Human epicardial fat: what is new and what is missing?

The Unrestrained Overeating Behavior and Clinical Perspective

Obesity-related co-morbidities decrease life quality, reduce working ability, and lead to early death. In the adult population, eating addiction manifests with excessive food consumption and the unrestrained overeating behavior, which is associated with increased risk of morbidity and mortality and defined as the binge eating disorder (BED). This hedonic intake is correlated with fat preference and the total amount of dietary fat consumption is the most potent risk factor for weight gain. Long-term BED leads to greater sensitivity to the rewarding effects of palatable foods and results in obesity fatefully. Increased plasma concentrations of non-esterified free fatty acids and lipid-overloaded hypertrophic adipocytes may cause insulin resistance. In addition to dietary intake of high-fat diet, sedentary lifestyle leads to increased storage of triglycerides not only in adipose tissue but also ectopically in other tissues. Lipid-induced apoptosis, ceramide accumulation, reactive oxygen species overproduction, endoplasmic reticulum stress, and mitochondrial dysfunction play role in the pathogenesis of lipotoxicity. Food addiction and BED originate from complex action of dopaminergic, opioid, and cannabinoid systems. BED may also be associated with both obesity and major depressive disorder. For preventing morbidity and mortality, as well as decreasing the impact of obesity-related comorbidities in appropriately selected patients, opiate receptor antagonists and antidepressant combination are recommended. Pharmacotherapy alongside behavioral management improves quality of life and reduces the obesity risk; however, the number of licensed drugs is very few. Thus, stereotactic treatment is recommended to break down the refractory obesity and binge eating in obese patient. As recent applications in the field of non-invasive neuromodulation, transcranial magnetic stimulation and transcranial direct current stimulation are thought to be important in image-guided deep brain stimulation in humans. Chronic overnutrition most likely provides repetitive and persistent signals that up-regulate inhibitor of nuclear factor kappa B (NF-κB) kinase beta subunit/NF-κB (IKKβ/NF-κB) in the hypothalamus before the onset of obesity. However, how the mechanisms of high-fat diet-induced peripheral signals affect the hypothalamic arcuate nucleus remain largely unknown.

Epicardial adipose tissue and cardiac lipotoxicity: A review

Epicardial adipose tissue (EAT) has morphological and physiological contiguity with the myocardium and coronary arteries, making it a visceral fat deposit with some unique properties. Under normal circumstances, EAT exhibits biochemical, mechanical, and thermogenic cardioprotective characteristics. Under clinical processes, epicardial fat can directly impact the heart and coronary arteries by secreting proinflammatory cytokines via vasocrine or paracrine mechanisms. It is still not apparent what factors affect this equilibrium. Returning epicardial fat to its physiological purpose may be possible by enhanced local vascularization, weight loss, and focused pharmacological therapies. This review centers on EAT's developing physiological and pathophysiological dimensions and its various and pioneering clinical utilities.

Cardiac System during the Aging Process

The aging process is accompanied by a continuous decline of the cardiac system, disrupting the homeostatic regulation of cells, organs, and systems. Aging increases the prevalence of cardiovascular diseases, thus heart failure and mortality. Understanding the cardiac aging process is of pivotal importance once it allows us to design strategies to prevent age-related cardiac events and increasing the quality of live in the elderly. In this review we provide an overview of the cardiac aging process focus on the following topics: cardiac structural and functional modifications; cellular mechanisms of cardiac dysfunction in the aging; genetics and epigenetics in the development of cardiac diseases; and aging heart and response to the exercise.

Sodium-glucose co-transporter-2 inhibitors and epicardial adiposity

Epicardial adipose tissue is a layer of adipocytes that physiologically surround the myocardium and play some physiologic roles in normal heart function. However, in pathologic conditions, the epicardial adipose tissue can present a potent cardiac risk factor that is capable of impairing heart function through several pathways, increasing the risk of dysrhythmia and creating an inflammatory milieu around the heart tissues. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) are a relatively newly introduced class of antidiabetes drugs which effectively normalize blood glucose via overt glycosuria. Some recent reports suggest that these drugs are able to modulate epicardial adiposity and decrease the risk of cardiac complications in diabetic patients who are at higher risk of epicardial adiposity-dependent cardiac disorders. If proven to be true, these antidiabetic drugs can provide dual benefits as both hypoglycemic agents and as epicardial adiposity normalizing agents, thus providing cardiac benefits. In this study, we discuss the physiological and pathophysiological importance of epicardial adiposity and the potential positive effects of SGLT2is in the diabetic milieu.

Benefits of GLP-1 Mimetics on Epicardial Adiposity

The epicardial adipose tissue, which is referred to as fats surrounding the myocardium, is an active organ able to induce cardiovascular problems in pathophysiologic conditions through several pathways, such as inflammation, fibrosis, fat infiltration, and electrophysiologic problems. So, control of its volume and thickness, especially in patients with diabetes, is highly important. Incretin-based pharmacologic agents are newly developed antidiabetics that could provide further cardiovascular benefits through control and modulating epicardial adiposity. They can reduce cardiovascular risks by rapidly reducing epicardial adipose tissues, improving cardiac efficiency. We are at the first steps of a long way, but current evidence demonstrates the sum of possible mechanisms. In this study, we evaluate epicardial adiposity in physiologic and pathologic states and the impact of incretin-based drugs.

Adverse association of epicardial adipose tissue accumulation with cardiac function and atrioventricular coupling in postmenopausal women assessed by cardiac magnetic resonance imaging

Background

This study aims to investigate the association of epicardial adipose tissue (EAT) accumulation with cardiac function and atrioventricular coupling in a cohort of postmenopausal women assessed by cardiac magnetic resonance imaging (CMR).

Materials and methods

Overall, 283 postmenopausal women (mean age 61.5 ± 9.1 years) who underwent CMR examination were enrolled. Participants were classified into four groups by the quartile of EAT volume. EAT volume was quantified on short-axis cine stacks covering the entire epicardium. CMR-derived cardiac structure and function, including left atrial (LA)- volume, emptying fraction, deformation, and left ventricular (LV)- mass, volume, ejection fraction, and deformation, were compared among the four groups of graded EAT volume.

