Plasma viscosity is increased in subjects with elevated ankle brachial index

Peripheral artery occlusive disease (PAOD) is associated with increased cardiovascular risk (CVR). Recently it has been reported that also the increased stiffness of lower limb arteries is associated with increased CVR. In particular, subjects with poorly compressible arteries (PCA) appear to have a CVR even higher than that of subjects with PAOD. Limited data are available on the role of hemorheological factors in determining increase in arterial stiffness. Our study aimed to investigate possible association between blood and plasma viscosity and elevated ankle brachial index (ABI).

Subjects were free-living participants to a cardiovascular disease screening campaign. Sixty-two subjects with ABI ranging 1.3-1.4, and 20 with ABI >1.4 were matched with 124 and 40 control subjects, respectively. Cardiovascular disease risk factors (blood pressure, blood lipids, glucose, cigarette smoking, obesity) were evaluated by routine methods. Blood and plasma viscosities were measured by a cone-plate viscometer. Ankle-brachial index was computed as measure of arterial stiffness.

Compared with controls, who were carefully matched for age, sex and all cardiovascular risk factors, subjects with elevated ABI values had increased levels of plasma viscosity (1.42 ± 0.11 vs. 1.35 ± 0.10 cP, p <  0.001, for subjects with ABI ranging 1.3-1.4, and 1.41 ± 0.10 vs. 1.33 ± 0.10 cP, p <  0.01, for subjects with ABI >1.4). No difference in blood viscosity was observed.

The present investigation provides evidence that plasma viscosity is increased in subjects with elevated ABI values, independently of other cardiovascular risk factors. This finding contributes to explain the high CVR of patients with PCA.