His bundle pacing capture threshold stability during long-term follow-up and correlation with lead slack

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• His bundle pacing (HBP) is the most physiologic pacing method.
• Long-term stability of HBP capture thresholds and predictive lead characteristics are not well-defined.

Purpose of the Study:

• To characterize His bundle capture thresholds during follow-up.
• To identify lead characteristics at implantation that predict capture threshold instability.

Main Methods:

• Analysis of His bundle capture thresholds, comorbidities, and lead slack in 294 patients undergoing HBP.
• Tracking of capture threshold increases (≥1V above implant values) and lead revisions.

Main Results:

• 15% of patients (44/294) experienced a ≥1V threshold increase, often early in follow-up.
• Abnormal lead slack shape showed a trend toward threshold increase (HR 2.07).
• Non-perpendicular lead insertion angle significantly predicted threshold increase (HR 2.81, P<0.01).

Conclusions:

• His bundle capture thresholds are stable in 85% of patients.
• Implant lead characteristics, particularly insertion angle, can predict threshold rise.
• Further research into threshold increase etiology and device design may improve long-term stability.