Background and aims: Endothelial dysfunction and atherosclerosis are linked by multiple mechanisms. Brachial artery flow-mediated dilation (FMD) rate is used to evaluate endothelial function and has been independently associated with adverse cardiac outcomes. The relationship between brachial artery FMD rate and severity of subclinical atherosclerosis by coronary computed tomography angiography (CCTA) is not understood. We hypothesized that brachial FMD is inversely associated with burden of subclinical atherosclerosis measured by CCTA.
Methods: This is a retrospective study of 100 participants with intermediate cardiac risk and atypical symptoms to examine association between brachial artery FMD rate and surrogate markers of severity of subclinical atherosclerosis on CCTA. Multivariate linear regression analysis was used to understand the relationship between brachial artery FMD rate and markers of plaque burden on CCTA including coronary artery calcium (CAC) score, segment involvement score (SIS; total number of segments with any plaque), segment stenosis score (SSS, sum of maximal stenosis score per segment), and total plaque score (TPS, the sum of all segments plaque burden).
Results: 52 participants (42%) were female. Mean age of the cohort was 59.3 ± 10.4 years. After adjusting for traditional risk factors, brachial artery FMD rate was inversely associated with higher CAC, TPS, SIS and SSS (p < 0.05 for all). FMD <4.5 predicted the presence of CAC >0 and ≤ 100 most effectively, with a sensitivity of 62.2% and a specificity of 66.7%, respectively (area under the curve (AUC) of 0.5729, p = 0.0302). FMD <2.7 predicted the presence of CAC >100 most effectively, with a sensitivity of 34% and a specificity of 83% respectively (AUC of 0.6226, p = 0.0095).
Conclusions: Brachial FMD is independently associated with the presence and extent of subclinical atherosclerosis on CCTA. Our findings provide more detailed evidence that mechanistically, FMD, a surrogate marker of systemic endothelial dysfunction is a correlate of atherosclerotic burden, assessed by CCTA and CAC.
Keywords: Coronary CTA; Flow mediated dilation; Severity of subclinical atherosclerosis.
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