Improved outcomes of conduction system pacing in heart failure with reduced ejection fraction: A systematic review and meta-analysis.

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 controlled trials (RCTs) and non-RCTs that compare CSP (HBP and 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% confidence interval [CI] -26.1 to -14.5 ms; P < .05; I= 87.1%) vs BVP. For LVEF, a weighted mean increase of 5.2% (95% CI 3.5%-6.9%; P < .05; I = 55.6) was observed after CSP vs BVP. The mean NYHA score was reduced by -0.40 (95% CI -0.6 to -0.2; P < .05; I = 61.7) after CSP vs BVP. A subgroup analysis of outcomes stratified by LBBAP and HBP demonstrated statistically significant weighted mean improvements of QRSd and LVEF with both CSP modalities compared with BVP. LBBAP resulted in NYHA improvement compared with BVP, without differences between CSP subgroups. LBBAP is associated with a significantly lowered mean pacing threshold of -0.51 V (95% CI -0.68 to -0.38 V) while HBP had increased the mean threshold (0.62 V; 95% CI -0.03 to 1.26 V) compared with 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.