Relation of vascular stiffness with epicardial and pericardial adipose tissues, and coronary atherosclerosis

Determinants of Arterial Stiffness in Patients with Morbid Obesity. The Role of Echocardiography and Carotid Ultrasound Imaging

Background and objective: Morbid obesity is accompanied by an increased cardiovascular (CV) risk, which justifies a multidisciplinary, integrative approach. Arterial stiffness has a well-defined additional role in refining individual CV risk. Given that echocardiography and carotid ultrasound are usual methods for CV risk characterization, we aimed to identify the imaging parameters with a predictive value for early-onset arterial stiffness. Material and methods: We conducted a study in which 50 patients (divided into two equal groups with morbid obesity and without obesity), age and gender matched, untreated for cardiovascular risk factors, were addressed to bariatric surgery or non-inflammatory benign pathology surgery. Before the surgical procedures, we evaluated demographics, anthropometric data and biochemical parameters including adipokines (chemerin, adiponectin). Arterial stiffness was evaluated using the Medexpert ArteriographTM TL2 device. Transthoracic echocardiography and carotid ultrasound were also performed. We also analyzed adipocyte size and vascular wall thickness in intraoperative biopsies. Results: Left ventricle (LV) mass index (p = 0.2851), LV ejection fraction (LVEF) (p = 0.0073), epicardial adipose tissue thickness (p = 0.0001) as echocardiographic parameters and carotid intima–media thickness (p = 0.0033), relative wall thickness (p = 0.0295), wall to lumen thickness ratio (p = 0.0930) and carotid cross-sectional area (p = 0.0042) as ultrasound parameters were significant measures in our groups and were assessed in relation to adipocyte size, blood vessel wall thickness and adipokines serum levels. Statistical analysis revealed directly proportional relationships between LV mass index (p = 0.008), carotid systolic thickness of the media (p = 0.009), diastolic thickness of the media (p = 0.007), cross-sectional area (p = 0.001) and blood vessel wall thickness. Carotid relative wall thickness positively correlates with adipocyte size (p = 0.023). In patients with morbid obesity, chemerin and adiponectin/chemerin ratio positively correlates with carotid intima–media thickness (p = 0.050), systolic thickness of the media (p = 0.015) and diastolic thickness of the media (p = 0.001). The multiple linear regression models revealed the role of epicardial adipose tissue thickness and carotid cross-sectional area in predicting adipocyte size which in turn is an independent factor for arterial stiffness parameters such as pulse wave velocity, subendocardial viability ratio and aortic augmentation index. Conclusions: Our results suggest that epicardial adipose tissue thickness, carotid intima–media thickness, relative wall thickness and carotid cross-sectional area might be useful imaging parameters for early prediction of arterial stiffness in patients with morbid obesity.

EAT Thickness as a Predominant Feature for Evaluating Arterial Stiffness in Patients with Heart Failure with Preserved Ejection Fraction

OBJECTIVE

Heart failure with preserved ejection fraction (HFpEF) is an intricacy heterogeneous syndrome. However, the association between EAT and arterial stiffness in HFpEF patients remains unknown.

METHODS

A total of 102 patients were enrolled into the study, and brachial-ankle pulse-wave velocity (baPWV), epicardial adipose tissue (EAT) and body composition were assessed. Linear regression analysis was carried out to model the relationship between variables (especially EAT thickness) and baPWV.

RESULTS

The results showed that patients with the thicker EAT fat pad (≥3.55 mm) tended to have comorbidities of hypertension, coronary artery disease (CAD), diabetes and hyperlipidemia, also with a higher level of obesity, fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), total cholesterol (TC) and triglyceride (TG). The level of baPWV was higher in EAT ≥3.55 mm group than the other group. BaPWV was positively associated with EAT, age, heart rate, waist circumference, visceral fat area, systolic and diastolic blood pressure, CRP and FBG. After adjusting for EAT, age and visceral fat area, EAT thickness (β = 0.256, P = 0.009) and visceral fat area (β = 0.229, P = 0.036) significantly associated with baPWV.

