Aetiology and epidemiology of bradyarrhythmias

Abstract

Bradyarrhythmias, including sinus node dysfunction and atrioventricular (AV) conduction disturbances, are a common clinical finding among elderly people. Ageing is associated with increased fat and collagen deposition surrounding the sinus node, which may cause temporary failure of sinus impulse formation and propagation. Moreover, age-related fibrosis and calcification of the cardiac skeleton may determine different degrees of AV conduction disorders. Other causes of AV blocks are represented by neuromuscular disorders, sarcoidosis, amyloidosis, Lyme disease, and post-radiation therapy. Isolated congenital complete AV block is a rare disease associated with exposure to maternal autoantibodies. If reversible extrinsic causes of bradyarrhythmias or underlying treatable diseases are ruled out, cardiac pacing is usually the therapy of choice in symptomatic bradyarrhythmias. During the last 20 years, cardiac pacing has faced dramatic changes in terms of increased implant rates, technology development, and implementation of indications in clinical practice. While in the 1960s and 1970s only AV blocks were treated, today the majority of pacemakers are implanted for sinus node disease. After being introduced in the 1980s and 1990s, dual-chamber pacing has become the most adopted pacing modality in patients with sinus node disease or AV block.