Conduction system pacing as a primary strategy for cardiac resynchronization therapy in reduced ejection fraction: An updated systematic review and meta-analysis of randomized controlled trials

BACKGROUND Biventricular pacing (BVP) is the standard for cardiac resynchronization therapy (CRT), particularly in left bundle branch block (LBBB). However, conduction system pacing (CSP) may offer superior outcomes as a physiological alternative. We evaluated the clinical efficacy of CSP compared with BVP as a primary strategy for patients with heart failure indicated for CRT. METHODS A systematic review and meta-analysis was conducted using MEDLINE and the Cochrane Library databases. We included randomized controlled trials (RCTs) comparing CSP with BVP in patients with heart failure and a left ventricular ejection fraction below 50%. Pooled estimates were determined using a random-effects model for all outcomes. RESULTS Twelve RCTs involving 1223 patients were included. CSP significantly improved the echocardiographic response compared with BVP in the overall cohort (odds ratio [OR]: 1.73; 95% confidence interval [CI]: 1.19-2.52) and the LBBB subgroup (OR: 1.74; 95% CI: 1.15-2.62). CSP revealed significant improvements in NYHA functional class (standardized mean difference: -0.27; 95% CI: -0.46 to -0.08) and 6-min walk distance (mean difference: 21.6 m; 95% CI: 8.07 to 35.14). While composite endpoints (OR: 0.59; 95% CI: 0.33 to 1.08) and mortality (OR: 0.90; 95% CI: 0.39 to 2.11) showed trends favoring CSP, neither reached statistical significance. There was no significant difference in procedural crossovers between the groups (OR: 1.24; 95% CI: 0.54 to 2.87). CONCLUSION Compared with BVP, CSP improved echocardiographic and functional response in patients requiring CRT. CSP as a primary strategy may be considered in selected patients, but large RCTs with hard clinical endpoints are needed.