A Randomized Controlled Trial Comparing Different Programming Strategies of Left Bundle Branch Area Pacing on Left Atrial Volume and Atrial High-Rate Episodes in Patients With Sinus Node Dysfunction.

Left bundle branch area pacing (LBBAP) is a physiological pacing modality that preserves ventricular synchrony. In patients with sinus node dysfunction, who frequently exhibit delayed intrinsic atrioventricular conduction, the optimal postimplant programming strategy remains uncertain. Minimal ventricular pacing algorithms prioritize intrinsic conduction but may permit nonphysiological atrioventricular (AV) prolongation, potentially contributing to left atrial remodeling and atrial tachyarrhythmias. This is a prospective, single-center, randomized, open-label trial with blinded endpoint assessment (PROBE design). A total of 216 patients with sinus node dysfunction and successful LBBAP implantation will be randomized 1:1 to either a fixed optimized AV delay strategy (paced AV 150 ms; sensed AV 120 ms; minimal ventricular pacing algorithms disabled) or a minimal ventricular pacing strategy using device-specific algorithms (paced AV 200 ms; sensed AV 150 ms). The primary endpoint is the change in left atrial volume from baseline to 12 months, evaluated in a noninferiority comparison. Secondary endpoints include device-detected atrial high-rate episodes and atrial fibrillation burden (AF burden). In conclusion, this trial is designed to determine whether active optimization of AV synchrony after LBBAP implantation is noninferior to a conventional minimal ventricular pacing strategy in preventing left atrial remodeling and whether it may reduce atrial arrhythmia burden.