Left Septal or Deep Septal Pacing to Prevent Pacing-induced Cardiomyopathy

Inclusion Criteria: * First implant of a single-chamber or dual chamber pacemaker due to persistent bradycardia associated with high degree atrio-ventricular (AV) block (complete AV block or second degree type II AV block), with second-degree type I AV block (symptomatic or associated with intra-hisian or infra-hisian block), or with atrial fibrillation with symptomatic slow ventricular rate (\<45lpm). * LVEF\>50% at echocardiography performed maximum 7 days before pacemaker implant. * Informed consent signature. Exclusion Criteria: * Life expectancy \<12 months * Severe cardiac valvular abnormality requiring intervention * Unstable Angina, Acute myocardial infarction, coronary revascularization, valvular surgery or valvular percutaneous intervention in the 90 days prior to pacemaker implant. * Inclusion in another trial which may influence the results of this study.