Post-shock acute electrical parameters of left bundle branch area defibrillation (LBBAD) leads
Authors: Huybrechts W , Bergonti M , Saenen J , Miljoen H , Van Assche L , Van Leuven O , De Cleen D , Sarkozy A , Van Herck P , Heidbuchel H 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Conduction system pacing is a growing field in bradycardia-treatment. Evidence for His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) to prevent pacing induced cardiomyopathy is growing. Promising data is also emerging to use CSP as an additional tool in cardiac-resynchronisation therapy (CRT). (1-5).
Very often patients requiring an ICD also have an indication for bradycardia or resynchronisation pacing. Adding CSP-treatment to these patients requires an additional pacing lead (HBP or LBBAP) and the use of a CRT-D device.
As opposed to HBP, in LBBAP atrial oversensing cannot occur. Using an ICD-lead in this position could reduce the number of intracardiac leads needed while maintaining the possibility of sensing and treating ventricular arrhythmias.

Purpose
We evaluated the acute electrical parameters before and after delivering an ICD shock with an ICD-lead positioned in the left bundle branch area (LBBA). As this ICD-lead position has never been described before, no data is available on dislocation after shock-delivery. We looked at the electrical parameters of the successful LBBAP ICD-lead implants in our LBBAD (Left Bundle Branch Area Defibrillator) pilot-trial which is a proof-of-concept study for LBBA-ICD lead implantation.

Methods
In the LBBAD pilot trial, we implant an ICD lead in the LBBA to evaluate for feasibility of implantation and functionality of defibrillation. As this is a proof of concept trial, after testing the lead is re-implanted in a conventional ventricular position.
In this abstract we report the evaluation of the electrical parameters of the first 3 successfully implanted LBBAD-leads (n=3).

Results
After LBBA implantation initial electrical parameters were measured. The pacing threshold was 0,8 +/- 0,6 V @ 0,4 ms, while the sensed R-wave and the impedance measured 7,0 +/- 2,7 mV and 512,3 +/- 38,8 Ohms respectively. The shock-coil impedance was 68,0 +/- 7,0 Ohms. All these parameters are in range with the parameters seen in conventional ICD-lead implantation.
After performing the defibrillation threshold test (DFT) all electrical parameters were re-evaluated. Sensing, threshold and impedance were 7,6 +/- 2,2 mV, 0,8 +/- 0,7 V @ 0,4 ms, 516,3 +/- 47,8 Ohms and 71,7 +/- 8,2 Ohms respectively.
These post-shock measurements remained stable within normal ICD-lead functioning range precluding acute dislocation.

Conclusions
Our LBBAD pilot trial is the first-in-human experience with ICD-leads implanted in the LBBA. This pilot trial evaluates for implant-feasibility and also looked at the pre- and post shock electrical parameters of the ICD-lead. As the parameters remained in normal working range, precluding acute shock-induced dislocation, these results open the possibility in patients with an LBBAP-indication as well as an ICD-indication, for a follow-up study to implant an LBBAD-lead and perform longer-term evaluation.