Reference values for local arterial stiffness. Part B: Femoral artery
Objective: Carotid-femoral pulse wave velocity (PWV) is considered the gold standard measure of arterial stiffness, representing mainly aortic stiffness. As compared with the elastic carotid and aorta, the more muscular femoral artery may be differently associated with cardiovascular risk factors (CV-RFs), or, as shown in a recent study, provide additional predictive information beyond carotid-femoral PWV. Still, clinical application is hampered by the absence of reference values. Therefore, our aim was to establish age and sex-specific reference values for femoral stiffness in healthy individuals and to investigate the associations with CV-RFs. Methods: Femoral artery distensibility coefficient, the inverse of stiffness, was calculated as the ratio of relative diastolic-systolic distension (obtained from ultrasound echo-tracking) and pulse pressure among 5069 individuals (49.5% men, age range: 15-87 years). Individuals without cardiovascular disease (CVD), CV-RFs and medication use (n=1489; 43% men) constituted a healthy subpopulation used to establish sex-specific equations for percentiles of femoral artery distensibility coefficient across age. Results: In the total population, femoral artery distensibility coefficient Z-scores were independently associated with BMI, mean arterial pressure (MAP) and total to high-density lipoprotein (HDL) cholesterol ratio. Standardized βs, in men and women, respectively, were -0.18 [95% confidence interval (95% CI) -0.23 to -0.13] and -0.19 (-0.23 to -0.14) for BMI; -0.13 (-0.18 to -0.08) and -0.05 (-0.10 to -0.01) for MAP; and -0.07 (-0.11 to -0.02) and -0.16 (-0.20 to -0.11) for total-to-HDL cholesterol ratio. Conclusion: In young and middle-aged men and women, normal femoral artery stiffness does not change substantially with age up to the sixth decade. CV-RFs related to metabolic disease are associated with femoral artery stiffness.