BACKGROUND: Previous studies have not shown that routine catheterization and appropriate revascularization offers better outcomes than more conservative approaches in patients with unstable angina or myocardial infarction (MI) without ST-segment elevation. The authors hypothesized that the effectiveness of glycoprotein IIb/IIIa inhibitors and coronary stenting in patients treated with percutaneous coronary revascularization (PCR) would lead to better outcomes in patients with unstable coronary syndromes who are treated with an early invasive strategy.
POPULATION STUDIED: The investigators enrolled 2220 patients presenting with prolonged or recurrent angina at rest or with minimal effort, or with an accelerating pattern of angina. Patients also had to have 1 or more of the following: (1) electrocardiographic evidence of ischemia, (2) abnormal cardiac enzymes, or (3) documented coronary artery disease. Patients were excluded if they had persistent ST-segment elevation, secondary angina, PCR or coronary artery bypass surgery (CABG) within 6 months, left bundle branch block or a paced rhythm, factors associated with increased bleeding risk, severe congestive heart failure or cardiogenic shock, serious systemic disease, serum creatinine higher than 2.5 mg per dL, or recent treatment with ticlopidine, clopidogrel, or warfarin.
STUDY DESIGN AND VALIDITY: This was a randomized controlled trial. Investigators used a central center to randomize patients to immediate (within 48 hours) cardiac angiography with appropriate revascularization or to conservative therapy. Patients receiving conservative therapy had angiography if they met criteria for recurrent ischemia, infarction, hemodynamic instability, ischemia on exercise testing, or readmission. All conservatively managed patients without recurrent ischemia had a treadmill before discharge. All patients received intravenous heparin, aspirin, a b-blocker, nitrates, and tirofiban, a glycoprotein IIb/IIIa inhibitor. Patients were followed up for up to 6 months. The study is methodologically sound. Only 27 patients (1.2 %) were lost to follow-up at 6 months. A weakness of this study is that fewer patients in the conservative strategy group undergoing PCR received tirofiban (59%, vs 95% in the invasive strategy group). An appropriate stratified analysis of this unplanned treatment difference showed no difference in the results.
OUTCOMES MEASURED: The primary outcome was the combined incidence of death, nonfatal MI, and rehospitalization for an acute coronary syndrome at 6 months.
RESULTS: In the invasive strategy arm, 97% of patients received angiography within a median of 22 hours of randomization, and 60% underwent PCR or CABG. An additional 1% required revascularization by 6 months. Among conservatively managed patients, 51% had angiography, and 36% had revascularization during or soon after their initial hospitalization. An additional 8% had revascularization within 6 months. CABG and PCR rates were similar among patients in the 2 groups who underwent catheterization. Most patients (80%) in each group undergoing PCR received stenting.
An early invasive strategy improves outcomes among patients with unstable angina or MI without ST-segment elevation who have a troponin T greater than 0.01 ng per mL or a TIMI score greater than 2. The benefit of this strategy for patients taking aspirin is uncertain. Family physicians should refer appropriate patients with acute coronary syndromes to catheterization labs that perform large volumes of procedures with low complication rates and that routinely use tirofiban and coronary stents when performing PCR.