Abstract 4144811: Durability of Left Bundle Branch Area Capture over Time: A Single Center Retrospective Analysis

Background: Left bundle branch area pacing (LBBAP) is a rapidly growing and widely adopted conduction system pacing (CSP) technique. However, little is known about the durability of left bundle branch area capture (LBBAC) over time. Objective: Evaluate durability of LBBA capture after achieving acute LBBAC at time of implant. Methods: Consecutive LBBAP implants or CSP upgrades by a single operator were retrospectively evaluated. A Medtronic (MDT) C315 sheath was used to deliver a MDT 3830 lead to the LBBA in all cases. QRS width, LV activation time (LVAT), V6-V1 inter-peak interval (V6-V1I) and the presence of R’ in V1 at the time of initial CSP implant and at most recent follow up ECG were measured to determine durability of LBBAC over time. LBBAC was defined as presence of R’ in V1, along with LVAT < 90 msec. Loss of LBBAC was defined as loss of R’ in V1 in follow up along with either increase in QRS duration and/or LVAT. Results: We attempted LBBAP in 108 pts with acute success in 92 (85.2%). The remaining 16 patients (14.8%) demonstrated deep septal pacing. Mean QRS duration at implant for those achieving acute LBBA capture was 130 +/- 12 msec, with mean LVAT of 72 +/- 12 msec, and V6-V1I of 46 +/- 18 msec. After excluding patients with minimal RV pacing and those lost to follow up, 46 patients with acute LBBAC had follow up ECGs available. After a median follow up of 300 days, 44 patients (96%) retained LBBAC with stable QRS duration (125 +/- 16 msec), LVAT (70 +/- 16 msec), and V6-V1I (43 +/- 19 msec). Two patients (4.3%) lost LBBAC, as evidenced by loss of R’, transition to an RV septal paced morphology, and increased LVAT and paced QRS duration. Pacing thresholds remained stable over time. No patients required upgrade for pacing induced cardiomyopathy. Conclusion: In this retrospective study, LBBAC is durable over approximately one year follow up. Longer term follow up data is required to determine long-term durability of this pacing technique, particularly in patients with CRT indications.