Wall shear stress is associated with intima-media thickness and carotid atherosclerosis in subjects at low coronary heart disease risk.

BACKGROUND AND PURPOSE Systemic and local coronary heart disease (CHD) risk factors participate in atherogenesis. The role of wall shear stress, a major local risk factor, remains to be elucidated. METHODS Two hundred thirty-four subjects were carefully characterized for the presence of hypertension, hyperlipidemia, diabetes mellitus, obesity, and cigarette smoking and were divided into low- and high-risk groups. They underwent echo-Doppler examination of the carotid arteries. Atherosclerotic plaques and stenoses were detected, intima-media thickness (IMT) was measured, and wall shear stress was calculated. RESULTS One hundred eight subjects were classified as low-risk individuals. The prevalence of carotid atherosclerosis in this group was 18.5%. Wall shear stress was 24.23+/-7.21 dyne/cm(2) in individuals without atherosclerosis and 16.89+/-5.48 in those with atherosclerosis (P<0.000). In multiple regression analyses, wall shear stress, body mass index, and HDL cholesterol were inversely associated and total cholesterol was directly associated with the presence of atherosclerosis; only wall shear stress was associated with IMT. In the high-risk group the prevalence of atherosclerosis was 45.2%. Wall shear stress was 20.44+/-6.82 dyne/cm(2) in subjects without atherosclerosis and 17.84+/-6.88 dyne/cm(2) in those with atherosclerosis (P=0.037). Age was the only variable associated with both carotid atherosclerosis and IMT. CONCLUSIONS In subjects traditionally considered at low CHD risk, intima-media thickening and carotid atherosclerosis are significantly associated with low wall shear stress. In contrast, in subjects at high CHD risk, the contribution of wall shear stress seems to be masked, and age becomes the only factor significantly associated with both carotid atherosclerosis and IMT.