Left bundle branch-optimized cardiac resynchronization therapy in a dextrocardia patient: a case report

Background Mirror-image dextrocardia presents unique challenges for cardiac device implantation. Here we report a case of left bundle branch optimized cardiac resynchronization therapy (LOT-CRT) for a patient with dextrocardia with heart failure with mid-range ejection fraction (HFmrEF). Case Summary A 69-year-old woman with mirror-image dextrocardia was electively admitted to our hospital with a complaint of chest distress and shortness of breath. 24-hour Holter showed sinus arrest with junctional rhythm, intermittent first-degree atrioventricular block with complete left bundle branch block (QRS 154ms). Echocardiography revealed left ventricular ejection fraction (LVEF) of 46%. In contrast to previous research utilizing the modified C315 sheath, the LOT-CRT implant was successfully achieved using a standard-curve C315 delivery sheath. At the nine-month follow-up, the patient demonstrated a significant improvement in LVEF compared to baseline (60% vs. 46%). Discussion This case demonstrates the clinical viability of LOT-CRT as a physiologic pacing strategy in patients with congenital heart disease. By directly targeting the conduction system, this approach may circumvent the anatomical challenges posed by traditional biventricular pacing in complex cardiac anatomies, offering a promising therapeutic alternative for resynchronization in select populations.