Distance From Pacing Lead Tip to Left Ventricular Cavity Predicts Long-term Loss of Left Bundle Branch Capture: Insights From the IMAGE-LBBP Cohort.

BACKGROUND

Left bundle branch (LBB) pacing (LBBP) has been an emerging pacing modality that preserves physiological activation. However, data on the long-term durability of conduction system capture remain limited. In this study we aimed to assess the long-term stability of LBBP capture and identify predictors of capture loss.

METHODS

We analyzed data from the multicentre, prospective Image Location and Performance of Left Bundle Branch Pacing (IMAGE-LBBP) cohort. Of 50 patients with bradycardia who underwent mid-term cardiac computed tomography imaging after left bundle branch area pacing implantation, 34 with confirmed LBBP and analyzable imaging at mid-term were included in the long-term analysis. Data on lead-related complications and pacing parameters were prospectively collected. The main outcome was new-onset loss of LBB capture after the mid-term assessment.

RESULTS

During a mean follow-up of 60.1 ± 7.9 months, new-onset LBB capture loss occurred in 20.6% (7/34) of patients. Multivariate Cox regression identified mid-term lead tip to left ventricular cavity (Tip-LV) distance as an independent predictor of long-term capture loss (hazard ratio, 2.26; 95% confidence interval [CI], 1.17-4.35; P = 0.015). A cutoff of 2.0 mm yielded high predictive accuracy (area under the receiver operating characteristic curve, 0.881; 95% CI, 0.756-1.0), with 85.7% sensitivity and 77.8% specificity. Kaplan-Meier analysis showed a significantly greater risk of capture loss in patients with a Tip-LV distance > 2 mm compared with those with ≤ 2 mm (hazard ratio, 7.4; 95% CI, 1.6-34.8; log rank P = 0.012).

CONCLUSIONS

LBB capture loss is progressive and occurs in approximately 20% of patients during long-term follow-up. A Tip-LV distance > 2 mm at mid-term is strongly associated with subsequent capture loss, highlighting the importance of optimal lead implantation and mid-term anatomical assessment to ensure durable conduction system pacing.

CLINICAL TRIAL REGISTRATION: NCT04119323.