His bundle pacing, selective and non-selective: are they equally safe and effective?
Authors: Piemontese G P , Ziacchi M , Bartoli L , Angeletti A , Massaro G , Statuto G , Spadotto A , Biffi M 
Published: October 2022

Abstract

Background
Permanent His Bundle Pacing (HBP) is the most physiological form of ventricular pacing. His bundle stimulation can be selective (s-HBP) or non-selective (ns-HBP). Few comparative data in terms of safety and efficacy among the two are available in literature.

Purpose
Evaluate the safety and efficacy of s-HBP and ns-HBP stimulation and identify predictors of one or the other stimulation.

Methods
Prospective analysis of patients with HBP implanted between December 2018 and July 2021. The clinical and instrumental parameters were collected at implant and at long-term follow-up. Follow-up data were collected both at outpatient visits and by remote monitoring systems.

Results
130 patients in need for antibradyarrhythmia therapy and 26 patients with an indication for cardiac resynchronization therapy were enrolled, 134 (86%) had successful HBP (34% s-HBP and 66% ns-HBP). There were no significant clinical differences between the two populations with the exception of the presence of right bundle branch block (RBBB: 17.4% s-HBP and 34.1% ns-HBP; p = &lt;0.05) and baseline QRS duration (116.5±27.5 ms in s-HBP and 129.9±34.7 ms in ns-HBP; p = &lt;0.05). There were no significant predictors of ns-HBP (Figure 1). At implantation and at an average 16-month follow-up there were no significant differences in the electrical parameters between the two HBP stimulation modalities.
Twenty-one patients (15.7% of the population, 24% of s-HBP and 12.5% of ns-HBP; p=0.38) had conduction system disease progression, manifested either by a significant increase in pacing threshold (13.3% of s-HBP and 10.2% of ns-HBP recipients; p=0.64; Figure 2A) or by loss of capture (6.5% of s-HBP and 2.2% of ns-HBP recipients; p=0.69). No statically significant predictors of conduction system disease progression were found (Figure 2B). While seventeen patients who had significant threshold elevation underwent device output reprogramming, four patients, who lost capture, and a single one experiencing lead dislodgment (nS-HBP patient) required lead repositioning (8.7% of s-HBP and 4.5% of ns-HBP recipients; p=0.33). s-HBP was significantly more vulnerable to atrial oversensing that required sensitivity reprogramming (17.4% of s-HBP and 4.5% of ns-HBP recipients; p&lt;0.05).
No significant differences in clinical endpoints (cardiovascular death, heart failure, atrial fibrillation, syncope) were observed at follow-up.

Conclusions
In patients indicated to ventricular stimulation, the potential benefit represented by HBP is burdened by a non-negligible number of complications. Though no significant differences were detected at medium-long term between s-HBP and ns-HBP stimulation, s-HBP stimulation appears to be more affected by pacing threshold increase and progression of conduction tissue disease, which resulted in an almost 2-fold (although statistically not significant) incidence of repeated surgery.

Funding Acknowledgement
Type of funding sources: None.