Arterial compliance influences the measurement of flow-mediated vasodilation, but not acetylcholine-mediated forearm blood flow. The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study.
Flow-mediated vasodilation (FMD) is low even in healthy elderly and therefore relations between FMD and cardiovascular risk factors might be hard to evaluate in the elderly. Using data from the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, we investigated if a reduced arterial distensibility could influence FMD measurements. In the population-based PIVUS study (1016 subjects aged 70), assessments of arterial distensibility by ultrasound in the carotid artery (CCA) and FMD were performed. Endothelium-dependent vasodilation was also evaluated with the invasive forearm technique with acetylcholine (EDV) and by pulse wave analysis following terbutaline injection. A poor CCA distensibility was defined as <25th percentile in the healthy part of the population (n=131). FMD was significantly related to the Framingham risk score only in those with a good CCA distensibility (r=-0.16, p=0.0081 versus r=-0.06, p=0.17 in those with a poor CCA distensibility, p=0.0001 for difference). In contrast, the relationship between EDV and coronary risk was not affected by CCA distensibility (r=-0.11, p=0.018 versus r=-0.13, p=0.027). A reduced CCA distensibility could in part explain the low FMD values in the elderly. FMD correlated to the Framingham risk score only in those with a good CCA distensibility, exemplifying a limitation of the use of FMD in elderly populations. On the contrary, EDV was not affected by arterial stiffness.