Characterization of Septal Scar After Left Bundle Branch Area Pacemaker Implantation

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Cardiovascular Imaging

Background:

• Left bundle branch area pacing (LBBAP) is an emerging technique for ventricular pacing, requiring precise lead placement within the septal region.
• The impact of lead repositioning during LBBAP implantation on septal myocardial fibrosis is not well understood.

Purpose of the Study:

• To evaluate the safety of cardiac magnetic resonance imaging (cMRI) in patients with LBBAP pacemakers.
• To assess septal myocardial tissue characteristics using cMRI after LBBAP implantation and compare them to standard right ventricular endocardial pacing (RVP).

Main Methods:

• A retrospective analysis of patients (age >18) who underwent LBBAP or RVP implantation between 2021 and 2023 and had at least one post-implant cMRI.
• Verification of LBBAP versus RVP based on established criteria.
• Characterization of myocardial scar using delayed-enhancement cMRI and native T1 relaxation times.

Main Results:

• 34 patients were included: 20 with LBBAP and 14 with RVP. No ventricular septal defects were observed post-implant.
• LBBAP lead parameters remained stable before and after cMRI, and up to 9 months post-implantation.
• In patients with matched pre- and post-implant cMRIs (n=9 for LBBAP), one patient showed new scar tissue on the inferoseptal side adjacent to the LBBAP lead, suggesting potential implant-related fibrosis.

Conclusions:

• Cardiac magnetic resonance imaging (cMRI) is confirmed as a safe imaging modality for patients with LBBAP pacemakers, with stable device parameters observed.
• The identification of new septal scar in a patient following LBBAP implantation raises concerns about potential lead-related fibrosis.
• Larger studies are necessary to determine the frequency of lead-related fibrosis in LBBAP patients and whether the observed case is an isolated finding.