Carotid and femoral artery wall thickness and stiffness in patients at risk for cardiovascular disease, with special emphasis on hyperhomocysteinemia

Recent developments in ultrasound technology enable the noninvasive measure ment of structural and functional vessel wall changes. Until now, the effec t of homocysteine on the arterial wall has remained unclear: reports on int ima-media thickness (IMT) yield conflicting results, whereas data on vessel wall stiffness are lacking. Because several cardiovascular risk factors re sult in an increased IMT or stiffness, different groups at risk for atheros clerotic disease, with special emphasis on hyperhomocysteinemia, were studi ed. Nineteen patients homozygous and 14 subjects heterozygous for cystathio nine beta-synthase (CBS) deficiency, 21 patients with familial hypercholest erolemia (FH), 15 patients with essential hypertension, 20 smokers, and 28 control subjects were studied. The IMT values (both right and left) of the common carotid artery (CCA), bulb (BUL), internal carotid artery (ICA), and common femoral artery (CFA) were measured in millimeters by high-resolutio n ultrasound (Biosound). The distensibility (DC, in 10(-3).kPa(-1)) and com pliance (CC in mm(2).kPa(-1)) coefficients of the CCA (right and left) and CFA (right) were determined by a wall track system (Pie Medical). The mean IMT of the posterior wall in the CCA was 0.70+/-0.09 mm in healthy controls . For patients with vascular disease, FH, and hypertension and in smokers, the mean CCA IMT was larger, whereas no major differences in IMT were obser ved in patients either homozygous or heterozygous for CBS deficiency. The D C and CC in the right CCA were 23.5+/-6.9 (10(-3).kPa(-1)) and 0.9+/-0.3 (m m(2).kPa(-1)) in healthy subjects, slightly lower in patients homozygous fo r CBS deficiency, and clearly lower in patients with vascular disease, FH, and hypertension. No positive correlation was found between plasma homocyst eine level and either IMT, CC, or DC. Because smoking was a confounder in e ach risk group, a stepwise regression analysis was carried out to assess th e contribution of each risk factor on IMT and arterial wall stiffness. Age explained most of the variation in IMT of the CCA (coefficient of determina tion R-2 of 0.34), whereas R-2 values for serum low density lipoprotein cho lesterol, smoking (pack-years), and systolic blood pressure were 0.08, 0.07 , and 0.06, respectively. Homocysteine did not contribute to variation in I MT in both the CCA and CFA. Age and smoking contributed to the variation in IMT in the CFA. The variation in DC and CC in the right CCA and right CFA could in part be explained by age, low density lipoprotein cholesterol, and blood pressure. Plasma homocysteine concentration explained only a small p roportion of the variation in DC in the CCA (R-2=0.02) and in CC in the CFA (R-2=0.04). In this study, no relationship was found between homocysteine level and the thickness of the arterial wall, with only a marginal influenc e on stiffness.