Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilized multigate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5 ± 4.9 yr, 19 females) were analyzed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were postprocessed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that nonparabolic flow profiles within the cardiac cycle and under different flow states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute ( R² = 0.25) and percent ( R² = 0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24 ± 0.10 mm (monophasic) vs. 0.17 ± 0.09 mm (biphasic), P < 0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology. NEW & NOTEWORTHY An estimation of wall shear rate (WSR) near the arterial wall by conventional Doppler ultrasound is inherently difficult. Using a recently developed integrated flow-mediated dilation ultrasound system, we were able to accurately estimate WSR near the wall and identified a number of novel WSR variables that may prove to be useful in the measurement of endothelial function, an important biomarker of vascular physiology and disease.

The concept of vascular age (VA) was proposed to provide patients with an understandable explanation of cardiovascular (CV) risk and to improve the performance of prediction models. The present study compared risk-based VA derived from Framingham Risk Score (FRS) and Systematic Coronary Risk Estimation (SCORE) models with value-based VA derived from the measurement of the common carotid artery (CCA) distensibility coefficient (DC), and it assessed the impact of DC-based VA on risk reclassification. In 528 middle-aged individuals apparently free of CV disease, DC was measured by radiofrequency-based arterial wall tracking that was previously utilised to establish sex- and age-specific reference values in a healthy population. DC-based VA represented the median value (50th percentile) for given sex in the reference population. FRS-based and SCORE-based VA was calculated as recommended. We observed a good agreement between DC-based and FRS-based VA, with a mean difference of 0.46 ± 12.2 years (p = 0.29), while the mean difference between DC-based and SCORE-based VA was higher (3.07 ± 12.7 years, p < 0.0001). When only nondiabetic individuals free of antihypertensive therapy were considered (n = 341), the mean difference dropped to 0.70 ± 12.8 years (p = 0.24). Substitution of chronological age with DC-based VA in FRS and SCORE models led to a reclassification of 28% and 49% of individuals, respectively, to the higher risk category. Our data suggest that the SCORE prediction model, in which diabetes and antihypertensive treatment are not considered, should be used as a screening tool only in healthy individuals. The use of VA derived from CCA distensibility measurements could improve the performance of risk prediction models, even that of the FRS model, as it might integrate risk prediction with additional risk factors participating in vascular ageing, unique to each individual. Prospective studies are needed to validate the role of DC-based VA in risk prediction.

Several noninvasive vascular biomarkers have been proposed to improve risk stratification for atherothrombotic events. To identify biomarkers suitable for detecting intermediate-risk individuals who might benefit from lipid-lowering treatment in primary prevention, the present study tested the association of plasma LDL-cholesterol with coronary artery calcification (CAC) Agatston score, high carotid and femoral intima-media thickness (IMT), low carotid distensibility and high carotid-femoral pulse-wave velocity in 260 asymptomatic individuals at intermediate cardiovascular risk and without diabetes and lipid-lowering treatment. High or low vascular biomarkers were considered when their value was above the 95th or below the 5th percentile, respectively, of the distribution in the healthy or in the study population. LDL-cholesterol was independently associated with the CAC score = 0 (OR 0.67; 95%CI 0.48–0.92, p = 0.01), CAC score > 100 (1.59; 1.08–2.39, p = 0.01) and high common femoral artery (CFA) IMT (1.89; 1.19–3.06, p < 0.01), but not with other biomarkers. Our data confirm that in individuals at intermediate risk, lipid-lowering treatment can be avoided in the presence of a CAC score = 0, while it should be used with a CAC score > 100. CFA IMT could represent a useful biomarker for decisions regarding lipid-lowering treatment. However, sex- and age-specific reference values should be established in a large healthy population.

Background/Objectives: This study compares the power of the radiofrequency (RF) signal reflected from the media layer (media power) of the common carotid artery (CCA) and the CCA stiffness between individuals with and without type 2 diabetes mellitus (T2DM). It also evaluates the associations of CCA media power with plasma glucose and lipid levels, as well as carotid stiffness. Methods: A total of 540 individuals, 115 with and 425 without T2DM (273 males, mean age = 64 ± 8 years) were studied using RF-based tracking of the right CCA. The following parameters were measured: CCA media thickness, luminal diameter, wall tensile stress (WTS), local pulse wave velocity (PWV), and media power. Results: Compared to the non-diabetic individuals, the T2DM patients had significantly higher CCA media thickness (652 ± 122 vs. 721 ± 138 microns, p < 0.005), luminal diameter (6.12 ± 0.78 vs. 6.86 ± 0.96 mm, p < 0.0005), media power (36.1 ± 4.8 vs. 39.3 ± 4.6, p < 0.0001), and PWV (7.65 ± 1.32 vs. 8.40 ± 1.89 m/s; p < 0.01), but comparable WTS (32.7 ± 10.4 vs. 33.1 ± 10.7 kPa; p = 0.25). In the entire population, CCA media power was independently associated with male sex, pulse pressure, current smoking, and T2DM; when T2DM was not included in the model, triglycerides emerged as an independent determinant of media power. The CCA PWV was independently associated with age, pulse pressure, media power, and T2DM. Conclusions: Our findings suggest the presence of structural changes in the arterial media of T2DM patients, leading to carotid stiffening and remodeling, aiming to preserve WTS. T2DM-related changes in arterial wall composition may be driven by high plasma triglyceride levels, which have previously been associated with both arterial stiffening and the incidence of CV events.

Several noninvasive vascular biomarkers have been suggested for improving the risk stratification for atherothrombotic events. To identify biomarkers suitable for detecting intermediate-risk individuals who might benefit from lipid-lowering treatment (L-LT) in primary prevention, the present study tested the association of plasma LDL-cholesterol with coronary artery calcification (CAC) Agatston score, high carotid and femoral intima-media thickness (IMT), low carotid distensibility and high carotid-femoral pulse-wave velocity in 260 asymptomatic individuals at intermediate cardiovascular risk and free of diabetes and L-LT. High or low vascular biomarkers were considered when their value was above the 95th or below the 5th percentile, respectively, of the distribution in the healthy or in the study population. LDL-cholesterol was independently associated with the CAC score =0 (OR 0.67; 95%CI 0.48-0.92, P=0.01), CAC score >100 (1.59; 1.08-2.39, P=0.01) and with high femoral IMT (1.89; 1.19-3.06, P100. Femoral artery IMT could represent a useful biomarker for decision regarding L-LT, however the reference values according to sex and age should be established in a large healthy population