CONCLUSION

The study assessed for the first time that the increased EAT thickness was closely related with baPWV in HFpEF patients, suggesting patients with the thicker EAT may be independently associated with arterial stiffness under the context of HFpEF.

The relationship between global cardiac and regional left atrial sympathetic innervation and epicardial fat in patients with atrial fibrillation

AIM

To investigate the relationship between epicardial adipose tissue (EAT) volume and distribution and the parameters of global cardiac and regional left atrial (LA) sympathetic activity in patients with atrial fibrillation (AF).

METHODS AND RESULTS

The data of the 45 consecutive patients scheduled for an index catheter ablation (CA) for AF were analyzed. Total and peri-atrial EAT volumes were measured by cardiac CT. Parameters of global cardiac sympathetic activity and discrete sympathetic regions around LA were assessed by 123I-mIBG SPECT/CT. The patients were followed up for AF recurrences assessment during 12 months after CA. A total of 133 (mean per patient 2.96 ± 1.07) discrete 123I-mIBG uptake areas (DUAs), corresponding to typical anatomical locations of LA ganglionated plexi (GP), were identified. Peri-atrial EAT volume was associated with the number of DUAs (regression estimate, 5.1 [95% CI, 0.3-9.9], p = 0.03). There was no statistically significant association between either total or peri-atrial EAT volumes and risks of AF recurrence. The washout rate (WR) was associated with reduced risk of AF recurrence (HR = 0.95; 95% CI 0.92-0.99; p = 0.01), while left ventricular (LV) myocardium 123I-mIBG summed defect score (SDS) was linked to increased hazards of AF recurrence (HR = 1.04; 95% CI 1.01-1.08; p = 0.03).

CONCLUSION

Peri-atrial EAT volume is associated with regions of sympathetic activity corresponding to typical anatomical locations of LA GP. The WR was associated with reduced risk of AF recurrence while LV myocardial SDS was linked to increased hazards of AF recurrence.

Pericardial adipose tissue is an independent risk factor of coronary artery disease and is associated with risk factors of coronary artery disease

Objective

Pericardial adipose tissue volume (PATV) is related to the mechanism of coronary artery disease (CAD), but its association with CAD risk factors is not clear. This study aimed to investigate the relationships between PATV and its associated factors.

Methods

A total of 682 inpatients were consecutively enrolled in this study. Patients were divided into the high PATV group (PATV ≥174.5 cm³; n = 506) and low PATV group (PATV  < 174.5 cm³; n = 176). Multiple linear regression analysis was conducted to evaluate the related factors of PATV. Multivariable logistic regression was used to analyze the risk factors of CAD.

Results

Left ventricular fat volume, right ventricular fat volume, body mass index, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were significant and independent risk factors of enlargement of PATV. Increased PATV was identified as an independent risk factor of CAD, and increased pulse pressure was also independently and positively correlated with CAD.

Conclusions

PATV is significantly correlated with the classic risk factors of CAD. Pulse pressure is also correlated with PATV. PATV is an independent risk factor of CAD, and pericardial adipose tissue may alternatively be used in non-invasive diagnostic examination of CAD.

Fast fully automatic heart fat segmentation in computed tomography datasets

Heart diseases affect a large part of the world's population. Studies have shown that these diseases are related to cardiac fat. Various medical diagnostic aid systems are developed to reduce these diseases. In this context, this paper presents a new approach to the segmentation of cardiac fat from Computed Tomography (CT) images. The study employs a clustering algorithm called Floor of Log (FoL). The advantage of this method is the significant drop in segmentation time. Support Vector Machine was used to learn the best FoL algorithm parameter as well as mathematical morphology techniques for noise removal. The time to segment cardiac fat on a CT is only 2.01 s on average. In contrast, literature works require more than one hour to perform segmentation. Therefore, this job is one of the fastest to segment an exam completely. The value of the Accuracy metric was 93.45% and Specificity of 95.52%. The proposed approach is automatic and requires less computational effort. With these results, the use of this approach for the segmentation of cardiac fat proves to be efficient, besides having good application times. Therefore, it has the potential to be a medical diagnostic aid tool. Consequently, it is possible to help experts achieve faster and more accurate results.

