Closed loop stimulation in left bundle branch area pacing

Introduction: Closed Loop Stimulation (CLS) is a rate-responsive algorithm that adjusts heart rate (HR) based on changes in intracardiac impedance measured from the right ventricle lead. However, the use of CLS in conduction system pacing has not been investigated. In this retrospective study, we aimed to assess whether CLS with left bundle branch area pacing (LBBAP) can generate an appropriate distribution of HR in daily life. Methods and Results: Our study included 24 patients with CLS pacing and chronotropic incompetence, comparing them with 19 patients receiving DDD pacing, all with LBBAP. Cumulative HR distribution charts were generated using data from a single device interrogation with a minimum follow-up period of 30 days. In DDD-CLS mode, there was a higher percentage of atrial pacing compared to DDD mode (median 58% [interquartile range 29%-83%] vs. 13% [10%-26%], p =.001), and CLS-paced beats were present across all frequency bins. The distribution of beats between the groups was similar (p =.643), resulting in comparable mean HR (72 bpm [70-77] vs. 73 bpm [65-75], p =.615). Conclusions: In the context of LBBAP, CLS effectively modulates pacing rates over a wide frequency range. This lead position does not adversely affect the rate-responsive performance of the algorithm.