Effect of Anemia on Frequency of Short- and Long-Term Clinical Events in Acute Coronary Syndromes (from the Acute Catheterization and Urgent Intervention Triage Strategy Trial)

There are limited data on the impact of anemia on clinical outcomes in unstable angina and non–ST-segment elevation myocardial infarction treated with an early invasive strategy. We sought to determine the short- and long-term clinical events among patients with and without anemia enrolled in the Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trial. Anemia was defined as baseline hemoglobin of <13 g/dl for men and <12 g/dl for women. The primary end points were composite ischemia (death, myocardial infarction, or unplanned revascularization for ischemia) and major bleeding assessed in-hospital, at 1 month, and at 1 year. Among the 13,819 patients in the ACUITY trial, information regarding anemia was available in 13,032 (94.3%), 2,199 of whom (16.9%) had anemia. Patients with anemia compared with those without anemia had significantly increased adverse event rates in-hospital (composite ischemia 6.6% vs 4.8%, p = 0.0004; major bleeding 7.3% vs 3.3%, p <0.0001), at 1 month (composite ischemia 10% vs 7.2%, p <0.0001, major bleeding 8.8% vs 3.9%, p <0.0001), and 1 year (composite ischemia 21.7% vs 15.3%, p <0.0001). Anemia was an independent predictor of death at 1 year (hazard ratio 1.77, 95% confidence interval [CI] 1.29 to 2.44, p = 0.0005). Composite ischemia was significantly more common among patients who developed in-hospital non–coronary artery bypass surgery major bleeding compared with those who did not (anemic patients 1-year relative risk 2.19, 95% CI 1.67 to 2.88, p <0.0001; nonanemic patients relative risk 2.16, 95% CI 1.76 to 2.65, p <0.0001). In conclusion, in the ACUITY trial, baseline anemia was strongly associated with adverse early and late clinical events, especially in those who developed major bleeding.