Left Bundle Branch Pacing: JACC Review Topic of the Week.

Right ventricular pacing causes electric and mechanical dyssynchrony, which is associated with an increased risk for heart failure and atrial fibrillation. Cardiac resynchronization therapy with biventricular pacing reduces ventricular dyssynchrony and results in clinical benefits in subsets of patients with heart failure with QRS prolongation. Recently, His bundle pacing has increased in use as a physiological pacing modality but is limited by difficult implantation, lower success rates in patients with QRS prolongation, and high, often unstable, pacing capture threshold. Thus, the concept of pacing the conduction system distal to the His bundle to bypass the region of conduction block was proposed. Early clinical studies demonstrated the procedural feasibility of left bundle branch pacing using a transventricular septal approach that generates narrow paced QRS duration, fast synchronized left ventricular activation, and correction of left bundle branch block. The current status and future direction of left bundle branch pacing are summarized in this paper.