Myocardial Infarction: The New Definition After Revascularization
Reporter: Aviva Lev-Ari, PhD, RN
UPDATED on 7/31/2014
Myocardial Ischemia Symptoms
Reporter: Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2014/07/29/myocardial-ischemia-symptoms/
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Gregg Stone, MD
Co-DIrector, Medical Research & Education Division Cardiovascular Research Foundation
Primary source: Journal of the American College of Cardiology
Source reference: Moussa I, et al “Consideration of a new definition of clinically relevant myocardial infarction after coronary revascularization: an expert consensus document from the Society for Cardiovascular Angiography and Interventions (SCAI)” J Am Coll Cardiol2013; 62: 1563-1570.
Additional source: Journal of the American College of Cardiology
Source reference:White H “Avatar of the universal definition of periprocedural myocardial infarction” J Am Coll Cardiol 2013; 62: 1571-1574.
Moussa reported that he had no conflicts of interest.
Stone is a consultant for Boston Scientific, Eli Lilly, Daiichi Sankyo, and AstraZeneca. The other authors reported relationships with Guerbet, The Medicines Company, Bristol-Myers Squibb/Sanofi, Merck, Maya Medical, AstraZeneca, Abbott Vascular, Regado Biosciences, Janssen Pharma, Lilly/Daiichi Sankyo, St. Jude Medical, Medtronic, Terumo, Bridgepoint/Boston Scientific, Gilead, Boston Scientific, Eli Lilly, and Daiichi Sankyo.
White is co-chairman for the Task Force for the Universal Definiton of Myocardial Infarction; has received research grants from sanofi-aventis, Eli Lilly, The Medicines Company, the NIH, Pfizer, Roche, Johnson & Johnson, Schering-Plough, Merck Sharpe & Dohme, AstraZeneca, GlaxoSmithKline, Daiichi Sankyo Pharma Development, and Bristol-Myers Squibb; and has served on advisory boards for AstraZeneca, Merck Sharpe & Dohme, Roche, and Regado Biosciences.
WASHINGTON, DC — A “clinically meaningful” definition of MI following PCI or CABG is urgently needed to replace the arbitrarily chosen “universal definition” proposed in recent years that has no relevance to patients and may be muddying clinical-trial results. Those are the conclusions of a new expert consensus document released Monday by the Society of Cardiovascular Angiography and Interventions (SCAI)[1].
The notion of a “universal definition of MI” was first proposed in 2000 and updated in 2007 and 2012. The 2012 document defines a PCI-related MI as an increase in cardiac troponin (cTn) of more than five times the upper limit of normal (ULN) during the first 48 hours postprocedure plus specific clinical or ECG features. Post-CABG, the definition is a cTn increase of >10 times the ULN, plus different clinical or ECG features.
The problem, lead author Dr Issam Moussa (Mayo Clinic, Jacksonville, FL) told heartwire , is that these cutoffs were arbitrarily chosen and not based on any hard evidence that these biomarker levels spelled a poor prognosis. Moreover, “overnight, the rate of MI went from 5% following these procedures to 20% to 30%!” he said.
The SCAI committee, in its new document, focuses on post-PCI procedures and highlights the importance of acquiring baseline cardiac biomarkers and differentiating between patients with elevated baseline CK-MB (or cTn) in whom biomarker levels are stable or falling, as well as those in whom it hasn’t been established whether biomarkers are changing.
SCAI’s Proposed Clinically Meaningful MI Definitions
| Group | Definition |
| Normal baseline CK-MB | CK-MB rise of >10x ULN or >5x ULN with new pathologic Q-waves in at least 2 contiguous leads or new persistent left bundle branch block OR In the absence of baseline CK-MB, a cTn rise of >70x ULN or a rise of>35 ULN plus new pathologic Q-waves in at least 2 contiguous leads or new persistent left bundle branch block |
| Elevated baseline biomarkers that are stable or falling | A CK-MB or cTn rise that is equal (by an absolute increment) to the definitions described for patients with normal CK-MB at baseline. |
| Elevated baseline biomarkers that have not been shown to be stable or falling | A CK-MB or cTn rise that is equal (by an absolute increment) to the definitions described for patients with normal CK-MB at baseline Plus New ST-segment elevation or depression Plus New-onset or worsening heart failure or sustained hypotension or other signs of a clinically relevant MI. |
Moussa is quick to emphasize that these new clinically meaningful definitions have limited evidence to support them—and most of what exists supports CK-MB definitions, not cTn—but that the new document is based on the best scientific evidence available.
