Procedural Endpoint in Left Bundle Branch Area Pacing: Conduction System Capture Versus LV Septal Capture

This is a prospective, multicenter, randomized controlled trial designed to determine whether direct capture of the left ventricular conduction system must be achieved as the procedural endpoint of left bundle branch area pacing (LBBAP), or whether left ventricular septal capture alone is sufficient to obtain comparable clinical outcomes. A total of 300 patients aged 19 years or older who have a guideline-based indication for permanent pacemaker implantation for bradyarrhythmia, an expected ventricular pacing burden of 40% or more, and a planned LBBAP procedure will be enrolled at 5 or more centers in the Republic of Korea. Participants will be randomly assigned in a 1:1 ratio, stratified by baseline left ventricular ejection fraction (LVEF \=50%), to one of two procedural strategies: 1. LBBP mandatory group - the implanting operator continues the procedure, repositioning the lead as required, until left bundle branch pacing (LBBP) or left fascicular pacing (LFP) is confirmed by at least one predefined conduction system capture criterion. 2. LVSP enough group - the operator may complete the procedure at his or her discretion once left ventricular septal pacing (LVSP) is confirmed, irrespective of whether direct conduction system capture is achieved. The same commercially approved lead and pulse generator platform is used in both groups, so the randomized variable is the procedural endpoint strategy rather than the device. The primary outcome measure is the absolute change in LVEF from baseline to 12 months, adjudicated by a blinded central echocardiography core laboratory. Secondary outcome measures include echocardiographic response, pacing-induced cardiomyopathy, procedure-related major complications, procedure and fluoroscopy time, paced QRS duration, acute procedural success, achievement and long-term maintenance of conduction system capture, all-cause death, cardiovascular death, heart failure hospitalization, upgrade to cardiac resynchronizat