Left bundle branch pacing in patients with structural heart disease: personalizing cardiac resynchronization therapy.

Biventricular pacing remains the cornerstone of cardiac resynchronization therapy (CRT) in patients with heart failure, with well-established benefits. Left bundle branch pacing (LBBP) offers a physiologic alternative by engaging the native conduction system to restore synchrony and has generated significant enthusiasm. However, the growing adoption of LBBP should be tempered by recognition that a one-size-fits-all approach may not address the underlying substrate, particularly in those with intraventricular conduction delay. While a less-than-optimal LBBP implant may be sufficient in bradycardia patients, its adequacy in heart failure patients, who may require more precise consideration of conduction disease, remains uncertain. This review gives a comprehensive framework for integrating LBBP into CRT, including pre-implant, intraprocedural, and post-implant assessment. It also provides practical guidance on when to pursue LBBP alone, when to supplement with a coronary sinus lead, and when to consider conventional biventricular pacing, with an emphasis on a personalized approach to the underlying conduction substrate for maximal therapeutic benefit.