Abstract 3721: The Brachial Artery Remodels Appropriately to Maintain Local Shear Stress Despite the Presence of Obesity and Systemic Atherosclerosis
Chronic changes in blood flow stimulate parallel changes in arterial size. Under physiological conditions this arterial remodeling process maintains local shear stress at a constant level. Prior studies suggest that risk factors may cause maladaptive outward remodeling that produces relatively large arteries with relatively low shear stress for a given level of flow. Patients with risk factors and CVD events have larger brachial arteries, but it remains unclear whether these differences in arterial size reflect adaptive or maladaptive remodeling. We hypothesized that risk factors and prevalent atherosclerosis (CAD or peripheral arterial disease) would lead to inappropriate remodeling and relatively low shear stress in the brachial artery. To test this hypothesis, we measured brachial diameter and flow by ultrasound and calculated shear stress in a diverse cohort of 1,435 volunteers (age 52 ± 17, 36% female, 46% prevalent atherosclerosis). The brachial artery was free of visible plaque in all subjects. In univariable analyses, risk factors correlated with larger diameter. Unexpectedly, prevalent atherosclerosis correlated with smaller brachial diameter. In age and sex-adjusted multivariable models, brachial diameter related to body mass index (BMI) (β = 0.230, p<0.001) and atherosclerosis (β = −0.170, p<0.001), while other risk factors were no longer significant. Extent of atherosclerosis correlated with lower diameter and flow, while level of obesity correlated with higher diameter and flow (Table⇓). Notably, shear stress did not differ among groups. Thus, obesity is associated with outward remodeling and atherosclerosis is associated with inward remodeling of the brachial artery to accomodate changes in blood flow. Shear stress is maintained at a constant level, suggesting that the plaque-free brachial artery retains the ability to remodel appropriately to match demand despite the presence of risk factors, CAD, and peripheral arterial disease.