Rationale and design of AVERROES: Apixaban versus acetylsalicylic acid to prevent stroke in atrial fibrillation patients who have failed or are unsuitable for vitamin K antagonist treatment

BACKGROUND: Many patients with atrial fibrillation (AF) at moderate or high risk for stroke are not treated with a vitamin K antagonist (VKA). Presently, the only alternative to a VKA with a labeled indication for AF is antiplatelet therapy with acetylsalicylic acid (ASA), which is much less effective than a VKA for prevention of stroke. The novel oral factor Xa inhibitor, apixaban, is being developed for prevention of stroke in AF. A …