Inclusion Criteria:  Age>18 years old Patients with atrioventricular block and EF>50% with a predicted ventricular pacing rate>20% Patients with intraventricular septal diameter>8mm Written informed consent  Exclusion Criteria:  Indication for CRT or ICD device Patients with no subclavian approach, who are candidates for leadless devices Presence of severe tricuspid regurgitation Patients who are candidates for implantation from the right side, as currently the provided tools for left bundle branch pacing fascilitate only left sided pacemaker implantations