Analytical Issues and the Evolution of Cutoff Concentrations for Cardiac Markers

Abstract

Cardiac troponin has been shown to be very useful for the determination of minor myocardial damage (MMD) for patients who present with chest pain. Subsequent outcome studies have shown that patients with an increase in troponin are at high short-term risk (4 wk) for death and myocardial infarction (MI). These clinical trials together with a better understanding of the pathophysiology of acute coronary syndromes (ACS) have led the European Society of Cardiology (ESC) and the American College of Cardiology (ACC) to formulate a joint committee to redefine the criteria for acute myocardial infarction (AMI) (1). Their recommendation was that, in the context of cardiac ischemia, any increase in the concentration of cardiac troponin or creatine kinase (CK) in blood is indicative of AMI. A working subgroup of the ESC/ACC Committee have recommended that the cutoff concentration for cardiac markers be set at the 99% of the reference range (2). However, as summarized in Table 1, the acceptance and implementation of these new standards have been slowed by the continued lack of sensitivity for commercial troponin assays. Another of the major issues is the proper determination of the appropriate cutoff concentrations. These issues are discussed in this chapter.