Abstract Background Cases of ventricular arrhythmias (VAs) associated with QT prolongation after electrical cardioversion (ECV) for atrial fibrillation have been reported. Purpose To assess the incidence, timing and clinical characteristics of patients with VAs post-ECV for AF. Methods This is a multicenter international study. Seventy-seven centers were approached. Data was received from 13 worldwide centers. VAs included were torsades de pointes (TdP), NSPVT&amp;gt;3 beats or SCD within 7 days of ECV. The total number of ECVs performed at each center during the time period for which data was sent was provided. Results VAs occurred after ECV at an estimated incidence of 0.16%, range 0- 1.3% at different centers. Twenty-three patients with VAs were identified from 8 European centers, from 2008-2023, of whom 18 (78%) were from 2019-2023. There were 13 (56.5%) females, aged 71+11 years, mean LVEF=45+9%. AF duration prior to ECV was 72+65 days. Antiarrhythmic drugs (AADs) used prior to ECV were amiodarone in 9 (39%), sotalol in 4 (17%), class Ic in 3 (13%), beta blockers in 19 (83%), CCB in 1(4%) and digoxin in 4 (17%) patients. Five (22%) patients received QT prolonging drugs other then AADs. Baseline hypokalemia &amp;lt;3.5mmol/L was seen in 3(13%) patients (range 2.9-3.4mmol/L). ECV was elective, urgent and emergent in 10 (43%), 12 (52%) and 1(4%) patient, respectively. The arrhythmias documented were TdP in 17(74%), NSPVT &amp;gt;3 beats in 5(22%) and 1(4%) SCD. Arrhythmia documentation was available in 19 (83%) patients. Baseline mean HR pre-ECV was 115+30bpm and QT 388+61ms, both significantly differed from post-ECV mean HR which was 58+11bpm and QT 469+63ms, P&amp;lt;0.0001. Arrhythmia occurred 45+54 hours post-ECV, median 28.5 hours, range 5 minutes- 10 days. Figure 1 demonstrates an example of serial ECG changes from baseline to TdP occurrence. An arrhythmic storm occurred in 11 (48%) patients. Arrhythmia reoccurred in 9 (39%) patients, mean 13.25 + 15 (range 0.5-48) hours after the index event. The arrhythmias which reoccurred were TdP in 5 (22%), VF in 2 (9%), NSPVT in 1 (4%) and monomorphic VT in 1 (4%) patient. Acute therapy with DCCV was needed in 10 (43%) patients. AADs were discontinued in 16 patients. IV electrolytes were helpful in arrhythmia control in 16 (89%) of 18 patients, IV isoproterenol was helpful in 1 (25%) of 4 patients, temporary pacing with arrhythmia control in 2(40%) of 5 patients in whom it was used. ICD was implanted in 7 patients and a pacemaker in 4 others. Two (8.7%) patients expired, 1 died suddenly at home 12 hours after ECV and 1 suffered from acute heart failure and fatal TdP 72 hours after ECV while hospitalized. Conclusion VAs associated with QT prolongation after ECV for AF occur mainly 24-48 hours after ECV and may reoccur. Prolonged monitoring prior to discharge should be considered for prevention of fatal outcomes in patients with any evidence of QT prolongation following ECV.Figure 1

Ventricular arrhythmias associated with electrical cardioversion for atrial fibrillation, a multicenter study