Acute procedural comparison between left bundle branch pacing and left ventricular septal pacing

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Left bundle branch area pacing (LBBAP) includes both left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP). The implant procedure characteristics of these two pacing modalities have not been yet fully described. We sought to compare 2 different LBBAP implant strategies: the first one accepting LVSP as a procedure endpoint and the second one aiming at achieving LBBP in every patient. METHODS: Consecutive patients undergoing LBBAP at our centre from January 2020 to October 2022 were included. After our initial LBBAP learning curve, LVSP was accepted as a procedure endpoint in the first 217 patients. Thereafter, LBBP was attempted in every patient with a maximum of 5 lead deployment attempts or > 30 minutes for lead implant even if LVSP had been previously achieved. Definition of LBBP or LVSP was established according to currently accepted criteria. Procedure characteristics including total procedure time, LBBAP lead implant time, radiation exposure parameters, electrical parameters and acute complications were evaluated. RESULTS: A total of 422 consecutive patients were included in the analysis (217 patients with LVSP as acceptable endpoint, and 205 patients with LBBP as final endpoint). Baseline characteristics of the patients are described in table 1. In the LVSP group, the final capture pattern was LVSP in 57.6% and LBBP in 29% whereas in the LBBP group the final capture pattern was LVSP in 19.5% and LBBP in 71.2%. Failure of LBBAP occurred in 13.4% of LVSP group and 9.3% of LBBP group. LBBAP lead position in the septum was basal in 12,5% of LVSP group vs. 23,9% of LBBP group and medium in 81.7% and 72%, respectively (Table 2). A discrete LB potential was identified in 21.2% of LVSP group patients and in 45.8% of LBBP patients, p<0.0001. The LBBP strategy was associated with significantly longer LBBAP lead implant time (19±11min vs. 17±10 min, p=0.05), higher number of lead deployment attempts (3.4±1.8 vs 2.9±1.9, p=0.004), higher number of lead turns (22.4±4.3 vs. 18.3±4,1, p<0,0001) and higher fluoroscopy time (13.2±9.5 min vs. 10.6±9.3 min, p=0.003). Incidence of septal perforation was comparable between the 2 groups (10.6% for LVSP group and 7.8% for LBBP group, p=0.4) but development of complete AV block during implant tended to be more frequent in LBBP group (3.9% vs. 1.4%, p=0.13). The final paced QRS width, measured from the pacing spike, was comparable between the 2 groups: 161±18 ms for LVSP group and 158±19 ms for LBBP group, p=0.2. CONCLUSIONS: LBBP can be achieved in more than 70% of unselected patients with significantly prolonged procedure time, higher number of lead deployment attempts and higher radiation exposure. When LVSP is accepted as an outcome, LBBP can be achieved in up to 29% of cases. The final paced QRS duration is comparable between the two implant strategies. Any potential clinical benefit of LBBP over LVSP in the long-term remains to be proven. [Figure: see text] [Figure: see text]