Posterosuperior Bundle Pacing for Prevention of Atrial Fibrillation in Patients With Sinus Node Dysfunction

Inclusion Criteria:

* Age ≥18 years
* Indication for permanent pacemaker implantation, including:
* Sinus node dysfunction, defined as at least one of the following:
* Symptomatic sinus bradycardia
* Tachy-brady syndrome
* Chronotropic incompetence
* Sinus pause / arrest
* Atrioventricular block (if present); if ventricular pacing is required, left bundle branch area pacing is planned
* Expected survival \>1 year
* Panned implantation of a device capable of detecting atrial high-rate episodes
* Willing and able to provide informed consent

Exclusion Criteria:

* Persistent atrial fibrillation (AF) (\>7 days), long-standing persistent AF, permanent AF, or prior atrioventricular node ablation
* Prior cardiac implantable electronic device (CIED) requiring replacement, upgrade, or revision
* Indication for cardioverter-defibrillator (ICD) or cardiac resynchronization therapy (CRT-D)
* Prior cardiac surgery, severe hepatic or renal dysfunction, or other life-threatening systemic diseases
* Acute myocardial infarction within 3 months before enrollment
* Persistent left superior vena cava or dextrocardia
* Pregnant or breastfeeding women, or women of childbearing potential not using effective contraception
* Participation in another clinical trial that may interfere
* Any condition that, in the opinion of the investigator, makes participation unsuitable