LOCAlizaTion and clinical corrElation of Left Bundle Branch Pacing lead: Insights from a computed tomographic angiography (LOCATE LBBP) study

Background: Left bundle branch pacing (LBBP) provides physiological activation with stable pacing parameters. However, there is a paucity of data on direct assessment of lead stability.

Objectives: The purpose of this study was to assess the stability of an LBBP lead using computed tomographic angiography (CTA) during medium-term follow-up and to correlate the anatomic location of the lead and electrophysiological characteristics of LBBP.

Methods: Consecutive patients with successful LBBP using a lumenless lead were included. Patients without LBB capture, contrast allergy, and renal dysfunction were excluded. CTA was performed postimplantation and at 6 months. Primary endpoint was defined as consistent left bundle branch (LBB) capture with helix tip separated from the left ventricular (LV) blood pool by <2 mm by CTA at 6 months. Secondary endpoints were defined as loss of conduction system capture (LOCSC) or perforation with complete capture loss at 6 months.

Results: Overall, 67 of 105 patients who underwent CTA after successful LBBP were included. Mean follow-up was 33.8 ± 4.4 months. Nonselective to selective capture transition was noted in 82% (n = 55). The lead remained stable at 6 months, with no difference in mean distance between LV blood pool and helix tip (-0.5 ± 1.8 mm vs -0.1 ± 2.1 mm; P = .23). Primary endpoint was achieved in 89.5% (n = 60). Consistent LBB capture (group I) at 6 months was noted in 94% (n = 63). LOCSC (group 2) was noted in 6% (n = 4) at 6 months. No perforation into the LV cavity with complete loss of capture was seen. Lead displacement by >2 mm away from the LV blood pool (sensitivity 100%; specificity 95%) and lack of nonselective to selective capture transition during implantation (odds ratio 18.0; 95% confidence interval 1.7-192.7; P = .01) were LOCSC predictors.

Conclusion: Deep septal deployment of the lead in the LV subendocardium for LBB capture is safe, with 94% of patients showing consistent conduction system capture during follow-up.