The investigators will nationally investigate the prevalence of Transthyretin Amyloidosis wildtype (ATTRwt) in patients of ≥ 65 years with left ventricular hypertrophy who present with high degree atrioventricular block (AV-block) and are admitted for pacemaker implantation. The investigators aim to characterize the group of patients with positive screening of ATTR and compare the ATTRwt disease stage at time of diagnosis for patients identified with ATTR at screening with a control group of routinely clinically diagnosed ATTRwt patients.

Inclusion Criteria:

• Men ≥65years or women ≥75years with unexplained AV-block with pacemaker indication, as decided per treating physician and presence of left ventricular hypertrophy ≥12mm.

Exclusion Criteria:

• Reversible causes for AV-block, som as AV-node disturbing medicament, ion-disturbances, hypothyroidism, hypoxia, ischemia, new heart surgery <1month, endocarditis.

Patients admitted for pacemakerimplantation with advanced AV-block fulfilling eligibility criteria as described.