Results

Left ventricular mass (LVM) and LV remodeling index were both increased in the group with the highest EAT volume, compared to those in the lowest quartile (p = 0.016 and p = 0.003). The LV global longitudinal strain (LV-GLS), circumferential strain (LV-GCS), and LA- reservoir strain (LA-RS), conduit strain (LA-CS), and booster strain (LA-BS), were all progressively decreased from the lowest quartile of EAT volume to the highest (all p < 0.05). Multivariable linear regression analyses showed that EAT was independently associated with LV-GLS, LA-RS, LA-CS, and LA-BS after adjusting for body mass index and other clinical factors.

Conclusion

Epicardial adipose tissue accumulation is independently associated with subclinical LV and LA function in postmenopausal women. These associations support the role of EAT in mediating deleterious effects on cardiac structure and function.

Cellular cross talk between epicardial fat and cardiovascular risk

A variety of fat compartments have several local and systemic effect and play a crucial role in the maintenance of health and development of disease. For the past few years, special attention has been paid to epicardial fat. It is the visceral fat compartment of the heart and has several local and systemic effects. It can perform a role in the development of cardiometabolic risk. The epicardial adipose tissue (EAT) is a unique and multifunctional fat compartment of the heart. It is located between the myocardium and the visceral pericardium. During normal physiological conditions, the EAT has metabolic, thermogenic, and mechanical (cardioprotective) characteristics. The EAT can produce several adipocytokines and chemokines depending on microenvironments. It can influence through paracrine and vasocrine mechanism and participate in the development and progression of cardiovascular (CVS) diseases. In addition, metabolic disease leads to changes in both thickness and volume of the EAT, and it can modify the structure and the function of heart. It has been associated with various CVS diseases such as, cardiomyopathy, atrial fibrillation, and coronary artery disease. Therefore, EAT is a potential therapeutic target for CVS risk.

Conductance Artery Wall Layers and Their Respective Roles in the Clearance Functions

Evolutionary organization of the arterial wall into layers occurred concomitantly with the emergence of a highly muscularized, pressurized arterial system that facilitates outward hydraulic conductance and mass transport of soluble substances across the arterial wall. Although colliding circulating cells disperse potential energy within the arterial wall, the different layers counteract this effect: (1) the endothelium ensures a partial barrier function; (2) the media comprises smooth muscle cells capable of endocytosis/phagocytosis; (3) the outer adventitia and perivascular adipocytic tissue are the final receptacles of convected substances. While the endothelium forms a physical and a biochemical barrier, the medial layer is avascular, relying on the specific permeability properties of the endothelium for metabolic support. Different components of the media interact with convected molecules: medial smooth muscle cells take up numerous molecules via scavenger receptors and are capable of phagocytosis of macro/micro particles. The outer layers-the highly microvascularized innervated adventitia and perivascular adipose tissue-are also involved in the clearance functions of the media: the adventitia is the seat of immune response development, inward angiogenesis, macromolecular lymphatic drainage, and neuronal stimulation. Consequently, the clearance functions of the arterial wall are physiologically essential, but also may favor the development of arterial wall pathologies. This review describes how the walls of large conductance arteries have acquired physiological clearance functions, how this is determined by the attributes of the endothelial barrier, governed by endocytic and phagocytic capacities of smooth muscle cells, impacting adventitial functions, and the role of these clearance functions in arterial wall diseases.

The Role of Epicardial Adipose Tissue in the Development of Atrial Fibrillation, Coronary Artery Disease and Chronic Heart Failure in the Context of Obesity and Type 2 Diabetes Mellitus: A Narrative Review

Cardiovascular diseases (CVDs) are a significant burden globally and are especially prevalent in obese and/or diabetic populations. Epicardial adipose tissue (EAT) surrounding the heart has been implicated in the development of CVDs as EAT can shift from a protective to a maladaptive phenotype in diseased states. In diabetic and obese patients, an elevated EAT mass both secretes pro-fibrotic/pro-inflammatory adipokines and forms intramyocardial fibrofatty infiltrates. This narrative review considers the proposed pathophysiological roles of EAT in CVDs. Diabetes is associated with a disordered energy utilization in the heart, which promotes intramyocardial fat and structural remodeling. Fibrofatty infiltrates are associated with abnormal cardiomyocyte calcium handling and repolarization, increasing the probability of afterdepolarizations. The inflammatory phenotype also promotes lateralization of connexin (Cx) proteins, undermining unidirectional conduction. These changes are associated with conduction heterogeneity, together creating a substrate for atrial fibrillation (AF). EAT is also strongly implicated in coronary artery disease (CAD); inflammatory adipokines from peri-vascular fat can modulate intra-luminal homeostasis through an “outside-to-inside” mechanism. EAT is also a significant source of sympathetic neurotransmitters, which promote progressive diastolic dysfunction with eventual cardiac failure. Further investigations on the behavior of EAT in diabetic/obese patients with CVD could help elucidate the pathogenesis and uncover potential therapeutic targets.

Epicardial adipose tissue as a mediator of cardiac arrhythmias

Obesity is associated with higher risks of cardiac arrhythmias. Although this may be partly explained by concurrent cardiometabolic ill-health, growing evidence suggests that increasing adiposity independently confers risk for arrhythmias. Among fat depots, epicardial adipose tissue (EAT) exhibits a proinflammatory secretome and, given the lack of fascial separation, has been implicated as a transducer of inflammation to the underlying myocardium. The present review explores the mechanisms underpinning adverse electrophysiological remodeling as a consequence of EAT accumulation and the consequent inflammation. We first describe the physiological and pathophysiological function of EAT and its unique secretome and subsequently discuss the evidence for ionic channel and connexin expression modulation as well as fibrotic remodeling induced by cytokines and free fatty acids that are secreted by EAT. Finally, we highlight how weight reduction and regression of EAT volume may cause reverse remodeling to ameliorate arrhythmic risk.

