This prospective multicenter registry will evaluate the long-term electrical, echocardiographic, and clinical outcomes of conduction system pacing (CSP). There is currently limited data in the literature regarding the long-term results and benefits of CSP. The long-term maintenance of conduction system (His bundle or Left Bundle Branch) capture and physiological ventricular activation is an essential prerequisite for the expected benefits of this technique.

There is currently no prospective study evaluating the preservation of CSP during long-term follow-up. The design of the present study will allow reliable evaluation of CSP maintenance at 2 years follow-up. The prospective collection of electrical data (pacing thresholds, impedance, R wave sensing) during pacemaker follow-up visits will confirm thresholds stability over the long term. The incidence of atrial fibrillation episodes will also be precisely evaluated and will provide new information. Although pathophysiological studies have demonstrated less impairment of left atrial function with conduction system pacing, there is currently no data on the incidence of atrial fibrillation in patients implanted with a CSP pacemaker.

Echocardiographic data will be prospectively collected in order to analyse the evolution of left ventricular ejection fraction (LVEF) after CSP. This systematic follow-up is rarely found in CSP studies, often retrospective, with significant missing echocardiographic data. The hypothesis is that patients benefiting from CSP will not develop the deleterious effects demonstrated with conventional right ventricular pacing, such as left ventricular dilation and LVEF impairment. Inter- and intraventricular asynchrony criteria will also be systematically evaluated during follow-up echocardiography.Finally, this prospective cohort will also systematically collect clinical follow-up data (hospitalizations for heart failure and NYHA stage).

Inclusion Criteria:

• Patient who had undergone conduction system pacing attempt
• Age > 18 yo
• Capacity to understand the nature of the study, legal ability and willingness to give informed consent

Exclusion Criteria:

• Patient under guardianship, trusteeship, or legal protection.
• Pregnant woman (positive urine pregnancy test) or breastfeeding or lack of proven effective contraception (according to the WHO definition) or menopausal without confirmed diagnosis (non-medically induced amenorrhea for at least 12 months before the inclusion visit).

All patients referred for conduction system pacing