Heart failure exacerbation associated with newly developed atrioventricular dyssynchrony after chemical conversion to a sinus rhythm in a patient receiving cardiac resynchronization therapy.

A 58-year-old woman with chronic heart failure (CHF) received cardiac resynchronization-defibrillator (CRT-D) therapy without atrial lead implantation due to longstanding atrial fibrillation (AF). Three months after oral amiodarone therapy was initiated for the treatment of non-sustained ventricular tachycardia detected by the CRT-D device, the patient's heart failure symptoms worsened and 12-lead electrocardiography showed newly emerged p-waves with atrioventricular (AV) dissociation. Immediately after the device was upgraded to the DDD-biventricular pacemaker, the patient's heart failure symptoms and cardiac function dramatically improved, which suggests that AV dissociation has a much more negative impact on the cardiac function than AF in patients with CHF.