Improved Outcomes of Conduction System Pacing in Heart Failure with Reduced Ejection Fraction - A Systematic Review and Meta-analysis.

Abstract

Conduction system pacing (CSP) - His bundle pacing (HBP) and Left bundle branch area pacing (LBBAP) - are emerging alternatives to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) in heart failure. However, evidence is largely limited to small and observational studies. We conducted a meta-analysis including a total of 15 randomized control trials (RCTs) and non-RCTs that compare CSP (HBP & LBBAP) with BVP in patients with CRT indications. We assessed the mean differences in QRS duration (QRSd), pacing threshold, left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class score. CSP resulted in a pooled mean QRSd improvement of -20.3 ms (95% CI -26.1 - -14.5, p<0.05, I2=87.1%) versus BVP. For LVEF, a weighted mean increase of 5.2% (95% CI 3.5-6.9, p<0.05, I2=55.6) was observed following CSP versus BVP. The mean NYHA score was reduced by -0.40 (95% CI -0.6 - -0.2, p<0.05, I2=61.7) post-CSP versus BVP. Subgroup analysis of outcomes by LBBAP and HBP demonstrated statistically significant weighted mean improvements from both CSP modalities for QRSd and LVEF compared to BVP. LBBAP resulted in NYHA improvement compared to BVP without differences between CSP subgroups. LBBAP is associated with a significantly lowered mean pacing threshold of -0.51V (95% CI -0.68 - -0.38) whilst HBP had increased the mean threshold (0.62V, 95% CI -0.03 - 1.26) compared to BVP, however, this was associated with significant heterogeneity. Overall, both CSP techniques are feasible and effective CRT alternatives for heart failure. Further RCTs are needed to establish long-term efficacy and safety.