Early Monitoring of Serum Cardiac Troponin I for Assessment of Coronary Reperfusion Following Thrombolytic Therapy

The authors report the use of cardiac troponin I (cTnI) for the early, noninvasive determination of coronary reperfusion following thrombolytic therapy. Cardiac troponin I, creatine kinase (CK)-MB, and myoglobin concentrations were measured in early serum specimens at 30, 60, and 90 minutes after initiation of therapy (0 minutes) in 25 consecutive patients given front-loaded rt-PA during acute myocardial infarction. Angiography, determined at 90 minutes after therapy, was used to classify patients as follows: group I (n = 17) reperfusion (TIMI flow grade 2, 3); and group 2 (n = 8) absence of reperfusion (TIMI flow grade 0, 1). The authors calculated the ratio increase in cTnI (delta cTnI), CK-MB (delta CK-MB), and myoglobin (delta myoglobin) 90 minutes after therapy in group 1 and 2. Serum cTnI, CK-MB and myoglobin concentrations significantly increased at 60 and 90 minutes in group 1, but not in group 2. Delta cTnI, delta CK-MB, and delta myoglobin levels were significantly increased in group 1 versus group 2 at 90 minutes. Further, delta cTnI was significantly greater at 90 minutes within group 1 compared to delta CK-MB and delta myoglobin. The sensitivity for detecting reperfusion at 90 minutes angiography using threshold values of 6.0 for delta cTnI, 7.0 for delta CK-MB, and 5.0 for delta myoglobin were: delta cTnI 82.4%; delta CK-MB 64.7%; delta myoglobin 76.5%; respectively. This study indicates that early serial measurements of cTnI were a more accurate predictor of early coronary artery reperfusion 90 minutes after thrombolytic therapy compared to CK-MB and myoglobin. Larger population studies will be necessary to confirm these finding.