Randomized Trial of Left Bundle Branch Pacing vs Right Ventricular Pacing in Vulnerable Cardiac Function.

Abstract

Right ventricular pacing (RVP) is associated with an increased risk of pacing-induced cardiomyopathy (PICM) in high pacing burden patients. Left bundle branch pacing (LBBP), a more physiological pacing modality, may better preserve cardiac function. This randomized trial aimed to evaluate the clinical outcomes of LBBP versus RVP in high pacing burden patients with high risk of cardiac dysfunction. In this prospective, multicenter, randomized controlled trial, 160 high pacing burden patients with high risk of cardiac dysfunction were randomly assigned in a 1:1 ratio to either LBBP or RVP. The primary endpoint was a composite of all-cause mortality, heart failure hospitalization (HFH), or PICM. Secondary endpoints included the individual components of the primary endpoints, echocardiographic parameters, and New York Heart Association (NYHA) functional class. During a median follow-up duration of 36 months, the primary endpoint occurred in 9 patients in the LBBP group and in 25 patients in the RVP group (11.6% vs. 33.9%; HR 0.310, 95% CI 0.145-0.664; P=0.001), mainly driven by PICM (6.5% vs. 18.2%; sHR 0.324, 95% CI 0.119-0.883; P=0.028). No significant differences were observed in all-cause mortality (P=0.391) and HFH (P=0.100) between two groups. LBBP showed superior improvements than RVP in left ventricular ejection fraction (LVEF) (mean difference: 5.34, 95% CI: 3.18-7.50; P <0.001), left ventricular end-diastolic diameter (LVEDD) (mean difference: -3.06, 95% CI: -4.38- -1.73; P <0.001) and left ventricular end-systolic diameter (LVESD) (mean difference: -3.74, 95% CI: -5.07- -2.41; P <0.001) from baseline to 36 months. Patients in the LBBP group also showed favored NYHA functional class compared with those in the RVP group at 36-month follow-up (1.66 ± 0.60 vs. 1.90 ± 0.56, P = 0.014). In high pacing burden patients with high risk of cardiac dysfunction, LBBP significantly reduced the risk of the composite outcome, driven primarily by a decreased risk of PICM, and is associated with better echocardiographic improvements and clinical function. This LBBP-FAVOUR randomized trial is the first multi-center, prospective, randomized controlled trials to evaluate the clinical efficacy of left bundle branch pacing (LBBP) vs right ventricular pacing (RVP) in patients with high risk of cardiac dysfunction. During a median follow-up of 36 months, LBBP significantly reduced the risk of the composite endpoint including pacing-induced cardiomyopathy (PICM), heart failure hospitalization, and all-cause mortality compared with RVP, and this benefit was mainly driven by the reduction in PICM risk. This work lays a solid foundation for future larger randomized trials in specific patient populations to further validate these findings.