefits of rehabilitation extend to the elderly and to women. Cardiac rehabilitation reinforces pharmacological therapy and smoking cessation and should be offered to all eligible patients after CABG.

13. Emotional Dysfunction and Psychosocial Considerations

Lack of social participation and low religious strength are independent predictors of death in elderly patients undergoing CABG. Although controversial, the high prevalence of depression after bypass surgery may reflect a high prevalence preoperatively. Cardiac rehabilitation has a highly beneficial effect in patients who are moderately or severely depressed. Evaluation of social supports and attempts to identify and treat underlying depression should be part of routine post-CABG care.

14. Rapid Sustained Recovery After Operation

Rapid recovery and early discharge are standard goals after CABG. The shortest in-hospital postoperative stays are followed by the fewest rehospitalizations. Important components of “fast-track” care are careful patient selection, patient and family education, early extubation, prophylactic antiarrhythmic therapy, dietary considerations, early ambulation, early outpatient telephone follow-up, and careful coordination with other physicians and healthcare providers.

15. Communication Between Caregivers

Maintenance of appropriate and timely communication between treating physicians regarding care of the patient is crucial. When possible, the primary care physician should follow up the patient during the perioperative course. The referral physician needs to provide clear, written reports of the findings and recommendations to the primary care physician, including discharge medications and dosages along with long-term goals.

VI. Impact of Evolving Technology

A. Less-Invasive Coronary Bypass Surgery

Technical modifications of CABG have been developed to decrease the morbidity of the operation, either by using limited incision or by eliminating cardiopulmonary bypass. Currently, “less-invasive” CABG surgery can be divided into 3 categories: (1) off-bypass CABG performed through a median sternotomy with a smaller skin incision, (2) minimally invasive direct CABG (MID-CAB) performed through a left anterior thoracotomy without cardiopulmonary bypass, and (3) port-access CABG with femoral-to-femoral cardiopulmonary bypass and cardioplegic arrest with limited incision.

Off-bypass coronary surgery is performed on a beating heart after reduction of cardiac motion with a variety of pharmacological and mechanical devices. These include slowing the heart with β-blockers and calcium channel blockers and use of a mechanical stabilizing device to isolate and stabilize the target vessel. Retraction techniques may elevate the heart to allow access to vessels on the lateral and inferior surfaces of the heart. Because this technique generally uses a median sternotomy, its primary benefit is the avoidance of cardiopulmonary bypass, not a less extensive incision.

MID-CAB refers to bypass surgery without median sternotomy and without the use of cardiopulmonary bypass. Generally, this is performed with a small left anterior thoracotomy, exposing the heart through the fourth intercostal interspace with access to the LAD and diagonal branches and occasionally, the anterior marginal vessels. The right coronary artery can be approached by using a right anterior thoracotomy. MID-CAB procedures are generally performed on only 1 or 2 coronary targets. Observational studies have suggested that MID-CAB is associated with a reduced average length of stay and an earlier return to work. Although initial reports of 2-year actuarial and event-free survival are encouraging, the data must be viewed with caution. Because the number of anastomoses performed on a beating heart is usually 1 or occasionally 2, the potential long-term effects of incomplete revascularization are unknown.

The closed-chest, port-access, video-assisted CABG operation uses cardiopulmonary bypass and cardioplegia of a globally arrested heart. Vascular access for cardiopulmonary bypass is achieved via the femoral artery and vein. A triple-lumen catheter with an inflatable balloon at its distal end is used to achieve endovascular aortic occlusion, cardioplegia delivery, and LV decompression. With cardiopulmonary bypass and cardioplegic arrest, CABG can be performed with video assistance on a still and decompressed heart through several small ports. In comparison with the MID-CAB, port access allows access to different areas of the heart, thus facilitating more complete revascularization, and the motionless heart may allow a more accurate anastomosis. Compared with conventional CABG, median sternotomy is avoided. However, potential morbidity of the port-access operation includes multiple wounds at port sites, the limited thoracotomy, and the groin dissection for femoral-femoral bypass. Vigorous scrutiny of the long-term benefits versus risks of port access is required.

B. Arterial and Alternate Conduits

Another area of evolving technology is the use of arterial and alternate conduits. The 5-year patency of coronary artery–vein bypass grafts is 74%, and at 10 years, just 41%. Contrariwise, patency rates of the internal mammary artery implanted into the LAD are as high as 83% at 10 years. As a consequence of improved patency, patients receiving an LAD graft with an internal mammary artery have improved survival compared with patients receiving only vein grafts. Currently, routine use of the left internal mammary artery for LAD grafting with supplemental saphenous vein grafts to other coronary lesions is generally accepted as a standard grafting method. The use of bilateral internal mammary arteries appears to be safe and efficacious. However, there is a higher rate of deep sternal wound infection when both internal mammary arteries are used. This is particularly true for patients with obesity and diabetes and perhaps for those requiring prolonged ventilatory support. The benefits of bilateral internal mammary artery use include lower rates of recurrent angina, MI, and need for reoperation and a trend for better survival. Recently, the radial artery has been used more frequently as a conduit for coronary bypass surgery. Five-year patency appears to be in the range of 85% (compared with nearly 90% for the internal mammary graft). In patients for whom mammary artery, radial artery, and standard vein conduits are unavailable, the in situ right gastroepiploic artery, the inferior epigastric free artery graft, and either lesser saphenous or upper-extremity vein conduits have been used. Long-term patency of these alternative grafts has not been extensively studied.

C. Percutaneous Technology

Technological improvements in percutaneous coronary angioplasty have included the introduction of new devices and improved medical therapy of patients in whom angioplasty is performed. The most notable improvement has been the introduction of intracoronary stents that have reduced late restenosis and the frequency with which emergency bypass surgery is required after PTCA. Intracoronary stents have been used to treat saphenous vein graft stenosis in patients with previous CABG. However, stented patients still have an ≈25% combined rate of death, MI, need for repeat CABG, or re-revascularization of the target vessel. For some patients, hybrid procedures may be the best choice, such as the combined use of CABG surgery and coronary angioplasty. Such an approach is relevant to the patient whose ascending aorta is involved with severe atherosclerosis, for which the implantation of free vein grafts or arterial grafts leads to risk for atheroembolism. In such a patient, the use of in situ internal mammary artery grafting without cardiopulmonary bypass combined with additional coronary angioplasty in other diseased vessels represents a strategy to provide complete revascularization without the concomitant risks of cardiopulmonary bypass and/or manipulation of the ascending aorta.

