ATRIAL FIBRILLATION WITHOUT COMORBIDITIES AND STROKE RISK IN THE REASONS FOR GEOGRAPHIC AND RACIAL DIFFERENCES IN STROKE (REGARDS) STUDY

Abstract

While most patients with atrial fibrillation (AF) warrant anticoagulation for stroke prevention, optimal treatment remains uncertain for patients with AF without comorbidities because the stroke risk in this population is unclear. Participants (n = 28,253) from REGARDS were categorized into one of four groups based on the presence or absence of AF at baseline and the presence or absence of cardiovascular comorbidities. Cox proportional hazards analysis compared the risk of incident ischemic stroke after adjustment for covariates. During 244,560 person-years, 1,206 strokes occurred. Compared to participants with neither AF nor comorbidities, participants with AF without comorbidities did not have an increased stroke risk (HR 1.23, 95% CI 0.62 – 2.18; p = 0.511) after adjustment for covariates. Participants without AF but with comorbidities, however, had both an elevated stroke risk (HR 1.77, 95% CI 1.48 – 2.18; p < 0.0001) and an increased risk of cardioembolic stroke (HR 2.34, 95% CI 1.48 – 3.90; p = 0.0002). In this report of the largest cohort of participants with AF without comorbidities, AF itself, without cardiovascular comorbidities, did not confer an increase in stroke risk. These findings support an important role for the atrial cardiopathy-dependent theory of atrioembolic stroke over the classical arrhythmia-dependent model.