There is a wealth of evidence for the effectiveness of anticoagulation therapy to prevent stroke and thromboembolism, but while anticoagulants have been demonstrated to be highly effective at preventing stroke and embolic events among AF patients, they are also known to increase the risk of major bleeding events. Anticoagulation with warfarin and other VKA drugs can be complex to manage. These drugs have narrow therapeutic windows and require close monitoring to stay within the target international normalized ratio (INR). They also have many known food and drug interactions.