D. Transmyocardial Revascularization

A fourth area that is rapidly evolving is transmyocardial revascularization. The use of transmyocardial laser revascularization has generally been performed surgically for patients with severe angina refractory to medical therapy and who are not suitable candidates for standard surgical revascularization, PTCA, or heart transplant. While several studies have suggested improvement in angina severity with transmyocardial laser revascularization, the mechanism by which angina improves and the overall benefit on long-term angina and/or survival await further clarification.

VII. Special Patient Subsets

A. Elderly Patients

Elderly patients being considered for CABG have a higher average risk for mortality and morbidity in a direct relation to age, LV function, extent of coronary disease, and comorbid conditions and whether the procedure is urgent, emergent, or a reoperation. Nonetheless, functional recovery and sustained improvement in the quality of life can be achieved in the majority of such patients. The patient and physician together must explore the potential benefits of improved quality of life with the attendant risks of surgery versus alternative therapies that take into account baseline functional capacities and patient preferences. Age alone should not be a contraindication to CABG if it is thought that long-term benefits outweigh the procedural risk.

B. Women

A number of earlier reports had suggested that female sex was an independent risk factor for mortality and morbidity after CABG. More recent studies have suggested that women on average have a disadvantageous, preoperative clinical profile that accounts for much of this perceived difference. Thus, the issue is not necessarily sex itself but the comorbid conditions that are particularly associated with the later age at which women present for coronary surgery. Thus, CABG should not be delayed in or denied to women who have appropriate indications.

C. Diabetic Patients

Coronary heart disease is the leading cause of death among adult diabetics and accounts for 3 times as many deaths among diabetics as among nondiabetics. While CABG carries an increased morbidity and mortality in diabetics, data suggest that in appropriate candidates, the absolute risk reduction provided by successful revascularization remains high. The BARI trial suggested that diabetics with multivessel coronary disease derived advantage from bypass surgery compared with angioplasty. Several of the other randomized trials, albeit with smaller numbers of patients, failed to show this trend. Diabetics who are candidates for renal transplantation have a particularly high incidence of coronary artery disease, even in the absence of symptoms or signs. In appropriate candidates, CABG appears to offer morbidity and mortality benefit in such patients.

D. Patients With Chronic Obstructive Pulmonary Disease

Because CABG is associated with variable degrees of postoperative respiratory insufficiency, it is important to identify patients at particular risk for pulmonary complications. The intent is to treat reversible problems that may contribute to respiratory insufficiency in high-risk patients, with the hope of avoiding prolonged periods of mechanical ventilation after CABG. High-risk patients often benefit from preoperative antibiotics, bronchodilator therapy, a period of cessation from smoking, perioperative incentive spirometry, deep-breathing exercises, and chest physiotherapy. If pulmonary venous congestion or pleural effusions are identified, diuresis often improves lung performance.

Although preoperative spirometry directed to identifying patients with a low (eg, <1 L) 1-second forced expiratory volume has been used by some to qualify or disqualify candidates for CABG, clinical evaluation of lung function is likely as important if not more so. Patients with advanced chronic obstructive pulmonary disease are at particular risk for postoperative arrhythmias that may be fatal. While moderate to severe degrees of obstructive pulmonary disease represent a significant risk factor for early mortality and morbidity after CABG, it is also true that with careful preoperative assessment and treatment of the underlying pulmonary abnormality, many such patients are successfully carried through the operative procedure.

E. Patients With End-Stage Renal Disease

Coronary artery disease is the most important cause of mortality in patients with end-stage renal disease. Many of such patients have diabetes and other coronary risk factors, including hypertension, myocardial dysfunction, abnormal lipids, anemia, and increased plasma homocysteine levels. Although patients on chronic dialysis are at higher risk when undergoing coronary angioplasty or bypass, they are at even higher risk with conservative medical management. Thus, in patients with modest reductions in LV function, significant left main or 3-vessel disease, and/or unstable angina, coronary revascularization can lead to relief of coronary symptoms, improvement in overall functional status, and improved long-term survival in this select high-risk patient population.

F. Reoperative Patients

Operative survival and long-term benefit of reoperative CABG are distinctly inferior to first-time operations. Patients undergoing repeated CABG have higher rates of postoperative bleeding, perioperative MI, and neurological and pulmonary complications. Nevertheless, reasonable 5- and 10-year survival rates after reoperation for coronary disease can be achieved, and the operation is appropriate if the severity of symptoms and anticipated benefit justify the immediate risk. Data suggest that the need for reoperation is less common in patients undergoing internal mammary artery grafting to the LAD. More recently, short-term follow-up studies suggest that patients undergoing multiple arterial grafts have even lower rates of reoperation. These early results are consistent with the known superior graft patency of arterial conduits compared with vein grafts.

G. Concomitant Peripheral Vascular Disease

The presence of clinical and subclinical peripheral vascular disease is a strong predictor of increased hospital and long-term mortality rates in patients undergoing CABG. However, the absolute benefit offered by coronary revascularization is elevated in patients with peripheral vascular disease, particularly those with 3-vessel coronary disease, more advanced angina, and/or a depressed LVEF. Excess perioperative mortality in such patients is related to an increased incidence of heart failure and dysrhythmias rather than peripheral arterial complications.

H. Poor LV Function

Patients with severe LV dysfunction have increased perioperative and long-term mortality compared with patients with normal LV function. However, studies suggest that the beneficial effects of myocardial revascularization in patients with ischemic heart disease and severe LV dysfunction are sizeable when compared with medically treated patients of similar status in terms of symptom relief, exercise tolerance, and survival.