Physical Exercise Potentially Targets Epicardial Adipose Tissue to Reduce Cardiovascular Disease Risk in Patients with Metabolic Diseases: Oxidative Stress and Inflammation Emerge as Major Therapeutic Targets

Excess epicardial adiposity, within a state of obesity and metabolic syndrome, is emerging as an important risk factor for the development of cardiovascular diseases (CVDs). Accordingly, increased epicardial fat thickness (EFT) implicates the exacerbation of pathological mechanisms involving oxidative stress and inflammation within the heart, which may accelerate the development of CVDs. This explains increased interest in targeting EFT reduction to attenuate the detrimental effects of oxidative stress and inflammation within the setting of metabolic syndrome. Here, we critically discuss clinical and preclinical evidence on the impact of physical exercise on EFT in correlation with reduced CVD risk within a setting of metabolic disease. This review also brings a unique perspective on the implications of oxidative stress and inflammation as major pathological consequences that link increased EFT to accelerated CVD risk in conditions of metabolic disease.

Right Heart Morphology and Its Association With Excessive and Deficient Cardiac Visceral Adipose Tissue

Visceral adipose tissue is an independent risk factor for the development of atherosclerotic coronary disease, arterial hypertension, diabetes and metabolic syndrome. Right heart morphology often involves the presence of adipose tissue, which can be quantified by non-invasive imaging methods. The last decade brought a wealth of new insights into the function and morphology of adipose tissue, with great emphasis on its role in the pathogenesis of heart disease. Cardiac adipose tissue is involved in thermogenesis, mechanical protection of the heart and energy storage. However, it can also be an endocrine organ that synthesises numerous pro-inflammatory and anti-inflammatory cytokines, the effect of which is accomplished by paracrine and vasocrine mechanisms. Visceral adipose tissue has several compartments that differ in their embryological origin and vascularisation. Deficiency of cardiac adipose tissue, often due to chronic pathological conditions such as oncological diseases or chronic infectious diseases, predicts increased mortality and morbidity. To date, knowledge about the influence of visceral adipose tissue on cardiac morphology is limited, especially the effect on the morphology of the right heart in a state of excess or deficient visceral adipose tissue.

The impact of epicardial adipose tissue in patients with acute myocardial infarction

AIMS

Epicardial adipose tissue (EAT) has been linked to impaired reperfusion success after percutaneous coronary intervention (PCI). Whether EAT predicts myocardial damage in the early phase after acute myocardial infarction (MI) is unclear. Therefore, we investigated whether EAT in patients with acute MI is associated with more microvascular obstruction (MVO), greater ST-deviation, larger infarct size and reduced myocardial salvage index (MSI).

METHODS AND RESULTS

This retrospective analysis of a prospective observational study including patients with acute MI (n = 54) undergoing PCI and 12 healthy matched controls. EAT, infarct size and MSI were analyzed with cardiac magnetic resonance imaging, conducted 3-5 days and 12 weeks after MI. Patients with acute MI showed higher EAT volume than healthy controls (46 [25.;75. percentile: 37;59] vs. 24 [15;29] ml, p < 0.001). The high EAT group (above median) showed significantly more MVO (2.22 [0.00;5.38] vs. 0.0 [0.00;2.18] %, p = 0.004), greater ST-deviation (0.38 [0.22;0.55] vs. 0.15 [0.03;0.20] mV×10-1, p = 0.008), larger infarct size at 12 weeks (23 [17;29] vs. 10 [4;16] %, p < 0.001) and lower MSI (40 [37;54] vs. 66 [49;88] %, p < 0.001) after PCI than the low EAT group. After accounting for demographic characteristics, body-mass index, heart volume, infarct location, TIMI-flow grade as well as apnea-hypopnea index, EAT was associated with infarct size at 12 weeks (B = 0.38 [0.11;0.64], p = 0.006), but not with MSI.

CONCLUSIONS

Patients with acute MI showed higher volume of EAT than healthy individuals. High EAT was linked to more MVO and greater ST-deviation. EAT was associated with infarct size, but not with MSI.

Are Interactions between Epicardial Adipose Tissue, Cardiac Fibroblasts and Cardiac Myocytes Instrumental in Atrial Fibrosis and Atrial Fibrillation?

Atrial fibrillation is very common among the elderly and/or obese. While myocardial fibrosis is associated with atrial fibrillation, the exact mechanisms within atrial myocytes and surrounding non-myocytes are not fully understood. This review considers the potential roles of myocardial fibroblasts and myofibroblasts in fibrosis and modulating myocyte electrophysiology through electrotonic interactions. Coupling with (myo)fibroblasts in vitro and in silico prolonged myocyte action potential duration and caused resting depolarization; an optogenetic study has verified in vivo that fibroblasts depolarized when coupled myocytes produced action potentials. This review also introduces another non-myocyte which may modulate both myocardial (myo)fibroblasts and myocytes: epicardial adipose tissue. Epicardial adipocytes are in intimate contact with myocytes and (myo)fibroblasts and may infiltrate the myocardium. Adipocytes secrete numerous adipokines which modulate (myo)fibroblast and myocyte physiology. These adipokines are protective in healthy hearts, preventing inflammation and fibrosis. However, adipokines secreted from adipocytes may switch to pro-inflammatory and pro-fibrotic, associated with reactive oxygen species generation. Pro-fibrotic adipokines stimulate myofibroblast differentiation, causing pronounced fibrosis in the epicardial adipose tissue and the myocardium. Adipose tissue also influences myocyte electrophysiology, via the adipokines and/or through electrotonic interactions. Deeper understanding of the interactions between myocytes and non-myocytes is important to understand and manage atrial fibrillation.

Evaluation of epicardial adipose tissue and carotid intima-media thickness as a marker of atherosclerosis in patients with inflammatory bowel disease

BACKGROUND AND AIM

this study aimed to compare carotid intima media (CIMT) and epicardial adipose tissue (EAT) measurements, which are considered as markers for the detection of early atherosclerosis in healthy controls and inflammatory bowel disease (IBD) cases.

