Apixaban Versus Aspirin for Stroke Prevention in Atrial Fibrillation

At two years, the rate of permanent discontinuation of the study medication was 17.9% per year for the apixaban group and 20.5% per year in the aspirin group. The risk of permanent discontinuation was 12% lower in the apixaban group than in the aspirin group.

“Significantly, fewer patients in the apixaban group than in the aspirin group had a serious adverse event (22% vs 27%), mostly owing to a reduced number of events related to vascular disorders of the CNS among patients taking apixaban,” reported Dr. Diener and colleagues.

The investigators pointed out that the early termination of the trial could theoretically have inflated the estimate of benefit. However, “the statistical threshold for stopping the trial was very high, and boundary had to be exceeded on two consecutive formal reviews, thereby ensuring the robustness of the findings,” they noted.

End of the Line for Aspirin in Atrial Fibrillation and Stroke?
The researchers believe that their study, along with previous research that found a much lower risk of hemorrhagic stroke with dabigatran as compared with warfarin, indicates that reduction of intracranial bleeding will be one of the most important benefits of the newer oral antithrombotic drugs compared with vitamin K antagonist therapy.

“The results of this trial will change medical practice,” Dr. Diener commented. “One-half of all patients with atrial fibrillation who are treated at present with aspirin in the future will be treated by a factor Xa antagonist or other new anticoagulants. But the only drug for which we have scientific evidence that it is clearly better than aspirin is apixaban.

“If validated by future studies, I think this is the end of aspirin as a drug to prevent stroke in patients with atrial fibrillation,” Dr. Diener concluded.