Left bundle branch area pacing: feasible, safe and successful
Authors: Estevez Paniagua A , Briongos Figuero S , Sanchez Hernandez A , Munoz Aguilera R 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Frequent conventional pacing of the right ventricle (RVP) can be deleterious. In the last 3 years, pacing of the left bundle branch area (LBBAP) has experienced great development for the specific conduction system stimulation, displacing His bundle pacing.

Methods
Prospective study of consecutive patients who received LBBAP for bradicardia or heart failure indications (bailed-out strategy). A 3830-69 lead was implanted using a C-315-His sheath, aiming for left bundle branch pacing (LBBP) in all procedures. We used current criteria to define LBAPP, LBBP (selective or non-selective), and left ventricle septal pacing (LVSP). The purpose of our study was to analyze the feasibility of changing from RVP to LBBAP in bradycardia indication, or LBBAP after sinus coronary lead failure, focusing on the safety and success of the technique.

Results
We enrolled 149 consecutive patients from our hospital who underwent a LBBAP attempt between Feb/20 and Jan/22. Baseline characteristics and pacing indications are shown in table 1. Mean baseline QRS width was 119.3 ± 29.5 ms. 48.3% of patients showed wide (&gt;120 ms) QRS complex. LBBAP was considered successful in 97.3% of the patients: 78.9% was interpreted as LBBP (44.4% considered selective), and 21.1% as LVSP. Regarding the achievement of criteria to define LBBAP, R´ wave in V1 was obtained in 83% of patients, left bundle branch potential (LBBPo) in 44%, with a mean interval time of LLBPo-local ventricular electrogram of 18.1 ± 6.0 ms. The left ventricular activation time (LVAT) in V5/V6 was 80.1 ± 11.3 ms, and in aVL was 83.7 ± 14.7 ms. Mean procedure time was 21.3 ± 18.0 minutes and the fluoroscopy time was 9.9 ± 10.1 minutes. Mean paced QRS was 115.5 ± 14.8 ms, with mean variation from the baseline QRS of + 4.31 ± 24.7 ms. Mean implant parameters were: R wave amplitude 10.9 ± 5.4 mV, impedance 1004.1 ± 233.6 ohms (monopolar), and threshold 0.94 ± 0.65 V (0.4 ms). In the first follow-up (85.2 ± 38.0 days), parameters were similar or better (Table 1). There were only two patients (1.1%) who presented complications related to the technique: one lead dislodgement and one significant threshold increase. When comparing the first 30 cases with the following ones (Table 2), there was a significant difference in the percentage of implant success (90% vs. 99.1%, p = 0.026), in the LVAT-aVL (94.8 ± 13.6 vs. 81.1 ± 13.7 ms, p &lt;0.001) and a marked trend in the LVAT-V5/V6 (83.8 ± 11.8 vs. 79.3 ± 11.1 ms, p = 0.06). A trend towards a shorter duration of paced QRS was found in the initial cases (110.9 ± 11.8 vs. 116.6 ± 15.2, p = 0.07), which could be explained by the lower percentage of SLBPP (23.5% vs. 48%, p = 0.05).

Conclusions
LBBAP as elective type of ventricular pacing is feasible, with a high success rate, which improves with the learning curve, showing safety and efficacy. The procedure and fluoroscopy times seem acceptable, considering that know-how may help reduce them.