Atrial Fibrillation Burden and Short-Term Risk of Stroke

Abstract

Background—The temporal relationship of atrial fibrillation (AF) and stroke risk is controversial. We evaluated this relationship via a case-crossover analysis of ischemic strokes in a large cohort of patients with cardiac implantable electronic devices. Methods and Results—We identified 9850 patients with cardiac implantable electronic devices remotely monitored in the Veterans Administration Health Care System between 2002 and 2012. There were 187 patients with acute ischemic stroke and continuous heart rhythm monitoring for 120 days before the stroke (age, 69±8.4 years; 98% with an implantable defibrillator). We compared each patient’s daily AF burden in the 30 days before stroke (case period) with their AF burden during days 91 to 120 pre stroke (control period). Defining positive AF burden as ≥5.5 hours of AF on any given day, 156 patients (83%) had no positive AF burden in both periods and, in fact, had little to no AF; 15 (8%) patients had positive AF burden in both periods. Among the discordant (i...