Are adverse events following an invasive strategy in patients with non-ST-segment elevation acute coronary syndromes more frequent at US sites versus Non-US sites? analysis from the ACUITY trial

Objective To compare outcomes between US and non-US (OUS) sites in patients with non ST-elevation acute coronary syndromes (NSTEACS) and to evaluate potential reasons for differences in outcomes. Background There are little data comparing outcomes at US versus OUS sites in patients with NSTEACS managed with an invasive strategy. Methods The ACUITY trial randomized 13,819 patients with NSTEACS in 17 countries to an invasive approach with one of three strategies: (1) heparin plus glycoprotein platelet inhibitors (GPI), (2) bivalirudin plus GPI, or (3) bivalirudin alone. Results US patients were more often female, were younger, heavier, and had more diabetes, prior myocardial infarction (MI), and prior bypass surgery. US patients were less often treated with percutaneous coronary intervention but had more frequent drug-eluting stent use. US patients had lower mortality and higher MI rates at 30 days and 1 year and higher composite ischemic outcome at 30 days. After adjusting for differences in baseline variables, US patients had higher rates of MI and composite ischemic outcome at 30 days and higher rates of MI at 1 year {HR [95% confidence interval (CI)] = 1.36 [1.18-1.56], P < 0.0001} with no differences in mortality. There were no differences in treatment effects comparing bivalirudin with the other strategies between US and OUS sites. Conclusions US versus OUS patients with NSTEACS had higher adjusted rates of MI and ischemia. The reasons for these differences are not clear but may be due to unmeasured confounders, different thresholds for event reporting, or valid differences in systems of care which may impact outcomes.