Higher lactate production from glucose in cultured adipose nucleated stromal cells than for rat adipocytes

White adipose tissue (WAT) nucleated stromal cells (NSC) play important roles in regulation, defense, regeneration and metabolic control. In WAT sites, the proportions and functions of NSC change under diverse physiological or pathologic conditions. We had previously observed the massive anaerobic wasting of glucose to lactate and glycerol in rat epididymal adipocytes. To test site variability, and whether the adipocyte extensive anaerobic metabolism of glucose was found in NSC, we analyzed, in parallel, subcutaneous, mesenteric and epididymal WAT of male adult Wistar rats. Adipocytes and NSC fractions, were isolated, counted and incubated (as well as red blood cells: RBC) with glucose, and their ability to use glucose and produce lactate, glycerol, and free fatty acids was measured. Results were computed taking into account the number of cells present in WAT samples. Cell numbers were found in proportions close to 1:13:100 (respectively, for adipocytes, NSC and RBC) but their volumes followed a reversed pattern: 7,500:10:1. When counting only non-fat cell volumes, the ratios changed dramatically to 100:10:1. RBC contribution to lactate production was practically insignificant. In most samples, NSC produced more lactate than adipocytes did, but only adipocytes secreted glycerol (and fatty acids in smaller amounts). Glucose consumption was also highest in NSC, especially in mesenteric WAT. The heterogeneous NSC showed a practically anaerobic metabolism (like that already observed in adipocytes). Thus, NSC quantitative production of lactate markedly contributed (i.e. more than adipocytes) to WAT global use (wasting) of glucose. We also confirmed that glucose-derived glycerol is exclusively produced by adipocytes.

Epicardial adipose tissue is related to arterial stiffness and inflammation in patients with cardiovascular disease and type 2 diabetes

Background

Epicardial adipose tissue (EAT) is an emerging cardio-metabolic risk factor and has been shown to correlate with adverse cardiovascular (CV) outcome; however the underlying pathophysiology of this link is not well understood. The aim of this study was to evaluate the relationship between EAT and a comprehensive panel of cardiovascular risk biomarkers and pulse wave velocity (PWV) and indexed left ventricular mass (LVMI) in a cohort of patients with cardiovascular disease (CVD) and diabetes compared to controls.

Methods

One hundred forty-five participants (mean age 63.9 ± 8.1 years; 61% male) were evaluated. All patients underwent cardiovascular magnetic resonance (CMR) examination and PWV. EAT measurements from CMR were performed on the 4-chamber view. Blood samples were taken and a range of CV biomarkers was evaluated.

Results

EAT measurements were significantly higher in the groups with CVD, with or without T2DM compared to patients without CVD or T2DM (group 1 EAT 15.9 ± 5.5 cm² vs. group 4 EAT 11.8 ± 4.1 cm², p = 0.001; group 3 EAT 15.1 ± 4.3 cm² vs. group 4 EAT 11.8 ± 4.1 cm², p = 0.024). EAT was independently associated with IL-6 (beta 0.2, p = 0.019). When added to clinical variables, both EAT (beta 0.16, p = 0.035) and IL-6 (beta 0.26, p = 0.003) were independently associated with PWV. EAT was significantly associated with LVMI in a univariable analysis but not when added to significant clinical variables.

Conclusions

In patients with cardio-metabolic disease, EAT was independently associated with PWV. EAT may be associated with CVD risk due to an increase in systemic vascular inflammation. Whether targeting EAT may reduce inflammation and/or cardiovascular risk should be evaluated in prospective studies.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0770-z) contains supplementary material, which is available to authorized users.

