LBBAP Versus ILR in Patients With New-Onset LBBB and Moderately Reduced LVEF After TAVI

Patients with new-onset complete LBBB (QRS \> 120 ms, persisting \> 24 h after TAVI) and moderately reduced LVEF (35-50%) will be screened in participating centers. Eligible patients will be centrally randomized 1:1 (stratified by center and atrial fibrillation (yes/no)) to either: * Experimental arm: Left bundle branch area pacing (LBB(AP)) with Biotronik pacemaker and dedicated conduction system pacing leads. * Control arm: Implantable loop recorder (ILR, Biotronik BIOMONITOR IV) for rhythm monitoring. The occurrence of the following events within 12 months of randomization will be evaluated: hospitalization for heart failure, syncope or hemodynamically significant dizziness, or high-grade atrioventricular conduction disturbance. The impact of LBB(AP) compared to ILR monitoring will be evaluated at 6, 12, 24, and 36 months regarding: incidence of atrial fibrillation; incidence of non-sustained ventricular tachycardia; evolution of left ventricular ejection fraction; quality of life; hospitalizations; mortality; medico-economic outcomes; qccurrence of high-grade AV conduction disorders beyond 12 months; omplications related to pacemaker or ILR implantation; unscheduled pacemaker implantation in the ILR group. Patients will be monitored following a regular schedule that includes clinical visits, transthoracic echocardiography , ECG, remote device monitoring, and EQ-5D at 6, 12, 24 and 36 months.

Inclusion Criteria: 1. Patients with new-onset complete left bundle branch block (LBBB) defined as QRS duration \>120 ms, occurring after TAVI and persisting for \>24 hours on ECG. New-onset complete LBBB will be confirmed by QRS duration \>120 ms together with standard morphological criteria (broad, notched or slurred R waves in leads I, aVL, V5 and V6, with absence of Q waves in V5-V6), assessed by the site cardiologist and confirmed by the adjudication committee, in line with current ESC and ACC/AHA/HRS recommendations. 2. Left ventricular ejection fraction (LVEF) between 35% and 50%, assessed within one month before TAVI, in a stable hemodynamic state. 3. Patients implanted with a self-expanding or balloon-expandable valve. 4. Age ≥ 18 years. 5. TAVI procedure performed according to current ESC guidelines. The applicable reference is the 2025 ESC/EACTS Guidelines for the management of valvular heart disease (Praz, et al. Eur Heart J. (2025) 46, 4635-4736), or any subsequent official ESC update in force at the time of each patient's procedure. 6. Life expectancy \> 1 year. 7. Affiliation to a social security scheme 8. Written informed consent provided before study enrollment. Exclusion Criteria: 1. Permanent pacemaker implantation (PPI) before TAVI. 2. Complete atrioventricular block after TAVI leading to immediate PPI. 3. Permanent pacemaker implantation after TAVI for another indication (non-protocol). 4. Pre-existing LBBB before TAVI. 5. Trans-venous permanent pacemaker implantation: No superior vena cava access or mechanical tricuspid valve. 6. Pregnancy or breastfeeding. 7. No affiliation to a social security scheme. 8. Refusal to participate or withdrawal of informed consent. 9. Incapacity to consent. 10. Adults under legal protection (trusteeship, guardianship, curatorship).