Ability of minor elevations of troponins I and T to predict benefit from an early invasive strategy in patients with unstable angina and non-ST elevation myocardial infarction - Results from a randomized trial

Context Cardiac troponins I (cTnI) and T (cTnT) are useful for assessing pr ognosis in patients with unstable angina and non-ST-segment elevation myoca rdial infarction (UA/NSTEMI). However, the use of cardiac troponins for pre dicting benefit of an invasive vs conservative strategy in this patient pop ulation is not clear. Objective To prospectively test whether an early invasive strategy provides greater benefit than a conservative strategy in acute coronary syndrome pa tients with elevated baseline troponin levels. Design Prospective, randomized trial conducted from December 1997 to June 2 000. Setting One hundred sixty-nine community and tertiary care hospitals in 9 c ountries. Participants A total of 2220 patients with acute coronary syndrome were enr olled. Baseline troponin level data were available for analysis in 1821, an d 1780 completed the 6-month follow-up. Interventions Patients were randomly assigned to receive (1) an early invas ive strategy of coronary angiography between 4 and 48 hours after randomiza tion and revascularization when feasible based on coronary anatomy (n = 111 4) or (2) a conservative strategy of medical treatment and, if stable, pred ischarge exercise tolerance testing (n = 1106). Conservative strategy patie nts underwent coronary angiography and revascularization only if they manif ested recurrent ischemia at rest or on provocative testing. Main Outcome Measure Composite end point of death, AAI, or rehospitalizatio n for acute coronary syndrome at 6 months. Results Patients with a cTnI level of 0.1 ng/mL or more (n = 1087) experien ced a significant reduction in the primary end point with the invasive vs c onservative strategy (15.3% vs 25.0%; odds ratio [OR], 0.54; 95% confidence interval [CI], 0.40-0.73). Patients with cTnI levels of less than 0.1 ng/m L had no detectable benefit from early invasive management (16.0% vs 12.4%; OR, 1.4; 95% CI, 0.89-2.05; P<.001 for interaction). The benefit of invasi ve vs conservative management through 30 days was evident even among patien ts with low-level (0.1-0.4 ng/mL) cTnI elevation (4.4% vs 16.5%; OR, 0.24; 95% Cl, 0.08-0.69). Directionally similar results were observed with cTnT. Conclusion In patients with clinically documented acute coronary syndrome w ho are treated with glycoprotein IIb/IIIa inhibitors, even small elevations in cTnI and cTnT identify high-risk patients who derive a large clinical b enefit from an early invasive strategy.