METHODS

a total of 60 IBD patients (25 Crohn's disease and 35 ulcerative colitis) and 60 healthy patients (as a control group) were included in the study. The measurements of CIMT and EAT were performed using echocardiography and ultrasonography, respectively. Statistical analysis was used to determine the relationship between the parameters.

RESULTS

the thickness of bilateral (right and left) CIMT and EAT were significantly higher in IBD than in the control group (p < 0.05). There was a positive correlation between EAT and bilateral (right and left) CIMT in IBD patients (p < 0.05).

CONCLUSION

IBD is associated with an increased thickness of EAT and CIMT. Chronic inflammation in IBD may increase the risk of atherosclerotic heart disease. Thus, only measuring the thickness of EAT and CIMT can be used as an objective, easy, simple, affordable, non-invasive and accessible assessment method in order to screen for this risk.

Cardiac Adipose Tissue Contributes to Cardiac Repair: a Review

Cardiac adipose tissue is a metabolically active adipose tissue in close proximity to heart. Recent studies emphasized the benefits of cardiac adipose tissue in heart remodeling, such as reducing infarction size, enhancing neovascularization and regulating immune response, through a series of cellular mechanisms. In the present manuscript, we provide a comprehensive review regarding the role of cardiac adipose tissue in cardiac repair. We focus on different cardiac adipose tissues according to their distinguished anatomical structures. This review summarizes the latest evidence on the relationship between cardiac adipose tissue and cardiac repair. Cardiac adipose tissues (CAT) were systematically reviewed in the current manuscript which focused on the components of CAT, debates about cardiac adipose stem cells and their effect on heart.

Increased epicardial adipose tissue thickness is associated with microalbuminuria in hypertensive patients with left ventricular hypertrophy

OBJECTIVE

Epicardial adipose tissue (EAT) is a cardiometabolic risk factor, and its possible relationship with hypertension has been previously reported. Microalbuminuria (MA) is associated with target-organ damage, especially in patients with hypertension with left ventricular hypertrophy (LVH) and suggest endothelial dysfunction. This study aimed to investigate the relationship between echocardiographic EAT thickness and presence of MA in patients with hypertension.

METHODS

A total of 297 newly diagnosed hypertension patients who applied to the outpatient clinic were enrolled consecutively in this study. Patients were divided into two groups regarding the presence of LVH in echocardiography. An age and gender matched control group was set including 156 healthy patients without HT. All subjects underwent transthoracic echocardiography for the measurement of EAT thickness. Spot urine samples were collected for the assessment of MA.

RESULTS

In hypertensive patients with LVH, the EAT thicknesses (6.6 ± 1.8 vs 5.3 ± 1.5 vs 5.1 ± 1.3, p < .001; respectively) and prevalence of MA (41.2 vs 20.1 vs 3.2%; p < .001 respectively) were significantly higher than the other two groups. In hypertensive patiens without LVH, no relationship was found between the presence of MA and EAT thickness. In multivariate regression analyses, EAT thickness (OR: 3.141, 95%CI: 2.425-6.123, p < .001) and left ventricular mass index (OR: 1.339, 95%CI: 1.145-2.143, p = .003) were determined as independent predictors for MA development in hypertensive patients with LVH.

CONCLUSION

Measurement of EAT thickness may help to identify high-risk hypertensive patients for target-organ damage especially among patients with LVH.

Obesity, malnutrition, and trace element deficiency in the coronavirus disease (COVID-19) pandemic: An overview

The world is currently facing the coronavirus disease (COVID-19) pandemic which places great pressure on health care systems and workers, often presents with severe clinical features, and sometimes requires admission into intensive care units. Derangements in nutritional status, both for obesity and malnutrition, are relevant for the clinical outcome in acute illness. Systemic inflammation, immune system impairment, sarcopenia, and preexisting associated conditions, such as respiratory, cardiovascular, and metabolic diseases related to obesity, could act as crucial factors linking nutritional status and the course and outcome of COVID-19. Nevertheless, vitamins and trace elements play an essential role in modulating immune response and inflammatory status. Overall, evaluation of the patient's nutritional status is not negligible for its implications on susceptibility, course, severity, and responsiveness to therapies, in order to perform a tailored nutritional intervention as an integral part of the treatment of patients with COVID-19. The aim of this study was to review the current data on the relevance of nutritional status, including trace elements and vitamin status, in influencing the course and outcome of the disease 3 mo after the World Health Organization's declaration of COVID-19 as a pandemic.

Physical exercise and epicardial adipose tissue: A systematic review and meta-analysis of randomized controlled trials

We performed a meta-analysis of the effects of exercise on epicardial adipose tissue (EAT). A systematic search was conducted in PubMed and Scopus (since inception to 1 February 2020) of randomized controlled trials assessing the effects of exercise interventions alone (with no concomitant weight loss intervention) on EAT. The standardized mean difference (Hedges' g) and 95% confidence interval between interventions were computed using a random effects model. Ten studies (including 521 participants who had, on average, overweight/obesity) met all inclusion criteria. Interventions were supervised and lasted 2 to 16 weeks (≥3 sessions·per week). Exercise significantly reduced EAT (g = 0.82 [0.57-1.07]) irrespective of the duration of the intervention or the EAT imaging assessment method. Exercise benefits were separately confirmed for endurance (six studies, n = 287; g = 0.83 [0.52-1.15]) but not for resistance exercise training (due to insufficient data for quantitative synthesis). It was not possible to compare the effect of high-intensity interval training (HIIT) versus moderate-intensity continuous training (two studies, one reporting higher benefits with HIIT and the other no differences). Physical exercise interventions-particularly endurance training, with further evidence needed for other exercise modalities-appear as an effective strategy for reducing EAT in individuals with overweight/obesity, which supports their implementation for cardiovascular risk reduction.

Epicardial fat attenuation, not volume, predicts obstructive coronary artery disease and high risk plaque features in patients with atypical chest pain

OBJECTIVE

This study sought to investigate the association between volume and attenuation of epicardial fat and presence of obstructive coronary artery disease (CAD) and high-risk plaque features (HRPF) on CT angiography (CTA) in patients with atypical chest pain and whether the association, if any, is independent of conventional cardiovascular risk factors and coronary artery calcium score (CACS).

