Serum levels of cardiac troponin I and troponin T in estimating myocardial infarct size soon after reperfusion.

Background: Cardiac troponin I (TnI) and troponin T (TnT) are highly specific myocardial markers.
Objective: To determine whether their serum levels can be used to estimate myocardial infarct size soon after reperfusion.
Methods: We measured the serum levels of TnI, TnT, and creatine kinase every 3 h, and the serum cardiac myosin light chain I (MLCI) every 24 h, in 42 patients with acute myocardial infarction in whom reperfusion therapy had successfully been performed. We calculated the severity of regional hypokinesis by analyzing the follow-up ventriculograms with the centerline method.
Results: The time from reperfusion to the peak level for TnI was 6.1 +/- 3.5 h, significantly shorter than those for creatine kinase (7.5 +/- 4.1 h) and MLCI (55 +/- 28 h). The time to peak level for TnT (6.8 +/- 4.0 h) differed significantly from that for MLCI but not from that for creatine kinase. There was a significant correlation between the peak levels of TnI and TnT (r = 0.86). The peak TnI and TnT levels were correlated well to the peak creatine kinase level (r = 0.67 and 0.69, respectively), total creatine kinase release (r = 0.66 and 0.66), and the peak MLCI level (r = 0.71 and 0.80). We observed excellent correlations between the peak levels of TnI and TnT, and regional hypokinesis (r = -0.84 and -0.85, respectively). These were comparable to the correlations between regional hypokinesis and the peak creatine kinase level (r = 0.75), total creatine kinase release (r = -0.72), and the peak MLCI level (r = -0.76).
Conclusions: These results suggest that the peak serum levels of TnI and TnT in patients with successful reperfusion are accurate and early indices of infarct size.