RESUMO
This study sought to find out a correlation, if any, between serum cardiac troponin I values and extent and severity of coronary artery disease in patients with unstable angina. Eighty patients with unstable angina and normal serum creatine kinase values were studied and a comparative evaluation of serum cardiac troponin I values with clinical findings, electrocardiography, quantitative coronary angiography and follow-up events was performed. Among 80 patients, 34 (43%) had cardiac troponin I values of 0.6 microgram/L or higher (group I) and 46 (57%), below 0.6 microgram/L (group II). The mean cardiac troponin I in group I was 2.6 +/- 1.7 micrograms/L and 0.2 +/- 0.1 microgram/L in group II. The patients in group I had more type C lesions, frequent triple vessel and left main coronary artery involvement, and higher mean percentage diameter stenosis in the coronary arteries than those in group II. Early follow-up showed that more patients in group I required procedures earlier (including PTCA and CABG) than those from group II. Mid-term follow-up (9.5 +/- 4 months) data also showed greater occurrence of cardiac events (i.e. myocardial infarction and the increased need of PTCA) in group I. Patients with elevated cardiac troponin I more often experienced Braunwald's class III (A and B) unstable angina associated with presence of marked ST-T changes on the electrocardiography than those from group II. Our study suggests elevated values of serum cardiac troponin I to be evenly associated with the severity and extent of coronary lesions, clinical severity of unstable angina and marked electrocardiographic changes. Follow-up results confirm the potential value of this marker in predicting the course of coronary artery disease.