Warfarin has been the cornerstone therapy for stroke prevention in non-valvular atrial fibrillation (NVAF), particularly in patients at high risk of ischemic stroke or thromboembolism. Warfarin use in NVAF results in a 64% relative reduction in the incidence of ischemic stroke and several trials have demonstrated warfarin to be superior to aspirin alone (relative risk reduction-22%). However, anticoagulation with warfarin is associated with increased bleeding, especially in the elderly population. Anticoagaulation with warfarin requires close monitoring of the international standardized ratio (INR), which can be inconvenient to patients. Additionally, large numbers of patients on coumadin have a subtherapeutic INR level, which increases the risk of thromboembolic episodes. In part due to the above mentioned reasons, anticoagulation with warfarin is underutilized for stroke prevention.