The Initial Experience of Left Bundle Branch Area Pacing in Patients with Hypertrophic Cardiomyopathy

Clinical outcomes of left bundle branch area pacing: Prognosis and specific applications

Cardiac pacing has become a widely accepted treatment strategy for bradyarrhythmia and heart failure. However, conventional right ventricular pacing (RVP) has been associated with electrical dyssynchrony, which may result in atrial fibrillation and heart failure. To achieve physiological pacing, Deshmukh et al. reported the first case of His bundle pacing (HBP) in 2000. This strategy was reported to have preserved ventricular synchronization by activating the conventional conduction system. Nonetheless, due to the anatomical location of the His bundle (HB), several issues such as high pacing thresholds, lead fixation, and early battery depletion may pose a challenge. Recently, left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing strategy to achieve conduction system pacing by capturing the left bundle branch through the deep septum. Additionally, several studies have investigated the clinical outcomes of LBBAP. In this paper, we describe the pacing parameters, QRS duration (QRSd), cardiac function, complications, and specific applications of LBBAP in recent years.

Conduction system pacing for ventricular pacing requirement is feasible and effective on patients with hypertrophic cardiomyopathy and cardiac dysfunction

Objective

We aimed to evaluate the feasibility and safety of his-bundle pacing (HBP) and left bundle branch pacing (LBBP) in patients with hypertrophic cardiomyopathy (HCM) and heart failure (HF).

Methods

Patients with HF and interventricular septal thickness (IVST) ≥ 13 mm resulted from HCM, who accepted conduction system pacing (CSP) with a percentage of ventricular pacing > 40% from May 2018 to April 2022 were consecutively enrolled in our center. LBBP was preferred and HBP was the alternative therapy unless IVST ≥ 16 mm or LBBP failed, whereas LBBP would be the alternative therapy if HBP failed in patients with IVST ≥ 16 mm. All patients were followed up for at least one year. Data including clinical, echocardiographic parameters and electrocardiogram measurements, were collected and evaluated in patients with and without left ventricular ejection fraction (LVEF) < 50%.

Results

A total of 27 patients (65.93 ± 9.09 years old) were enrolled and only 3 patients failed in CSP (11.11%) via LBBP (6/13) and HBP (18/21) procedures. LVEF (P = 0.521), left ventricular end-diastolic diameter (LVEDD) (P = 0.816), and QRS duration (P = 0.928) did not worsen after CSP, and left atrial diameter (LAD) (49.58 ± 8.99 mm vs.47.04 ± 9.82 mm, P = 0.045) tended to improve slightly after 19.19 ± 7.71 months follow-up. Of note, LVEF (39.22%±7.51% vs. 45.22%±9.59%, P = 0.015), LVEDD (52.11 ± 10.10 mm vs. 48.33 ± 9.07 mm, P = 0.037), LAD (50.33 ± 8.93 mm vs. 46.11 ± 5.97 mm, P = 0.013) and New York Heart Association (NYHA) grade (2.67 ± 0.5 vs. 1.38 ± 1.02, P = 0.029) improved in 9 patients with LVEF < 50%, whereas LVEF (P = 0.372), LVEDD (P = 0.665), LAD (P = 0.093) and NYHA grade (P = 0.452) did not deteriorate in patients with preserved ejection fraction.

Conclusion

CSP was safe and feasible in patients with HCM and cardiac dysfunction, and did not worsen cardiac performance especially in patients with LVEF < 50%. HBP might be an effective alternative to LBBP in patients with significantly thickened interventricular septum.

Feasibility and safety of left bundle branch area pacing in patients with septal hypertrophy

INTRODUCTION

Left bundle branch area pacing (LBBAP) aims to provide physiological ventricular activation during pacing. Left ventricular septal hypertrophy (LVSH) might be challenging for LBBAP due to the thickness of the interventricular septum and potential presence of septal scar. This study assesses the feasibility, safety, and outcome of LBBAP in patients with LVSH using primarily stylet-driven leads (SDL).

METHODS

Adult patients with LVSH who underwent LBBAP between March 2019 and November 2022 were enrolled. Baseline patient characteristics, procedural data and postprocedural results were collected. The feasibility of LBBAP in LVSH patients was compared to a cohort of LBBAP patients with normal septal wall thickness (NST).

