Background: Abdominal aortic calcification (AAC) represents advanced atherosclerotic plaques and has been associated with poor prognosis. AAC stiffens the aorta which is hypothesised to increase systemic afterload, promote atrial remodelling, fibrosis, and heart strain; overall increasing the risk for atrial fibrillation (AF). No previous study has investigated if the presence of AAC is associated with incident AF or atrial flutter (AF/F)
Methods: Lateral spine images from GE iDXA in participants from the UK Biobank Imaging Study (2014-2022) were read by a validated machine learning tool to automatically estimate AAC based on a semi-quantitative 24-point scale (ML-AAC24)1. Incident AF/F was obtained through record linkage within the UK Biobank. Cox proportional hazards models were used to estimate the risk of incident AF/F in those with severe AAC (scores 6+) compared to those with moderate (2-5) and those with low/none (0-1), with adjustment for age and sex, and then cardiovascular disease (CVD) risk factors.
Results: 42,079, participants without prior atherosclerotic CVD had images for ML-AAC24 assessment including 22,258 (52.9%) women, 15,752 (37.4%) reported ever smoking and a mean age of 63.9±7.7 years. There were 1032 AF/F events reported (rate=2.41%). After adjustment for traditional risk factors AAC, was associated with an approximate 29% increased risk of AF/F (95%CI=1.03 to 1.62) only in those with severe AAC. However, after inclusion of lipids in the final model, this lost significance with only a marginal change in the effect estimate suggestive of a clinically important effect being observed.
Interpretation: Only the presence of severe AAC was associated with a clinically important increased risk of AF/F. Therefore, AAC captured at the time of bone density testing may have application in identifying individuals at risk of AF/F and possibly explains the excess cardiovascular burden in patients with osteoporosis given the robust inverse relationship between bone density and AAC.