His bundle ablation for supraventricular arrhythmias to avoid spurious shocks of an implanted defibrillator.

Atrial fibrillation with fast ventricular response remains a matter of concern in patients treated with an implantable cardioverter defibrillator (ICD). A patient with dilated cardiomyopathy, suffering from atrial arrhythmias and recurrent cardiac arrest due to both ventricular tachycardia and ventricular fibrillation, is presented. Ablation of the AV node by means of low-energy direct-current shocks with subsequent pacemaker implantation was performed before ICD implantation. The patient received shocks after four months, when he had recurrence of AV conduction with a slow ventricular rate. Pacemaker interaction was excluded, and no short ventricular arrhythmias were observed. During electrophysiologic study after electrical conversion of atrial fibrillation, persistent second degree heart block was documented, giving further evidence that atrial arrhythmias were not responsible for the shocks. The patient's functional status remains good after more than 18 months of follow-up.