Epicardial adipose tissue volume estimation by postmortem computed tomography of eviscerated hearts

Epicardial adipose tissue (EAT) may play a role in the development of coronary artery disease. The purpose of this study was to evaluate a method based on postmortem computed tomography (PMCT) for the estimation of EAT volume. We PMCT-scanned the eviscerated hearts of 144 deceased individuals, who underwent a medicolegal autopsy. Using Mimics® we performed segmentation of the images and obtained the volumes of EAT and myocardium. Total heart volume was calculated by adding the volumes of EAT and myocardium. Total heart weight, including EAT, myocardium and attached vessels, was measured during autopsy. Inter-observer analysis was performed on 30 randomly chosen subjects. We included 132 individuals in the results (age range: 22-94 years; 56% men). Twelve individuals were excluded due to inadequate PMCT scanning. Median EAT volume was 73.0 mL (Interquartile range; IQR: 45.6-113.7 mL) in men and 64.8 mL (IQR: 44.0-98.0 mL) in women, which accounted for 20.4 ± 10.2% and 21.9 ± 9.5% of total heart volume, respectively. This corresponded with former autopsy studies. Total heart volume measured by PMCT was highly correlated with heart weight (R² = 90%). Mean inter-observer difference of EAT volume was -1.7 mL (95% limits of agreement: -37.0-33.6 mL), with an Intra Class Correlation of 0.91. It was possible to estimate EAT volume using PMCT on eviscerated human hearts. Our method was fast and accurate with good inter-observer agreement. This is a useful method to determine EAT at autopsy, and we will apply this method in future research.

Semiautomatic Epicardial Fat Segmentation Based on Fuzzy c-Means Clustering and Geometric Ellipse Fitting

Automatic segmentation of particular heart parts plays an important role in recognition tasks, which is utilized for diagnosis and treatment. One particularly important application is segmentation of epicardial fat (surrounds the heart), which is shown by various studies to indicate risk level for developing various cardiovascular diseases as well as to predict progression of certain diseases. Quantification of epicardial fat from CT images requires advance image segmentation methods. The problem of the state-of-the-art methods for epicardial fat segmentation is their high dependency on user interaction, resulting in low reproducibility of studies and time-consuming analysis. We propose in this paper a novel semiautomatic approach for segmentation and quantification of epicardial fat from 3D CT images. Our method is a semisupervised slice-by-slice segmentation approach based on local adaptive morphology and fuzzy c-means clustering. Additionally, we use a geometric ellipse prior to filter out undesired parts of the target cluster. The validation of the proposed methodology shows good correspondence between the segmentation results and the manual segmentation performed by physicians.

Automated recognition of the pericardium contour on processed CT images using genetic algorithms

This work proposes the use of Genetic Algorithms (GA) in tracing and recognizing the pericardium contour of the human heart using Computed Tomography (CT) images. We assume that each slice of the pericardium can be modelled by an ellipse, the parameters of which need to be optimally determined. An optimal ellipse would be one that closely follows the pericardium contour and, consequently, separates appropriately the epicardial and mediastinal fats of the human heart. Tracing and automatically identifying the pericardium contour aids in medical diagnosis. Usually, this process is done manually or not done at all due to the effort required. Besides, detecting the pericardium may improve previously proposed automated methodologies that separate the two types of fat associated to the human heart. Quantification of these fats provides important health risk marker information, as they are associated with the development of certain cardiovascular pathologies. Finally, we conclude that GA offers satisfiable solutions in a feasible amount of processing time.

Machine learning in the prediction of cardiac epicardial and mediastinal fat volumes

We propose a methodology to predict the cardiac epicardial and mediastinal fat volumes in computed tomography images using regression algorithms. The obtained results indicate that it is feasible to predict these fats with a high degree of correlation, thus alleviating the requirement for manual or automatic segmentation of both fat volumes. Instead, segmenting just one of them suffices, while the volume of the other may be predicted fairly precisely. The correlation coefficient obtained by the Rotation Forest algorithm using MLP Regressor for predicting the mediastinal fat based on the epicardial fat was 0.9876, with a relative absolute error of 14.4% and a root relative squared error of 15.7%. The best correlation coefficient obtained in the prediction of the epicardial fat based on the mediastinal was 0.9683 with a relative absolute error of 19.6% and a relative squared error of 24.9%. Moreover, we analysed the feasibility of using linear regressors, which provide an intuitive interpretation of the underlying approximations. In this case, the obtained correlation coefficient was 0.9534 for predicting the mediastinal fat based on the epicardial, with a relative absolute error of 31.6% and a root relative squared error of 30.1%. On the prediction of the epicardial fat based on the mediastinal fat, the correlation coefficient was 0.8531, with a relative absolute error of 50.43% and a root relative squared error of 52.06%. In summary, it is possible to speed up general medical analyses and some segmentation and quantification methods that are currently employed in the state-of-the-art by using this prediction approach, which consequently reduces costs and therefore enables preventive treatments that may lead to a reduction of health problems.

