Left Bundle Branch Area Versus Biventricular Pacing for Cardiac Resynchronization: Meta-Analysis

Introduction: Left bundle branch area pacing (LBBAP) has emerged as an alternative to conventional biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT). While observational studies have suggested potential advantages of LBBAP in some domains. However, recent randomized controlled trials (RCTs) have reported conflicting results, and contemporary evidence has not been yet synthesized. Hypothesis: To compare the efficacy and safety of LBBAP/conduction system pacing (CSP) versus conventional BiVP for CRT using currently available randomized controlled trial data. Methods: PubMed, Cochrane Library, Google Scholar, and major cardiovascular conference proceedings were searched from January 2016 through May 2026. Randomized controlled trials comparing LBBAP/CSP with BiVP in patients undergoing CRT were included. The primary outcome was all-cause mortality. Secondary outcomes included heart failure hospitalization, change in left ventricular ejection fraction (LVEF), QRS duration, clinical/echocardiographic response, pacing capture threshold, and procedural complications. Random-effects models with restricted maximum likelihood estimation and Hartung-Knapp adjustment were used. Results: Six fully published randomized trials comprising 792 patients (401 assigned to LBBAP/CSP and 391 to BiVP) were included in the primary analysis. All-cause mortality was similar between strategies (RR 0.56, 95% CI 0.12-2.72; P=.37; I 2 =51%). Likewise, no significant differences were observed in heart failure hospitalization (RR 0.67, 95% CI 0.24-1.89; P=.34), clinical/echocardiographic response (RR 0.99, 95% CI 0.89-1.11; P=.87), or change in LVEF (MD 0.54%, 95% CI –3.61 to 4.69; P=.75). LBBAP/CSP was associated with significantly narrower paced QRS duration (MD –7.88 ms, 95% CI –14.89 to –0.88; P=.03) and lower pacing capture thresholds (MD –0.38 V, 95% CI –0.67 to –0.09; P=.02). Procedural complication rates were comparable between groups (RR 0.97, 95% CI 0.64-1.48; P=.87). Subgroup analysis demonstrated a significant improvement in LVEF among trials employing a pure left bundle branch pacing protocol (MD 5.57%, 95% CI 4.86-6.28), whereas mixed CSP strategies showed no significant advantage (P<.0001 for interaction). Conclusions: LBBAP/CSP provides superior electrical resynchronization characterized by narrower paced QRS duration and lower capture thresholds while maintaining a safety profile comparable to conventional BiVP. However, these mechanistic advantages did not translate into significant improvements in mortality, heart failure hospitalization, CRT response, or overall LVEF in currently available randomized trials. Larger adequately powered studies are needed to determine whether the physiological benefits of LBBAP result in meaningful long-term clinical advantages.