The new anticlotting drug rivaroxaban is as effective as warfarin in preventing stroke and blood clots, and does not increase bleeding risk among atrial fibrillation patients, according to a randomised, double-blind clinical trial presented at the American Heart Association’s Scientific Sessions 2010 in Chicago, USA.
In ROCKET AF (Stroke prevention using the oral direct factor Xa inhibitor rivaroxaban compared with warfarin in patients with nonvalvular atrial fibrillation) investigators compared rivaroxaban with warfarin in 14,264 patients with AF 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%. Patients spent on average 11.9% of time above the therapeutic range, while they were below this range 19.7% of the time.
“The main implication is that we have an alternative to warfarin,” said Robert M Califf, Duke University School of Medicine in Durham, USA, co-principal investigator of the study. “Equally important, there was no increase in bleeding, so we have a drug you can take once a day, without monitoring, that is at least as good as warfarin and carries no additional risk.”
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 emboli 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<0.001 for non-inferiority, p=0.018 for superiority. Major bleeding complications were comparable in both treatment groups, occurring at a rate of 3.60 per 100 patient-years (395 patients) with rivaroxaban and 3.45 per 100 patient-years (386 patients) with warfarin (p=0.576).
The full intention-to-treat analysis, which counts all events from the time of randomisation until study completion, regardless of whether participants were taking medication, found fewer strokes and blood clots occurred in participants assigned to rivaroxaban (269 patients) versus warfarin (306 patients). However, this difference fell short of statistical significance for declaring rivaroxaban superior to warfarin (p=0.177). Bleeding inside the skull cavity and/or brain tissue occurred in 55 patients on rivaroxaban and 84 on warfarin (p=0.019).