The therapeutic effect of rosuvastatin and propylthiouracil on ameliorating high-cholesterol diet-induced rabbit aortic atherosclerosis and stiffness

BACKGROUND

We tested the hypothesis that arteriosclerosis-augmented aortic pulse wave velocity (PWV) and -impaired vasorelaxation were attenuated by rosuvastatin (Rosu) and propylthiouracil (PTU) therapy.

METHODS AND RESULTS

Thirty-two New Zealand rabbits were equally divided into group 1 (sham-control), group 2 [high-cholesterol-diet (HCD) for 8weeks], group 3 [HCD-Rosu (20mg/kg/day administration after 4-week HFD for 4weeks)], and group 4 [HCD-PTU (0.1% PTU in drinking water), the treatment course as group 3]. KCl-induced vasoconstriction of carotid artery (CA) was significantly higher in group 2 than in other groups (all p<0.01), but showed no differences among groups 1, 3 and 4, whereas acetylcholine-induced vasorelaxation exhibited an opposite pattern of KCl-induced vasoconstriction among the four groups (p<0.001). Basic nitric-oxide release from endothelial cells of CA was highest in group 1, lowest in group 2, but showed no difference between groups 3 and 4 (all p<0.001). PWV value was highest in group 2, lowest in group 1, and significantly higher in group 4 than in group 3 (all p<0.001). Serum levels of total-cholesterol, LDL and TG showed an identical pattern to PWV (all p<0.001), whereas the levels of free T4, sugar, and body weight did not differ among the four groups (all p>0.4). Aortic inflammatory biomarkers in cellular (CD68+/IL-1β+/CD14+) and protein (TNF-α/NF-κB/IL-1β/MMP-9/MCP-1/ICAM-1/PDGF) levels, and aortic oxidative-stress biomarkers in cellular (8-OHdG) and protein (NOX-1/NOX-2/oxidized protein) levels showed an identical pattern to PWV among the four groups (all p<0.001).

CONCLUSION

Rosu-PTU therapy ameliorated aortic stiffness and inflammation/oxidative-stress, and improved endothelial-cell function after HCD challenge in rabbit.

Effects of habitual aerobic exercise on the relationship between intramyocellular or extramyocellular lipid content and arterial stiffness

The accumulation of intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) is associated with arterial stiffness in middle-aged and older adults. Habitual aerobic exercise induces the improvement of arterial stiffness with reduction in fat accumulation. However, the relationship between aerobic exercise-induced changes in muscular lipids and arterial stiffness remains unclear. The purpose of this study was to investigate whether habitual aerobic exercise-induced changes in IMCL and EMCL content would lead to an improvement of arterial stiffness. First, in a cross-sectional study, we investigated whether cardiorespiratory fitness level affects the association between IMCL or EMCL content and arterial stiffness in 60 middle-aged and older subjects (61.0±1.3 years). Second, in an intervention study, we examined whether aerobic exercise training-induced changes in IMCL and EMCL content are associated with a reduction in arterial stiffness in 18 middle-aged and older subjects (67.0±1.7 years). In the cross-sectional study, IMCL content was negatively correlated with brachial-ankle pulse wave velocity (baPWV) (r=-0.47, P<0.05), whereas EMCL content was positively correlated with baPWV (r=0.48, P<0.05) in the low-fitness group, but was not correlated in the high-fitness group. Furthermore, 8-week aerobic exercise training in older adults increased IMCL content and reduced EMCL content. The training-induced change in baPWV was negatively correlated with training-induced changes in IMCL but was positively correlated with training-induced changes in EMCL. These findings suggest that aerobic exercise training-induced changes in IMCL and EMCL content may be related to a reduction in arterial stiffness in middle-aged and older adults.

