Association of ankle-brachial Index with coronary and extra-coronary calcification in older adults: ARIC study

Aims To investigate potentially distinct associations of ankle brachial index (ABI), a marker of subclinical atherosclerosis, with calcification in different vascular beds and cardiac valves. Methods and results We studied 1420 ARIC participants (mean age 80.2 [SD 4.1] years, 60.2% female, and 16.6% Blacks). ABI was measured at visit 6 (2016–17) or visit 7 (2018–19), and coronary artery calcification (CAC) and extra-coronary calcification (thoracic aorta, aortic valve, and mitral valve) were assessed through non-contrast cardiac-gated computed tomography. We ran multivariable logistic regression models, with any (Agatston score >0) and high (≥75th percentile) calcification as primary and secondary outcome variables, respectively. For any calcification, ABI ≤0.9 had the strongest association with any CAC (odds ratio 9.51 [95%CI 1.26, 71.84]), followed by descending aorta calcification (6.01 [1.36, 26.56]), and weakest for cardiac valve calcification. Using high calcification as an outcome, ABI ≤0.9 was significantly associated with all vascular and valvular calcification tested, but weakest for aortic valve. High ABI [>1.3] tended to be more strongly associated with valvular calcification than vascular calcification with any calcification as an outcome. Conclusion Low ABI was most robustly associated with CAC. Its association was weaker for thoracic aorta calcification and weakest for valvular calcification. These findings further support distinct pathophysiology of calcification across vascular beds and cardiac valves.