Storms of ventricular fibrillation responsive to isoproterenol in an idiopathic ventricular fibrillation patient demonstrating complete right bundle branch block

A 45-year-old male was admitted to our hospital after successful resuscitation of cardiac arrest. Ventricular fbrilla-tion (VF) had occurred during breakfast and was defbrillated by an automated external defbrillator operated by emergency medical service staff. On admission, his ECG demonstrated complete right bundle branch block as the sole abnormality. Intensive examination could not detect any structural disease leading to a diagnosis of idiopathic VF and implantation of an ICD. VF storm occurred one month after hospital discharge and beta-blocker, amiodarone, and sedative administration had no effect on VF. Likewise, catheter ablation for triggering premature ventricular beats failed to control the VF storm. The VF storm then subsided in the following weeks and the patient was discharged on amiodarone. A half month later VF storm recurred and the patient was admitted again. This time, isoproterenol infusion was effective in suppressing VF, and thereafter the patient was administered bepridil and followed up without recurrence of VF for 1.5 years. From these benefcial effects, the VF of the patient was suggested to share common arrhythmogenic characteristics to those of Brugada syndrome or J-wave associated VF.