Stroke with intermittent atrial fibrillation: Incidence and predictors during aspirin therapy

OBJECTIVE This study was performed to characterize the risk of stroke in el derly patients with recurrent intermittent atrial fibrillation (AF). BACKGROUND Although intermittent AF is common, relatively little is known a bout the attendant risk of stroke. METHODS A longitudinal cohort study was performed comparing 460 participant s with intermittent AF with 1,552 with sustained AF treated with aspirin in the Stroke Prevention in Atrial Fibrillation studies and followed for a me an of two years. Independent risk factors for ischemic stroke were identifi ed by multivariate analysis. RESULTS Patients with intermittent AF were, on average, younger (66 vs. 70 years, p < 0.001), were more often women (37% vs. 26% p < 0.001) and less o ften had heart failure (11% vs. 21%, p < 0.001) than those with sustained A F. The annualized rate of ischemic stroke was similar fur those with interm ittent (3.2%) and sustained AF (3.3%). In patients with intermittent AF, in dependent predictors of ischemic stroke were advancing age (relative risk [ RR] = 2.1 per decade, p < 0.001), hypertension (RR = 3.3, p = 0.003) and pr ior stroke (RR = 4.1, p = 0.01). Of those with intermittent AF predicted to be high risk (24%), the observed stroke rate was 7.8% per year (95% confid ence interval 4.5 to 14). CONCLUSIONS In this large cohort of AF patients given aspirin, those with i ntermittent AF bad stroke rates similar to patients with sustained AF and s imilar stroke risk factors. Many elderly patients with recurrent intermitte nt AF have substantial rates of stroke and Likely benefit from anticoagulat ion. High-risk patients with intermittent AF can be identified using the sa me clinical criteria that apply to patients with sustained AF. (C) 1999 by the American College of Cardiology.