Lead-to-Port Reversal Mimicking Loss of Cardiac Resynchronization Therapy After CRT-D Generator Replacement

Lead-to-port misconnections are a rare but clinically significant complication after cardiac device generator replacement and may mimic true lead failure or loss of capture, leading to diagnostic confusion and unnecessary interventions.

A 72-year-old man with ischemic cardiomyopathy and a previously implanted cardiac resynchronization therapy defibrillator presented with worsening dyspnea following elective generator replacement performed at another center. Postprocedural electrocardiogram demonstrated loss of biventricular pacing. Chest radiography confirmed correct lead positions. High-output left ventricle (LV) pacing failed to produce capture, while unipolar LV pacing resulted in surface P waves, and AAI pacing revealed ventricular capture. Stepwise device interrogation excluded lead dislodgement and malfunction, establishing inadvertent LV-right atrium port reversal during generator replacement as the underlying cause.

This case highlights how systematic pacing maneuvers and careful electrocardiogram interpretation can rapidly differentiate electrical misconnection from mechanical lead failure, preventing misdiagnosis and inappropriate lead revision.