Incidence of Stroke in Paroxysmal Versus Sustained Atrial Fibrillation in Patients Taking Oral Anticoagulation or Combined Antiplatelet Therapy: An ACTIVE W Substudy Stefan H. Hohnloser, Dimitri Pajitnev, Janice Pogue, Jeff S. Healey, Marc A. Pfeffer, Salim Yusuf, Stuart J. Connolly, for the ACTIVE W Investigators The risk of stroke and non-cerebral embolism and the efficacy of oral anticoagulation (OAC) in paroxysmal atrial fibrillation (AF) as compared with sustained AF are not precisely known. ACTIVE W (Atrial Fibrillation Clopidogrel Trial With Irbesartan For Prevention Off Vascular Events) was a trial in 6,706 AF patients comparing OAC to antiplatelet therapy with aspirin plus clopidogrel for prevention of vascular events. The annualized risk of stroke or non-cerebral embolism was 2.0 in paroxysmal AF (n = 1,202) compared with 2.2 in sustained AF (n = 5,495) (relative risk 0.87, 95% confidence interval 0.59 to 1.30, p = 0.496). The incidence of stroke and non-central nervous system embolism was lower for patients treated with OAC irrespective of type of AF.