Carotid intima-media thickness as a measure of vascular target organ damage

A Novel Peptide Elabela is Associated with Hypertension-Related Subclinical Atherosclerosis

INTRODUCTION

Elabela is a newly identified peptide which, alongside apelin, acts as an endogenous ligand that activates the angiotensin receptor-like 1 receptor. Previous studies have shown the association of elabela with hypertension, but information about the role of elabela in hypertension-related subclinical atherosclerosis is scarce.

AIM

We aimed to determine the elabela levels in hypertensive patients and explore its association with subclinical atherosclerosis.

METHODS

A total of 104 subjects with hypertension were included in the study. Elabela levels were measured using an enzyme-linked immunosorbent assay, by first extracting the peptide following the manufacturer's instructions. Subclinical atherosclerosis was assessed by measuring the carotid intima-media thickness (IMT) using ultrasound.

RESULTS

Compared to stage 1, elabela levels decreased in stage 2 hypertension (0.23 [0.13, 0.45] ng/ml vs. 0.14 [0.09, 0.23] ng/ml; P = 0.000), and in the group with increased carotid IMT compared to normal IMT (0.24 [0.13, 0.38] ng/ml vs. 0.15 [0.10, 0.23] ng/ml; P = 0.005). Additionally, a linear correlation analysis showed that elabela had a significant negative correlation with systolic blood pressure (r = - 0.340, P = 0.000) and carotid IMT (r = - 0.213; P = 0.030). In multivariate analysis, lower elabela levels were associated with a higher cardiovascular risk group in this study (OR 5.0, 95% CI 1.8-13.5, P < 0.001).

CONCLUSIONS

This study demonstrated for the first time that circulating elabela declined in a higher stage of hypertension and hypertensive patients with increased carotid IMT, implicating that elabela may be involved in the pathogenesis of hypertension-associated subclinical atherosclerosis.

Prevalence of Microalbuminuria and Its Association with Subclinical Carotid Atherosclerosis in Middle Aged, Nondiabetic, Low to Moderate Cardiovascular Risk Individuals with or without Hypertension

Microalbuminuria is closely associated with the risk of cardiovascular disease and all-cause mortality in the general population. Less is known about its relationship with subclinical atherosclerosis. We aimed to assess the prevalence of microalbuminuria and its relationship with subclinical atherosclerosis in middle-aged, nondiabetic, apparently healthy individuals (N = 187; 40.1% men, 59.9% women; aged 35–55 years) as well as to evaluate its potential associations with established risk modifiers, especially with the presence of carotid plaque. Clinical and laboratory parameters, the estimated 10-year fatal cardiovascular risk (SCORE), as well as circulating, functional (flow mediated vasodilation, ankle-brachial index, augmentation index, and pulse wave velocity), and morphological markers (mean carotid intima–media thickness, and carotid plaque) of subclinical atherosclerosis were analysed in group with vs. without microalbuminuria. Microalbuminuria was present in 3.8% of individuals with SCORE risk 0.43 ± 0.79%. Functional markers predominated in both groups. Carotid intima–media thickness (mean ± SD) in both groups was in range: 0.5–0.55 ± 0.09–0.14 mm. Carotid plaque was more frequent in group with (14.3%) vs. without (4.4%) microalbuminuria. Microalbuminuria had no statistically significant effect on most markers of subclinical atherosclerosis, but the increasing value of microalbuminuria was significantly associated with the occurrence of carotid plaque (p = 0.035; OR = 1.035; 95% CI = 1.002–1.07). Additional multiple logistic regression analysis, where variables belonged to microalbuminuria, number of risk factors, and family history, finally showed only two variables: microalbuminuria (p = 0.034; OR = 1.04; 95%CI = 1.003–1.09) and the number of risk factors (p = 0.006; OR = 2.15; 95% CI = 1.24–3.73) with independent and significant impact on the occurrence of carotid plaque. Our results may indicate an association of microalbuminuria with the presence of carotid atherosclerotic plaque; in addition, microalbuminuria and the number of risk factors appear to be possible predictors of the carotid plaque occurrence. Monitoring microalbuminuria may improve the personalized cardiovascular risk assessment in nondiabetic, low-to-moderate cardiovascular risk individuals with or without hypertension.

