Electrocardiographic Predictors of Cardiac Reverse Remodeling After Left Bundle Branch Area Pacing in Atrioventricular Block: Emphasis on Post‐Pacing <scp>QRS</scp> Duration

ABSTRACT Background and Aim Permanent pacing is essential for atrioventricular block, but conventional right ventricular pacing may cause electrical dyssynchrony and ventricular dysfunction. LBBAP offers a more physiological alternative, although response varies. This study aimed to identify electrocardiographic markers associated with reverse remodeling after LBBAP. Materials and Methods This retrospective single‐center study included 56 patients with atrioventricular block and reduced left ventricular ejection fraction who underwent LBBAP. Clinical, electrocardiographic, and echocardiographic data were assessed at baseline and 12‐month follow‐up. Reverse remodeling was defined as reduced LVESV with improved LVEF. Six post‐pacing ECG parameters were evaluated: QRS duration, LVAT, V6–V1 interpeak interval, spatial QRS–T angle, Tp–Te interval, and R to Q ratio. Multivariable logistic regression evaluated variables associated with reverse remodeling, while ROC analysis assessed discriminative performance. Results At 12 months, 40 patients (71.4%) achieved reverse remodeling. In univariable analysis, shorter post‐pacing QRS duration, LVAT, and Tp‐Te interval were associated with response. After multivariable adjustment, post‐pacing QRS duration remained significantly associated with reverse remodeling (OR 0.87 per ms; 95% CI 0.80–0.95; p = 0.002), whereas optimal GDMT, LVAT, and Tp–Te interval were not statistically significant. Post‐pacing QRS duration showed good discriminative performance (AUC 0.923). Conclusion Shorter post‐pacing QRS duration was associated with reverse remodeling after LBBAP and may serve as a practical marker of electrical resynchronization. QRS duration may provide additional prognostic information for patient selection and pacing optimization.