Carotid extra-media thickness increases with age, but is not related to arterial stiffness in adults

Background: Assessment of carotid artery perivascular adipose tissue through carotid artery extra-media thickness (EMT) ultrasonography has emerged as a novel assessment technique that might contribute unique information to comprehensive evaluations of arterial health. Currently, there is a lack of research examining relationships between EMT and existing measures of arterial health in adults. We investigated the relationships between EMT and established measures of arterial health, including aortic pulse wave velocity (aPWV), carotid distensibility, and intima-media thickness (IMT) in adults. Methods: Using a cross-sectional, observational design, we assessed resting aPWV, carotid distensibility, IMT and EMT in 81 participants who were categorized as younger healthy adults (YHA; n = 51; 25 ± 6 years), older healthy adults (OHA; n = 15; 70 ± 5 years) or older adults with coronary artery disease (CAD; n = 15; 68 ± 9 years). Results: EMT, IMT, and aPWV were higher while carotid distensibility was lower in OHA and CAD versus YHA (P < 0.05). EMT was correlated with age (r = 0.48; P < 0.01), aPWV (r = 0.43; P < 0.01), IMT (r = 0.41; P = 0.01), and distensibility (r = −0.37; P < 0.01). Despite significant correlations, EMT was not an independent predictor of any of the traditional measures of arterial health included in this study. Conclusions: The novel finding of this study is that while EMT is elevated in older versus younger adults, in agreement with established indicators of arterial health, it is not a predictive factor in these existing measures. EMT may, however, still have clinical utility as a target for comprehensive monitoring of interventions specifically designed to impact arterial structure and function.