Ventricular fibrillation refractory to ICD therapy.

A 14-year-old boy was admitted for the evaluation of recurrent syncope. His ECG on admission revealed a sinus rhythm with an undetermined QRS axis, T wave inversion at leads V3, V4 and abnormal q at leads I, aVL, V5 and V6. However, no underlying disease could be detected by any morphological examination. Programmed ventricular stimulation also induced no ventricular tachycardia or fibrillation (VF). Only signal-averaged ECG showed ventricular late potential and the cause of syncope was not clarified. As his brother with a similar ECG had died suddenly, he was prophylactically treated with an ICD. However, 14 months later he died suddenly after playing a video game. The ICD recorded VF, which was not converted despite 6 cardioversion attempts by the ICD. Progression of myocardial damages and/or elevation of defibrillation threshold may have been the cause of unsuccessful cardioversion.