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>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 <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 >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<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: see text]