Ventricular arrhythmias after atrial fibrillation electrical cardioversion: A multicenter study.

Background: Ventricular arrhythmias (VAs) after atrial fibrillation (AF) electrical cardioversion (ECV) have been reported.

Objective: We sought to assess incidence, timing, and clinical characteristics of patients with post-AF ECV-related VAs.

Methods: Multicenter observational retrospective study including 13 centers, incorporating patients with VAs or sudden cardiac death within 10 days of ECV. The total number of ECVs performed during the collecting period was provided. Patients with pre-ECV VAs were excluded.

Results: Twenty-three patients with VAs were identified out of 11,897 AF ECVs performed in 13 centers during a median 2-year period, suggesting post-ECV VA incidence of 0.2%. The patients' mean age was 71 ± 11 years, and 13 (56.5%) were female. AF duration prior to ECV was 71 ± 54 days. Congestive heart failure and hypertension were both found in 17 (74%) patients. QT-prolonging drugs were used by 17 (74%). Index VA occurred 28.5 (interquartile range 5.5-72) hours post-ECV, including torsades de pointes, nonsustained polymorphic ventricular tachycardia, and sudden cardiac death in 17 (74%), 5 (22%), and 1 (4%) patient, respectively. Post-ECV heart rate was slower and QT duration longer compared with pre-ECV (57 ± 11 beats/min vs 113 ± 270 beats/min; .001; QT duration 482 ± 61 ms vs 390 ± 60 ms; .001). VAs reoccurred in 9 (39%) patients, 11 (interquartile range 3-13.5) hours post-index VA. Two patients had an arrhythmic death within 72 hours post-ECV.

Conclusion: VAs post-AF ECV are rare, occur within 3 to 72 hours post-ECV, and are potentially fatal. Our study gives a signal of caution favoring prolonged monitoring in small subset of patients as congestive heart failure patients treated with class III antiarrhythmic drugs, with post-ECV bradycardia, especially (but not exclusively) when QT prolongation noted.