From short-term blood pressure variability to atherosclerosis: Relative roles of vascular stiffness and endothelial dysfunction

Both arterial blood pressure (BP) average levels and short-term BP variability (BPV) relate to hypertension-mediated organ damage, in particular increased carotid artery intima-media thickness (IMT) and carotid-femoral pulse wave velocity (PWV). Endothelial dysfunction possibly mediates such damage. The authors aimed at further investigating such role in hypertensive patients. In 189 recently diagnosed, untreated hypertensive patients the authors evaluated, in a cross-sectional design, the relationships of BP average levels and short-term systolic (S) BPV (standard deviation of awake SBP or of 24-hour-weighted SBP) with IMT and PWV, and how much these relationships are explained by endothelial function parameters-brachial artery flow-mediated dilation (FMD) and digital reactive hyperemia index (RHI). Multivariable models assessed the strength of these relationships to derive a plausible pathogenetic sequence. Both average SBP values and our measures of SBPV were significantly related to IMT (24-hour mean SBP: r = .156, P = .034; 24-hour-weighted SBPV: r = .157, P = .033) and to PWV (24-hour mean SBP: r = .179, P = .015; 24-hour-weighted SBPV: r = .175; P = .018), but only poorly related to FMD or RHI (P > .05 for all). At univariable regression analysis, FMD and RHI were both related to IMT, (P < .001), but not to PWV. When FMD and RHI were added to average SBP and SBPV parameters in a multivariable model, both significantly (P < .005) contributed to predict IMT, but not PWV. Thus, endothelial dysfunction relates to IMT independently of BP parameters, but appears to play a minor role in the association between BP variability-related variables and arterial stiffening.

Soluble Tumor Necrosis Factor Like Weak Inducer of Apoptosis and Vitamin D in Hemodialysis Patients: Relation to Carotid Intima-Media Thickness

Cardiovascular disease, as the leading cause of patient death with chronic kidney disease, could be predicted by carotid atherosclerosis. The aim of the present study was to evaluate a possible relationship between serum soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) and Vitamin D levels with mean right/left carotid intima-media thickness (cIMT), in the hemodialysis (HD) patients. In this cross-sectional study, serums were obtained from 50 stable chronic HD patients and 39 healthy controls. The serum levels of sTWEAK, Vitamin D, intact parathyroid hormone (iPTH) in both groups, and cIMT were determined in HD patients by standard methods. Serum levels of sTWEAK were higher [808.8 (521.6-5032.4) pg/ml vs. 664.4 (487.4-2955.8) pg/ml (p = 0.006)] and Vitamin D levels were lower [13.4 (2.5-153) ng/ml vs. 27.8 (18.4-59.0) ng/ml (p = 0.001)] in the hemodialysis patients than in the healthy control. No important correlation was found between sTWEAK Vitamin D levels (r = 0.010/p = 0.946), and mean right(r = -0.194/p = 0.178) and left (r = 0.061/p = 0.673) cIMT in the HD patients. Our study shows that sTWEAK levels are elevated in HD patients. This elevation has no association with the cIMT.

Carotid Intima-Media Thickness as a Cardiovascular Risk Factor and Imaging Pathway of Atherosclerosis

Assessment of carotid intima-media thickness (IMT) has emerged as a simple and noninvasive technique for measuring atherosclerotic burden. Although serum biomarkers have been linked to the risk of developing atherosclerosis, carotid IMT has the theoretical advantage of directly visualizing a final consequence of the disease itself, namely atherosclerosis in the vessel wall. The current widespread application of carotid IMT measurements has been based on the validity, standardization, and reproducibility of the measurement and the evidence that an increased carotid IMT can be regarded as an attractive biomarker of atherosclerosis and of increased cardiovascular risk, potentially useful as a therapeutic target in those at increased cardiovascular risk. The utilization of carotid IMT measurements as a surrogate end point in clinical trials evaluating a specific drug intervention may result in considerably smaller efforts and costs than when using a hard end point such as myocardial infarction, stroke, or death. In addition, the use of carotid IMT measurement as a screening tool in clinical practice in association with traditional risk factors may improve risk classification and decisions regarding therapeutic interventions. However, although carotid IMT may be correlated with clinical outcomes, changes in surrogate end points over time that result from a particular therapy may not necessarily be predictive of future cardiovascular events. Therefore, it is necessary to perform more clinical studies to clearly define the relationship between the modifications in carotid IMT and the changes in cardiovascular events. In an era of economic burden, when there is a clear combination of limited resources with high expense of innovation in drug development, carotid IMT represents a reasonable, worthwhile surrogate trial end point with a history of nearly 30 years of technical progress and clinical research. Current data strongly suggest that carotid IMT will continue to successfully be used as a valuable tool in clinical atherosclerosis research.

