Systematic review of randomized controlled trials of aspirin and oral anticoagulants in the prevention of graft occlusion and ischemic events after infrainguinal bypass surgery

AbstractPurpose: We sought to determine the efficacy of antiplatelet therapy and oral anticoagulants in maintaining graft patency and preventing ischemic complications in patients after infrainguinal bypass surgery. Methods: We performed a meta-analysis of randomized controlled trials of aspirin with or without other antiplatelet therapy and oral anticoagulants after infrainguinal bypass surgery. Outcome measures studied were graft occlusion, stroke, myocardial infarction, vascular and total mortality, and the composite outcome of stroke, myocardial infarction, and vascular mortality. Results: Five trials of antiplatelet therapy versus placebo were included. The relative risk (RR) for occlusion was 0.78 (95% CI, 0.64-0.95). For prevention of stroke, myocardial infarction, and death, and for the composite outcome, no significant effect was measured. Only one trial of oral anticoagulants versus control treatment was included. The RR for occlusion was 0.55 (95% CI, 0.30-0.99), and that for amputation was 0.30 (95% CI, 0.10-0.87). The mortality rate did not differ significantly between the groups. One trial of oral anticoagulant therapy plus aspirin versus aspirin alone in high-risk patients was included. The RR for occlusion was 0.38 (95% CI, 0.15-0.95). There were no significant differences for prevention of amputation, myocardial infarction, and death between the groups. Conclusion: Antiplatelet therapy and oral anticoagulants reduce the risk of graft occlusion. Oral anticoagulant therapy appears to be the more effective treatment in high-risk patients. Data on the reduction of the risk of stroke, myocardial infarction, and death are inconclusive. Evidence for the beneficial effects of antiplatelet and oral anticoagulant therapy after infrainguinal bypass surgery is based on a small number of trials only. There is no proof as to which modality is the most effective in the prevention of graft occlusion and ischemic events in patients after infrainguinal bypass surgery, which is reason for a randomized comparison of aspirin with oral anticoagulants. (J Vasc Surg 1999;30:701-9.