Abstract
A patient with hypertrophic cardiomyopathy experienced cardiopulmonary arrest. An automated external defibrillator administered defibrillation for ventricular fibrillation (A). The pacemaker recorded atrial tachycardia with a rapid ventricular response before the patient collapsed (B). After a few minutes, the pacemaker records dual tachyarrhythmia, characterized by the simultaneous presence of ventricular fibrillation (VF) and atrial fibrillation (AF) (C). This case demonstrates that VF induced by atrial tachyarrhythmia could contribute to AF-related sudden cardiac death.