This assumption may be underestimating the potential bene t of triple therapy vs dual antiplatelet therapy in reducing nonfatal stroke. e We estimated the annual rates of nonfatal stroke (ischemic and hemorrhagic) on aspirin clopidogrel by extrapolating from observed annual rates of ischemic stroke (fatal nonfatal), strati ed by CHADS score, in the aspirin arms of six historical RCTs in patients with AF (Gage et al ). Assumptions underlying these estimates are detailed in section of this article. f From clopidogrel (plus aspirin) arm of the PLATO trial of ticagrelor vs clopidogrel in patients with acute coronary syndrome. g Based on the absolute rate of non-coronary artery bypass graft-related major bleeding (TIMI de nition) reported in the clopidogrel (plus aspirin) arm of the PLATO trial minus the rate of fatal bleeding reported in this arm of the PLATO trial. h Estimate is derived from rate of systemic embolism on aspirin per patient-y) reported in the individual patient data meta-analysis by van Walraven et al and estimated relative risk of CI, for systemic embolism with combination aspirin clopidogrel therapy vs aspirin observed in ACTIVE A ( Table ). e564S Antithrombotic Therapy for Atrial Fibrillation these issues are not relevant for patients already receiving warfarin for AF. Finally, there are no studies comparing warfarin plus aspirin to triple therapy (eg, warfarin, aspirin, and clopidogrel) in patients with AF and recent ACS. Use of triple therapy in this situation would be appropriate only if the risk reduction in MI and stroke achieved by adding the second antiplatelet agent is greater than the increase in bleeding risk. This seems unlikely in patients who are not under- going stent placement and, thus, where there is no concern regarding stent thrombosis. 