Randomized trial of aspirin and clopidogrel versus aspirin alone for the prevention of coronary artery bypass graft occlusion: the Preoperative Aspirin and Postoperative Antiplatelets in Coronary Artery Bypass Grafting study

Abstract

Background: Routine use of postoperative aspirin after coronary artery bypass grafting (CABG) reduces graft failure and cardiovascular events. The efficacy and safety of adding clopidogrel to aspirin for the prevention of graft failure and cardiovascular events after CABG are unknown. We performed a pilot study measuring safety and efficacy outcomes of aspirin and clopidogrel therapy after CABG.

Methods: We randomized 100 patients undergoing CABG to receive placebo or clopidogrel started after surgery and for 30 days. All patients received aspirin 81 mg daily. Graft patency was measured by cardiac computed tomography angiography at 30 days.

Results: Clinical follow-up was complete for 99 patients, and 79 (80%) underwent computed tomography angiography. The proportion of patients with ≥1 occluded graft was not significantly different between placebo and clopidogrel groups (9/39 [23.1%] vs 7/40 [17.5%], relative risk 0.95, 95% CI 0.80-1.14, P=.54). Among radial artery grafts, the placebo group had a significantly higher number of occlusions or "string signs" compared with the clopidogrel group (7/16 [43.8%] vs 2/19 [10.5%], relative risk 0.24, 95% CI 0.06-1.00, P=.05). There was no difference between placebo and clopidogrel groups in the safety outcomes of total postoperative bleeding, transfusions, bleeding events, and reexploration and in the efficacy outcomes of nonfatal myocardial infarction, stroke, and death.

Conclusions: This pilot study confirms a high rate of graft occlusion after CABG surgery and suggests that the addition of clopidogrel to aspirin is feasible and safe and may be superior for prevention of graft failure in radial artery grafts.

Trial registration: ClinicalTrials.gov NCT00330772.