In patients with extracranial carotid or vertebral atherosclerosis who have had ischemic stroke or TIA, treatment with aspirin alone (75 325 mg daily), clopidogrel alone (75 mg daily), or the combination of aspirin plus extended-release dipyridamole (25 mg and 200 mg twice daily, respectively) should be started and continued.91,104,116 (Level of Evidence: B) 5. For patients with symptomatic atherosclerotic peripheral artery disease of the lower extremity, antiplatelet therapy with aspirin (75 325 mg daily) or clopidogrel (75 mg daily) should be started and continued.92,107,116,117 (Level of Evidence: A) 6. Antiplatelet therapy is recommended in preference to anticoagulant therapy with warfarin or other vitamin K antagonists to treat patients with atherosclerosis.93,94,105,110 (Level of Evidence: A) If there is a compelling indication for anticoagulant therapy, such as atrial fibrillation, prosthetic heart valve, left ventricular thrombus, or concomitant venous thromboembolic disease, warfarin should be administered in addition to the low-dose aspirin (75 81 mg daily).95,99 102 (Level of Evidence: A) For patients requiring warfarin, therapy should be administered to achieve the recommended INR for the specific condition.81,96 (Level of Evidence: B) Use of warfarin in conjunction with aspirin and/or clopidogrel is associated with increased risk of bleeding and should be monitored closely.97,98,110 (Level of Evidence: A) Class IIa 1. If the risk of morbidity from bleeding outweighs the anticipated benefit afforded by thienopyridine therapy after stent implantation, earlier discontinuation (eg, 12 months) is reasonable. (Level of Evidence: C) (Note: the risk for serious cardiovascular events because of early discontinuation of thienopyridines is greater for patients with drug-eluting stents than those with bare-metal stents.) 2. After PCI, it is reasonable to use 81 mg of aspirin per day in preference to higher maintenance doses.84,85,118 122 (Level of Evidence: B) 3. 