Early monitoring of serum cardiac troponin I for assessment of coronary reperfusion following thrombolytic therapy

Abstract

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 1 (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 (ΔcTnI), CK-MB (ΔCK-MB), and myoglobin (Δmyoglobin) 90 minutes after therapy in groups 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. ΔcTnI, ΔCK-MB, and Δmyoglobin levels were significantly increased in group 1 versus group 2 at 90 minutes. Further, ΔcTnI was significantly greater at 90 minutes within group 1 compared to ΔCK-MB and Δmyoglobin. The sensitivity for detecting reperfusion at 90 minutes angiography using threshold values of 6.0 for ΔcTnI, 7.0 for ΔCK- MB, and 5.0 for Δmyoglobin were: ΔcTnI 82.4%; ΔCK-MB 64.7%; Δmyoglobin 76.5%; respectively. This study indicates thai 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 findings.