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

Inclusion Criteria: A patient is eligible for inclusion in the study 2-4 days after surgery if all the following criteria are fulfilled: Informed consent obtained; Chronic background treatment with daily ASA, whatever the dose, started at least 4 weeks before surgery. A window of a few days without ASA before surgery is acceptable, according to local practice. Post-randomization use of ASA must be between 75 and 100 mg/day. Unilateral below knee bypass graft (i.e. the distal anastomosis is below the level of the knee joint) for atherosclerotic PAD within the previous 4 days; Demonstration of initial patency of the index graft by an objective measurement (e.g. intra-operative Doppler scanning, flow measurement, angiography, Duplex scanning) during bypass surgery, or between surgery and the time of randomization; No clinical evidence of graft occlusion at time of randomization. Exclusion criteria : PAD medical/surgical history Onset of PAD symptoms before the age of 40 years Non-atherosclerotic vascular disease (e.g. Buerger's disease, popliteal entrapment syndrome) Patient receiving aorto-bifemoral, iliac-femoral or crossover (femoral-femoral) grafts, or undergoing peripheral transcutaneous angioplasty (PTA), with or without stenting, during the same surgery. Medical history related to bleeding risk Current active bleeding at surgical site Withdrawal of an epidural catheter less than 12 hours before randomization Current active bleeding or increased risk of bleeding, such as severe hepatic insufficiency, proliferative diabetic retinopathy, peptic ulceration, bleeding diathesis or coagulopathy Peptic ulceration within 12 months of randomization Previous or current intracranial hemorrhage or hemorrhagic stroke, or any previous stroke for which the diagnosis of hemorrhagic stroke cannot be excluded Any history of severe spontaneous bleeding such as gastrointestinal bleeding, gross hematuria, intraocular bleeding Other medical conditions Previous disabling stroke (severe cerebral deficit such that the patient is bedridden or demented) NYHA Class IV heart failure Uncontrolled hypertension: Systolic Blood Pressure (SBP) > 180 mm Hg, or Diastolic Blood Pressure (DBP) > 100 mm Hg