METHODS

Patients referred for coronary CTA with atypical chest pain and clinical suspicion of CAD were included in the study. Quantification of CACS, epicardial fat volume (EFV) and epicardial fat attenuation (EFat) was performed on non-contrast images. CTA was evaluated for presence of obstructive CAD and presence of HRPF.

RESULTS

255 patients (median age [interquartile range; IQR]: 51[41-60] years, 51.8% males) were included. On CTA, CAD, obstructive CAD (≥50% stenosis) and CTA-derived HRPFs was present in 133 (52.2%), 37 (14.5%) and 82 (32.2%) patients respectively. A significantly lower EFat was seen in patients with obstructive CAD than in those without (-86HU [IQR:-88 to -82 HU] vs -84 [IQR:-87 HU to -82 HU]; p = 0.0486) and in patients with HRPF compared to those without (-86 HU [IQR:-88 to -83 HU] vs -83 HU [-86 HU to -81.750 HU]; p < 0.0001). EFat showed significant association with obstructive CAD (unadjusted Odd's ratio (OR) [95% CI]: 0.90 [0.81-0.99];p = 0.0248) and HRPF (unadjusted OR [95% CI]: 0.83 [0.76-0.90];p < 0.0001) in univariate analysis, which remained significant in multivariate analysis. However, EFV did not show any significant association with neither obstructive CAD nor HRPF in multivariate analysis. Adding EFat to conventional coronary risk factors and CACS in the pre-test probability models increased the area-under curve (AUC) for prediction of both obstructive CAD (AUC[95% CI]: 0.76 [0.70-0.81] vs 0.71 [0.65-0.77)) and HRPF (AUC [95% CI]: 0.92 [0.88-0.95] vs 0.89 [0.85-0.93]), although not reaching statistical significance.

CONCLUSION

EFat, but not EFV, is an independent predictor of obstructive CAD and HRPF. Addition of EFat to traditional cardiovascular risk factors and CACS improves estimation for pretest probability of obstructive CAD and HRPF.

ADVANCES IN KNOWLEDGE

EFat is an important attribute of epicardial fat as it reflects the "quality" of fat, taking into account the effects of brown-white fat transformation and fibrosis, as opposed to mere evaluation of "quantity" of fat by EFV. Our study shows that EFat is a better predictor of obstructive CAD and HRPF than EFV and can thus explain the inconsistent association of increased EFV alone with CAD.

The role of ectopic adipose tissue: benefit or deleterious overflow?

Ectopic adipose tissues (EAT) are present adjacent to many organs and have predominantly been described in overweight and obesity. They have been suggested to be related to fatty acid overflow and to have harmful effects. The objective of this semi-comprehensive review is to explore whether EAT may play a supportive role rather than interfering with its function, when the adjacent organ is challenged metabolically and functionally. EAT are present adhered to different tissues or organs, including lymph nodes, heart, kidney, ovaries and joints. In this review, we only focused on epicardial, perinodal, and peritumoral fat since these locations have been studied in more detail. Evidence was found that EAT volume significantly increased, associated with chronic metabolic challenges of the corresponding tissue. In vitro evidence revealed transfer of fatty acids from peritumoral and perinodal fat to the adjacent tissue. Cytokine expression in these EAT is upregulated when the adjacent tissue is challenged. In these tissues, glycolysis is enhanced, whereas fatty acid oxidation is increased. Together with more direct evidence, this shows that glucose is oxidized to a lesser degree, but used to support anabolic metabolism of the adjacent tissue. In these situations, browning occurs, resulting from upregulation of anabolic metabolism, stimulated by uncoupling proteins 1 and 2 and possibly 3. In conclusion, the evidence found is fragmented but the available data support the view that accumulation and browning of adipocytes adjacent to the investigated organs or tissues may be a normal physiological response promoting healing and (patho)physiological growth.

The roles of epicardial adipose tissue in heart failure

Heart failure is a growing health problem resulting in the decreased life expectancy of patients and severely increased the healthcare burden. Penetrating research on the pathogenesis and regulation mechanism of heart failure is important for treatment of heart failure. Epicardial adipose tissue (EAT) has been demonstrated as not only a dynamic organ with biological functions but also an inert lipid store with regulating systemic metabolism. EAT mediates physiological and pathophysiological processes of heart failure by regulating adipogenesis, cardiac remodeling, insulin resistance, cardiac output, and renin angiotensin aldosterone system (RAAS). Moreover, EAT secretes a wide range of adipokines, adrenomedullin, adiponectin, and miRNAs through paracrine, endocrine, and vasocrine pathways, which involve in various extracellular and intracellular mechanism of cardiac-related cells in the progress of cardiovascular disease especially in heart failure. Nevertheless, mechanisms and roles of EAT on heart failure are barely summarized. Understanding the regulating mechanisms of EAT on heart failure may give rise to novel therapeutic targets and will open up innovative strategies to myocardial injury as well as in heart failure.

Epicardial adipose tissue is a predictor of ascending aortic dilatation in hypertensive patients, but not paracardial adipose tissue

BACKGROUND

Ascending aortic aneurysms are one of the major causes of mortality. In recent years, there is a growing interest of epicardial adipose tissue (EAT) and related diseases. The aim of this study was to investigate the relationship of EAT, and PAT with ascending aortic dilatation (AAD).

METHODS

We included 934 patients with hypertension in this study. The patients were evaluated by a complete transthoracic echocardiographic examination, including measurements of EAT, PAT, and aortic dimensions. Aortic size index (ASI) was used for diagnosing AAD. The patients were divided into two groups: dilated ascending aorta diameter (ASI ≥ 21 mm / m², n = 102) or normal aortic diameter (ASI < 21 mm / m2, n = 832) according to the ASI. Characteristics of these patients were compared before and after propensity score matching analysis.

