Transient ischemic attacks in patients with atrial fibrillation - Implications for secondary prevention: The European Atrial Fibrillation Trial and Stroke Prevention in Atrial Fibrillation III Trial

Background and Purpose - Transient ischemic attacks ( TIAs) are infrequent in patients with atrial fibrillation, and little is known about the long-term prognosis and response to antithrombotic therapy. Methods - This study was a pooled analysis of participants in 2 randomized trials, the European Atrial Fibrillation Trial and the Stroke Prevention in Atrial Fibrillation III Trial, comparing those with prior TIA to those with prior stroke. Results - Among 834 atrial fibrillation patients with prior TIA (n=222), prior ischemic stroke (n=551), or both (n=61), the mean age was 71 years, 64% were men, and 56% had hypertension. The frequency of major vascular risk factors was similar for both types of cerebral ischemia. The annualized rate of ischemic stroke during aspirin therapy was 7% per year ( 95% confidence interval, 4 to 12) for prior TIA and 11% per year ( 95% confidence interval, 9 to 15) for prior stroke (P = 0.08 for rate difference) and was reduced by 56% (P = 0.09) and 63% (P = 0.001), respectively, by anticoagulation. Conclusions - Atrial fibrillation patients with TIA have a lower long-term risk of subsequent stroke than those with prior stroke, but their stroke risk during aspirin therapy is still high. For atrial fibrillation patients with either type of cerebral ischemia, recent or remote, secondary prevention with adjusted- dose warfarin instead of aspirin results in substantial absolute reductions in ischemic stroke.