Interchangeability of carotid and femoral intima-media thickness in risk stratification?

Carotid intima-media thickness is a well documented marker for future cardiovascular, cerebrovascular and peripheral vascular events. It is used as an intermediate parameter not only for the local but also the global arterial status. In view of the concept of vascular heterogeneity, we aimed to investigate the relation between carotid artery intima-media thickness and femoral artery intima-media thickness in a population of normotensive healthy volunteers. A population of 88 healthy normotensive volunteers with wide age distribution between 18 and 65 years was studied (mean age 41.1 ± 13.4 years, 47% men, 53% women). Carotid and femoral IMT were measured using a 10 MHz vascular echography probe (Vingmed System Five). Three measurements of carotid and femoral artery IMT were performed 1 to 2 centimeters proximal of the right carotid and right femoral artery bifurcations respectively, and the results were averaged. Mean carotid IMT was 0.53 ± 0.13 mm. Mean femoral IMT was 0.63 ± 0.34 mm. Carotid and femoral IMT were significantly correlated (r = 0.380; p < 0.001). However femoral IMT values showed a significantly wider scatter with increasing age: Levene's test for >45y, *p<0.05 in table of quartiles of age. These results show differential effects of aging on elastic and muscular large arteries, fitting within the concept of vascular heterogeneity. Although carotid and femoral intima-media thicknesses correlate closely, the wide scatter of values of femoral IMT in all but the youngest age groups precludes this parameter from being used in risk stratification.