Left Bundle Branch Pacing Outperforms Traditional Pacing in High-Risk Cardiac Patients

Highlights

– Left bundle branch pacing (LBBP) reduced the risk of the composite primary endpoint by 69% compared to right ventricular pacing (RVP).

– The reduction in pacing-induced cardiomyopathy (PICM) was the primary driver of the observed benefits.

– LBBP significantly improved echocardiographic parameters like LVEF, LVEDD, and LVESD compared to RVP.

– Patients in the LBBP group showed better NYHA functional class at 36-month follow-up.

Background

Right ventricular pacing (RVP) has long been the standard approach for patients requiring chronic pacing. However, RVP is associated with an increased risk of pacing-induced cardiomyopathy (PICM), particularly in patients with high pacing burdens. PICM can lead to heart failure and increased mortality, presenting a significant unmet clinical need for alternative pacing strategies.

Left bundle branch pacing (LBBP) has emerged as a promising alternative, offering a more physiological pacing modality that preserves the normal electrical activation of the left ventricle. By directly capturing the left bundle branch, LBBP aims to reduce the dyssynchrony and subsequent cardiac dysfunction seen with RVP. The LBBP-FAVOUR trial sought to evaluate the clinical efficacy and safety of LBBP vs. RVP in high-risk patients.

Study Design

The LBBP-FAVOUR trial was a prospective, multicenter, randomized controlled trial including 160 high pacing burden patients at high risk of cardiac dysfunction. Patients were randomized 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 individual components of the primary endpoint, echocardiographic parameters (LVEF, LVEDD, LVESD), and NYHA functional class.

Key Findings

Over a median follow-up of 36 months, the primary endpoint occurred in 9 patients (11.6%) in the LBBP group versus 25 patients (33.9%) in the RVP group (HR 0.310, 95% CI 0.145-0.664; P=0.001). The reduction in PICM was particularly significant—6.5% in the LBBP group vs. 18.2% in the RVP group (sHR 0.324, 95% CI 0.119-0.883; P=0.028). All-cause mortality and HFH did not differ significantly between the two groups.

LBBP demonstrated superior improvements in cardiac function, including:

• LVEF: mean difference of +5.34% (95% CI 3.18-7.50; P <0.001)
• LVEDD: mean difference of -3.06 mm (95% CI -4.38 to -1.73; P <0.001)
• LVESD: mean difference of -3.74 mm (95% CI -5.07 to -2.41; P <0.001)

Patients in the LBBP group also had better NYHA functional class improvement (1.66 ± 0.60 vs. 1.90 ± 0.56, P=0.014).

Expert Commentary

The findings of LBBP-FAVOUR provide compelling evidence that LBBP mitigates the adverse effects of chronic pacing better than RVP, particularly in high-risk patients. The marked reduction in PICM suggests that LBBP’s physiological pacing preserves ventricular synchrony, preventing the deterioration of cardiac function. However, limitations include the single-blind design and the relatively small sample size. Future trials should explore LBBP in broader populations, including patients with pre-existing cardiomyopathy.

Conclusion

LBBP significantly reduces the risk of adverse cardiac outcomes, primarily driven by PICM reduction, and improves echocardiographic and clinical parameters in high pacing burden patients. These findings strongly support LBBP as a preferable alternative to RVP in this population, pending further large-scale validation.

Funding and ClinicalTrials.gov

The trial was supported by institutional grants, with details available at ClinicalTrials.gov (pending registration).