Lower limb atherosclerosis can lead to blocked blood vessels causing pain on walking (intermittent claudication) or, if more severe, pain at rest, ulceration and gangrene (critical limb ischaemia).
Surgery to bypass the blockage uses either a piece of vein from another part of the person’s body or a synthetic graft. The bypass may help improve blood supply to the leg but the graft can also become blocked, even in the first year. To help prevent this, people are given aspirin (an antiplatelet drug) or a vitamin K antagonist (anti-blood clotting or antithrombotic drug), or both, to try to stop loss of blood flow through the graft (patency). The review of trials found that patients undergoing venous grafts were more likely to benefit from treatment with vitamin K antagonists than platelet inhibitors. Patients receiving an artificial graft may benefit from platelet inhibitors (aspirin). However, the evidence is not conclusive. Although a total of 14 randomised, controlled trials involving 4970 patients were included in the review, trials with larger patient numbers are needed. This is because there was considerable variation between the included trials in whether patients received both types of drugs, anticoagulation levels and how they were measured, and the indications for surgery, intermittent claudication or critical limb ischaemia.