Combining Aspirin With Oral Anticoagulant Therapy

Marc Fisher MD Kennedy Lees MD Section Editors In persons with cerebral ischemia caused by atrial fibrillation (AF) and high risk of stroke based on an overall score of a validated risk stratification scheme such as CHADS2 *, adjusted-dose warfarin is recommended for those who have no clinically significant contraindication.1,2 When there is AF, adjusted-dose warfarin is estimated to reduce the risk of stroke by about 60% or more and by about 45% more than aspirin.1 The combination of adjusted-dose warfarin plus aspirin administered to AF patients may offer theoretical advantages such as enhanced stroke prevention efficacy in high-risk persons or improved protection against myocardial ischemic events in those who have coronary artery disease or diabetes.3 The recently published American Heart Association/American Stroke Association recurrent stroke prevention guideline suggests, however, no data indicate that either increasing the intensity of oral anticoagulation or add-on antiplatelet therapy provides further ischemic protection in AF patients.2 In a post hoc analysis, the Stroke Prevention Using an ORal Thrombin Inhibitor in atrial Fibrillation (SPORTIF) investigators studied the risks and benefits of combining aspirin with oral anticoagulant therapy in patients with AF.3SPORTIF III and V trials were designed to determine whether the direct oral thrombin inhibitor ximelagatran (36 mg twice daily) was noninferior to vitamin K antagonist therapy with adjusted-dose warfarin (international normalized ratio 2.0 to 3.0) for prevention of stroke and systemic embolism in high-risk patients with nonvalvular AF.3 The SPORTIF studies were multicenter, randomized trials. SPORTIF III was open-label and carried out in Europe, Asia, and Australasia, and SPORTIF V was double-blinded and carried out in the US and Canada. The primary outcome in both studies was the composite of ischemic and hemorrhagic strokes and systemic embolic events. Myocardial infarction was among the secondary events. Bleeding …