Arterial stiffness and coronary artery disease

PURPOSE OF REVIEW

The current traditional risk scores are not sufficient to predict the full incidence of cardiovascular disease. In this brief review, we discuss the pathophysiological mechanisms through which arterial stiffness affects cardiac function and the additive value of markers of arterial stiffness, to detect the presence of coronary artery disease (CAD) and predict adverse outcome in these patients.

RECENT FINDINGS

Arterial stiffness causes early arrival of wave reflections in systole instead of diastole and, thus, increases systolic afterload and reduces diastolic coronary perfusion pressure. Abnormal collagen turnover, cytokines, and metalloproteinase activity are common biochemical links between vascular and myocardial stiffness. Pulse wave velocity, augmentation index, and central pressures measured by simple noninvasive methods are related to atheromatic plaque vulnerability, incidence, severity, and extent of CAD. Recent meta-analyses have shown the additive value of markers of arterial stiffness, and particularly of pulse wave velocity, to detect CAD, predict cardiovascular events, and reclassify patients to a higher cardiovascular risk. Studies assessing whether reduction of arterial stiffness is associated with improved prognosis are lacking.

SUMMARY

Markers of arterial stiffness are useful tools to identify early atherosclerosis and adverse clinical outcomes in young adults and individuals with a modest risk factor profile. Assessing arterial stiffness may facilitate cardiovascular risk stratification beyond traditional risk scores.

A novel approach for the automated segmentation and volume quantification of cardiac fats on computed tomography

The deposits of fat on the surroundings of the heart are correlated to several health risk factors such as atherosclerosis, carotid stiffness, coronary artery calcification, atrial fibrillation and many others. These deposits vary unrelated to obesity, which reinforces its direct segmentation for further quantification. However, manual segmentation of these fats has not been widely deployed in clinical practice due to the required human workload and consequential high cost of physicians and technicians. In this work, we propose a unified method for an autonomous segmentation and quantification of two types of cardiac fats. The segmented fats are termed epicardial and mediastinal, and stand apart from each other by the pericardium. Much effort was devoted to achieve minimal user intervention. The proposed methodology mainly comprises registration and classification algorithms to perform the desired segmentation. We compare the performance of several classification algorithms on this task, including neural networks, probabilistic models and decision tree algorithms. Experimental results of the proposed methodology have shown that the mean accuracy regarding both epicardial and mediastinal fats is 98.5% (99.5% if the features are normalized), with a mean true positive rate of 98.0%. In average, the Dice similarity index was equal to 97.6%.

Intramyocellular and Extramyocellular Lipids Are Associated With Arterial Stiffness

BACKGROUND

Obese and overweight patients are at increased risk of arterial stiffness, and visceral, epicardial and hepatic fat accumulation is associated with cardiovascular disease risk. In general, muscular lipids are stored either in interstitial adipose tissue (extramyocellular lipid (EMCL)) or in lipid droplets within muscle cells (intramyocellular lipid (IMCL)). However, the association between IMCL or EMCL content and arterial stiffness remains unclear. This cross-sectional study aimed to clarify this association.

METHODS

A total of 237 subjects (18-81 years) were enrolled in this study. The IMCL and EMCL contents of the right vastus lateralis muscle were evaluated by proton magnetic resonance spectroscopy. Arterial stiffness was estimated using brachial-ankle pulse wave velocity (baPWV).

RESULTS

There were significant correlations between baPWV and the contents of both IMCL (R = -0.23, P < 0.001) and EMCL (R = 0.53, P < 0.001) in all subjects. The baPWV negatively correlated with IMCL content (R = -0.45, P < 0.001) in females only. In contrast, significant positive correlations were observed between baPWV and EMCL content in both males (R = 0.59, P < 0.001) and females (R = 0.55, P < 0.001). IMCL and EMCL contents contributed independently to baPWV variation after adjustment for age, sex, body mass index, visceral and subcutaneous abdominal fat, upper and lower limb fat, blood pressure, heart rate, and lipid profiles.

