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In One-Hour: A  Diagnosis of Heart Attack made possible by one Blood Test

Reporter: Larry H Bernstein, MD, FCAP

Voice of Dr. Larry:

This presents a dilemma for medicine with the pressure to discharge patients, and to save money for the system.  The practice of decision-making is still quite elemental.

TRAPID-AMI is a prospective observational study supported by Roche and investigated more than 1,200 patients with acute chest pain during 2011-2014. The study was conducted in twelve institutions from nine countries and three continents, led by Professors Christian Mueller, University of Basel (Switzerland), and Bertil Lindahl, University of Uppsala (Sweden). 

I have great respect for Mueller and Lindahl.  This is a prospective observational study and does not carry the same weight as a randomized study.   Moreover, there is nothing new in this, as you must know.

I think that the Roche hsTNT is the best method out there, but the study will not spur laboratories to switch from hsTnI.  The only condition for such a decision would be performing the test in the ED, which might be the case here. POCT is not without problems.

Only in the last 5 years we have seen much confusion about interpreting the hsTnT and hsTnI.  There is a sensitivity not achieved in earlier methods of the same proteins.  However, there was a tradeoff in specificity and accuracy of diagnosis.  It was great for cardiologists, and the measurement of a second assay in 3 hours was warranted.  However, it was certainly reasonable to carry out the one hour study because patients arrive at the ED perhaps 6 hrs after onset.  There was a time that while the CK-MB was increased and the second assay was in decline, The LD1 assay was needed for a late arrival because of placement on the curve. LD1 is no longer done, and patient awareness is much better than 15-20 years ago.  I had a patent on an LD1 assay that could be done on a centrifugal fast analyzer using the forward reaction PYR–LAC, with NADH oxdation rather than LAC–PYR.

This study indicates that a validation of the suspect diagnosis can be done in 1 hour based on the increase in a shorter time span.  It resolves some of the problem of hsTn’s. I’m not at all convinced that it is sufficient.  I would have to see something more definitive.

There is consensus on the reclassification of Acute Coronary Syndrome into plaque rupture and not plaque rupture.

This creates a problem for relying on a so called “magic bullet” approach.  It would certainly indicate that in order to classify correctly there has to be a minimum of two tests.  All patients with CKD would fall into the not plaque rupture category.  There are other patients who might have 50-60% narrowing and experience precordial symptoms, pressure, but without elevation. Are they very early AMI presentation, as my grandfather some 48 years ago?  

SOURCE

http://www.mdtmag.com/news/2016/01/blood-test-makes-one-hour-diagnosis-heart-attack-possible?et_cid=5054745&et_rid=461755519&type=cta