Impact of Left Bundle Branch Area Pacing on Echocardiographic Parameters and Symptoms: Data From the Conduction System Pacing Italian Network Group (C‐SING) Study

Introduction: Left bundle branch area pacing (LBBAP) has emerged as a physiologic alternative to conventional right ventricular and biventricular pacing, yet large real-world evidence remains limited. We aimed to assess changes in ventricular function and symptoms after LBBAP in patients with different clinical indications. Methods and Results: Consecutive patients discharged with confirmed LBBAP across 29 Italian centers underwent evaluation of echocardiographic parameters and New York Heart Association (NYHA) functional class at follow-up. A total of 697 patients were included: 532 with a bradycardia indication and 165 with a heart failure (HF) indication, assessed at a median follow-up of 12.4 months. In the bradycardia group, left ventricular ejection fraction (LVEF) showed a slight improvement from 55% (interquartile range, 50–60) to 56% (52–60) (p = 0.027). Paced-induced cardiomyopathy (PICM), defined as a ≥ 10% absolute LVEF reduction to < 50%, occurred in 3% of patients. Loss of LBBAP capture (p = 0.025) and lower LBBAP percentage (p = 0.024) were independent predictors of PICM. In the HF group, LVEF improved from 35% (30–41) to 45% (36–52) (p < 0.001). Overall, 61.8% were classified as responders (LVEF increase ≥ 5%), rising to 73.8% among patients with ≥ 12 months of follow-up. Higher LBBAP pacing percentage and absence of coronary artery disease independently predicted response. NYHA functional class improved significantly in both groups. Conclusions: In this large real-world cohort, LBBAP was associated with meaningful improvements in ventricular function and symptoms in both bradycardia and HF populations. A high percentage of effective LBBAP capture is essential for optimizing outcomes, supporting its role as an effective physiologic pacing strategy.