Sex-Based Differences in Left Bundle Branch Capture During Left Bundle Branch Area Pacing

Area of Science:

• Electrophysiology
• Cardiac Pacing
• Electrocardiography

Background:

• Left bundle branch area pacing (LBBAP) is an alternative to traditional pacing.
• Established criteria for LBB capture lack sex-specific considerations despite known sex differences in QRS duration.

Purpose of the Study:

• To investigate sex-based differences in meeting left bundle branch (LBB) capture criteria on postimplant electrocardiograms (ECGs).
• To determine if current LBB capture criteria require sex-specific adjustments in LBB area pacing.

Main Methods:

• Retrospective analysis of 222 patients (>18 years) who underwent dual-chamber LBBAP pacemaker implantation (2020-2023).
• Assessment of baseline and postoperative day 1 (POD1) ECGs for electrical dyssynchrony.
• Left bundle branch capture defined by R-wave peak times (RWPTs) per EHRA 2023 Consensus algorithm.

Main Results:

• Females had shorter baseline QRS duration than males (122 ms vs. 126 ms, p=0.018).
• LBB capture criteria were met by 58.0% of males and 70.9% of females (p=0.058).
• Females exhibited shorter V6-RWPTs (~7 ms shorter, p=0.0008); differences resolved when normalizing for smaller heart size.

Conclusions:

• Females with LBB capture show shorter V6-RWPTs, but this difference is size-dependent.
• Current LBB capture criteria may not be universally applicable across sexes.
• Further research is needed to establish sex-specific criteria for LBB capture assessment.