Clusters of ventricular fibrillation in a patient with an implantable cardioverter difibrillator treated with amiodarone.

A 44 year-old man with severe left ventricular dysfunction resulting from an old myocardial infarction developed clusters of ventricular fibrillation (VF). Although coronary bypass surgery was performed and heart failure was well controlled, the VF recurred during amiodarone therapy. Despite multiple deliveries of shocks by an implantable cardioverter defibrillator, the electrical storm could not be terminated. Some substrate for rapid ventricular tachyarrhythmias, refractory to class III drugs, can lead to death from arrhythmia.