Distance from pacing lead tip to left ventricular cavity predicts loss of left bundle branch capture: insights from the IMAGE-LBBP cohort with long-term follow-up

Background and Aims Left bundle branch 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. This study aimed to assess the long-term stability of LBBP capture and identify predictors of capture loss. Methods This study analyzed data from the multicenter, prospective IMAGE-LBBP cohort. Of 50 patients with bradycardia who underwent mid-term cardiac computed tomography imaging after LBBAP implantation, 34 with confirmed LBBP and analyzable imaging at mid-term were included in the long-term analysis. 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 (HR = 2.26; 95% CI, 1.17–4.35; P = 0.015). A cutoff of 2.0 mm yielded high predictive accuracy (AUC = 0.881; 95% CI, 0.756–1.0), with 85.7% sensitivity and 77.8% specificity. Kaplan–Meier analysis showed a significantly higher risk of capture loss in patients with a tip–LV distance >2 mm compared to those with ≤2 mm (HR = 7.4; 95% CI, 1.6–34.8; log-rank P = 0.012). Conclusion 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.