RESULTS

Seventeen LVSH and 133 NST patients underwent LBBAP with successful implantation achieved in 15 LVSH patients (88%). Mean implant depth was 17.2 ± 1.9 mm, with 53% proven left bundle branch (LBB) capture. Paced QRS duration (146 ± 14 ms) and V6 R-wave peak time (V6 RWPT; 79 ± 20 ms) were comparable between patients with and without septal hypertrophy, although patients with NST had higher rates of proven LBB capture (71% vs. 53%). In LVSH pacing thresholds (0.6 ± 0.3 V at 0.4 ms) and R-wave amplitude (13.9 ± 5.6 mV) were favorable and remained stable at follow-up. At 12 months, 87% of patients had stable or improved left ventricular ejection fraction.

CONCLUSION

The results of the study indicate that LBBAP in patients with LVSH is safe and feasible and no lead-related complications were observed despite a mean implant depth exceeding 15 mm. LBBAP using SDL results in favorable pacing and electrocardiographic characteristics in LVSH patients, comparable to patients with NST.

Predictors of implantation failure in left bundle branch area pacing using a lumenless lead in patients with bradycardia

Background

Left bundle branch area pacing (LBBAP) is a novel conduction system pacing technique. In this multicenter study, we aimed to evaluate the procedural success, safety, and preoperative predictors of procedural failure of LBBAP.

Methods

LBBAP was attempted in 285 patients with pacemaker indications for bradyarrhythmia, which were mainly atrioventricular block (AVB) (68.1%) and sick sinus syndrome (26.7%). Procedural success and electrophysiological and echocardiographic parameters were evaluated.

Results

LBBAP was successful in 247 (86.7%) patients. Left bundle branch (LBB) capture was confirmed in 54.7% of the population. The primary reasons for procedural failure were the inability of the pacemaker lead to penetrate deep into the septum (76.3%) and failure to achieve shortening of stimulus to left ventricular (LV) activation time in lead V6 (18.4%). Thickened interventricular septum (odds ratio [OR], 2.48; 95% confidence interval [CI], 1.15-5.35), severe tricuspid regurgitation (OR, 8.84; 95% CI, 1.22-64.06), and intraventricular conduction delay (OR, 8.16; 95% CI, 2.32-28.75) were preoperative predictors of procedural failure. The capture threshold and ventricular amplitude remained stable, and no major complications occurred throughout the 2-year follow-up. In patients with ventricular pacing burden >40%, the LV ejection fraction remained high regardless of LBB capture.

Conclusions

Successful LBBAP was affected by abnormal cardiac anatomy and intraventricular conduction. LBBAP is feasible and safe as a primary strategy for patients with AVB, depending on ventricular pacing.

Left Bundle Branch Pacing for Bradycardia in Non-obstructive Hypertrophic Cardiomyopathy Patients: Feasibility, Safety, and Effect

PURPOSE

Left bundle branch pacing (LBBP) is as an innovative physiological pacing approach. The research on LBBP in non-obstructive hypertrophic cardiomyopathy (NOHCM) patients is scarce. This study aimed to assess the feasibility, safety, and effect of LBBP in bradycardia NOHCM patients with permanent pacemaker (PPM) implantation indication.

METHODS

Thirteen consecutive patients with NOHCM who received LBBP were retrospectively enrolled as a hypertrophic cardiomyopathy (HCM) group. Following 1:3 matching, 39 patients without HCM were randomly matched as a control group. Echocardiographic index and pacing parameters were collected.

RESULTS

The successful LBBP was achieved in 96.2% of all cases (50/52), and the success rate of the HCM group was 92.3% (12/13). In the HCM group, the paced QRS duration (from the pacing stimulus to QRS end) was 145.6±20.8 ms. The stimulus to left ventricular activation time (s-LVAT) was 87.4±15.2 ms. In the control group, the paced QRS duration was 139.4±17.2 ms, and the s-LVAT was 79.9±14.1 ms. During the implantation, R-wave sensing and the pacing threshold of the HCM group were significantly higher than the control group (20.2±10.5 vs 12.5±5.9 mV, P < 0.05; 0.8±0.3 vs 0.6±0.2V/0.4 ms, P < 0.05). In addition, the fluoroscopic duration and procedural duration were longer in the HCM group (14.8±8.3 vs 10.3±6.6min, P = 0.07; 131.8±50.5 vs 101.4±41.6 min, P < 0.05). The lead insertion depth was 15±2 mm in the HCM group, and no procedure-related complications occurred. During the 12-month follow-up, pacing parameters remained stable and were of no significance in the two groups. The cardiac function did not deteriorate, and the left ventricular outflow tract gradient (LVOTG) did not increase in the follow-up.

CONCLUSION

LBBP might be feasible and safe for NOHCM patients with conventional bradycardia pacing indication, and there is no deterioration in cardiac function and LVOTG of patients with NOHCM.