CASPAR : Clopidogrel and Acetyl Salicylic Acid in Bypass Surgery for Peripheral ARterial Disease

Primary objective: To evaluate whether clopidogrel 75 mg o.d. versus placebo (on a background of ASA 75-100 mg/d) will lead to an increased rate of primary patency, limb salvage and survival, in patients receiving a below knee bypass graft for the treatment of PAD. Secondary objectives: Comparison, between the two treatment groups, of : * Primary patency, * Assisted primary patency, * Cardiovascular death / myocardial infarction / stroke / any amputation above the ankle. * Ankle Brachial Pressure Index (ABPI) changes from baseline