RESULTS

Patients with AAD were older (72.3 ± 11.6 vs. 61.7 ± 12.7 years, p <  0.001), had more female gender (66% vs. 54%,p = 0.021) than patients with normal ascending aorta (AA). After propensity score matching analysis (77 vs. 77), EAT [OR:1.461, %95CI (1.082-1.974), p = 0.013] was independently associated with AAD in multivariate logistic regression analysis. In ROC curve analysis, EAT > 0.45 cm had 51.9% sensitivity and 62.3% specificity [AUC = 0.617, P = 0.012, 95% CI (0.529-0.707)].

CONCLUSION

Based on our findings, increased EAT may be suggested as an independent risk factor for AAD due to local or systemic effects in hypertensive patients.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

The Gene and Protein Expression of the Main Components of the Lipolytic System in Human Myocardium and Heart Perivascular Adipose Tissue. Effect of Coronary Atherosclerosis

The aim of our study was to examine the regulation of triacylglycerols (TG) metabolism in myocardium and heart perivascular adipose tissue in coronary atherosclerosis. Adipose triglyceride lipase (ATGL) is the major TG-hydrolase. The enzyme is activated by a protein called comparative gene identification 58 (CGI-58) and inhibited by a protein called G0/G1 switch protein 2 (G0S2). Samples of the right atrial appendage and perivascular adipose tissue were obtained from two groups of patients: 1—with multivessel coronary artery disease qualified for coronary artery bypass grafting (CAD), 2—patients with no atherosclerosis qualified for a valve replacement (NCAD). The mRNA and protein analysis of ATGL, HSL, CGI-58, G0S2, FABP4, FAT/CD36, LPL, β-HAD, CS, COX4/1, FAS, SREBP-1c, GPAT1, COX-2, 15-LO, and NFκβ were determined by using real-time PCR and Western Blot. The level of lipids (i.e., TG, diacylglycerol (DG), and FFA) was examined by GLC. We demonstrated that in myocardium coronary atherosclerosis increases only the transcript level of G0S2 and FABP4. Most importantly, ATGL, β-HAD, and COX4/1 protein expression was reduced and it was accompanied by over double the elevation in TG content in the CAD group. The fatty acid synthesis and their cellular uptake were stable in the myocardium of patients with CAD. Additionally, the expression of proteins contributing to inflammation was increased in the myocardium of patients with coronary stenosis. Finally, in the perivascular adipose tissue, the mRNA of G0S2 was elevated, whereas the protein content of FABP-4 was increased and for COX4/1 diminished. These data suggest that a reduction in ATGL protein expression leads to myocardial steatosis in patients with CAD.

Effects of epicardial fat reduction on P-wave duration of morbidly obese patients submitted to bariatric surgery: an observational study

Introduction: Epicardial fat (EF) is biologically active and, through its paracrine effect, interacts with the atrial myocardium and may be involved in the atrial remodeling observed in obese individuals. P-wave duration (PWD) is a non-invasive marker of atrial conduction time and reflects changes related to atrial remodeling. The effects of the reduction of EF induced by bariatric surgery on PWD have not yet been defined. Methods: We prospectively recruited 22 morbidly obese patients with no other comorbidities at the Unidade de Cirurgia Bariátrica (Bariatric Surgery Unit) of Unviversidade de São Paulo’s Hospital das Clínicas. The patients were submitted to clinical and laboratorial evaluations, 12-lead eletrocardiography (ECG), two-dimensional echocardiogram and 24 h Holter. The same evaluation was performed 12 months after bariatric surgery. In order to make a comparison of the continuous variables, we used the paired and Wilcoxon T tests. To evaluate the association between independent variables, a regression model was used for repeated measures. Results: A total of 20 patients completed the protocol (age: 36.35 ± 10.26 years, 18 women). There was a significant reduction of PWD, body mass index (BMI) and EF after bariatric surgery (p<0.05). There was also an average reduction of 11.55 ± 8.49 ms in PWD. In the multiple regression analysis, an association was observed between the reduction of PWD and the reduction of EF and BMI. Conclusions: In morbidly obese patients with no other comorbidities, the reduction of EF after bariatric surgery was associated with an improvement in atrial remodeling indicated by a significant reduction in PWD.

Efeitos da Redução da Gordura Epicárdica na Duração da Onda P de Obesos Mórbidos Submetidos à Cirurgia Bariátrica: um Estudo Observacional

Introduction: Epicardial fat (EF) is biologically active and, through its paracrine effect, interacts with the atrial myocardium and may be involved in the atrial remodeling observed in obese individuals. P-wave duration (PWD) is a non-invasive marker of atrial conduction time and reflects changes related to atrial remodeling. The effects of the reduction of EF induced by bariatric surgery on PWD have not yet been defined. Methods: We prospectively recruited 22 morbidly obese patients with no other comorbidities at the Unidade de Cirurgia Bariátrica (Bariatric Surgery Unit) of Unviversidade de São Paulo’s Hospital das Clínicas. The patients were submitted to clinical and laboratorial evaluations, 12-lead eletrocardiography (ECG), two-dimensional echocardiogram and 24 h Holter. The same evaluation was performed 12 months after bariatric surgery. In order to make a comparison of the continuous variables, we used the paired and Wilcoxon T tests. To evaluate the association between independent variables, a regression model was used for repeated measures. Results: A total of 20 patients completed the protocol (age: 36.35 ± 10.26 years, 18 women). There was a significant reduction of PWD, body mass index (BMI) and EF after bariatric surgery (p<0.05). There was also an average reduction of 11.55 ± 8.49 ms in PWD. In the multiple regression analysis, an association was observed between the reduction of PWD and the reduction of EF and BMI. Conclusions: In morbidly obese patients with no other comorbidities, the reduction of EF after bariatric surgery was associated with an improvement in atrial remodeling indicated by a significant reduction in PWD.

