Safety and efficacy of His bundle pacing validated by extracardiac vagal nerve stimulation (HIS-STORY)

Abstract

Growing interest in His bundle pacing (HBP) is being seen worldwide. HBP is an attractive op-tion for permanent cardiac pacing as it maintains a physiological pattern of ventricular activation and thus may prevent the development of right ventricular pacing-induced cardiomyopathy. The permanent HBP procedure has a two-decade track record and has been refined and improved along the way [1]. However, despite general optimism on ’physiological pacing’, concerns about the per-formance, safety, and clinical benefits of HBP still exist. In the 2021 European Society of Cardiology (ESC) guidelines on cardiac pacing an abstaining prevails and there is no first-class recommendation with HBP as first-line therapy [2]. Hypothesized herein, that in a situation of vagal surge some patients with HBP may be en-dangered by loss of capture due to parasympathetic influence on His-Purkinje system (HPS). For this group of patients a change to left bundle branch pacing, which is usually not selective, thereby as-suring direct ventricular myocardium stimulation, or implantation of the back-up right ventricular electrode may be necessary. Another reasonable approach, based on a relatively novel therapeutic technique — cardioneuroablation (CNA), i.e., percutaneous radiofrequency ablation of the para-sympathetic ganglionated plexi of the heart [3]. The implementation of extracardiac vagal nerve stimulation (ECANS) and recently introduced ultrasound-guided ECANS (US-ECANS) enables validation of impact of right and left vagal nerve stimulation on parameters of automaticity and conduction [4]. Although, ECANS is associated with sinus asystole or atrioventricular (AV) block during atrial pacing, the incidence of vagally mediated HBP exit block and changes in pacing threshold have not been investigated. To test the present hypothesis it was decided to conduct a study on the effects of ECANS on pacing parameters in patients with permanent HBP [5]. The aim of this clinical investigation is to assess efficacy of HBP during strong activation of parasympathetic system. As ECANS is a novel, non-standardized diagnostic method, another aim of the study is an assessment of effects of left-versus right-sided ECANS on underlying rhythm and/or HBP parameters.