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

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.