The role of cardiac troponin-I (cTnI) in risk stratification of patients with unstable coronary artery disease

In patients with chest pain at rest but no ST-segment elevation on the electrocardiogram, the diagnoses of unstable angina and non-Q-wave myocardial infarction (MI) are usually considered together because they cannot be differentiated clinically or angiographically. Since the extent of myocardial necrosis is an important determinant of the risk of death, it is important to identify serum markers with which to predict prognosis, in order to initiate appropriate medical treatment and/or invasive procedures in these patients. Cardiac troponin-I (cTnI), one of the subunits of the troponin regulatory complex, binds to actin and inhibits interactions between actin and myosin. The presence of elevated cTnI in serum is a significant prognostic indicator in patients with unstable angina and non-Q wave MI. Its independent prognostic potential persists even after adjustment for independent baseline variables known to be significantly associated with an increased risk of cardiac events. The use of cTnI in the triage of patients with unstable coronary disease may identify those at greater risk for adverse cardiac events.

Troponin-T as a serum marker for myocardial infarction

We report here our experience with serum troponin T (TnT), measured with the sandwich immunoassay introduced by Boehringer Mannheim as a marker for myocardial infarction. We assayed TnT in serial serum samples from 30 patients with time courses of serum CK, CK-MB, AST, and LD that we consider typical of acute myocardial infarction (MI). In every patient but one, TnT rose in parallel with both CK-MB and AST, but remained elevated significantly longer. The ratios of the elevations of the different markers varied from patient to patient with marked variation in the ratio of TnT to CK-MB. There appeared to be a significant association between the magnitude of that ratio with the level of ALT.