Thromboembolic Events in Paroxysmal vs. Permanent Non-Valvular Atrial Fibrillation - Subanalysis of the J-RHYTHM Registry

Background: It is disputed whether the risk of cardiogenic embolism varies with type of atrial fibrillation (AF). Although several studies have found that the risk of cardiogenic embolism was similar among paroxysmal and persistent/permanent AF, a few studies have found that patients with paroxysmal AF had a lower rate of stroke and systemic embolism than those with persistent/permanent AF. In the present study, post-hoc analysis of the J-RHYTHM Registry was done to compare the risk of thromboembolic events among 3 types of non-valvular AF (NVAF). Methods and Results: A total of 7,406 NVAF patients were followed up prospectively for 2 years. At baseline, warfarin was used for 78.6%, 90.0%, and 91.8% of patients with paroxysmal, persistent, and permanent AF, respectively. There were 126 thromboembolic events during the follow-up period. The crude event rate was 2-fold higher among the patients with permanent NVAF (2.29%) than among those with paroxysmal (1.16%) or persistent (1.20%) NVAF (P=0.001). After adjusting for warfarin use and CHA2DS2-VASc score components, however, the hazard ratio for thromboembolism did not differ between paroxysmal (reference) and permanent NVAF (1.007; 95% confidence interval: 0.955-1.061). Conclusions: The crude rate of thromboembolic events was higher in permanent NVAF than in paroxysmal NVAF, but after adjusting for warfarin use and CHA2DS2-VASc score components, paroxysmal and permanent NVAF patients had similar risk of thromboembolism.