Rivaroxaban is an oral anticoagulant that directly inhibits Factor Xa. The ROCKET AF study compared rivaroxaban to warfarin in over 14,000 patients with nonvalvular atrial fibrillation and found it to be non-inferior in preventing strokes and systemic embolisms while showing comparable rates of bleeding. The patients in the ROCKET AF study had higher risks of stroke than previous similar studies, with 90% having a CHADS2 score of 3 or higher.