I. CABG in Acute Coronary Syndromes

Coronary bypass surgery offers a survival advantage compared with medical therapy in patients with unstable angina and LV dysfunction, particularly in the presence of 3-vessel disease. However, the risk of bypass surgery in patients with unstable or postinfarction angina or early after non–Q wave infarction and during acute MI is increased severalfold compared with patients with stable angina. Although this risk is not necessarily higher than that with medical therapy, it has led to the argument to consider angioplasty or to delay CABG in such patients if medical stabilization can be easily accomplished.

VIII. Institutional and Operator Competence

Studies suggest that mortality after CABG is higher when carried out in institutions that annually perform fewer than a minimum number of cases. Similar conclusions have been drawn regarding individual surgeons’ volumes. This observation strengthens the argument for careful outcome tracking and supports the monitoring of institutions or individuals who annually perform <100 cases. It is also true that there is a wide variation in risk-adjusted mortality rates in low-volume situations. Thus, some institutions and practitioners maintain excellent outcomes despite relatively low volumes.

Outcome reporting in the form of risk-adjusted mortality rates after bypass has been effective in reducing mortality rates nationwide. Public release of hospital and physician-specific mortality rates has not been shown to drive this improvement and has failed to effectively guide consumers or alter physician referral patterns.

IX. Cost-Effectiveness of Bypass Surgery

A variety of studies of CABG have found the technique to be cost-effective in patients for whom survival and/or symptomatic benefit is demonstrable. Within these subsets, the cost-effectiveness of CABG compares favorably with that of other accepted medical therapies.

When compared with PTCA, the initial hospital cost of CABG is significantly higher. However, by 5 years, the cumulative cost of PTCA compared with initial surgical therapy is within 5% of CABG, or a difference of <$3000. Observational studies showing a poorer survival effect of PTCA in patients with more advanced disease suggest that there may be a significant cost gradient for PTCA as the extent of disease increases, which is not apparent for coronary bypass surgery.

X. Indications

A. Indications for CABG in Asymptomatic or Mild Angina

Class I

1. Significant left main coronary artery stenosis.

2. Left main equivalent: significant (≥70%) stenosis of proximal LAD and proximal left circumflex artery.

3. Three-vessel disease. (Survival benefit is greater in patients with abnormal LV function; eg, with an EF <0.50.)

Class IIa

1. Proximal LAD stenosis with 1- or 2-vessel disease.*1

Class IIb

1. One- or 2-vessel disease not involving the proximal LAD.†2

Class III

See text.

B. Indications for CABG in Stable Angina

Class I

1. Significant left main coronary artery stenosis.

2. Left main equivalent: significant (≥70%) stenosis of proximal LAD and proximal left circumflex artery.

3. Three-vessel disease. (Survival benefit is greater when LVEF is <0.50.)

4. Two-vessel disease with significant proximal LAD stenosis and either EF <0.50 or demonstrable ischemia on noninvasive testing.

5. One- or 2-vessel coronary artery disease without significant proximal LAD stenosis, but with a large area of viable myocardium and high-risk criteria on noninvasive testing.

6. Disabling angina despite maximal medical therapy, when surgery can be performed with acceptable risk. If angina is not typical, objective evidence of ischemia should be obtained.

Class IIa

1. Proximal LAD stenosis with 1-vessel disease.*1

2. One- or 2-vessel coronary artery disease without significant proximal LAD stenosis, but with a moderate area of viable myocardium and demonstrable ischemia on noninvasive testing.

Class III

1. One- or 2-vessel disease not involving significant proximal LAD stenosis, in patients (1) who have mild symptoms that are unlikely due to myocardial ischemia or have not received an adequate trial of medical therapy and (A) have only a small area of viable myocardium or (B) have no demonstrable ischemia on noninvasive testing.

2. Borderline coronary stenoses (50% to 60% diameter in locations other than the left main coronary artery) and no demonstrable ischemia on noninvasive testing.

3. Insignificant (<50% diameter) coronary stenosis.

C. Indications for CABG in Unstable Angina/Non–Q Wave MI

Class I

1. Significant left main coronary artery stenosis.

2. Left main equivalent: significant (≥70%) stenosis of proximal LAD and proximal left circumflex artery.

3. Ongoing ischemia not responsive to maximal nonsurgical therapy.

Class IIa

1. Proximal LAD stenosis with 1- or 2-vessel disease.*1

Class IIb

2. One- or 2-vessel disease not involving the proximal LAD.†2

Class III

See text.

D. Indications for CABG in ST-Segment Elevation (Q-Wave) MI

Class I

None.

Class IIa

1. Ongoing ischemia/infarction not responsive to maximal nonsurgical therapy.

Class IIb

1. Progressive LV pump failure with coronary stenosis compromising viable myocardium outside the initial infarct area.

2. Primary reperfusion in the early hours (≤6 to 12 hours) of an evolving ST-segment elevation MI.

Class III

1. Primary reperfusion late (≥12 hours) in evolving ST-segment elevation MI without ongoing ischemia.

E. Indications for CABG in Poor LV Function

Class I

1. Significant left main coronary artery stenosis.

2. Left main equivalent: significant (≥70%) stenosis of proximal LAD and proximal left circumflex artery.

3. Proximal LAD stenosis with 2- or 3-vessel disease.

Class IIa

1. Poor LV function with significant viable, noncontracting, revascularizable myocardium without any of the aforementioned anatomic patterns.

Class III

1. Poor LV function without evidence of intermittent ischemia and without evidence of significant revascularizable, viable myocardium.

F. Indications for CABG in Life-Threatening Ventricular Arrhythmias

Class I

1. Left main coronary artery stenosis.

2. Three-vessel coronary disease.

Class IIa

1. Bypassable 1- or 2-vessel disease causing life-threatening ventricular arrhythmias.‡3

2. Proximal LAD disease with 1- or 2-vessel disease.‡3

Class III

1. Ventricular tachycardia with scar and no evidence of ischemia.

G. Indications for CABG After Failed PTCA

Class I

1. Ongoing ischemia or threatened occlusion with significant myocardium at risk.

2. Hemodynamic compromise.

Class IIa

1. Foreign body in crucial anatomic position.

2. Hemodynamic compromise in patients with impairment of coagulation system and without previous sternotomy.

Class IIb

1. Hemodynamic compromise in patients with impairment of coagulation system and with previous sternotomy.

Class III

1. Absence of ischemia.

2. Inability to revascularize owing to target anatomy or no-reflow state.

H. Indications for CABG in Patients With Previous CABG

Class I

1. Disabling angina despite maximal noninvasive therapy. (If angina is not typical, then objective evidence of ischemia should be obtained.)

