Microcirculatory damage of common carotid artery wall in obese and non obese subjects

The objective of the present study was to determine whether the intima-medi a thickness (IMT) is independently related with obesity, and central fat ac cumulation in healthy subjects. Common carotid artery IMT, parameters of bo dy fat accumulation and distribution (body mass index, waist circumference, waist-to-hip ratio), blood pressure levels, and circulating fasting insuli n, glucose, and lipid (cholesterol, HDL-cholesterol, triglycerides, LDL-cho lesterol) levels were determined in a population of non-diabetic normal wei ght and obese subjects. Smoking habits (packs-years) were also taken into a ccount. 239 healthy subjects (143 women and 96 men), with age ranging betwe en 18 and 45 years, were enrolled into the study. They were divided indo tw o groups according to the body mass index (BMI), obese (132 subjects, 77 wo man and 55 men, with BMI greater than 27.0) and controls (107 subjects: 66 women and 41 men, with BMI lower than 27.0). Common carotid artery intima-media thickness was measured by B-mode ultraso und imaging. Fasting plasma metabolic parameters (glucose and lipids) and i nsulin levels were determined by enzymatic and radioimmunological assays, r espectively. Insulin sensitivity was estimated by insulin tolerance test (I TT) and the rate constant for plasma glucose disappearance (KITT) during th e 3- to 15-min period following the regular insulin injection was taken as a measure of in vivo insulin action. Obese patients showed higher IMT than controls, and IMT was significantly associated with BMI in the whole popula tion (r = 0.316, p < 0.001). Age (r = 0.327, p < 0.001), KITT (r = -0.201, p < 0.01), fasting blood glucose (r = 0.187, p < 0.01), LDL-chol (r = 0.201 , p < 0.01), smoking (r = 0.147, p < 0.05), MBP levels (r = 0.154, p < 0.05 ), cholesterol (r = 0.152, p < 0.05) and HDL-chol (r = -0.159, p < 0.05) we re also significantly associated with IMT. Age (r = 0.330, p < 0.05), BMI ( r = 0.299, p < 0.01), waist (r = 0.312, p < 0.001), WHR (r = 0.266, p < 0.0 01) and KITT (r = -0.259, p < 0.01) were the parameters most strongly corre lated with IMT in women, and age (r = 0.324, p < 0.001), BMI (r = 0.338, p < 0.001) waist (r = 0.325, p < 0.001) and LDL-chol (r = 0.283, p < 0.01) wh ere the parameters most strongly correlated with IMT in men. When a stepwis e multiple regression analysis was performed for the whole population, only age (p < 0.001) and BMI (p < 0.001) maintained a significant positive rela tionship with IMT. When a stepwise multiple regression analysis was perform ed separately for men and women, BMI or waist circumference or WHR were alt ernatively entered into the model; interestingly, only age, BMI and waist w ere still significantly correlated with IMT, whereas WHR did not maintain a significant correlation with IMT. In conclusion, BMI and waist circumference, but not WHR, are strongly and i ndependently associated with the IMT of common carotid artery. These result s suggests that central fat accumulation may accelerate the development of earlier clinically silent stages of atherosclerosis, thus possibly explaini ng the higher prevalence of cardiovascular diseases in patients with abdomi nal obesity.