Antithrombotic therapy after infrainguinal bypass.

OBJECTIVE: Bypass surgery is regularly performed for the treatment of critical limb ischemia, but the risk of occlusion remains significant. Antiplatelet therapy in patients with arterial disease is useful for secondary cardiovascular and bypass occlusion prevention. However, despite the common use of an antiplatelet agent, especially aspirin, which became the standard of care, the risk of graft occlusion persists. The best antithrombotic treatment for bypass patency therefore remains a matter of debate.
METHODS: We conducted a systematic literature search to identify studies and consensus reporting the use of antithrombotic treatment to prevent bypass occlusion. We excluded case reports and clinical trials with a placebo arm.
RESULTS: Aspirin remains the mainstay of treatment to improve infrainguinal bypass patency; however, the effect differs according to the bypass material used. The greatest beneficial effect of antiplatelet agents was observed with prosthetic bypasses. In such cases, the addition of clopidogrel to aspirin, for at least 1 year, in patients who benefited from a below-knee bypass graft significantly improved bypass patency (occlusion 32% vs 47% for aspirin alone; P = .02) and the amputation rate (9.4% vs 19.2% for aspirin alone; P = .03), without increasing the incidence of major hemorrhage. In contrast, antiplatelet regimens were less efficacious for autologous vein bypasses. The addition of a vitamin K antagonist (VKA) is not routinely proposed because of the increased incidence of associated major hemorrhage. The use of VKA alone, instead of aspirin, should probably be discussed in selected patients, and a combination of VKA and antiplatelet agents should be discussed in patients with venous infrainguinal bypasses considered to be at a high risk for occlusion.
CONCLUSIONS: Although aspirin remains the first-line treatment to prevent infrainguinal bypass occlusion, future studies are needed to define stronger recommendations.