Class IIa

1. Bypassable distal vessel(s) with a large area of threatened myocardium on noninvasive studies.

Class IIb

1. Ischemia in the non-LAD distribution with a patent internal mammary graft to the LAD supplying functioning myocardium and without an aggressive attempt at medical management and/or percutaneous revascularization.

Class III

See text.

Footnotes

  • “ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery: Executive Summary and Recommendations: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1991 Guidelines for Coronary Artery Bypass Graft Surgery)” was approved by the American College of Cardiology Board of Trustees in March 1999 and by the American Heart Association Science Advisory and Coordinating Committee in July 1999.

  • When citing this document, the American College of Cardiology and the American Heart Association request that the following citation format be used: Eagle KA, Guyton RA, Davidoff R, Ewy GA, Fonger J, Gardner TJ, Gott JP, Herrmann HC, Marlow RA, Nugent W, O’Connor GT, Orszulak TA, Rieselbach RE, Winters WL, Yusuf S. ACC/AHA guidelines for coronary artery bypass graft surgery: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1991 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation. 1999;100:1464-1480.

  • This document is available on the World Wide Web sites of the American College of Cardiology (www.acc.org) and the American Heart Association (www.americanheart.org). A single reprint of the executive summary and recommendations is available by calling 800-242-8721 (US only) or writing the American Heart Association, Public Information, 7272 Greenville Ave, Dallas, TX 75231-4596. Ask for reprint No. 71-0173. To obtain a reprint of the complete guidelines published in the October 1999 issue of the Journal of the American College of Cardiology, ask for reprint No. 71-0174. To purchase additional reprints (specify version and reprint number): up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 214-706-1466, fax 214-691-6342, or . To make photocopies for personal or educational use, call the Copyright Clearance Center, 978-750-8400.

  • 1 Becomes Class I if extensive ischemia documented by noninvasive study and/or an LVEF <0.50.

  • 2 If a large area of viable myocardium and high-risk criteria on noninvasive testing, becomes Class I.

  • 3 Becomes Class I if arrhythmia is resuscitated sudden cardiac death or sustained ventricular tachycardia.

  • CPB indicates cardiopulmonary bypass.

  • Data taken from (1) Townsend TR, Reitz BA, Bilker WB, Bartlett JG. Clinical trial of cefamandole, cefazolin, and cefuroxime for antibiotic prophylaxis in cardiac operations. J Thorac Cardiovasc Surg. 1993;106:664–670. (2) Antimicrobial prophylaxis in surgery. Med Lett Drugs Ther. 1997;39:97–101. (3) Vuorisalo S, Pokela R, Syrjala H. Comparison of vancomycin and cefuroxime for infection prophylaxis in coronary artery bypass surgery. Infect Control Hosp Epidemiol. 1998;19:234–239. (4) Romanelli VA, Howie MB, Myerowitz PD, Zvara DA, Rezaei A, Jackman DL, Sinclair DS, McSweeny TD. Intraoperative and postoperative effects of vancomycin administration in cardiac surgery patients: a prospective, double-blind, randomized trial. Crit Care Med. 1993;21:1124–1131.

