Patients with Ischemic Stroke and Incident Atrial Fibrillation: A Nationwide Cohort Study

Abstract

Background and Purpose - A substantial part of ischemic strokes is attributed to atrial fibrillation (AF). We hypothesized that patients with ischemic stroke without prior diagnosed AF were at higher risk of having a subsequent diagnosis of AF, and this was associated with multiple risk factors. Methods - This French longitudinal cohort study was based on the national database covering hospital care from 2008 to 2012 for the entire population. Results - Of 65 807 patients with ischemic stroke in 2009, 48 992 did not have AF at baseline. A total of 4828 of these patients were diagnosed as having AF during a follow-up of 15±15 months (incidence rate 7.9 per 100 person-years). By comparison, the yearly rate of new-onset AF for the 826 416 patients with a cardiac hospitalization was 5.9%. CHADS2 (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack) and CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack [doubled], vascular disease, age 65-75 years, and sex category [female]) scores were both associated with the risk of new-onset AF during follow-up (CHADS2: hazard ratio [HR] 1.70, 95% confidence interval [CI] 1.66-1.75; CHA2DS2-VASc: HR 1.45, 95% CI 1.42-1.48). The c statistics were 0.700 (95% CI 0.696-0.706) for CHADS2 and 0.706 (95% CI 0.702-0.710) with CHA2DS2-VASc (P=0.003 for comparison of the 2 scores). Independent predictors of subsequent diagnosis of AF were age 65 to 74 years (HR 2.29, 95% CI 2.06-2.54), age ≥75 years (HR 3.31, 95% CI 3.02-3.64), hypertension (HR 1.22, 95% CI 1.13-1.32), heart failure (HR 2.56, 95% CI 2.41-2.72), and vascular disease (HR 1.10, 95% CI 1.04-1.17). Conclusions - Ischemic stroke was associated with a substantially increased risk of incident AF, particularly among individuals with higher CHADS2 or CHA2DS2-VASc scores. These risk scores seem to be simple tools for identifying patients at higher risk of incident AF after ischemic stroke.