Development of chronic thresholds in His bundle pacing: single-center experience over 7 years in 426 patients

Abstract

Abstract Background Conduction system pacing (CSP), e. g. by His bundle pacing (HBP) has the potential to perform highly synchronized ventricular pacing in patients with AV block and narrow QRS complex or right bundle branch block. Therefore, CSP is recommended in these patients to prevent pacing-induced cardioomyopathy. However, there have been reports about an acute and chronic threshold increase in HBP that may cause asystole in pacemaker-dependent patients. Purpose We checked the development of chronic pacing thresholds, the incidence of dislodgements and of consecutive asystole in patients with HBP. Methods All consecutive patients with HBP attempted in our center between 6/2016 and 11/2023 were enrolled. Pacing and sensing parameters over 36 months together with the follwing events were collected and analyzed: His bundle lead dislodgement, loss of capture, threshold increase to ≥3.0V/1.0 ms, emergency admission due to syncope with loss of HBP and asystole. Results In 426 patients (78±11 years, 38% female, 90% AV block, left ventricular ejection fraction 54±10%), HBP was attempted and in 388 patients successful (47% non-selective, 53% selective HBP), 16 patients were converted to left bundle branch area pacing, 22 implantations attemps were unsuccessful. Pacing and sensing performance during follow-up are listed in the Fig. There were 3 lead dislodgements (2 patients with Twiddler syndrome), 1 loss of capture (patient with sinus node disease), and 13 increases of pacing thresholds to ≥3.0V/1.0 ms, summing up to 17 events over 3 years (4.3%). No patient had a clinical event due to threshold increase or loss of HBP capture. All His bundle threshold increases were clinically silent because patients were not pacemaker-dependent, had non-selective HBP with myocardial capture serving as a "back-up" or due to a previously implanted right ventricular back-up lead. Conclusions There is a modest pacing threshold increase in His bundle thresholds from 1.1 to 1.8V@1.0 ms over a period of 3 years. However, this did not cause clinically relevant events in our patient cohort.Chronic pacing and sensing parameters