Carotid wall sublayers and their association with atherosclerosis in hypertensive subjects

Introduction Intimal thickening is a characteristic and initial step of atherosclerosis. Carotid intima-media thickness (IMT) is considered a measure of subclinical atherosclerosis, but it can be influenced by increases not only of intima layer thickness (IT), but also of media layer thickness (MT). Hypertension is a risk factor for atherosclerosis, but may also stimulate media layer hypertrophy by increasing artery wall tension. However, little is known regarding the measures of carotid wall sublayers and their association with atherosclerosis in hypertensive subjects. Purpose To measure carotid IMT, MT and IT and evaluate their relationship with carotid atherosclerotic plaques in hypertensive subjects. Methods This cross-sectional study evaluated clinical and carotid characteristics of 186 hypertensive patients (age = 61±11 years, 43% men, BMI = 30.6±6.2 kg/m2) followed at a university outpatient clinic. High-resolution images of common carotid arteries wall and plaques were obtained by ultrasonography equipped with 10MHz-13MHz transducers. IMT, MT and IT were measured using an image processing software. Results Mean IT, MT and IMT values were 0.267±0.060, 0.475±0.107 and 0.742±0.142 mm, respectively. IMT showed stronger correlation with MT (r=0.92; p<0.001) than with IT (r=0.72; p<0.001). Patients with carotid plaques (n=100; 58% of the sample) had higher age (p<0.001) and carotid diastolic diameter (p=0.002) and a trend toward higher diabetes prevalence (p=0.06) than those without plaques. In logistic regression analysis adjusted for these variables, plaques showed stronger association with IT than with MT and IMT (Figure 1). In addition, IT showed greater area under the ROC curve (0.92; 95% CI 0.88–0.96) than IMT (0.79; 95% CI 0.72–0.85) and MT (0.64; 95% CI 0,56–0,72) to identify plaques. Conclusions MT is the main determinant of carotid IMT in hypertensive subjects. Conversely, IT showed stronger correlation and greater discriminatory value to identify atherosclerotic plaques than MT and IMT. These findings suggest that carotid IT may be a more accurate marker of atherosclerosis that MT or IMT in hypertensive subjects. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): CNPq