Torsade de Pointes in a Patient With Wolff-Parkinson-White Syndrome
A 17-year-old girl presented with syncope 1 year ago and complained of dizziness for 6 months. Her paternal aunt had died from sudden cardiac death at age 22. On the ECG, preexcitation was present, and Holter recording revealed recurrent wide QRS tachycardia with short cycle length. Episodes of atrial fibrillation with rapid anterograde conduction over the accessory pathway were suspected. The patient was referred for catheter ablation of an accessory pathway in Wolff-Parkinson-White (WPW) syndrome. On admission, analysis of the ECG revealed a QT prolongation (QTm 600 ms, QTc 577 ms; Figure, A) in addition to the delta wave. During Holter monitoring but before radiofrequency ablation of the accessory pathway,polymorphic ventricular tachycardias (torsade de pointes) were documented (Figure, B). The left inferoposterior accessory pathway was treated successfully by radiofrequency ablation (Figure, C). The WPW syndrome is commonly associated with nonlethal arrhythmias. If the accessory pathway presents a short refractory period, then the occurrence of atrial fibrillation may allow the induction of ventricular fibrillation during rapid conduction across the bypass tract. In our patient, however, vertigo and syncope were not related to the WPW syndrome but to a hereditary congenital long-QT syndrome. Therefore, radiofrequency ablation is not curative in our patient. Consequently, β-blocker treatment was started, and a cardioverter defibrillator was implanted.