Procedural Endpoint in Left Bundle Branch Area Pacing: Conduction System Capture Versus LV Septal Capture

Summary

This is a prospective, multicenter, randomized controlled trial designed to determine whether direct capture of the left ventricular conduction system must be achieved as the procedural endpoint of left bundle branch area pacing (LBBAP), or whether left ventricular septal capture alone is sufficient to obtain comparable clinical outcomes.

A total of 300 patients aged 19 years or older who have a guideline-based indication for permanent pacemaker implantation for bradyarrhythmia, an expected ventricular pacing burden of 40% or more, and a planned LBBAP procedure will be enrolled at 5 or more centers in the Republic of Korea. Participants will be randomly assigned in a 1:1 ratio, stratified by baseline left ventricular ejection fraction (LVEF \<50% versus \>=50%), to one of two procedural strategies:

1. LBBP mandatory group - the implanting operator continues the procedure, repositioning the lead as required, until left bundle branch pacing (LBBP) or left fascicular pacing (LFP) is confirmed by at least one predefined conduction system capture criterion.
2. LVSP enough group - the operator may complete the procedure at his or her discretion once left ventricular septal pacing (LVSP) is confirmed, irrespective of whether direct conduction system capture is achieved.

The same commercially approved lead and pulse generator platform is used in both groups, so the randomized variable is the procedural endpoint strategy rather than the device.

The primary outcome measure is the absolute change in LVEF from baseline to 12 months, adjudicated by a blinded central echocardiography core laboratory. Secondary outcome measures include echocardiographic response, pacing-induced cardiomyopathy, procedure-related major complications, procedure and fluoroscopy time, paced QRS duration, acute procedural success, achievement and long-term maintenance of conduction system capture, all-cause death, cardiovascular death, heart failure hospitalization, upgrade to cardiac resynchronization therapy, and new-onset atrial fibrillation.

All participants are followed for 12 months after implantation, with study visits at 2 weeks to 1 month, 6 months, and 12 months. The primary analysis follows the intention-to-treat principle, with a prespecified per-protocol analysis according to whether conduction system capture was actually achieved.

Conditions

• Bradycardia
• Atrioventricular Block
• Sick Sinus Syndrome
• Cardiac Pacing
• Artificial
• Heart Conduction System
• Bundle-Branch Block
• Ventricular Dysfunction
• Left
• Cardiomyopathies

Interventions

PROCEDURE

LBBAP with mandatory left ventricular conduction system capture (LBBP or LFP)

Left bundle branch area pacing is performed with an Ingevity Plus active-fixation helical pacing lead (Boston Scientific) and a commercially approved Boston Scientific pulse generator. The lead is advanced into the interventricular septum until direct capture of the left conduction system is confirmed by at least one of the following: a diagnostic QRS morphology transition during threshold testing or programmed stimulation (non-selective to selective LBBP, or LBBP to LVSP); S-V6RWPT \<75 ms with narrow QRS or simple right bundle branch block, or \<80 ms with advanced ventricular conduction disturbance; an LBB potential-to-V6RWPT interval equal to the stimulus-to-V6RWPT interval within 10 ms; or a V6-V1 interpeak interval \>44 ms. The lead is repositioned and the attempt repeated if capture is not obtained; more than three attempts are generally not recommended.

PROCEDURE

LBBAP with left ventricular septal capture as the accepted procedural endpoint (LVSP)

Left bundle branch area pacing is performed with the same Ingevity Plus active-fixation helical pacing lead (Boston Scientific) and commercially approved Boston Scientific pulse generator used in the comparator group. The procedure may be completed once left ventricular septal pacing is confirmed, defined as stable lead fixation in the deep interventricular septum reaching the left ventricular subendocardial region with a terminal R-wave present in lead V1, and without fulfilment of conduction system capture criteria. Deep septal position may be verified by the fluoroscopic fulcrum sign, contrast injection, echocardiography, or post-procedural computed tomography. Additional lead advancement to attempt conduction system capture is permitted at the operator's discretion but is not required by protocol.

Sponsors & Collaborators

• Yonsei University

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

19 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-10-01

Primary Completion

2029-10-01

Completion

2029-11-30