Abstract Background A significant percentage of patients develops a persistent complete left bundle branch block (LBBB) following TAVI. Electrophysiological (EP) study could be useful to stratify the risk of atrioventricular block (AVB) in these patients, guiding the need of follow-up and the indication of definite pacemaker. Purpose The primary objective of the study was describing the incidence of bradyarrhythmic events in the 30-day follow-up of patients with new-onset LBBB: AV block with ECG long-term monitoring system (Nuubo) in patients with negative EP study, and ≥ 5 % of ventricular stimulation in patients with positive EP study and pacemaker implantation. Methodology Observational prospective study of consecutive patients without previous permanent pacemaker implantation where transfemoral TAVI was implanted between 2021 and 2023. In case new-onset complete LBBB was present after TAVI, an EP study was performed. EP study was considered positive when His-Ventricule interval was more than 70ms, or after procainamide infusion at 10mg/kg, more than 100ms or more than double the basal HV interval. In case EP was positive, a permanent pacemaker was implanted. In case EP was negative, a 30-day follow-up with ECG long-term monitoring system (Nuubo) was performed. Results In this cohort, 266 patients without pacemaker following TAVI were included. Persistent new-onset left bundle branch block was present in 10,15% of patients (n=27). EP study was positive in 29.62% of patients (n=8), following a definite pacemaker implantation. During follow-up, only one patient (12.5%) was dependent of ventricular stimulation. The group with negative EP study (n=19) were monitored with a 30-day ECG long-term monitoring system (Nuubo). No bradyarrhythmic events were registered in this group. Conclusions Approximately one tenth of patients develop persistent new-onset LBBB after TAVI. Events were seldom in both study groups. Positive EP study patients were dependent of ventricular stimulation in 12.5% of cases, and there was no bradyarrhythmic event registered in EP negative group. EP study could be a safe tool to stratify AVB risk in new-onset LBBB following TAVI.