An evidence-based review of apixaban and its potential in the prevention of stroke in patients with atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia, especially in the elderly population. It is associated with cardioembolic complications, particularly strokes, resulting in severe functional deficit or death. AF patients are first stratified into low, intermediate, and high risk for thromboembolic events using the CHADS(2) and CHA(2)DS(2)-VASc score systems. Depending on their risks, patients are treated with either therapeutic anticoagulation with warfarin or acetylsalicylic acid for stroke prevention. Although warfarin is the recommended therapy, it is underutilized clinically due to concern for narrow therapeutic window, drug-to-drug and drug-to-food interactions, and hemorrhagic complications. Newer anticoagulant agents such as dabigatran (a direct thrombin inhibitor) and rivaroxaban (a direct factor Xa inhibitor) have already been approved by US Food and Drug Administration for stroke prevention in patients with nonvalvular atrial fibrillation. Apixaban is the newest oral direct factor Xa inhibitor and it has been extensively studied in the AVERROES and ARISTOTLE trials. Apixaban demonstrated reduced incidence of primary outcome of stroke and bleeding events when compared with warfarin. Apixaban is currently being reviewed by the Food and Drug Administration as a stroke prophylactic agent. In addition, there are several other indirect factor Xa inhibitors and vitamin K antagonists under study presently. Results from these studies will provide us with information about possible alternatives to warfarin.