Articles citing this article

  • Postoperative cognitive dysfunction after cardiac surgeryContin Educ Anaesth Crit Care Pain. 2013;0:mkt022v1-mkt022,
  • Atherosclerotic Changes in Common Carotid Artery, Common Femoral Artery, and Ascending Aorta/Aortic Arch in Candidates for Coronary Artery Bypass Graft SurgeryANGIOLOGY. 2012;63:630-631,
  • Impact of chronic obstructive pulmonary disease severity on surgical outcomes in patients undergoing non-emergent coronary artery bypass graftingEur J Cardiothorac Surg. 2012;42:108-113,
  • EQUIPMENT, MONITORING, AND ENGINEERING TECHNOLOGYBr J Anaesth. 2012;108:ii109-ii144,
  • Impact of obesity on outcome of patients undergoing off-pump coronary artery bypass grafting using aorta no-touch techniqueInteract CardioVasc Thorac Surg. 2010;11:234-237,
  • Prevalence of Asymptomatic Coronary Artery Disease in Ischemic Stroke Patients: The PRECORIS StudyCirculation. 2010;121:1623-1629,
  • Is there any difference in carotid stenosis between male and female patients undergoing coronary artery bypass grafting?Interact CardioVasc Thorac Surg. 2009;9:823-826,
  • Selective Screening for Asymptomatic Carotid Artery Disease Prior to Isolated Heart Valve SurgeryANGIOLOGY. 2009;60:633-636,
  • Off-Pump Coronary Revascularization for Left Main Coronary Artery StenosisAsian Cardiovascular and Thoracic Annals. 2008;16:473-478,
  • Risk Stratification Models for Cardiac SurgerySEMIN CARDIOTHORAC VASC ANESTH. 2008;12:167-174,
  • Prognostic value of Doppler-derived mitral deceleration time on left ventricular reverse remodelling after undersized mitral annuloplastyEur Heart J Cardiovasc Imaging. 2008;9:631-640,
  • Medication Adherence following Coronary Artery Bypass Graft Surgery: Assessment of Beliefs and AttitudesAnn Pharmacother. 2008;42:192-199,
  • Staged Carotid Angioplasty and Stenting Followed by Cardiac Surgery in Patients With Severe Asymptomatic Carotid Artery Stenosis: Early and Long-Term ResultsCirculation. 2007;116:2036-2042,
  • Risk of Coronary and Other Nonstroke Vascular Death in Relation to the Presence and Extent of Atherosclerotic Disease at the Carotid BifurcationStroke. 2006;37:2904-2909,
  • Perioperative Amino Acid Infusion Improves Recovery and Shortens the Duration of Hospitalization After Off-Pump Coronary Artery Bypass GraftingAnesth. Analg.. 2006;103:1386-1393,
  • Assessment of Coronary Artery Disease by Cardiac Computed Tomography: A Scientific Statement From the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical CardiologyCirculation. 2006;114:1761-1791,
  • Outcomes in off-pump vs. on-pump coronary artery bypass grafting stratified by pre-operative risk profile: an assessment using propensity scoreEur Heart J. 2006;27:2473-2480,
  • Isolated and Significant Left Main Coronary Artery Disease: Demographics, Hemodynamics and Angiographic FeaturesANGIOLOGY. 2006;57:464-477,
  • Risk factor awareness and secondary prevention of coronary artery disease: are we doing enough?Interact CardioVasc Thorac Surg. 2006;5:268-271,
  • Left Main Coronary Revascularization at the CrossroadsCirculation. 2006;113:2480-2484,
  • Impact of avoiding cardiopulmonary bypass for coronary surgery on perioperative cardiac enzyme release and survivalEur J Cardiothorac Surg. 2006;29:729-735,
  • Comparison of 19 pre-operative risk stratification models in open-heart surgeryEur Heart J. 2006;27:867-874,
  • Determinants of Morbidity and Intensive Care Unit Stay after Coronary SurgeryAsian Cardiovascular and Thoracic Annals. 2006;14:114-118,
  • Risk of Myocardial Infarction and Vascular Death After Transient Ischemic Attack and Ischemic Stroke: A Systematic Review and Meta-AnalysisStroke. 2005;36:2748-2755,
  • Assessing the risk of waiting for coronary artery bypass graft surgery among patients with stenosis of the left main coronary arteryCMAJ. 2005;173:371-375,
  • Mental Disorders and Revascularization Procedures in a Commercially Insured SamplePsychosom. Med.. 2005;67:568-576,
  • Left internal mammary artery use in patients with poor left ventricular ejection fraction: a propensity-matched analysis of mid-term survivalInteract CardioVasc Thorac Surg. 2005;4:184-188,
  • Influence of Racial Disparities in Procedure Use on Functional Status Outcomes Among Patients With Coronary Artery DiseaseCirculation. 2005;111:1284-1290,
  • 2004 Carolyn Sherif Award Address: Heart Disease and Gender InequityPsychology of Women Quarterly. 2005;29:15-23,
  • In vitro differences between venous and arterial-derived smooth muscle cells: potential modulatory role of decorinCardiovasc Res. 2005;65:702-710,
  • External validation of compliance to perfusion quality indicatorsPerfusion. 2004;19:295-299,
  • Expression of Angiogenic Factors During Acute Coronary Syndromes in Human Type 2 DiabetesDiabetes. 2004;53:2383-2391,
  • Influence of obesity on in-hospital and early mortality and morbidity after myocardial revascularizationEur J Cardiothorac Surg. 2004;26:535-541,
  • Concomitant Peripheral Arterial Disease and Coronary Artery Disease: Therapeutic OpportunitiesCirculation. 2004;109:3136-3144,
  • Factor V Leiden and Perioperative RiskAnesth. Analg.. 2004;98:1623-1634,
  • Isolated high-grade lesion of the proximal LAD: a stent or off-pump LIMA?Eur J Cardiothorac Surg. 2004;25:567-571,
  • Treatment of Inoperable Coronary Disease and Refractory Angina: Spinal Stimulators, Epidurals, Gene Therapy, Transmyocardial Laser, and CounterpulsationSEMIN CARDIOTHORAC VASC ANESTH. 2004;8:43-58,
  • The midlands trial of empirical amiodarone versus electrophysiology-guided interventions and implantable cardioverter-defibrillators (MAVERIC): a multi-centre prospective randomised clinical trial on the secondary prevention of sudden cardiac deathEuropace. 2004;6:257-266,
  • Patterns of Secondary Prevention in Older Patients Undergoing Coronary Artery Bypass Grafting During Hospitalization for Acute Myocardial InfarctionCirculation. 2003;108:II-24-II-28,
  • Coronary Risk Evaluation in Patients With Transient Ischemic Attack and Ischemic Stroke: A Scientific Statement for Healthcare Professionals From the Stroke Council and the Council on Clinical Cardiology of the American Heart Association/American Stroke AssociationCirculation. 2003;108:1278-1290,
  • Clinical Profiles and Outcomes of Acute Type B Aortic Dissection in the Current Era: Lessons From the International Registry of Aortic Dissection (IRAD)Circulation. 2003;108:II-312-II-317,
  • Coronary Risk Evaluation in Patients With Transient Ischemic Attack and Ischemic Stroke: A Scientific Statement for Healthcare Professionals From the Stroke Council and the Council on Clinical Cardiology of the American Heart Association/American Stroke AssociationStroke. 2003;34:2310-2322,
  • An evaluation of existing risk stratification models as a tool for comparison of surgical performances for coronary artery bypass grafting between institutionsEur J Cardiothorac Surg. 2003;23:935-942,
  • Validation of four different risk stratification systems in patients undergoing off-pump coronary artery bypass surgery: a UK multicentre analysis of 2223 patientsHeart. 2003;89:432-435,
  • The effect of obesity on mid-term survival following coronary artery bypass surgeryEur J Cardiothorac Surg. 2003;23:368-373,
  • Total arterial revascularisation as a primary strategy for coronary artery bypass graftingPostgrad. Med. J.. 2003;79:43-48,
  • Neurocognitive Sequelae Following Coronary Artery Bypass Graft: A Research Agenda for Behavioral ScientistsBehav Modif. 2003;27:68-82,
  • Risk of morbidity and in-hospital mortality in obese patients undergoing coronary artery bypass surgeryEur J Cardiothorac Surg. 2002;22:787-793,
  • The effect off-pump coronary artery bypass surgery on in-hospital mortality and morbidityEur J Cardiothorac Surg. 2002;22:255-260,
  • ACC/AHA Guideline Update for Perioperative Cardiovascular Evaluation for Noncardiac Surgery–Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery)Circulation. 2002;105:1257-1267,
  • Predicting Death in Patients With Acute Type A Aortic DissectionCirculation. 2002;105:200-206,
  • A Simple Method to Determine Anastomotic Quality of Coronary Artery Bypass Grafting in the Operating RoomVascular. 2001;9:499-503,
  • Admission Plasma Glucose: An independent risk factor in nondiabetic women after coronary artery bypass graftingDiabetes Care. 2001;24:1634-1639,
  • Stroke in Relation to Cardiac Procedures in Patients With Non-ST-Elevation Acute Coronary Syndrome: A Study Involving >18 000 PatientsCirculation. 2001;104:269-274,
  • Simple Bedside Additive Tool for Prediction of In-Hospital Mortality After Percutaneous Coronary InterventionsCirculation. 2001;104:263-268,
  • Off-pump coronary artery bypass surgery for critical left main stem disease: safety, efficacy and outcomeEur J Cardiothorac Surg. 2001;19:239-244,
  • Predicting the Risk of Death from Heart Failure After Coronary Artery Bypass Graft SurgeryAnesth. Analg.. 2001;92:596-601,
  • Guideline for the management of patients with acute coronary syndromes without persistent ECG ST segment elevationHeart. 2001;85:133-142,
  • Effects of a Residential Exercise Training on Baroreflex Sensitivity and Heart Rate Variability in Patients With Coronary Artery Disease : A Randomized, Controlled StudyCirculation. 2000;102:2588-2592,

