Impact of Atrioventricular Delay Optimization on Ventricular Function in Conduction System Pacing

Conduction system pacing has emerged as a physiological pacing strategy that preserves ventricular electrical activation and minimizes pacing-induced dyssynchrony. However, the optimal atrioventricular delay setting in patients undergoing conduction system pacing remains uncertain. This study aims to evaluate the effects of individualized echocardiography-guided atrioventricular delay optimization on ventricular function and hemodynamic performance in patients with conduction system pacing. Echocardiographic parameters including global longitudinal strain, left ventricular ejection fraction, left ventricular outflow tract velocity-time integral, cardiac output, and diastolic function indices will be assessed before and after atrioventricular delay optimization. The study will investigate whether optimization of atrioventricular timing provides additional mechanical and hemodynamic benefits beyond physiological ventricular activation achieved by conduction system pacing alone.

Inclusion Criteria: * Age between 18 and 80 years * Permanent conduction system pacing implantation for atrioventricular block * At least 1 month elapsed since device implantation * Sinus rhythm at the time of enrollment * Left ventricular ejection fraction \>40% * Adequate echocardiographic image quality for comprehensive assessment * Ability and willingness to provide informed consent Exclusion Criteria: * Permanent or persistent atrial fibrillation * Significant valvular heart disease * Active malignancy * Severe systemic illness with limited life expectancy * Sinus node dysfunction requiring alternative pacing strategies * Inadequate echocardiographic image quality * Inability to comply with study procedures * Refusal to participate in the study