Marked QT Prolongation and Torsades de Pointes Following Pulsed Field Ablation for Persistent Atrial Fibrillation

Pulsed field ablation (PFA) is increasingly used for pulmonary vein isolation (PVI), but its effects on ventricular repolarization remain incompletely understood.A man in his 70s with persistent atrial fibrillation, a left ventricular ejection fraction of 18%, previous nonsustained ventricular tachycardia, and three months of amiodarone therapy underwent PVI using the FARAPULSE system (Boston Scientific Corporation, Marlborough, MA, USA).Approximately one month before PFA, automated electrocardiographic measurements showed a QT interval of 316 ms and a corrected QT interval (QTc) of 395 ms.One hour after PFA, the QT/QTc values were 356/431 ms.On postoperative day one, the QT/QTc values increased to 602/610 ms, accompanied by frequent premature ventricular contractions and a serum potassium concentration of 3.2 mEq/L.On postoperative day two, telemetry demonstrated a short-longshort sequence immediately before torsades de pointes, which was initiated by a premature ventricular contraction when the QT/QTc values were 490/510 ms and serum potassium was 3.0 mEq/L.Altered consciousness developed, and one 150-J direct-current shock terminated the arrhythmia.After potassium and magnesium replacement, no recurrence occurred.The QTc decreased to 479 ms on postoperative day four and 403 ms at one month.The event was probably multifactorial; severe ventricular dysfunction, residual amiodarone effects, hypokalemia, and transient postprocedural hypoxemia prevent attribution of causality to PFA alone.Nevertheless, the marked but reversible QT prolongation after the procedure supports careful monitoring of the QT interval, ventricular ectopy, and electrolytes after PFA in susceptible patients.