Racial Differences in Aortic Stiffness in Children

OBJECTIVE

To investigate racial differences in central blood pressure and vascular structure/function as subclinical markers of atherosclerotic cardiovascular disease in children.

STUDY DESIGN

This cross-sectional study recruited 54 African American children (18 female, 36 male; age 10.5 ± 0.9 years) and 54 white children (27 female, 26 male; age 10.8 ± 0.9 years) from the Syracuse City community as part of the Environmental Exposures and Child Health Outcomes study. Participants underwent blood lipid and vascular testing on 2 separate days. Carotid artery intima-media thickness and aortic stiffness were measured by ultrasonography and carotid-femoral pulse wave velocity, respectively. Blood pressure was assessed at the brachial artery and estimated in the carotid artery using applanation tonometry.

RESULTS

African American children had significantly higher pulse wave velocity (4.8 ± 0.8 m/s) compared with white children (4.2 ± 0.7 m/s; P < .05), which remained significant after adjustment for confounding variables including socioeconomic status. African American children had significantly higher intima-media thickness (African American 0.41 ± 0.06, white 0.39 ± 0.05 mm), and carotid systolic blood pressure (African American 106 ± 11, white 102 ± 8 mm Hg; P < .05) compared with white children, although these racial differences were no longer present after covariate adjustments for height.

CONCLUSIONS

Racial differences in aortic stiffness are present in childhood. Our findings suggest that racial differences in subclinical cardiovascular disease occur earlier than previously recognized.

Assessing the clinical utility of biomarkers in medicine

Biomarkers in medicine have gained immense scientific and clinical interest in recent years. Biomarkers are potentially useful in the contexts of primary, secondary and tertiary prevention. Some of the characteristics of an ideal biomarker include that they are safe and easy to measure, are associated with acceptable costs (including those of the follow-up tests), and there is scientific evidence to suggest that biomarker use/modification influences disease outcomes. Additionally, variation in biomarker levels with gender and ethnicity should be elucidated, and the biomarker should have 'good performance characteristics' (i.e., sensitivity, specificity, positive- and negative-predictive values and positive- and negative-likelihood ratios). Risk prediction scores can combine information from several different biomarkers in order to estimate an individual's risk of developing an outcome, such as disease or death. Three commonly employed methods to test if a biomarker will add to traditional risk prediction models are model discrimination, model calibration and risk reclassification. 'Multimarker' strategies serve to integrate information from multiple biomarkers into risk prediction but may be limited by the presence of highly correlated biomarkers, economic costs and selection bias of biomarker candidates in a particular study sample. In the future, integration of biomarkers identified using emerging technologies from the 'omics fields (including genomics, proteomics, metabolomics, lipomics, ribomics and pharmacogenomics) may be useful for the 'personalization' of treatment/disease prevention.

Rate of atherosclerotic plaque formation predicts cardiovascular events in ESRD

Carotid intima media thickness (IMT) is a strong, independent predictor of cardiovascular events in both the general population and among those with end-stage renal disease (ESRD), but it is unknown whether changes in IMT or other ultrasound-measured indicators of atherosclerosis over time provide additional prognostic information. The progression of atherosclerosis with carotid ultrasound was followed in a cohort of 135 ESRD patients, 103 of whom had a repeat ultrasound after 15 mo of follow-up. The number of plaques and the proportion of patients with severe atherosclerosis increased substantially during the follow-up period, but IMT, common carotid artery diameter, common carotid artery wall-to-lumen ratio, and cross-sectional area, did not change. The rate of formation of new plaques was a strong, independent predictor of incident cardiovascular events, even after adjusting for baseline plaque burden and other potential confounders. New plaque formation over time was independently predicted by background plaque burden and serum C-reactive protein (P = 0.004 and P = 0.02, respectively). Changes in IMT and the other ultrasound-measured indicators of atherosclerosis progression did not predict cardiovascular outcomes. Therefore, monitoring IMT over time is unlikely to provide additional prognostic information compared with a single measurement, but longitudinal ultrasound monitoring of plaque formation may be useful for cardiovascular risk stratification in the ESRD population.

