BACKGROUND: Whether the glycoprotein IIb/IIIa inhibitor abciximab is beneficial in patients undergoing elective percutaneous coronary intervention after pretreatment with clopidogrel is unknown. METHODS: We enrolled 2159 patients with coronary artery disease who underwent a percutaneous coronary intervention: 1079 patients were randomly assigned in a double-blind manner to receive abciximab and 1080 patients to receive placebo. All patients were pretreated with a 600-mg dose of clopidogrel at least two hours before the procedure. The primary end point of the trial was the composite of death, myocardial infarction, and urgent target-vessel revascularization within 30 days after randomization. RESULTS: The incidence of the primary end point was 4 percent (45 patients) in the abciximab group, as compared with 4 percent (43 patients) in the placebo group (relative risk, 1.05; 95 percent confidence interval, 0.69 to 1.59; P=0.82). Most adverse events were myocardial infarctions: the incidence was 4 percent (40 patients) in the abciximab group and 4 percent (41 patients) in the placebo group (P=0.91). Twelve patients (1 percent) in the abciximab group and eight patients (1 percent) in the placebo group had major bleeding complications (P=0.37). Profound thrombocytopenia occurred in 10 patients (1 percent) in the abciximab group but in none in the placebo group (P=0.002). CONCLUSIONS: Our data suggest that in patients at low-to-intermediate risk who undergo elective percutaneous coronary intervention after pretreatment with a high loading dose of clopidogrel, abciximab is associated with no clinically measurable benefit within the first 30 days. Copyright 2004 Massachusetts Medical Society