F10 and atrial fibrillation: Direct-acting oral anticoagulants (DOACs), including the factor Xa (FXa) inhibitors rivaroxaban and apixaban, have been proven to be effective and safe alternatives to warfarin in treatment of venous thrombosis and prevention of stroke in patients with atrial fibrillation.1,2 These drugs exert their anticoagulant effect by binding FXa and consequently inhibiting the conversion of prothrombin to thrombin.