Losartan but not atenolol reduce carotid artery hypertrophy in essential hypertension. A LIFE substudy

BACKGROUND

We wanted to investigate whether treatment with losartan, an angiotensin II receptor blocker, induced regression of carotid artery hypertrophy as compared to the beta-receptor blocker, atenolol.

METHODS

In 45 patients recruited for the LIFE Study with stage II-III hypertension and ECG left ventricular (LV) hypertrophy, we measured blood pressure, intima-media thickness (IMT) and lumen in the common carotid arteries by ultrasound, and minimal forearm vascular resistance (MFVR) by plethysmography, after 2 weeks of placebo treatment and after 1, 2 and 3 years of anti-hypertensive treatment with either atenolol- or losartan-based regimens. We measured the same parameters in 26 normal subjects matched for age and gender.

RESULTS

The patients had as compared to normotensive controls higher IMT (0.87 vs 0.76 mm, p = 0.001) and intima-media cross-sectional area (IMA) (19.7 vs 15.5 mm2, p<0.001). Systolic and diastolic blood pressures were reduced to the same degree in patients treated with losartan as compared to atenolol. However, IMA decreased significantly only in patients treated with losartan (19.2 vs 17.6 mm2, p = 0.001) and the average relative decrease in IMA during the 3 years of treatment was significantly higher in patients treated with losartan as compared to atenolol (-7.4 vs -2.0%, p<0.05).

CONCLUSION

Patients with hypertension and LV hypertrophy had hypertrophy of the common carotid arteries. Losartan, but not atenolol, induced regression of this hypertrophy. Because carotid artery hypertrophy has been associated with strokes, our findings may explain the lower incidence of strokes in the LIFE study in patients treated with losartan as compared to atenolol.

Non-invasive cardiovascular risk assessment in women with type 2 diabetes

This study assessed and compared carotid intima-media thickness (IMT) in postmenopausal women with type 2 diabetes with that in postmenopausal women without type 2 diabetes and compared risk factors that contribute to increased carotid IMT in these groups of women. Carotid IMT, a non-invasive assessment of cardiovascular risk, was measured using high-resolution ultrasound in 20 postmenopausal women with type 2 diabetes and 20 postmenopausal women without type 2 diabetes who had no known coronary heart disease. Risk factors (age, race, family history, diabetes, hypertension, high cholesterol, years past menopause, use of hormone replacement therapy, perceived level of physical activity, and body mass index) known to contribute to coronary heart disease were also assessed. Mean carotid IMT was .88 mm for women with type 2 diabetes compared with .74 mm for women without type 2 diabetes. There were no differences between groups in age, race, cholesterol, and perceived level of physical activity. Women with type 2 diabetes, however, reported more hypertension ( P = .004), greater body mass index ( P = .026), and less use of hormone replacement therapy ( P = .027). Of concern is that 10% of the women with diabetes had stenosis that required surgical intervention. Findings suggest that carotid IMT is a valid way to screen for cardiovascular risk, particularly in postmenopausal women who are at high risk for coronary heart disease. It may also be a feasible, non-invasive method for the detection and prevention of the macrovascular complications of diabetes.

Effects of antihypertensive therapy on hypertensive vascular disease

Hypertension is associated with alterations in the structure, function, and mechanical properties of large and small arteries. Changes in the endothelium, smooth muscle cell, extracellular matrix, and possibly the adventitia, contribute to complications of hypertension. In large arteries, vascular hypertrophy is found, often with increased stiffness of media components. In small arteries, particularly in mild hypertension, rearrangement of smooth muscle cells around a smaller lumen without changes in media volume (eutrophic remodeling) occurs; in more severe hypertension, hypertrophic remodeling with increased vascular stiffness can be found. Vascular remodeling is accompanied by an increase in the extracellular matrix, particularly collagen deposition. Recent studies have demonstrated that vascular remodeling and endothelial dysfunction of small and large vessels may be normalized by treatment with some antihypertensive agents (angiotensin converting enzyme inhibitors, angiotensin AT(1) receptor antagonists, and long-acting calcium channel blockers). Angiotensin converting enzyme inhibitors have now been shown to improve outcomes in hypertensive patients, an effect that may in part be related to the vascular protective effects reviewed here.