Rivaroxaban Enters the Arsenal for Stroke Prevention in AFib

Summary and Comment |
August 10, 2011

Rivaroxaban Enters the Arsenal for Stroke Prevention in AFib

  1. Harlan M. Krumholz, MD, SM

Another anticoagulant proves noninferior to warfarin.

  1. Harlan M. Krumholz, MD, SM

Rivaroxaban, an oral factor Xa inhibitor, might be a new alternative to warfarin for anticoagulation in patients with atrial fibrillation (AF). The ROCKET AF study was a multicenter, double-blind, industry-sponsored, randomized trial of once-daily oral rivaroxaban compared with dose-adjusted warfarin in moderate-to-high-risk patients with nonvalvular AF. The authors hypothesized that rivaroxaban is noninferior to warfarin at preventing the composite of stroke (ischemic and hemorrhagic) and systemic embolism. The 14,264 enrolled patients (median age, 73; 40% women) had a mean CHADS2 score of 3.5; about half had a CHADS2 score of ≥4.

Median follow-up was 707 days. In the warfarin group, the overall mean proportion of time in therapeutic international normalized ratio range was 55%. In the on-treatment noninferiority study, the primary event rate was 1.7% in rivaroxaban recipients and 2.2% in warfarin recipients (P<0.001 for noninferiority). In superiority analyses conducted after noninferiority was demonstrated, the primary event rate was slightly but significantly lower with rivaroxaban than with warfarin by on-treatment analysis but not by intention-to-treat analysis. The rate of major or nonmajor bleeding was similar in the two groups, although intracranial and fatal bleeding were significantly more common in warfarin recipients than in rivaroxaban recipients.


These findings were presented at the American Heart Association meeting in 2010, and the published article contains no surprises. The authors appropriately emphasize the noninferiority results and play down the superiority finding in the on-treatment analysis. They do highlight the lower intracranial and fatal bleeding rates in the rivaroxaban group, but these findings are more intriguing than definitive. This study supports adding rivaroxaban to the growing list of anticoagulant agents to prevent stroke and systemic embolism in patients with atrial fibrillation. So, how best to choose among these agents for particular patients given cost, compliance, and safety issues? Neither these investigators nor the authors of an accompanying editorial answer that question.


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