Evaluation of cardiac synchrony in left bundle branch pacing: Insights from echocardiographic research

Feasibility and stability of left bundle branch pacing in patients after prosthetic valve implantation

BACKGROUND

Left bundle branch pacing (LBBP) has emerged as a promising pacing modality for preventing pacing induced cardiomyopathy in patients complicated with conduction abnormalities (CAs) after prosthetic valve (PV) implantation.

OBJECTIVE

The present study aimed to evaluate the safety and feasibility of LBBP in this patient population.

METHODS

LBBP was attempted in 20 patients complicated with atrioventricular block after PV implantation. Surface, intracardiac electrical measurements, and echocardiographic data were documented. Lead parameters and complications were routinely tracked at implantation and each follow-up visit.

RESULTS

LBBP was successful in 90% (18/20) participants. The paced QRS duration and the stimulus to left ventricular activation time were 106.8 ± 6.8 ms and 65.5 ± 5.4 ms, respectively. Left bundle branch (LBB) potential was recorded in 61.1% (11/18) patients who succeeded in LBBP. During the procedure, the mean unipolar myocardium capture threshold was 0.51 ± 0.15 V@0.4 ms while the unipolar bundle capture threshold was 0.84 ± 0.51 V@0.4 ms. The mean fluoroscopic exposure time and the radiation dose were 13.0 ± 9.2 min and 81.7 ± 8.3 mGy, respectively. The average follow-up period was 10.4 ± 5.9 months (range 3-23 months). Pacing parameters remained stable and no significant lead-related complications occurred during the whole observation period.

CONCLUSIONS

LBBP was safe and feasible in patients with PVs. Acceptable and stable pacing parameters could be expected during the procedure and the follow-ups.

Short-term and intermediate-term performance and safety of left bundle branch pacing

Introduction

Left bundle branch pacing (LBBP) is a promising new method for patients with pacing indications. This study aims to evaluate the safety and feasibility of LBBP in a relatively longer time span.

Methods and Results

A total of 164 patients were recruited for LBBP in this study. Among these patients, 148 patients had pacing indications due to symptomatic bradycardia while the other 16 patients had indications for cardiac resynchronization therapy (CRT). LBBP was successful in 89.0% (146/164) of all recruited patients. Intracardiac and surface electrographic parameters and image data were documented during the LBBP procedure. The mean paced QRS duration (pQRSD) and the mean stimulus to left ventricular activation time (stim‐LVAT) was 106.0 ± 12.9 ms and 64.4 ± 13.7 ms respectively. Left bundle branch (LBB) potentials were recorded in 89 patients. Forty‐three of whom had sick sinus syndrome (SSS), and 46 had atrioventricular block (AVB). The presence of LBB potential was more common in patients with SSS (82.7% vs 57.5%, P = .002). No significant differences in pQRSD, stim‐LVAT, or capture threshold were detected between patient groups with or without LBB potential. Patients were followed up at 1 month, 3 months, 6 months, and 1 year after the procedure. Pacing parameters and the echocardiographic data remained stable within a mean follow‐up period of 8.6 ± 4.3 months. No serious complication caused by this procedure was found in this study.

Conclusions

Successful LBBP carried an aspect of short pQRSD and stim‐LVAT while the LBB potential was not the prerequisite and necessary feature. The LBBP procedure had a high success rate with satisfied and stable lead parameters during short and intermediate‐term observations.

Evaluation of cardiac synchrony in left bundle branch pacing: Insights from echocardiographic research

AIM

The aim of this study is to assess if left bundle branch pacing (LBBP) can preserve physiological cardiac synchrony and deliver favorable hemodynamic effects.

METHODS

Consecutive patients undergoing dual chamber pacemaker implantation for sick sinus syndrome (SSS) and a normal cardiac function with a narrow QRS complex were recruited for the study. Electrocardiogram and echocardiographic examinations were performed during ventricular pacing-on and native-conduction modes. The QRS duration (QRSd), systolic dyssynchrony index (SDI), and the standard deviation of time-to-peak contraction velocity in left ventricular (LV) 12 segments (Tsd-12-LV) were measured to evaluate LV synchrony. The stroke volume (SV) and the degree of atrioventricular valvular regurgitation were also assessed.

RESULTS

A total of 40 patients underwent LBBP, while another 38 patients underwent right ventricular septum pacing (RVSP) as control group. Baseline characteristics were similar between the two groups. With LBBP, the paced QRSd was slightly wider than the intrinsic QRSd (101.03 ± 8.79 ms vs 91.06 ± 14.17 ms, P < .0001) while the LV mechanical synchrony during LBBP pacing mode was similar to that of native-conduction mode (SDI, 3.14 ± 2.49 vs 2.70 ± 1.68, P = 0.129; Tsd-12-LV, 26.43 ± 15.55 vs 25.61 ± 16.07, P = .671) in the LBBP group. The LV synchrony in the LBBP group was superior to the RVSP group significantly. No significant differences in SV (64.08 ± 16.97 mL vs 65.45 ± 18.68 mL, P = .241) or the degree of atrioventricular valvular regurgitation were noted between LBBP capture and native-conduction modes.

CONCLUSION

LBBP could preserve satisfactory LV synchrony and result in favorable hemodynamic effects.