Incidence of Stroke or Systemic Embolism in Paroxysmal Versus Sustained Atrial Fibrillation

Abstract

Background and Purpose— There is controversy on the relationship of the type of atrial fibrillation (AF) to stroke. Although several studies show that patients with paroxysmal AF (PAF) have a stroke risk similar to those with persistent or permanent AF, recent studies suggest that PAF is associated with a lower rate of stroke. Limited data on stroke risk associated with PAF are evident in Asian populations. Methods— The Registry Study of Atrial Fibrillation Patients in Fushimi-ku (Fushimi AF Registry) is a community-based survey of patients with AF in Fushimi-ku, Kyoto, Japan. Patients were categorized into 2 types of AF: PAF or sustained (persistent or permanent) AF. We compared clinical events between PAF (n=1588) and sustained AF (n=1716). Results— Patients with PAF were younger, had less comorbidities, and received oral anticoagulants (OAC) less commonly. A lower risk of stroke/systemic embolism during follow-up period in the patients with PAF was consistently observed (non-OAC users: hazard ratio, 0.45; 95% confidence intervals, 0.27–0.75; P <0.01 and OAC users: hazard ratio, 0.59; 95% confidence interval, 0.35–0.93; P =0.03). The composite end point of stroke/systemic embolism/all-cause mortality was also lower in PAF, whether among OAC users (hazard ratio, 0.77; 95% confidence interval, 0.59–0.99; P =0.046) or non-OAC users (hazard ratio, 0.59; 95% confidence interval, 0.46–0.75; P <0.01). On multivariate analysis, PAF was an independent predictor of lower stroke/systemic embolism risk. Conclusions— In this large cohort of Japanese patients with AF, PAF was independently associated with lower incidence of stroke/systemic embolism than sustained AF. This may aid decision making for anticoagulation, especially in those patients with AF with few stroke risk factors. Clinical Trial Registration— URL: http://www.umin.ac.jp/ctr/index.htm . Unique identifier: UMIN000005834.