Atrial fibrillation as a risk factor for stroke recurrence

Background Although atrial fibrillation is a well-known risk factor for ischemic stroke, the extent to which it increases the risk of stroke recurrence, particularly in elderly patients, is less certain. Methods We performed a retrospective cohort study of 915 patients aged 50 to 94 years who were admitted with an ischemic stroke. The rates of recurrent strokes and recurrent severe strokes were estimated with the Kaplan-Meier method. The effects of atrial fibrillation on stroke risk were analyzed with proportional hazards models. Results Of the 829 patients who survived the initial hospitalization, 163 (20%) had a stroke during follow-up. Of the 203 patients with atrial fibrillation during index hospitalization who were not anticoagulated, 54 (27%) had recurrent strokes, compared with 18% (19/103) among those with atrial fibrillation who were anticoagulated and 17% (90/523) among those without atrial fibrillation. The age-adjusted hazard ratio for recurrent stroke among those with atrial fibrillation who were not treated with anticoagulants was 2.1 (95% confidence interval [CI]: 1.4 to 2.9; P<0.001), whereas the hazard ratio for recurrent severe stroke was 2.4 (95% CI: 1.6 to 3.6; P<0.001). The increased risk was observed even in patients aged ≥80 years and persisted during the follow-up for more than 5 years. Conclusion Atrial fibrillation was an independent risk factor for stroke recurrence over a wide age range.