CONCLUSION

These results suggest that IMCL and EMCL contents may be a risk factor for arterial stiffness, and this association differed with gender and age.

Prognostic value of epicardial fat volume measurements by computed tomography: a systematic review of the literature

OBJECTIVES

To perform a systematic review of the growing body of literature evaluating the prognostic value of epicardial fat volume (EFV) quantified by cross-sectional imaging.

METHODS

Two independent reviewers performed systematic searches on both PubMed and Scopus using search terms developed with a medical librarian. Peer-reviewed articles were selected based on the inclusion of outcome data, utilization of epicardial fat volume and sufficient reporting for analysis.

RESULTS

A total of 411 studies were evaluated with nine studies meeting the inclusion criteria. In all, the studies evaluated 10,252 patients. All nine studies were based on CT measurements. Seven studies evaluated the prognostic value of EFV unadjusted for calcium score, and six of these studies found a significant association between EFV and clinical outcomes. Seven studies evaluated the incremental value of EFV beyond calcium scoring, and six of these studies found a significant association.

CONCLUSIONS

The majority of studies suggest that EFV quantification is significantly associated with clinical outcomes and provides incremental prognostic value over coronary artery calcium scoring. Future research should use a binary cutoff of 125 mL for evaluation of EFV to provide consistency with other research.

KEY POINTS

• Epicardial fat volume (EFV) has prognostic value for adverse cardiac events • Establishment of standardized quantitative categories for EFV is needed • Quantification of EFV could improve risk assessment with calcium scoring.

Increased epicardial adipose tissue thickness is linked to aortic stiffness in patients with primary hypertension

AIMS

In patients with hypertension (HT), increased aortic stiffness is related to higher cardiovascular morbidity and mortality. Recent investigations have shown that epicardial adipose tissue (EAT) is a new potential cardiometabolic risk factor. The aim of our study was to examine the relation between echocardiographically measured EAT thickness and aortic stiffness in patients with primary HT.

METHODS

The study included 144 newly diagnosed and untreated essential hypertensive outpatients. Transthoracic echocardiographic EAT thickness and aortic stiffness measurements were performed for all study participants. Afterwards patients were divided in two groups according to their median EAT thickness values. The patients with EAT thickness of < 7 mm were included in group 1 and patients with EAT thickness of ≥ 7 mm were included in group 2.

RESULTS

Aortic strain and distensibility parameters of group 2 were lower than in group 1. The aortic stiffness index of group 2 was found to be higher than group 1. Multivariate regression analysis revealed that EAT thickness was the only independent variable for all three parameters of aortic stiffness index, aortic strain and aortic distensibility.

CONCLUSION

In patients with newly diagnosed primary HT, increased EAT thickness was significantly linked to impaired aortic elastic properties independently of other conventional adiposity measurements.

Regulation of tissue fibrosis by the biomechanical environment

The biomechanical environment plays a fundamental role in embryonic development, tissue maintenance, and pathogenesis. Mechanical forces play particularly important roles in the regulation of connective tissues including not only bone and cartilage but also the interstitial tissues of most organs. In vivo studies have correlated changes in mechanical load to modulation of the extracellular matrix and have indicated that increased mechanical force contributes to the enhanced expression and deposition of extracellular matrix components or fibrosis. Pathological fibrosis contributes to dysfunction of many organ systems. A variety of in vitro models have been utilized to evaluate the effects of mechanical force on extracellular matrix-producing cells. In general, application of mechanical stretch, fluid flow, and compression results in increased expression of extracellular matrix components. More recent studies have indicated that tissue rigidity also provides profibrotic signals to cells. The mechanisms whereby cells detect mechanical signals and transduce them into biochemical responses have received considerable attention. Cell surface receptors for extracellular matrix components and intracellular signaling pathways are instrumental in the mechanotransduction process. Understanding how mechanical signals are transmitted from the microenvironment will identify novel therapeutic targets for fibrosis and other pathological conditions.