Safety of rapid switching from amiodarone to dofetilide in atrial fibrillation patients with an implantable cardioverter–defibrillator

Background: Dofetilide is a class III antiarrhythmic drug commonly used for treatment of atrial fibrillation. Drug guidelines mandate a 3-month waiting period before initiating dofetilide after amiodarone use. Whether patients with an implantable cardioverter–defibrillator (ICD) can be rapidly switched from amiodarone to dofetilide is not known. Objective: The purpose of this study was to evaluate whether rapid switching from amiodarone to dofetilide is safe in atrial fibrillation patients with an ICD. Methods: In this retrospective observational study, we assessed the feasibility and the short- and long-term safety of rapid switching from amiodarone to dofetilide in hospitalized atrial fibrillation with an ICD. Results: The study included a total of 179 patients who were followed for 12.6 ± 2.2 months. All patients had drug initiation during hospitalization. Dofetilide resulted in successful cardioversion in 66% (118/179). Twenty percent of patients (36/179) required dofetilide dose adjustments in the initiation phase because of QT prolongation and decreased creatinine clearance. A total of 6.1% of patients (11/179) required drug discontinuation. The incidence of torsades de pointes was 1.1% (2/179) during initiation. One patient (0.5%) had self-terminating ventricular tachycardia at follow-up. No other significant adverse events were noted during follow-up. Conclusion: Atrial fibrillation patients with an ICD can be rapidly switched to dofetilide after 7 days of discontinuation of amiodarone without significant arrhythmia-related complications. Prospective studies with large sample sizes, especially of women, should be performed to further validate these findings.