A new anti-clotting drug, Rivaroxaban ( Xarelto ) is as effective as the standard medication in preventing stroke and blood clots, and does not increase bleeding risk among patients with the most common form of irregular heartbeat, atrial fibrillation.

In ROCKET AF ( Stroke Prevention Using the Oral Direct Factor Xa Inhibitor Rivaroxaban Compared With Warfarin in Patients with Nonvalvular Atrial Fibrillation ), researchers compared Rivaroxaban with the traditional medicine Warfarin ( Coumadin ) in 14,264 patients with atrial fibrillation that was not related to heart valve disease.
The median time that patients spent in the therapeutic range with Warfarin during the course of the trial was 57.8 percent. Patients spent on average 11.9 percent of time above the therapeutic range, while they were below this range 19.7 percent of the time.

In the primary analysis, measuring what happened to research participants while they were actually taking the study drug, those taking Rivaroxaban compared with Warfarin had fewer strokes and blood clots to other parts of the body. With Rivaroxaban there were 1.71 events per 100 patient-years ( 188 patients ) and with Warfarin 2.16 ( 241patients ), p