Intraprocedural transthoracic echocardiography to facilitate left bundle branch pacing: EC-LBBP

Background: Left bundle branch (LBB) pacing (LBBP) has gained rapid adoption. Evidence for direct LBB capture has varied from 30%-95% depending on the criteria.

Objective: The purpose of this study was to assess the feasibility and efficacy of intraprocedural transthoracic echocardiographic guidance to achieve LBB capture.

Methods: This was a prospective, nonrandomized, case-control study (ClinicalTrials.gov Identifier: NCT05646251). The pectoral region including echocardiographic windows were sterile-draped using Ioban. The lead was placed in the right ventricular septum and sheath orientation adjusted under echocardiography. The lead was advanced under echocardiographic visualization until the tip reached the left ventricular subendocardium. LBB capture was strictly defined: transition from nonselective to selective/left ventricular septal capture; LBB potential with injury current; and Delta (HBP-LBBP) V₆RWPT ≥10.

Results: Thirty patients underwent echocardiography-guided left bundle branch pacing (EC-LBBP) and compared with 30 patients (standard approach): mean age 74.4 ± 10 years; female 45%; hypertension 92%; cardiomyopathy 43%; atrioventricular block/atrioventricular nodal ablation 75%. Total procedural and fluoroscopy durations were similar. Left bundle branch area pacing (LBBAP or left ventricular septal pacing) was successful in all patients in both groups. EC-LBBP was 97% successful in achieving LBB capture vs 70% (P = .02) with LBB potentials (LB-V 23 ± 6 ms) in 95% vs 77% (22 ± 6 ms). Morphology transition confirming LBB capture was seen in 87% vs 67% (P = .02). Lead tip was visualized at the left ventricular subendocardium in 100% of patients in EC-LBBP.

Conclusion: EC-LBBP was 97% successful in achieving LBB capture using strict criteria. LBBP lead was subendocardial in all patients. EC-LBBP is practical, feasible, safe, and highly effective in achieving LBB capture.