Detection of atrial fibrillation after stroke and the risk of recurrent stroke.

Failure to expeditiously diagnose atrial fibrillation (AF) as the cause of ischemic stroke has unclear consequences. We studied the association between detection of AF after discharge and the risk of recurrent stroke. We followed a prospectively assembled cohort of patients hospitalized for stroke for 1 year for new diagnoses of AF and recurrent stroke. We compared rates of recurrent stroke in patients with a new diagnosis of AF and those without a new diagnosis of AF after discharge using Kaplan-Meier survival statistics. We conducted Cox proportional hazards analysis of the diagnosis and timing of AF and recurrent stroke after adjustment for age, sex, race, preexisting AF, hypertension, dyslipidemia, diabetes, previous stroke, and use of antithrombotic and statin medications. Among 5575 patients with stroke, 113 (2.0%) received a new diagnosis of AF after discharge, and 221 (4.0%) had recurrent stroke. At 1 year, the Kaplan‒Meier rate of recurrent stroke was 18.9% in those with a new diagnosis of AF and 4.5% in others, including those with AF diagnosed before or during the index hospitalization (P = .001). The association between a new diagnosis of AF and stroke recurrence persisted after adjustment for potential confounders (hazard ratio, 5.6; 95% confidence interval, 3.4-9.1). A new diagnosis of AF after discharge for stroke is associated with an increased risk of recurrent stroke, even compared with patients with known AF. These findings identify a subset of patients at high risk for recurrent stroke and highlight the importance of timely detection of AF in patients with stroke.