Canadian-American Differences in the Management of Acute Coronary Syndromes in the GUSTO IIb Trial

Abstract

Background —Little information exists concerning practice patterns between Canada and the United States in the management of myocardial infarction (MI) patients without ST-segment elevation and unstable angina. Methods and Results —We examined the practice patterns and 1-year outcomes of 2250 US and 922 Canadian patients without ST-elevation acute coronary syndromes in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb trial. The US hospitals more commonly had on-site facilities for angiography and revascularization. These procedures were performed more often and sooner in the United States than Canada, whereas Canadian patients were more likely to undergo noninvasive stress testing. The length of initial hospital stay was 1 day longer for Canadian than US patients. Recurrent and refractory ischemia was more common in Canada. One-year mortality was comparable between the 2 countries. However, at 6 months, even after baseline differences were accounted for, the (re)MI rate was significantly higher in Canadian than US patients with unstable angina (8.8% versus 5.8%, P =0.039), as was the composite rate of death or (re)MI (13.1% versus 9.1%, P =0.016). Conclusions —One-year mortality was comparable between Canada and the United States in both MI and unstable angina cohorts despite higher intervention rates in the United States. However, outcomes at 6 months among patients with unstable angina differed. Whereas more frequent coronary interventions were not associated with reduced recurrent MI or death among MI patients without ST elevation, they may favorably affect outcomes in patients with unstable angina.