The objective of the study is to evaluate the functional benefit of left bundle branch of His pacing compared to right ventricular pacing in patients implanted with a pacemaker prior to a atrioventricular node ablation procedure for rapid atrial fibrillation

Inclusion Criteria:

1/ Pacemaker implanted patient with LBTP lead and back-up right ventricular lead who subsequently underwent successful atrioventricular node ablation for rapid AF 2) NAV ablation procedure performed less than 15 days ago 3) Age ≥ 18 years 4) Woman of childbearing age with effective contraception (estrogen-progestin or intrauterine device or tubal ligation) for at least 1 month and for the duration of the study, and a negative urine pregnancy test by B-HCG at inclusion Or, Postmenopausal woman: confirmatory diagnosis (non-medically induced amenorrhea for at least 12 months prior to the inclusion visit).

5) Membership of a social security scheme 6) Patient follow-up feasible 7) Patient has read and understood the information leaflet and signed the informed consent form

Exclusion Criteria:

1. Impairment of autonomy such that a maximal cardiorespiratory effort test (VO2 Max test) cannot be performed under good conditions (ADL scale < 5).
2. LVEF < 40% at inclusion
3. Person deprived of liberty by an administrative or judicial decision, or person under court protection, sub-guardianship or curatorship.
4. Patient participating in another interventional trial
5. Any history of illness or psychological or sensory abnormality likely to prevent the subject from fully understanding the conditions required for participation in the protocol, or from giving informed consent.
6. Pregnant, parturient or breast-feeding women, or those without proven contraception