Association of Cardiovascular Risk Factors with Microvascular and Conduit Artery Function in Hypertensive Subjects

Background Alterations in microvascular and conduit artery function contribute to target organ damage in hypertension. We investigated the association of cardiovascular (CV) risk factors with microvascular and conduit artery function in hypertensive subjects. Methods Participants included 504 hypertensives (aged 62.1 ± 9.8 years, 42% men) from the community, without history of symptomatic CV disease. Brachial artery ultrasound was performed to measure forearm blood flow (FBF) at rest and during reactive hyperemia (markers of microvascular function) and flow-mediated dilatation (FMD) of the brachial artery (a marker of conduit artery endothelial function). The association of conventional and novel (homocysteine, C-reactive protein, fibrinogen, and lipoprotein a CV risk factors with microvascular function and FMD was tested in multivariable regression models. Results Variables independently associated with higher resting FBF were male sex, higher body mass index (BMI), smoking, and lower HDL-cholesterol; variables associated with lower hyperemic FBF included greater age, female sex, and diabetes. Higher plasma homocysteine was associated with lower hyperemic FBF in obese subjects (P for log homocysteine × BMI interaction = .0008). Variables independently associated with lower FMD were greater age, sex gender, history of smoking, and not using statins. Higher homocysteine was associated with lower FMD in subjects with higher systolic blood pressure (P for interaction = .0004). Hyperemic flow velocity was independently associated with FMD (P = .0006), but its inclusion as a covariate did not influence the association of CV risk factors with FMD. Conclusions In asymptomatic subjects with essential hypertension, select CV risk factors were associated with microvascular and conduit artery function. Furthermore, the association of CV risk factors with conduit artery function appeared to be independent of downstream microvascular function.