The outcome of coronary angioplasty performed for unstable angina is determined, in part, by the acuteness and severity of the clinical presentation. The risk of abrupt vessel closure is increased in patients with postinfarction angina. The Hirulog Angioplasty Study compared the efficacy and safety of bivalirudin with weight-adjusted heparin in patients undergoing percutaneous transluminal coronary angioplasty (PTCA) for unstable or postinfarction angina. We report the results of the intent-to-treat analysis using adjudicated data for the prespecified group of 741 patients who underwent angioplasty within 2 weeks of documented myocardial infarction. Patients received either bivalirudin or heparin immediately before angioplasty. The primary efficacy endpoint was procedural failure defined as abrupt vessel closure, death, myocardial infarction, or revascularization during hospitalization. Bivalirudin significantly (p = 0.004) decreased the incidence of procedural failure compared with heparin (5.1% vs 10.8%, odds ratio 0.45; 95% CI 0.25-0.79). The improved efficacy of bivalirudin was replicated for each individual clinical endpoint. The incidence of major bleeding was significantly (p = 0.001) lower in bivalirudin-treated patients compared with heparin-treated patients (2.4% vs 11.8%, respectively). The benefits observed with bivalirudin are of similar magnitude as those reported for platelet glycoprotein (GP) IIb/IIIa inhibitors, such as abciximab. Bivalirudin may be a more effective foundation anticoagulant than heparin in patients undergoing coronary angioplasty for postinfarction angina.