DDD mode-switching and loss of atrioventricular synchrony evokes heart failure: A rare but possible trigger of pacing-induced cardiomyopathy.

Pacing-induced cardiomyopathy (PICM), defined as left ventricular dysfunction, occurs in the setting of chronic, high burden right ventricular pacing. We describe an unusual case of PICM. A 64-year-old man underwent a medical check-up and was diagnosed with complete atrioventricular block (AVB) with regular and slow ventricular contractions at 38 beats/min (bpm). The patient underwent a pacemaker implantation with a dual-chamber pacing (DDD) pacemaker. This patient had no symptoms or signs of PICM during complete AVB or the period after undergoing dual-chamber pacing. However, PICM developed within a short time after the onset of atrial flutter (AFL). During AFL, the automatic mode switch of the DDD pacemaker to the DDIR mode worked normally, and the ventricles were paced with a stable and regular rate (60 bpm). Despite the administration of ß-blockers and diuretics, his symptoms and status did not improve. After the elimination of the AFL and restoration of AV synchrony with a DDD mode by catheter ablation, the deteriorated condition rapidly improved. In this patient, the coexistence of the loss of AV synchrony and high burden RV pacing during AFL might have caused this unusual PICM. Learning objective: Even when patients have no symptoms or signs of pacing-induced cardiomyopathy (PICM) during complete atrioventricular block or the period after undergoing dual-chamber pacing, automatic mode-switching to the DDI mode during atrial tachyarrhythmias could rapidly cause PICM. PICM could occur with a much more rapid time course than the historical model of PICM where cardiomyopathy may take several years to develop. Much attention should be paid during the follow-up to patients receiving DDD pacemakers to avoid any unusual PICM as in this case.