SOURCE

Read Full Post »


Stem Cell Therapy for Coronary Artery Disease (CAD)

Author and Curator: Larry H. Bernstein, MD, FCAP

and

Curator: Aviva Lev-Ari, PhD, RN

 

There is great interest and future promise for stem cell therapy in ischemic heart disease.  This is another report for the active work in cardiology with stem cell therapy by MA Gaballa and associates at University of Arizona.

Stem Cell Therapy for Coronary Heart Disease

Julia N. E. Sunkomat and Mohamed A. Gaballa

The University ofArizona Sarver Heart Center, Section of Cardiology, Tucson, Ar
Cardiovascular Drug Reviews 2003: 21(4): 327–342

Keywords: Angiogenesis — Cardiac therapy — Coronary heart disease — Heart failure — Myoblasts — Myocardial ischemia — Myocardial regenera­tion — Stem cells

ABSTRACT

Coronary artery disease (CAD) remains the leading cause of death in the Western world. The high impact of its main sequelae, acute myocardial infarction and congestive heart failure (CHF), on the quality of life of patients and the cost of health care drives the search for new therapies. The recent finding that

stem cells contribute to neovascularization and possibly improve cardiac function after myocardial infarction makes stem cell therapy the most highly active research area in cardiology. Although the concept of stem cell therapy may revolutionize heart failure treatment, several obstacles need to be ad­dressed. To name a few:

  1.  Which patient population should be considered for stem cell therapy?
  2.  What type of stem cell should be used?
  3.  What is the best route for cell de­livery?
  4.  What is the optimum number of cells that should be used to achieve functional effects?
  5.  Is stem cell therapy safer and more effective than conventional therapies?

The published studies vary significantly in design, making it difficult to draw conclusions on the efficacy of this treatment. For example, different models of

  1. ischemia,
  2. species of donors and recipients,
  3. techniques of cell delivery,
  4. cell types,
  5. cell numbers and
  6. timing of the experiments

have been used. However, these studies highlight the landmark concept that stem cell therapy may play a major role in treating cardiovascular diseases in the near future. It should be noted that stem cell therapy is not limited to the treatment of ischemic cardiac disease.

  • Non-ischemic cardiomyopathy,
  • peripheral vascular disease, and
  • aging may be treated by stem cells.

Stem cells could be used as vehicle for gene therapy and eliminate the use of viral vectors. Finally, stem cell therapy may be combined with phar­macological, surgical, and interventional therapy to improve outcome. Here we attempt a systematic overview of the science of stem cells and their effects when transplanted into ischemic myocardium.

INTRODUCTION

Background

Congestive heart failure (CHF) is the leading discharge diagnosis in patients over the age of 65 with estimates of $24 billion spent on health care in the US (1,11). The number one cause of CHF is coronary artery diseases (CAD). Coronary care units, reperfusion therapy (lytic and percutaneous coronary intervention) and medical therapy with anti-pla­telet agents, statins, ACE-inhibitors and â-adrenoceptor antagonists all significantly reduce morbidity and mortality of CAD and CHF (9), but it is very difficult to regenerate new viable myocardium and new blood vessels.

Identification of circulating endothelial progenitor cells in peripheral blood that incor­porated into foci of neovascularization in hindlimb ischemia (4) and the successful engraftment of embryonic stem cells into myocardium of adult dystrophic mice (31) intro­duced a new therapeutic strategy to the field of cardiovascular diseases: tissue regeneration. This approach is supported by the discovery of primitive cells of extracardiac origin in cardiac tissues after sex-mismatched transplants suggesting that an endogenous repair mechanism may exist in the heart (35,45,54). The number of recruited cells varied significantly from 0 (19) to 18% (54), but the natural course of ischemic cardiomyopathy implies that cell recruitment for tissue repair in most cases is insufficient to prevent heart failure. Therefore, investigational efforts are geared towards

  • augmenting the number of multipotent stem cells and endothelial and myocardial progenitor cells at the site of ischemia to induce clinically significant angiogenesis and potentially myogenesis.

Stem and Progenitor Cells

Stem cells are defined by their ability to give rise to identical stem cells and progenitor cells that continue to differentiate into a specific tissue cell phenotype (23,33). The po­tential of mammalian stem cells varies with stage of development and age (Table 1).

In mammals, the fertilized oocyte and blastomere cells of embryos of the two to eight cell stage can generate a complete organism when implanted into the uterus; they are called totipotent stem cells. After the blastocyst stage, embryonic stem cells retain the ability to differentiate into all cell types, but

  • cannot generate a complete organism and thus are denoted pluripotent stem cells.

Other examples of pluripotent stem cells are embryo­nic germ cells that are derived from the gonadal ridge of aborted embryos and embryonic carcinoma cells that are found in gonadal tumors (teratocarcinomas) (23,33). Both these cell types can also differentiate into cells of all three germ layers, but are not as well inves­tigated as embryonic stem cells.

