Clinical Response to Resynchronization Therapy: Conduction System Pacing vs Biventricular Pacing: The CONSYST-CRT Trial
- PMID: 40372330
- DOI: 10.1016/j.jacep.2025.03.024
Clinical Response to Resynchronization Therapy: Conduction System Pacing vs Biventricular Pacing: The CONSYST-CRT Trial
Abstract
Background: Randomized studies comparing conduction system pacing (CSP) with biventricular pacing (BiVP) are scarce and do not include clinical outcomes.
Objectives: The CONSYST-CRT (Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS) trial aimed to test the noninferiority of CSP as compared with BiVP in patients with an indication for cardiac resynchronization therapy, with respect to a combined clinical endpoint at 1-year follow-up.
Methods: A total of 134 patients with cardiac resynchronization therapy indication were randomized to BiVP or CSP and followed up for 12 months. Crossover was allowed when the primary allocation procedure failed. The atrioventricular interval was optimized to obtain fusion with intrinsic conduction. The primary combined endpoint was all-cause mortality, cardiac transplant, heart failure hospitalization, or left ventricular ejection fraction (LVEF) improvement <5 points at 12 months. Secondary endpoints were LVEF increase, LV end-systolic volume (LVESV) decrease, echocardiographic response (≥15% LVESV decrease), QRS shortening, septal flash correction, NYHA functional class improvement, and a combined endpoint of all-cause mortality, cardiac transplantation, and heart failure hospitalization.
Results: Sixty-seven patients were allocated to each group. Eighteen patients (26.9%) crossed from CSP to BiVP; 5 (7.5%) crossed over from BiVP to CSP. Noninferiority (NI) was observed for CSP compared with BiVP for the primary endpoint (23.9% vs 29.8%, respectively; mean difference -5.9; 95% CI: -21.1 to 9.2; P = 0.02) and for the combined endpoint of all-cause mortality, cardiac transplantation, and heart failure hospitalization (11.9% vs 17.9%; P < 0.01 NI); echocardiographic response (66.6% vs 59.7%; P = 0.03 NI); NYHA functional class (P < 0.001 NI); and QRS shortening (P < 0.01). LVEF, LVESV, and septal flash endpoint values were similar, but noninferiority was not met (14.1% ± 10% vs 14.4% ± 10%, -27.9% ± 27% vs -27.9% ± 28%, -2.2 ± 2.7 mm vs -2.7 ± 2.4 mm, respectively).
Conclusions: CSP was noninferior to BiVP in achieving clinical and echocardiographic response, suggesting that CSP could be an alternative to BiVP. (Conduction System Pacing vs Biventricular Resynchronization Therapy in Systolic Dysfunction and Wide QRS [CONSYST-CRT]; NCT05187611).
Keywords: biventricular pacing; cardiac resynchronization therapy; conduction system pacing; left bundle branch pacing.
Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.
Conflict of interest statement
Funding Support and Author Disclosures Dr Pujol-López is funded (2023-2025) through Río Hortega contract CM22/00107 and M-AES MV23/00015 [Instituto de Salud Carlos III (ISCIII), Fondo Social Europeo (FSE)]; and has received the Josep Font contract 2019-2022 from Hospital Clínic Barcelona (Catalonia, Spain); the 2020 Catalan Society of Cardiology Research Grant (Catalonia, Spain); and the 2020 Research Grant from Asociación del Ritmo Cardiaco SECSEST-FOR-NAC 20/003 (Spanish Society of Cardiology). Drs Pujol-López, Jiménez-Arjona, and Tolosana received funding for Project in Conduction System Pacing (FIS PI21/00615) from Instituto de Salud Carlos III (Madrid, Spain). Dr Guichard is currently funded through “Contractes d’Investigació Avançada Fundació BBVA – Hospital Clínic Barcelona Joan Rodés – Josep Baselga 2022" (Contract HCB_BIO_001/2). Dr Mont was funded by a 2021 Support for Research Groups grant from the Catalan government (2021_SGR_01350, SGR21/GENCAT), Catalonia, Spain. Dr Pujol-Lopez has received speaker honoraria from Medtronic. Dr Guichard has received honoraria as a consultant from Microport CRM; has received honoraria as a lecturer from Microport CRM and Abbott; has received unrestricted grant support for a fellowship from Abbott Labs; and holds stock in Corify Care SL. Ms Regany-Closa holds stock in Corify Care SL. Dr Castel has received speaker honoraria from Microport CRM, Astra Zeneca, and Novartis; and has received support for attending meetings from Abbott and Microport CRM. Dr Arbelo has received speaker honoraria Biosense Webster, Medtronic, Bristol-Myers-Squibb (speaker honoraria) and Boston Scientific (consulting). Dr Porta-Sanchez has received honoraria as a lecturer and consultant from Biosense Webster, Abbott, Boston Scientific, Atricure Inc; and holds stock in Corify Care SL. Dr Sitges has received consultant fees and speaker honoraria from Abbott, Medtronic, General Electric, and Edwards Lifesciences. Dr Roca-Luque has received honoraria as a lecturer and consultant from Abbott, Boston, Biosense Webster, and holds stock in Corify Care SL. Dr Tolosana has received honoraria as a lecturer and consultant from Abbott, Boston Scientific, and Medtronic; and holds stock in Corify Care SL. Dr Mont has received research grants, fellowship program support for his work center, and honoraria as a lecturer and consultant from Abbott, Biotronik, Boston Scientific, and Medtronic; and holds stock in Galgo Medical SL and Corify Care SL. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.