BACKGROUND: An earlier index of reperfusion after thrombolytic therapy in patients with acute myocardial infarction is desirable to determine whether additional therapy is necessary to salvage the myocardium. Cardiac troponin-T has been developed as a new myocardial specific marker for myocardial injury and has been used for early assessment of reperfusion therapy. This study was performed to investigate the utility of cardiac troponim-T for assessment of reperfusion therapy using serial serum troponin-T and the rapid assay kit. METHODS: The study was comprised of 70patients(M/F : 64/6, mean age 56+/-2 year) with acute myocardial infarction and reperfusion therapy was initiated within 6 hours after the onset of symtoms. Blood samples for CK and troponin-T were taken before thrombolysis and then 60, 90 munutes, 3, 6, 12, 24, 48, and 72 hours after thrombolysis. We compared successful reperfusion index of troponin-T [successful Reperfusion Index : troponin-T90 or 60min-base> or =0.3 or 0.2ng/ml, Rapid Assay Kit(n=40) : Base(-), 90 or 60min(+)] with the real reperfusion that was assessed by coronary angiogram(TIMI grade 3 at 90 minutes after thrombolysis) or clinical reperfusion index defined as early peak of cardiac enzyme(within 12 hours for CK and within 24 hours for cardiac troponin-T). RESULTS: 1) The cardiac troponin-T and CK activity in patients with successful reperfusion showed early peak within 12 hours after thrombolysis was initiated. 2) Successful reperfusion by angiography or clinical reperfusion index were shown in 64(91%) of 70 patients with thrombolysis. 3) The sensitivity, specificity, positive and negative predictive value, and predictive accuracy for detecting reperfusion using a threshold value of 0.2ng/ml of delta troponin-T at 90 minutes after thrombolysis were 95%, 83%, 98%, 63%, and 96% respectively. 4) The sensitivity, specificity, positive, and negative predictive value, and predictive accuracy of successful reperfusion index using the rapid assay kit at 90 minutes after thrombolysis were 97%, 100%, 100%, 67%, and 97% respectively. CONCLUSIONS: The successful reperfusion index using delta troponin-T> or = 0.2ng/ml and the rapid assay kit at 90 min after thrombolysis are simple and usful for early assessment of reperfusion therapy. Thus bedside monitoring for cardiac troponin-T is now possible to improve the decision making process as to whether rescue angioplasty after thrombolysis is necessary to salvage the myocardium.