“We don’t want to come out with a definitive statement” saying this is the final word on MI definitions,” he stressed. “There is more science that needs to be done and there remains more uncertainty. We framed this to be inclusive and also to open the field for discussion.”
His hope is that this will lead to important changes in how patients are managed and money is spent. Currently, patients with clinically meaningless biomarker elevations may become unnecessarily panicked over news that they’ve had a “heart attack,” while hospital stays may be extended and further tests ordered on the basis of these results.
Moussa et al’s proposal also has important implications for clinical trials, he continued. Currently, for studies that include periprocedural MIs as an individual end point or as part of a composite end point, the very high number of biomarker-defined “MIs” collected in the trial could potentially overwhelm the true impact of any given therapy. “You are really using an end point that is truly not relevant to patients. . . . This could really affect the whole hypothesis.”
He’s expecting some push-back from cardiologists and academics, particularly those who championed the need for the universal definition in the first place, but believes most people will welcome a clinically meaningful definition.
“I think many in the medical community will accept this because they have not really been using the universal definition in their day-to-day practice anyhow.” What’s more, the National Cardiovascular Data Registry (NCDR) does not include the reporting of MI postangiography, in part because of concerns that the universal definition of MI overestimates the true incidence of this problem. “I think many in the community will look at this definition as more reflective of the true incidence of MI after angioplasty, and if it’s accepted, they are more likely to report it to databases like NCDR and use it to reflect quality-of-care processes.”
http://www.medscape.com/viewarticle/812533?nlid=35983_2105&src=wnl_edit_medp_card&uac=93761AJ&spon=2
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ESC/ACCF/AHA/WHF Expert Consensus Document
Circulation.2012; 126: 2020-2035 Published online before print August 24, 2012,doi: 10.1161/CIR.0b013e31826e1058
Third Universal Definition of Myocardial Infarction
- Kristian Thygesen;
- Joseph S. Alpert;
- Allan S. Jaffe;
- Maarten L. Simoons;
- Bernard R. Chaitman;
- Harvey D. White
- the Writing Group on behalf of the Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of Myocardial Infarction
- *Corresponding authors/co-chairpersons: Professor Kristian Thygesen, Department of Cardiology, Aarhus University Hospital, Tage-Hansens Gade 2, DK-8000 Aarhus C, Denmark. Tel: +45 7846-7614; fax: +45 7846-7619: E-mail: kristhyg@rm.dk. Professor Joseph S. Alpert, Department of Medicine, Univ. of Arizona College of Medicine, 1501 N. Campbell Ave., P.O. Box 245037, Tucson AZ 85724, USA, Tel: +1 520 626 2763, Fax: +1 520 626 0967, E-mail: jalpert@email.arizona.edu. Professor Harvey D. White, Green Lane Cardiovascular Service, Auckland City Hospital, Private Bag 92024, 1030 Auckland, New Zealand. Tel: +64 9 630 9992, Fax: +64 9 630 9915, E-mail: harveyw@adhb.govt.nz.
Table of Contents
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Abbreviations and Acronyms. . . . . . . . . . . . . . . . . . . .2021
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Definition of Myocardial Infarction. . . . . . . . . . . . . . .2022
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Criteria for Acute Myocardial Infarction. . . . . . . . . . . .2022
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Criteria for Prior Myocardial Infarction. . . . . . . . . . . .2022
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Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2022
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Pathological Characteristics of Myocardial Ischaemia and Infarction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2023
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Biomarker Detection of Myocardial Injury With Necrosis. . .2023
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Clinical Features of Myocardial Ischaemia and Infarction. . .2024
- Clinical Classification of Myocardial Infarction. . . .2024
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Spontaneous Myocardial Infarction (MI Type 1). . . .2024
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Myocardial Infarction Secondary to an Ischaemic Imbalance (MI Type 2). . . . . . . . . . . . . . . . . . . . . . . .2024
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Cardiac Death Due to Myocardial Infarction (MI Type 3). .2025
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Myocardial Infarction Associated With Revascularization Procedures (MI Types 4 and 5). . . . . . . . . . . . . . . . . . …
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New Definition for MI After Revascularization
The Society for Cardiovascular Angiography and Interventions (SCAI) has released a new definition for myocardial infarction (MI) following coronary revascularization aimed at identifying only those events likely to be related to poorer patient outcomes.
In the new criteria — published as an expert consensus document inCatheterization and Cardiovascular Interventions and the Journal of the American College of Cardiology — creatine kinase-myocardial band (CK-MB) is the preferred cardiac biomarker over troponin, and much greater elevations are required to define a clinically relevant MI compared with the universal definition of MI proposed in 2007 and revised in 2012.
