Abstract Body (Do not enter title and authors here): Background:
Leadless pacemakers are an emerging technology offering a less invasive alternative to traditional transvenous systems. Bachmann bundle (BB) pacing is a novel atrial pacing strategy that may promote more physiologic atrial activation. However, data on the feasibility, safety, and procedural characteristics of leadless pacemaker implantation targeting the Bachmann bundle remains limited.

Methods:
This retrospective case series was conducted at a tertiary center in Iowa City, USA. We included consecutive patients who underwent attempted BB targeted leadless pacemaker implantation between April 2024 and May 2025. Eligibility for the procedure was determined by the implanting physician. Outcomes included procedural success, procedure time, fluoroscopy duration, radiation dose (mGy), device parameters, EKG parameters, and complications. BB targeting was guided by fluoroscopic landmarks. Descriptive statistics summarized baseline characteristics and outcomes.

Results:
17 patients (mean age 67.2 ± 15.5 years; 53% male; 94% white) were included. Of those, 13 (76.5%) had successful BB region leadless pacemaker implantation. Most common indications were sinus node dysfunction (46.2%) and complete heart block (38.5%). The mean procedure time was 72.7 ± 35.1 minutes, fluoroscopy time 10 ± 6.1 minutes, and mean radiation dose was 56.6 ± 47.2 mGy. Initial device parameters (n=13) showed a mean capture threshold of 2.0 ± 0.8 V at 0.6 ± 0.3 ms, sensing amplitude of 1.9 ± 0.9 mV, and impedance of 308.5 ± 67.3 ohms. Follow-up device interrogation, available for 10 patients, showed a mean capture threshold decreased to 0.9 ± 0.5 V at 0.5 ± 0.3 ms, sensing amplitude increased to 3.5 ± 1.4 mV, and impedance decreased to 279 ± 35.7 ohms. P wave duration decreased post-implant (140.3 ± 21.5 ms) vs. pre-implant (154.9 ± 33.5 ms). No procedural complications were reported.

Conclusions:
Leadless pacemaker implantation targeting the Bachmann’s Bundle is feasible and safe, with a high success rate and encouraging early electrical outcomes. These findings support further investigation of physiologic atrial pacing using leadless technology.