Dofetilide-induced torsade de pointes in high-grade atrioventricular node dysfunction

A 64-year-old woman received 29 mm Mosaic mitral bioprosthesis in 2010 after failure of valve repair attempt. Subsequently she underwent percutaneous insertion of tricuspid valve Biocor Epic 31 prosthesis, which was complicated by complete atrioventricular (AV) block requiring dual-chamber pacing with a conventional right atrial lead placement and an unfixed left ventricular lead in the coronary sinus. Six years later, she developed persistent atrial fibrillation, which was controlled with repeated cardioversion, dofetilide (250 μg twice daily) and warfarin for primary stroke prophylaxis. Eleven months later, she presented to the emergency department with episodes of profound dyspnoea and intermittent loss of consciousness. ECG demonstrated loss of ventricular pacing capture and non-sustained, polymorphic ventricular tachycardia that represents torsade de pointes (TdP). AV block with loss of ventricular capture by a ventricular lead dysfunction yielded bradycardia, which was critical in generating this episode. Also, it was exacerbated by prolonged QT interval due to dofetilide treatment (figure 1). Figure 1 ECG at time of presentation showing non-sustained polymorphic ventricular tachycardia (torsade de pointes) with …