It is well established that embryonic stem cells can differentiate into cardiomyocytes (7,10,13,14,31,37,76), endothelial cells (55), and smooth muscle cells (5,22,78) in vitro, but it is unclear whether

  • pure populations of embryonic stem cell-derived cardiomyocytes can integrate and function appropriately in the heart after transplantation.
  • one study reported arrhythmogenic potential of embryonic stem cell-derived cardiomyocytes in vitro (80).

Adult somatic stem cells are cells that have already committed to one of the three germ layers: endoderm, ectoderm, or mesoderm (76). While embryonic stem cells are defined by their origin (the inner cell mass of the blastocyst), the origin of adult stem cells in mature tissues is still unknown. The primary role of adult stem cells in a living organism is thought to be maintaining and repairing the tissue in which they reside. They are the source of more identical stem cells and cells with a progressively more distinct phenotype of specialized tissue cells (progenitor and precursor cells) (Fig. 1). Until recently adult stem cells were thought to be lineage-specific, meaning that they can only differentiate into the cell-type of their original tissue. This concept has now been challenged with the discovery of multipotent stem and progenitor cells (26, 50, 51).

The presence of multipotent stem and progenitor cells in adult mammals has vast im­plications on the availability of stem cells to research and clinical medicine. Recent publi­cations, however, have questioned whether the adaptation of a phenotype in those dogma-challenging studies is really a result of trans-differentiation or rather a result of cell and nuclear fusion (60,68,75,79). Spontaneous fusion between mammalian cells was first re­ported in 1961 (8), but how frequently fusion occurs and whether it occurs in vivo is not clear.

The bone marrow is a known source of stem cells. Hematopoietic stem cells are fre­quently used in the field of hematology. Surface receptors are used to differentiate hematopoietic stem and progenitor cells from mature cells. For example, virtually all

  • hematopoietic stem and progenitor cells express the CD34+ glycoprotein antigen on their cell membrane (73),

though a small proportion of primitive cells have been shown to be CD34 negative (58).

The function of the CD34+ receptor is not yet fully understood. It has been suggested that it may act as a regulator of hematopoietic cell adhesion in the bone marrow microenvironment. It also appears to be involved in the maintenance of the hematopoietic stem/progenitor cell phenotype and function (16,21). The frequency of immature CD34+ cells in peripheral circulation diminishes with age.

  • It is the highest (up to 11%) in utero (69) and decreases to 1% of nucleated cells in term cord blood (63).
  • This equals the per­centage of CD34+ cells in adult bone marrow.
  • The number of circulating stem cells in adult peripheral blood is even lower at 0.1% of nucleated cells.

Since hematopoietic stem cells have been identified as endothelial progenitor cells (29,30,32) their low density in adult bone marrow and blood could explain the inadequacy of endogenous recruitment of cells to injured organs such as an ischemic heart. The bone marrow is also home to another stem cell population the so-called mesenchymal stem cells. These may constitute a subset of the bone marrow stromal cells (2,43). Bone marrow stromal cells are a mixed cell popu­lation that generates

  1. bone,
  2. cartilage,
  3. fat,
  4. connective tissue, and
  5. reticular network that sup­ports cell formation (23).

Mesenchymal stem cells have been described as multipotent (51,52) and as a source of myocardial progenitor cells (41,59). They are, however, much less defined than the hematopoietic stem cells and a characteristic antigen constellation has not yet been identified (44).

Another example of an adult tissue containing stem cells is the skeletal muscle. The cells responsible for renewal and growth of the skeletal muscle are called satellite cells or myoblasts and are located between the sarcolemma and the basal lamina of the muscle fiber (5). Since skeletal muscle and cardiac muscle share similar characteristics such as they both are striated muscle cells, satellite cells are considered good candidates for the repair of damaged myocardium and have been extensively studied (20,25,38–40,48,56, 64–67). Myoblasts are particularly attractive, because they can be autotransplanted, so that issues of donor availability, ethics, tumorigenesis and immunological compatibility can be avoided. They also have been shown to have a high growth potential in vitro and a strong resistance to ischemia in vivo (20). On the down side

  • they may have more arrhythmogenic potential when transplanted into myocardium than bone marrow or peripheral blood de­rived stem cells and progenitor cells (40).

Isolation of Cells Prior to Transplantation

Hematopoietic stem and progenitor cells are commonly identified by the expression of a profile of surface receptors (cell antigens). For example, human hematopoietic stem cells are defined as CD34+/CD59+/Thy-1+/CD38low//c-kit/low/lin, while mouse hema-topoietic stem cells are defined as CD34low//Sca-1+/Thy-1+/low/CD38+/c-kit+/lin (23). Additional cell surface receptors have been identified as markers for subgroups of hema-topoietic stem cells with the ability to differentiate into non-hematopoetic tissues, such as endothelial cells (57,78). These can be specifically targeted by isolation methods that use the receptors for cell selection (positive selection with antibody coated magnetic beads or fluorescence-activated cell sorting, FACS). Other stem cell populations are identified by their behavior in cell culture (mesenchymal stem cells) or dye exclusion (SP cells). Finally, embryonic stem cells are isolated from the inner cell mass of the blastocyst and skeletal myoblasts are mechanically and enzymatically dissociated from an easily acces­sible skeletal muscle and expanded in cell culture.

FIG. 1. Maturation process of adult stem cells: with acquisition of a certain phenotype the cell gradually loses its self-renewal capability.  (unable to transfer)

METHODICAL APPROACHES 

j.1527-3466.2003.tb00125.x  fig stem cell

FIG. 2. Intramyocardial injection:

the cells are injected directly into the myocardium through the epicardium. Usually a thoracotomy or sternotomy is required. Transendocardial injection: access can be gained from the ar­terial vasculature. Cells are injected through the endocardium into the myocardium, ideally after identifying the ischemic myocardium by perfusion studies and/or electromechanical mapping. Intracoronary injection: the coronary artery is accessed from the arterial vasculature. Stem cells are injected into the lumen of the coronary artery. Proximal washout is prevented by inflation of a balloon. Cells are then distributed through the capillary system. They eventually cross the endothelium and migrate towards ischemic areas.

