Context Cardiac troponins I (cTnI) and T (cTnT) are useful for assessing prognosis
in patients with unstable angina and non–ST-segment elevation myocardial
infarction (UA/NSTEMI). However, the use of cardiac troponins for predicting
benefit of an invasive vs conservative strategy in this patient population
is not clear.
Objective To prospectively test whether an early invasive strategy provides greater
benefit than a conservative strategy in acute coronary syndrome patients with
elevated baseline troponin levels.
Design Prospective, randomized trial conducted from December 1997 to June 2000.
Setting One hundred sixty-nine community and tertiary care hospitals in 9 countries.
Participants A total of 2220 patients with acute coronary syndrome were enrolled.
Baseline troponin level data were available for analysis in 1821, and 1780
completed the 6-month follow-up.
Interventions Patients were randomly assigned to receive (1) an early invasive strategy
of coronary angiography between 4 and 48 hours after randomization and revascularization
when feasible based on coronary anatomy (n = 1114) or (2) a conservative strategy
of medical treatment and, if stable, predischarge exercise tolerance testing
(n = 1106). Conservative strategy patients underwent coronary angiography
and revascularization only if they manifested recurrent ischemia at rest or
on provocative testing.
Main Outcome Measure Composite end point of death, MI, or rehospitalization for acute coronary
syndrome at 6 months.
Results Patients with a cTnI level of 0.1 ng/mL or more (n = 1087) experienced
a significant reduction in the primary end point with the invasive vs conservative
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/mL 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 invasive vs
conservative management through 30 days was evident even among patients with
low-level (0.1-0.4 ng/mL) cTnI elevation (4.4% vs 16.5%; OR, 0.24; 95% CI,
0.08-0.69). Directionally similar results were observed with cTnT.
Conclusion In patients with clinically documented acute coronary syndrome who are
treated with glycoprotein IIb/IIIa inhibitors, even small elevations in cTnI
and cTnT identify high-risk patients who derive a large clinical benefit from
an early invasive strategy.