Conduction system pacing versus biventricular pacing for cardiac resynchronization: the CSP-SYNC randomized single center study

Abstract Background There are limited prospective randomized studies comparing left bundle branch area pacing (LBBAP) and biventricular (BiV) pacing for cardiac resynchronization therapy (CRT). Aim The study tested whether LBBAP is noninferior to BiV pacing in patients with Class I indication for CRT. Methods The CSP-SYNC study is an investigator-initiated, randomized, single-center study. Sixty-two patients were randomized 1:1 to LBBAP or BiV. The primary study endpoint was change in left ventricular ejection fraction (LVEF) at 6 months. Secondary endpoints included changes in echo and clinical parameters after 6 months and 12 months. Results Thirty-one patients were randomized to each arm. Most patients were males (71%), and 32 % had ischemic cardiomyopathy. At 6 months, similar improvement of LVEF was observed in the LBBAP group compared to the BiV group (14.0% (95% CI: 11.2-16.8) in LBBAP vs. 8.5% (95% CI: 5.6-11.2) in BiV) with mean intergroup difference of 5.6% (95% CI: 1.6-9.5; P0.001 for noninferiority). Both groups showed comparable decrease in LVESV (-64 ml (95% CI: -78 to -50) vs -40 ml (95% CI: -54 to -25) respectively, mean difference -24 ml (CI 95%: -44 to -4); P0.001 for noninferiority), changes in 6-minute walk test (P0.001 for noninferiority) and NYHA class (P=0.011 for noninferiority). Temporal trends of LV remodelling and heart failure hospitalization rates were also comparable. Conclusions In patients with a Class I indication for CRT, LBBAP was noninferior to BiV pacing in improving LVEF and provided similar structural and electrical remodelling.