Optimal timing for cardioversion in patients with atrial fibrillation

Abstract

Background: Electrical cardioversion (CV) is essential in rhythm management of atrial fibrillation (AF). However, optimal timing of CV remains unknown. Hypothesis: Timing of CV in AF is associated with risk of adverse events. Methods: We analyzed the effect of AF episode duration on safety and efficacy of electrical CV in a multicenter, multicohort study exploring 4356 CVs in 2530 patients on oral anticoagulation. The composite adverse outcome included unsuccessful CV, acute arrhythmic complications, thromboembolic events, mortality, and AF recurrence within 30-day follow-up. Results: Study groups were stratified according to duration of index AF episode (<24 h, 24–48 h, 48 h–30d, and > 30d), consisting of 1767, 516, 632, and 1441 CVs, respectively. CVs were unsuccessful in 8.5% (<24 h), 5.4% (24–48 h), 11.1% (48 h–30d), and 13.9% (>30d), respectively (P < 0.01). Occurrence of thromboembolic events (0.1%), mortality (0.1%), and asystole >5 seconds (0.7%) within 30-day follow-up was infrequent and comparable in the study groups. AF recurrence within 30 days after initially successful CVs was 29.8% (<24 h), 26.5% (24–48 h), 37.3% (48 h–30d), and 30.3% (>30d), respectively (P < 0.01). Composite adverse outcome occurred in 1669 (38.4%) CVs, and index AF episode >48 hours was an independent predictor for the composite endpoint (OR: 1.49, 95% CI: 1.28–1.74, P < 0.01) in multivariate analysis. Conclusions: Optimal timing of CV for AF showed a J-shaped curve, with fewest adverse outcomes in patients with CV performed 24 to 48 hours after onset of AF. In patients with rhythm-control strategy, delaying CV >48 hours is associated with increased risk for adverse outcomes.