Combined antiplatelet therapy in atrial fibrillation: review of the literature and future avenues.

Atrial fibrillation (AF), the most commonly encountered cardiac rhythm disorder, affects approximately 1% of the general population and is associated with serious complications, most notably ischemic stroke. AF-associated stroke occurs at an annual rate of 4.5%. Anticoagulation therapy with warfarin has been demonstrated in randomized controlled trials to reduce the risk for AF-related stroke by two thirds, but warfarin therapy is markedly underused in clinical practice because of its narrow therapeutic window and its implications on quality of life. This article reviews the present knowledge and potential future research avenues for the role of antiplatelet therapy in AF as an alternative to anticoagulation with warfarin for prevention of AF-associated stroke. Antiplatelet therapy recently has been shown to be protective against thrombotic events related to blood stasis. There is ample evidence from experimental and clinical studies that a combination of different antiplatelet agents may increase antithrombotic efficacy compared to monotherapy. Accordingly, a series of randomized controlled trials (ACTIVE [Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events]) has been designed to vigorously examine the role of combined antithrombotic therapy for prevention of vascular events, including stroke in high-risk AF patients. The ACTIVE program began patient enrollment in spring 2003.