The intracoronary delivery of stem cells (Fig. 2) and distribution through the coronary system has also been explored (6,62,74). This approach was pioneered by Robinson et al. (56), who demonstrated successful engraftment within the coronary distribution after intracoronary delivery of genetically labeled skeletal myoblasts. The risk of intracoronary injection is comparable to that of a coronary angiogram and percutaneous transluminal coronary angioplasty (PTCA) (62), which are safe and clinically well established.

RESULTS IN ANIMAL STUDIES AND HUMAN TRIALS

Dif­ferentiation into cardiomyocytes was observed after transplantation of embryonic stem cells, mesenchymal stem cells, lin/c-kit+ and SP cells. The induction of angiogenesis was observed after transplantation of embryonic stem cells, mesenchymal stem cells, bone marrow-derived mononuclear cells, circulating endothelial progenitor cells, SP cells and lin/c-kit+ cells.

The use of embryonic stem cells in ischemia was examined in two studies (42,43). These studies demonstrated that mice embryonic stem cells transplanted into rat myo­cardium exhibited cardiomyocyte phenotype at 6 weeks after transplantation. In addition, generation of myocardium and angiogenesis were observed at 32 weeks after allogenic transplantation in rats. In these two studies no arrhythmias or cardiac tumors were reported.

Several studies have shown retardation of LV remodeling and improvement of cardiac function after administration of bone marrow-derived mononuclear cells. For example, decreases in infarct size, and increase in ejection fraction (EF), and left ventricular (LV) time rate change of pressure (dP/dtmax) were observed after direct injection of bone marrow-derived mononuclear cells 60 min after ischemia in swine (28). In humans, intra-coronary delivery and transendocardial injection of mononuclear cells leads to a decrease in LV dimensions and improvement of cardiac function and perfusion (49,62). A decrease in end systolic volume (ESV) and an increase in EF as well as regional wall motion were observed following intracoronary administration of CD34+/CD45+ human circulating en­dothelial cells (6). Injection of circulating human CD34+/CD117+ cells into infarcted rat myocardium induced neoangiogenesis and improved cardiac function (32). This study suggests that the improvement in LV remodeling after infarction appears to be in part me­diated by a decrease in apoptosis within the noninfarcted myocardium. Two other studies reported increased fractional shortening, improved regional wall motion and decreased left ventricular dimensions after transplantation of human CD34+ cells (29,30). Improved global left ventricular function and infarct perfusion was demonstrated after intramyo-cardial injection of autologous endothelial progenitor cells in humans (61).

DISCUSSION AND OUTLOOK

The idea of replacing damaged myocardium by healthy cardiac tissue is exciting and has received much attention in the medical field and the media. Therefore, it is important for the scientist to know what is established and what is based on premature conclusions. Currently, there are data from animal studies and human trials (Table 2). However, some of these data are not very concrete. For example,

  • many animal studies do not report the level of achieved neoangiogenesis and/or regeneration of myocardium.
  • In studies where the numbers of neovessels and new cardiomyocytes are specified, these numbers are often very low.

While these experiments confirm the concept that bone marrow and peripheral blood-derived stem and progenitor cells can differentiate into cardiomyocytes and endo­thelial cells when transplanted into ischemic myocardium, they also raise the question how effective this treatment is.

The results of the clinical trials that have been conducted are encouraging, but they need to be interpreted with caution. The common endpoints of these studies include left ventricular dimensions, perfusion, wall motion and hemodynamic function. While all studies report improvement after mononuclear cell, myoblast or endothelial progenitor cell transplantation, it is difficult to separate the effects of stem cell transplantation from the effects of the state-of-the art medical care that the patients typically received.

CONCLUSION

While the majority of studies demonstrate neoangiogenesis and some studies also show regeneration of myocardium after stem/progenitor cell transplantation, it remains unclear whether the currently achieved level of tissue regeneration is sufficient to affect clinical outcome. Long-term follow-up of patients that received stem/progenitor cells in clinical trials will provide important information on the potential risks of neoplasm and arrhythmias and, therefore, safety of this treatment. Ultimately, postmortem histological confirmation of scar tissue repair by transplanted cells and randomized placebo control trials with long-term follow-up are required to prove efficacy of this treatment.

REFERENCES (10)

1. American Heart Association Disease and Stroke Statistics-2003 Update, Dallas TX, American Heart Associ­ation; 2002 http://http://www.americanheart.org/downloadable/heart/10461207852142003HDSStatsBook.pdf

2. Arai A, Sheikh F, Agyeman K, et al. Lack of benefit from cytokine mobilized stem cell therapy for acute myocardial infarction in nonhuman primates. J Am Coll Cardiol 2003;41(Suppl 6A):371.

3. Asahara T, Masuda H, Takahashi T, et al. Bone marrow origin of endothelial progenitor cells responsible for postnatal vasculogenesis in physiological and pathological neovascularization. Circ Res 1999;85:221–228.

4. Asahara T, Murohara T, Sullivan A, et al. Isolation of putative progenitor endothelial cells for angiogenesis. Science 1997;275:964–967.

5. Asakura A, Seale P, Girgis-Gabardo A, Rudnicki M. Myogenic specification of side population cells in skeletal muscle. J Cell Biol 2002;159(1):123–134.

6. Assmus B, Schaechinger V, Teupe C, et al. Transplantation of progenitor cells and regeneration en­hancement in acute myocardial infarction (TOPCARE-AMI). Circulation 2002;106:r53–r61.

7. Bader A, Al-Dubai H, Weitzer G. Leukemia inhibitory factor modulates cardiogenesis in embryoid bodies in opposite fashions. Circ Res 2000;86(7):787–794.

8. Barski G, Sorieul S, Cornefert F. “Hybrid” type cells in combined cultures of two different mammalian cell strains. J Natl Cancer Inst 1961;26:1269–1291.

9. Boersma E, Mercado N, Poldermans D, Gardien M, Vos J, Simoons M. Acute myocardial infarction. Lancet 2003;361:847–58.

  1. 10.          Boheler K, Czyz J, Tweedie D, Yang H, Anisimov S, Wobus A. Differentiation of pluripotent embryonic stem cells into cardiomyocytes. Circ Res 2002;91:189–201.

Read Full Post »

Older Posts »