NONRHEUMATIC ATRIAL-FIBRILLATION - RISK OF STROKE AND ROLE OF ANTITHROMBOTIC THERAPY

The prevalence of atrial fibrillation is 3-5% in those more than 65 years old. Such patients have an annual risk of stroke of 4-5%, and their mortality is twice that of patients free of atrial fibrillation. The risk of stroke is similar regardless of whether rheumatic heart disease is present. Better understanding of this epidemiology and the potential benefits of warfarin and aspirin, with relatively low risk, have prompted the conduct of several large clinical trials among patients with nonrheumatic atrial fibrillation. Each of the three reported trials has shown at least a 59% reduction of stroke with warfarin therapy. Aspirin appears to confer benefit, but the magnitude appears to be less than with warfarin, and benefit may be confined to certain subgroups.