Stroke prevention in atrial fibrillation trial.

T he increasing recognition of the high risk of embolic stroke and other systemic emboli in patients with nonrheumatic atrial fibrillation, the widespread experience with lower-intensity warfarin regimens, and the extensive evidence for the efficacy of aspirin in a variety of vascular diseases led to the conduction of seven large trials of warfarin, four of which also included an evaluation of aspirin. Three of these trials have been published,1-4 and a fourth is in press.5 The Stroke Prevention in Atrial Fibrillation (SPAF) trial6 is reported in this issue of Circulation, and comment on the results is timely. The SPAF investigators evaluated both warfarin and aspirin among patients with nonrheumatic atrial fibrillation. The study examined two groups of patients defined on the basis of their eligibility for warfarin therapy. The 627 patients in group 1 were judged by their physicians to be eligible for warfarin therapy and were randomized equally to open-label warfarin (prothrombin time, 1.3-1.8xcontrol; INR, 2.8-4.5) or double-blind to aspirin (enteric coated, 325 mg daily) or matching placebo. The 703 patients in group 2 were considered ineligible for warfarin therapy and were randomly allocated in double-blind fashion to aspirin (enteric coated, 325 mg daily) or matching placebo.