Comparing the effects of left bundle branch pacing and leadless right ventricular pacing on intraventricular and interventricular dyssynchrony using in-silico modelling

Alphonsus C Liew^1,2*Marina Strocchi³Cristobal Rodero³Karli K Gillette^4,5,6Nadeev Wijesuriya¹Sandra Howell^1,2Felicity de Vere^1,2Edward Joseph Vigmond⁷Gernot Plank^4,8Steven Niederer^3,9Christopher Aldo Rinaldi^1,2

• ¹King's College London School of Biomedical Engineering & Imaging Sciences, London, United Kingdom
• ²Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
• ³Imperial College London National Heart and Lung Institute, London, United Kingdom
• ⁴Medizinische Universitat Graz, Graz, Austria
• ⁵The University Of Utah Department of Biomedical Engineering, Salt Lake City, United States
• ⁶University of Utah Scientific Computing and Imaging Institute, Salt Lake City, United States
• ⁷University of Bordeaux, CNRS, Bordeaux, France
• ⁸BioTechMed-Graz, Graz, Austria
• ⁹The Alan Turing Institute, London, United Kingdom

Introduction: Non-physiological right ventricular pacing (RVP) is the mainstay of treatment for patients with high-degree atrioventricular (AV) block and preserved left ventricular ejection fraction. Newer pacing strategies such as left bundle branch pacing (LBBP) and leadless cardiac pacemakers (LCPM) are increasingly adopted, each with advantages over RVP. However, no direct comparison exists between LCPM and LBBP on risk of pacing-induced cardiomyopathy, thought to arise from interventricular and intraventricular dyssynchrony. Using in-silico modelling, we compared the effects of LBBP and LCPM on ventricular synchrony. Methods: Using 19 four-chamber healthy heart geometries, we simulated LCPM at the right ventricular outflow tract-septum (RVOT-S), mid-septum (MS), and apical septum (AS), and proximal (PLBBP) and distal LBBP (DLBBP). Three conditions were tested: 1) intact left bundle conduction, 2) left bundle branch block (LBBB), and 3) septal scar involving the His–Purkinje system (HPS). Ventricular electrical uncoupling (VEU), absolute VEU, and left ventricular dyssynchrony index (LVDI) were measured. The shortest interval to activate 90% of both ventricles (BIVAT-90) was also calculated. Results: With intact conduction, combined LBBP had significantly lower VEU (−3.3 ± 5.1 vs 24.2 ± 7.6 ms, P < 0.01) and absolute VEU (5.0 ± 3.5 vs 24.2 ± 7.6 ms, P < 0.01) compared to combined LCPM. In proximal LBBB, combined LBBP again showed lower VEU (22.1 ± 0.5 vs 25.9 ± 7.9 ms, P < 0.01) and absolute VEU (22.1 ± 0.5 vs 25.9 ± 7.9 ms, P < 0.01) compared to LCPM. However, there was no significant difference when compared to RVOT-S alone (22.1 ± 0.5 vs 21.7 ± 9.0 ms, P = 0.86). In septal scar, combined LCPM had lower VEU than LBBP (31.0 ± 8.4 vs 41.7 ± 20.2 ms, P < 0.01). Combined LBBP produced lower LVDI and BIVAT-90 than LCPM in both intact conduction and LBBB, but not in septal scar. Conclusion: LBBP produces less dyssynchrony than LCPM in intact conduction and proximal LBBB, while LCPM is superior in extensive septal scarring. LCPM at the RVOT-S level may be noninferior to LBBP in proximal LBBB.