Feasibility of left bundle branch area defibrillator implantation using three-dimensional delivery systems and traditional high voltage leads
Authors: Mandurino C , Scolletta M , Di Gregorio L , Rodio G , Angelini A , Luzzi G 
Published: May 2024

Abstract

Background
Left bundle branch area (LBBA) pacing is an innovative cardiac pacing technique that provides physiological stimulation, which is useful in patients affected by atrioventricular block (preventing pacing-induced cardiomyopathy), and could be an alternative strategy to traditional cardiac resynchronization therapy. Recently, Huybrechts el al. have reported a proof-of-concept study concerning left bundle branch area defibrillator (LBBAD) implantation, evaluating the feasibility of positioning a standard high-voltage (HV) lead by manually pre-shaped delivery systems to achieve LBBAD. No follow-up data were available because the leads were moved to standard positions after testing.

Purpose
This study aimed to assess the safety and feasibility of definitively implanting a traditional HV lead, using novel three-dimensional delivery systems, to stimulate the LBBA and the lead performance in 1-month follow-up.

Methods
This is a single-center, non-randomized, prospective study. The study population consisted of consecutive patients referred for an ICD implantation between September and October 2023. LBBAD was attempted by exploiting three-dimensional delivery systems to reach the target transseptal location. After positioning an active fixation HV lead in the LBBA, acute pacing measurements were collected. Defibrillation testing was performed using either patient-tailored (DeFT Response) or fixed-tilt waveform. Echocardiographic evaluation using speckle tracking was performed after implantation. A short-term follow-up was planned in order to verify the stability of electrical parameters in one month.

Results
LBBAD was performed in 9 consecutive patients (mean age 69±11 years, 56% male). The mean time to implant the HV lead was 20 minutes. The HV lead was successfully implanted in 100% of patients, reaching LBBA in 6 (67%) patients at the first attempt and in 3 (33%) at the second attempt. LBBA pacing exhibited a mean QRS duration and V6 R-wave peak time of 128±9 ms and 64±12 ms. Acute LBBA pacing threshold, R-wave amplitudes, and pacing/shock impedances were 0.88±0.22 V at 0.5 ms, 8.4±2.8 mV, and 637±210 Ω/ 75±20 Ω. The defibrillation test (78% patient-tailored and 22% fixed-tilt waveform) was successful in 6 (75%) of patients at the first shock (~22J) and in 2 (25%) at the second shock (~33J)(test aborted in 1 patient due to respiratory issues during sedation). The mean peak strain dispersion of 31.7ms confirmed global synchrony during pacing. The electrical measurements remained stable, and no lead-related complications were observed at 1-month follow-up.

Conclusion
We performed for the first time ever LBBAD definitive implantation. This study proves the feasibility and safety of using three-dimensional delivery tools for LBBAD procedures and shows optimal results at the implant for up to one month. Nevertheless, a larger and long-term evaluation is needed to evaluate the performance of LBBAD implants.