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Atrioventricular block (AVB) is among the leading diagnoses requiring pacemaker implantation. The incidence of this cardiac conduction disorder increases with age: from the UK Biobank, a community-dwelling cohort of approximately half a million participants, conduction disorders were far more present in those ≥65 years of age versus under the age of 55 (55/10.000 vs 11/10.000, respectively).1 AVB is defined as delayed or interrupted impulse conduction and can be caused by anatomical or functional disorders of the conduction system. An extrinsic or physiological AVB can be secondary to increased parasympathetic tone, and is often self-limiting and does not require therapy. Intrinsic or pathological AVB is subdivided into suprahisian and infrahisian, the former being predominantly benign and the latter requiring treatment. Intrinsic AVB can be acquired by a wide variety of underlying diseases which cause infiltration or fibrosis in myocardial tissue, or imbalance to the otherwise healthy conduction system. When there is no overt underlying cause for AVB, it is referred to as idiopathic. The presumed main theory is fibrosis of the conduction system, which is probably correct for the elder population. In the young, however, caution should be exercised, for this appears to be a group at risk. A previous study in otherwise apparent idiopathic AVB under the age of 50 showed an hazard ration (HR) of 6.8 within the first 5 years of pacemaker implantation on a composite endpoint of death from any cause and hospitalisation due to heart failure, ventricular tachyarrhythmia or cardiac arrest when compared with healthy controls.2 The reason for this substantially elevated risk is not completely clear, but is likely associated with a concealed underlying disease. A different …
Contributors Both authors drafted the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Commissioned; internally peer reviewed.
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