QT prolongation-related ventricular arrhythmia associated with atrial fibrillation electrical cardioversion

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. INTRODUCTION: Atrial fibrillation (AF) is the most common arrhythmia, a leading cause of strokes, and associated with an increased mortality. Although electrical cardioversion of AF is considered a relatively safe procedure, post cardioversion QT prolongation-related ventricular arrhythmias (VA) may appear due to the combination of QT-prolonging anti-arrhythmic drugs, acute heart rate change from rapid AF into sinus bradycardia, electrolyte imbalance, etc. To date, there is still no consensus regarding the actual prevalence of this complication. Given the global tendency for early discharge during the same day of AF cardioversion, there is a crucial need to define the true prevalence of this phenomenon and the characteristics of these patients. PURPOSE: Evaluate the prevalence of post AF cardioversion prolonged QT-related VA, and describe the characteristics of patients developing this complication. METHOD: Single center retrospective analysis of all AF electrical cardioversions, during the last 3 years, which were followed by documented prolonged QT-related VA or sudden cardiac death (SCD) within 72 hours from cardioversion. Post cardioversion VA was detected by a computerized search of hospitalization records, 24-hour Holter recordings, and EMS strips. RESULTS: Out of 950 AF electrical cardioversions performed at our hospital during the last 3 years there were 4 cases with Torsades de Pointes (TdP) and 1 case of SCD occurring within 72 hours from cardioversion (5/950; 0.5%). All five patients were females, 3/5 with low LVEF and 4/5 on class III anti-arrhythmic drug (Amiodarone or Sotalol). Electrolyte abnormalities (including hypokalemia, hypomagnesemia, and hypocalcemia) were found in 3/5 patients and post cardioversion sinus bradycardia in 2/5 patients. CONCLUSION: The incidence of post-AF cardioversion life threatening VA is low although non-negligible. Prolonged ECG monitoring and cautious follow-up of QTc should be recommended among patients, especially females with low LVEF, treated by class III anti-arrhythmic drugs. Post AF cardioversion same day discharge should be discouraged in these patients.