Epicardial Adipose Tissue Accumulation and Essential Hypertension in Non-Obese Adults

Background and Objectives: Epicardial adipose tissue (EAT) is shown to be an important factor in the development of coronary artery disease, but numerous pathophysiological mechanisms of its action are still only partially understood. There is a lack of studies on its association with different grades of essential hypertension (EH). Therefore, we aimed to evaluate the association between size of EAT depots and the risk of EH taking into account its grade. Materials and Methods: Non-obese adult patients with various cardiovascular diseases were investigated: 157 of them had essential hypertension and 101 did not. Hypertensive patients were assigned to three groups according to the grade of hypertension. EAT volume and thickness on ventricular free walls (6 locations) and grooves (5 locations) were measured using cardiac magnetic resonance imaging and compared between groups. A regression model for the prediction of EH was constructed. Results: In general, thickness (in all locations) and volume of EAT depots was greater among hypertensive patients than in normotensive (NORM) group. Mean EAT thickness in all 11 locations and EAT volume were lower in NORM than in grade 1 hypertension group; similarly, EAT volume was lower in grade 1 than in grade 2 hypertension group. EAT accumulation did not differ between grade 2 and severe hypertension groups. EAT volume, dyslipidaemia status, body mass index, and age were independent predictors for EH in regression model. Conclusions: EAT accumulation is larger among hypertensive than normotensive individuals. Measurement of EAT depots could be beneficial for identification of hypertensive patients and prediction of hypertension severity.

Epicardial Adipose Tissue and Renal Disease

Epicardial adipose tissue (EAT) is derived from splanchnic mesoderm, localized anatomically between the myocardium and pericardial visceral layer, and surrounds the coronary arteries. Being a metabolically active organ, EAT secretes numerous cytokines, which moderate cardiovascular morphology and function. Through its paracrine and vasocrine secretions, EAT may play a prominent role in modulating cardiac function. EAT protects the heart in normal physiological conditions by secreting a variety of adipokines with anti-atherosclerotic properties, and in contrast, secretes inflammatory molecules in pathologic conditions that may play a dynamic role in the pathogenesis of cardiovascular diseases by promoting atherosclerosis. Considerable research has been focused on comparing the anatomical and biochemical features of EAT in healthy people, and a variety of disease conditions such as cardiovascular diseases and renal diseases. The global cardiovascular morbidity and mortality in renal disease are high, and there is a paucity of concrete evidence and societal guidelines to detect early cardiovascular disease (CVD) in this group of patients. Here we performed a clinical review on the existing evidence and knowledge on EAT in patients with renal disease, to evaluate its application as a reliable, early, noninvasive biomarker and indicator for CVD, and to assess its significance in cardiovascular risk stratification.

Vascular Oxidative Stress: Impact and Therapeutic Approaches

Oxidative stress has been defined as an imbalance between oxidants and antioxidants and more recently as a disruption of redox signaling and control. It is generally accepted that oxidative stress can lead to cell and tissue injury having a fundamental role in vascular dysfunction. Physiologically, reactive oxygen species (ROS) control vascular function by modulating various redox-sensitive signaling pathways. In vascular disorders, oxidative stress instigates endothelial dysfunction and inflammation, affecting several cells in the vascular wall. Vascular ROS are derived from multiple sources herein discussed, which are prime targets for therapeutic development. This review focuses on oxidative stress in vascular physiopathology and highlights different strategies to inhibit ROS production.

Epicardial adipose tissue and atrial fibrillation: pathophysiological mechanisms, clinical implications, and potential therapies

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with increased cardiovascular morbidity and mortality. Epicardial adipose tissue (EAT) serves as a biologically active organ with important endocrine and inflammatory function. Review An accumulating body of evidence suggests that EAT is associated with the initiation, perpetuation, and recurrence of AF, but the precise role of EAT in AF pathogenesis is not completely elucidated. Pathophysiological mechanisms involve adipocyte infiltration, profibrotic and pro-inflammatory paracrine effects, oxidative stress, neural mechanisms, and genetic factors.

CONCLUSIONS

Notably, EAT accumulation seems to be associated with stroke and adverse cardiovascular outcomes in AF. Weight loss, specific medications and ablation of ganglionated plexi (GP) seem to be potential therapies in this setting.

Opposite relations of epicardial adipose tissue to left atrial size in paroxysmal and permanent atrial fibrillation

Objectives:

Atrial fibrillation has been associated with obesity in epidemiological studies. Epicardial adipose tissue is an ectopic fat depot in the proximity of atria, with endocrine and inflammatory properties that is implicated in the pathophysiology of atrial fibrillation. Inflammation also has a role in atrial arrhythmogenesis. The aim of this study was to investigate the potential relations of epicardial adipose tissue to left atrial size and to adiponectin and the pro-inflammatory mediators, high-sensitivity C-reactive protein, and interleukin-6 in paroxysmal and permanent atrial fibrillation.

Methods:

This was a cross-sectional study of 103 atrial fibrillation patients, divided into two subgroups of paroxysmal and permanent atrial fibrillation, and 81 controls, in sinus rhythm. Echocardiography was used for estimation of epicardial adipose tissue and left atrial size and high-sensitivity C-reactive protein, interleukin-6 and adiponectin were measured in all subjects.

Results:

Atrial fibrillation patients had significantly larger epicardial adipose tissue compared with controls (0.43 ± 0.17 vs 0.34 ± 0.17 cm, p = 0.002). Atrial fibrillation presence was independently related to epicardial adipose tissue thickness (b = 0.09, p = 0.002). Opposite associations of epicardial adipose tissue with left atrial volume existed in atrial fibrillation subgroups; in the paroxysmal subgroup, epicardial adipose tissue was directly related to left atrial volume (R = 0.3, p = 0.03), but in the permanent one the relation was inverse (R = −0.7, p < 0.0001). Adiponectin, high-sensitivity C-reactive protein and interleukin-6 were elevated in both atrial fibrillation groups. Only interleukin-6 was related to epicardial adipose tissue size.

Conclusion:

Opposite associations of epicardial adipose tissue with left atrial size in paroxysmal and permanent Atrial fibrillation and elevated inflammatory markers, suggest a role of epicardial adipose tissue and inflammation in the fibrotic and remodeling process.