Also, the new definition uses the same biomarker elevation thresholds to identify MIs following both percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), whereas the universal definition has different thresholds for events following the two procedures.
“What we’ve really tried to emphasize in this classification scheme is the primary link between biomarker elevations and prognosis,” according to Gregg Stone, MD, of Columbia University Medical Center and the Cardiovascular Research Foundation in New York City, one of the authors of the document.
“In the universal definition of MI, they even acknowledged that their criteria were arbitrary,” Stone said in an interview. “We’ve tried to reduce the arbitrariness of the cutoff values that we selected so that the researcher, academician, clinician, hospital administrator, etc., can be confident that these levels that we’re recommending are the ones that are associated with a worse prognosis for patients suffering periprocedural complications.”
The Change
The existing universal definition for MI defines events following PCI according to an increase in cardiac troponin to greater than five times the 99th percentile upper reference limit (URL) within 48 hours when baseline levels are normal, with confirmation by electrocardiogram (ECG), imaging, or symptoms.
For CABG-related MI, the increase must be more than 10 times the 99th percentile URL within 48 hours when baseline levels are normal, with confirmation by ECG, angiography, or imaging.
But, Stone and colleagues wrote, the relationship between that degree of troponin elevation after a revascularization procedure and prognosis is not as strong as the association between a CK-MB elevation and patient outcomes.
Using a small elevation in troponin to define a post-procedure MI could find myocardial necrosis that is unlikely to be associated with poor clinical outcomes, which could have far-reaching implications, they wrote.
“Widespread adoption of an MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence,” they wrote.
To address that issue, the expert panel convened by SCAI sought to define clinically relevant MI after PCI or CABG.
A clinically relevant MI is defined in the new document based on an increase of at least 10 times the upper limit of normal in the level of CK-MB within 48 hours after a revascularization procedure when baseline levels are normal.
When the CK-MB level is not available, then an increase in troponin I or T of at least 70 times the upper limit of normal can be used to define a clinically relevant MI, according to the authors.
However, if an ECG shows new pathologic Q-waves in at least two contiguous leads or a new persistent left bundle branch block, then the thresholds can be lowered to at least five times and at least 35 times the upper limit of normal for CK-MB and troponin, respectively.
Further guidance is provided for identifying clinically relevant post-procedure MIs when the cardiac biomarker levels are elevated at baseline.
Dueling Definitions
Co-chairman of the Task Force for the Universal Definition of Myocardial Infarction, Harvey White, DSc, of Auckland City Hospital in Auckland, New Zealand, noted some limitations of the new definition, including the lack of a requirement for ischemic symptoms.
“Ischemic symptoms have always been a basic tenet of the diagnosis of MI, and it should be no different for a [PCI-related] MI,” he wrote in an accompanying editorial.
In addition, with the use of such large elevations in biomarker levels in the new definition, “there will be very few PCI-related events identified, and an opportunity to improve patient outcomes may be lost,” he wrote.
Troponin should remain the preferred biomarker over CK-MB, White argued, pointing to variability in and analytical issues with CK-MB assays, the need for sex-specific cutoffs for CK-MB levels, the need for higher thresholds of CK-MB to determine abnormalities because all individuals have circulating levels of the biomarker, and the reduced sensitivity and specificity of CK-MB.
Also, he said, CK-MB is becoming increasingly unavailable at medical centers.
“With CK-MB becoming obsolete, troponin will become the gold standard, and CK-MB will no longer have a role in defining PCI injury and infarction in clinical practice,” White wrote.
Stone admitted that troponin ultimately might be preferable to CK-MB because of its greater specificity, although the evidence does not yet support it.
“I think there’s a general desirability to move to troponins, although when you look at the data that’s out there it’s much stronger correlating CK-MB elevations to subsequent prognosis,” he said. “I think a lot of the troponin elevations are just noise or troponins are just too sensitive.”
Room for Both?
White noted in his editorial that “the rationale for the SCAI definition has been well articulated by its authors and may be appropriate in an individual trial, but it should not supplant the universal definition of MI,” he wrote.
When asked whether the new definition would replace the universal definition, Stone said there is a place for both sets of criteria.
“We would propose the clinically relevant definition be the one that is used to make most substantial decisions right now, [such as] trade-offs between efficacy and safety for new drugs and devices, in judging hospital systems and physicians, etc.,” he said. “But I do think there’s value in both, and they will both continue to evolve over time as new data becomes evident.”
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Third Universal Definition of Myocardial Infarction
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