Pathophysiological analysis of serum troponin T release kinetics in evolving ischemic myocardial injury.

The present study measured cardiac troponin T(TnT) for the pathophysiological analysis of evolving ischemic myocardial injury in 35 patients with unstable angina (3: Class IB, 32: Class IIIB) and in 40 patients undergoing coronary reperfusion therapy for acute myocardial infarction. Serum TnT, creatine kinase (CK), CKMB, myoglobin (Mb), and myosin light chain 1 (MLC1) were measured every 2-24 h for 10 days after admission to the CCU. In patients with unstable angina, positive test results were detected in 65.7% for TnT, 20% for CK, 37.1% for CKMB, 60.9% for Mb, and 26% for MLC1. Of the 23 patients with positive TnT, 12 (52.2%) had cardiac events. Of the 12 patients with negative TnT, 11 (91.6%) were event-free. All of the patients who developed cardiac events showed a persistent (n = 10) or delayed elevation (n = 2) pattern 28-120 h beforehand. The sensitivity for predicting cardiac events was 92.3% for TnT, 80% for Mb, 53.8% for CKMB, and 50% for MLC1. In patients with acute myocardial infarction, TnT release kinetics showed 2 peaks after coronary reperfusion therapy. TnT values at the 1st peak significantly correlated with maximum CKMB (r = 0.70, p < 0.05) and early-stage left ventricular wall motion score (r = 0.60, p < 0.05), while 2nd-peak TnT values significantly correlated with maximum MLC1 (r = 0.59, p < 0.05), the T1-SPECT score (r = 0.78, p < 0.05) and left ventricular ejection fraction (r = -0.74, p < 0.05) in the convalescent stage. The 2nd/1st-peak TnT ratio significantly correlated with the nQ/nST elevation index (ratio of the number of leads developing abnormal Q-wave 1 week after the onset to the number of leads showing ST elevation of more than 1 mm at admission) (r = 0.63, p < 0.05) in patients with anterior myocardial infarction. These data indicate that persistent release of TnT reflects progressive irreversible myocardial damage in unstable angina and indicates a risk of future cardiac events. In acute myocardial infarction, the 2nd/1st-peak TnT ratio in patients undergoing coronary reperfusion therapy may be useful for the quantitative evaluation of myocardial salvage.