Dofetilide-induced long QT and torsades de pointes

Abstract

Dofetilide, a new class III antiarrhythmic agent, has been approved as an antiarrhythmic agent for the treatment of atrial fibrillation and atrial flutter. Dofetilide selectively inhibits the rapid component of the delayed rectifier potassium current resulting in a prolongation of the effective refractory period. Like other drugs that affect potassium currents, the prolonged QT interval occurring in the patients treated with dofetilide can be complicated by torsades de pointes. We report four cases of dofetilide-induced QT prolongation and torsades de pointes. We discuss the risk factors for the development of dofetilide-induced long QT and torsades de pointes and review the current literature.

Figure 1

ECG 1. Patient 1. Twelve‐lead ECG showing sinus bradycardia, left atrial enlargement, left bundle branch block, and severe QT prolongation with a QTc of 0.8 seconds. Telemetry 1. Patient 1. Telemetry showing prolonged QTc and polymorphic ventricular tachycardia.

Figure 2

ECG 2. Patient 2. Before initiation of dofetilide. Twelve‐lead ECG showing atrial fibrillation, left bundle branch block, and QTc of 0.46 seconds.

Figure 3

ECG 3. Patient 2. After third dose of dofetilide. Twelve‐lead ECG showing NSR with ventricular capture spikes and a QTc of 0.57 seconds. Telemetry 2. Patient 2. Telemetry showing torsades de pointes.

Figure 4

ECG 4. Patient 3. Baseline before dofetilide. Twelve‐lead ECG showing atrial tachycardia with 2:1 atrioventricular block and a QTc of 0.43 seconds.

Figure 5

ECG 5. Patient 3. While on dofetilide and milrinone. Twelve‐lead ECG showing NSR with frequent ventricular premature contractions and a QTc of 0.67 seconds. Telemetry 3. Patient 3, Telemetry showing torsades de pointes.

Figure 6

ECG 6. Patient 4. Twelve‐lead ECG showing NSR followed by torsades de pointes. Telemetry 4. Patient 4. Telemetry showing torsades de pointes.