Relation Between Troponin T and the Risk of Subsequent Cardiac Events in Unstable Coronary Artery Disease

Abstract

Background Early risk assessment is important in patients with unstable coronary artery disease, ie, unstable angina or non–Q-wave myocardial infarction. Some previous small studies have indicated that patients with unstable angina and elevation of troponin T (tn-T) have worse short-term and long-term prognoses. In this study, the prognostic value of tn-T was evaluated and compared with other early available risk indicators. Methods and Results Nine hundred seventy-six patients participating in a randomized study of low-molecular-weight heparin in unstable coronary artery disease were followed for 5 months after the index episode. The risk of cardiac events increased with increasing maximal levels of tn-T obtained in the initial 24 hours. The lowest quintile (<0.06 μg/L) constituted a low-risk group, the second quintile (0.06 to 0.18 μg/L) an intermediate-risk group, and the three highest quintiles (≥0.18 μg/L) a high-risk group, with 4.3%, 10.5%, and 16.1% risk of either myocardial infarction or cardiac death, respectively. Troponin T level was identified together with age, hypertension, number of antianginal drugs, and ECG changes at rest as independent prognostic variables for myocardial infarction or cardiac death in a multivariate analysis. The prognostic value of tn-T was independent of the classification of index event into unstable angina or myocardial infarction. Conclusions Troponin T determination is an inexpensive and widely applicable method for early risk assessment in patients with unstable coronary artery disease. The maximum tn-T value obtained during the first 24 hours provides independent and important prognostic information.