Cardiovascular Medicine Section, Boston University Medical Center, Boston, Massachusetts 02118, USA. wilson.colucci@bmc.org The benefit of beta-blockers for secondary prevention of death and reinfarction after myocardial infarction (MI) has been conclusively demonstrated in randomized clinical trials. Before the Carvedilol Post-Infarct Survival Control in Left Ventricular Dysfunction Study (CAPRICORN)-a multicenter, multinational, double-blind, randomized, placebo-controlled trial that enrolled 1,959 patients who had an acute MI and a left ventricular ejection fraction of <==0.40-it was not known whether beta-blockers confer additional benefit when used in the context of modern post-MI management (eg, fibrinolytic therapy and primary percutaneous transluminal coronary angioplasty, aspirin, and angiotensin-converting enzyme inhibitors). Patients in CAPRICORN were treated with a maximum dose of 25 mg bid and observed until 633 validated primary end points had occurred. Because the overall mortality was lower than had been predicted, a co-primary end point was adopted that included the original primary end point (all-cause mortality) plus the first of the prespecified secondary end points (all-cause mortality or cardiovascular hospitalizations). A significant 23% reduction in the original primary end point of all-cause mortality was observed. A total of 340 (35%) patients died or had a cardiovascular hospitalization in the carvedilol group versus 367 (37%) in the placebo group. Therefore, the revised primary end point of all-cause mortality or cardiovascular hospitalization was reduced by 8%, which was not statistically significant. Significant reductions in cardiovascular mortality, nonfatal MI, and the combination of all-cause mortality or nonfatal MI were observed. Although statistical significance for the revised primary end point was not reached, CAPRICORN has an important role in guiding future use of beta-blockers in the early post-MI period.