REstoration of SYNChronous Cardiac Function Due to Physiologic cArdiac Pacing Modalities With Clinical Endpoints

The goal of this observational study is to evaluate the long-term clinical outcomes of physiologic cardiac resynchronization therapy (CRT) using conduction system pacing strategies compared with conventional biventricular CRT in patients with heart failure with reduced ejection fraction (HFrEF) and electrical dyssynchrony. The main questions it aims to answer are: * Does physiologic CRT (including left bundle branch area pacing \[LBBAP\] and LBBAP-optimized CRT) reduce the combined risk of all-cause mortality and heart failure hospitalization compared with conventional biventricular CRT? * Does physiologic CRT improve cardiac function and reverse ventricular remodeling more effectively than conventional CRT? Participants receiving physiologic CRT as part of routine clinical care will undergo standard follow-up evaluations, including electrocardiography, echocardiography, laboratory testing, and device interrogation. Clinical outcomes will be collected prospectively for 24 months and compared with a historical cohort of patients treated with conventional biventricular CRT. The study will assess clinical outcomes, echocardiographic response, electrical resynchronization parameters, and device-related safety in a real-world heart failure population.

Inclusion Criteria: * Age ≥18 years. * Symptomatic heart failure despite guideline-directed medical therapy. * Left ventricular ejection fraction (LVEF) ≤40%. * Indication for cardiac resynchronization therapy according to contemporary ESC guideline recommendations. * QRS duration ≥150 ms with either: Left bundle branch block (LBBB), or Intraventricular conduction delay (IVCD). * Planned implantation of a CRT system * Ability to provide written informed consent * Expected survival greater than 24 months. Exclusion Criteria: * Age \