Association of Epicardial Fat Tissue with Coronary Artery Disease and Left Ventricle Diastolic Function Indicators

Background

Epicardial fat tissue (EAT) acts as brown adipose tissue and protects the heart and coronary arteries against hypothermia. Recent studies demonstrated that EAT is a source of both anti-inflammatory and atherogenic cytokines. In this study, our aim was to investigate the association of vertical, horizontal, and area measurements of EAT thickness and their association with coronary artery disease, diastolic function, and myocardial performance index in patients who underwent coronary angiography.

Material/Methods

The study population consisted of patients who presented to our outpatient clinic with chest pain and whose non-invasive stress tests were positive between June 2015 and July 2017. Echocardiographic examinations were performed prior to the angiography. Coronary angiograms were performed using Judkins method from the femoral artery.

Results

Mean vertical thickness of EAT was 0.6 cm in patients with CAD and 0.46 cm in those without CAD (p=0.0001). Mean horizontal length of EAT was 2.91 cm in patients with CAD and was 2.41 cm in the subjects without CAD (p=0.001). ROC analysis showed 81% sensitivity and 53% specificity for a cut-off value of 0.45, and 67% sensitivity and 71% specificity for a cut-off value of 0.55 for EAT vertical (cm). Multivariate analysis showed that EAT is an independent risk factor for coronary artery disease.

Conclusions

Echocardiography is an inexpensive routine assessment for most patients. EAT thickness determined by echocardiography may be a useful indicator of increased CAD risk, but not diastolic dysfunction, of the left ventricle.

Increased fetal epicardial fat thickness: A novel ultrasound marker for altered fetal metabolism in diabetic pregnancies

OBJECTIVE

To evaluate whether fetal epicardial fat thickness (EFT) differs in diabetic and nondiabetic pregnant women.

METHODS

Retrospective case-control study of pregnancies between 24 and 36 weeks complicated by preexisting (PDM) or gestational (GDM) diabetes mellitus, matched one to one with controls for body mass index and gestational age (GA). Epicardial fat was identified as the hypoechogenic area between myocardium and visceral pericardium over the right ventricle and its thickness was measured by a single observer blinded to clinical condition and outcomes. A linear regression analysis was performed to assess the relationship between GA and EFT, and regression lines were compared between diabetics and controls.

RESULTS

53 PDM and 53 GDM pregnant women were matched with controls. With the exception of maternal age, the demographics were similar among groups. EFT increased significantly with advancing gestation in both diabetics and controls (P < 0.0001) and was significantly greater in diabetics than in controls (P < 0.0001). The best fit lines were different between diabetics (EFT = 0.05 × GA + 0.07 mm; R²  = 0.70) and controls (EFT = 0.07 × GA + 0.04 mm; R²  = 0.93) (P < 0.0001).

CONCLUSION

Fetal EFT was greater in diabetics than in nondiabetics, and even greater in pregestational diabetics. EFT maybe an additional and/or earlier marker to identify early changes in fetal metabolism before accelerated fetal growth and polyhydramnios is apparent.

Aging-Induced Biological Changes and Cardiovascular Diseases

Aging is characterized by functional decline in homeostatic regulation and vital cellular events. This process can be linked with the development of cardiovascular diseases (CVDs). In this review, we discussed aging-induced biological alterations that are associated with CVDs through the following aspects: (i) structural, biochemical, and functional modifications; (ii) autonomic nervous system (ANS) dysregulation; (iii) epigenetic alterations; and (iv) atherosclerosis and stroke development. Aging-mediated structural and biochemical modifications coupled with gradual loss of ANS regulation, vascular stiffening, and deposition of collagen and calcium often disrupt cardiovascular system homeostasis. The structural and biochemical adjustments have been consistently implicated in the progressive increase in mechanical burden and functional breakdown of the heart and vessels. In addition, cardiomyocyte loss in this process often reduces adaptive capacity and cardiovascular function. The accumulation of epigenetic changes also plays important roles in the development of CVDs. In summary, the understanding of the aging-mediated changes remains promising towards effective diagnosis, discovery of new drug targets, and development of new therapies for the treatment of CVDs.

Epicardial adipose tissue: new parameter for cardiovascular risk assessment in high risk populations

Epicardial adipose tissue (EAT) is localized between the myocardial surface and visceral layer of the pericardium. It is a metabolically active organ that secretes several cytokines which modulate cardiovascular morphology and function. EAT may interact locally with coronary arteries through paracrine secretion mechanisms. Cytokines from peri-adventitial EAT may pass through the coronary wall by diffusion from the outside to the inside, interacting with cells. An additional potential mechanism by which EAT interacts locally with coronary arteries may be the vasocrine secretion.EAT may play a significant role as a modulator of cardiac functions. In physiologic conditions, EAT has biochemical cardio-protective properties, secreting anti-atherosclerosis substances; in metabolic disease states, EAT secretes bioactive molecules that may play an important role in the pathogenesis of coronary artery disease and cardiac arrhythmias by promoting atherosclerosis. EAT has been evaluated both in the general population and in metabolic disease states that are characterized by inflammation, such as cardiovascular diseases and chronic kidney disease.This review focuses on the current state of knowledge on EAT as a reliable new parameter for cardiovascular risk stratification in high risk populations.

Is there relationship between epicardial fat and cardiovascular parameters in incident kidney transplant patients? A post-hoc analysis

Background

Epicardial fat (EF) has been related to increased cardiovascular risk in chronic kidney disease patients. Kidney transplantation is associated with weight gain, especially within the first 12 months. Recently an association between EF and left ventricular mass (LVM) has been suggested in kidney transplant (KTX) recipients.

Objective

Evaluate the EF in KTX recipients and its association with cardiovascular parameters in a 12-month follow-up study.

Methods

EF volume was determined using thoracic computed tomography. The EF progressor group (EF gain) was defined by any increment in EF after 12 months. LVM and LVM index were calculated by echocardiography.

Results

Ninety-eight incident KTX patients [57% men, 41.2 ± 10.1 years, mean dialysis time prior to transplant of 24 (11–60) months] were analyzed. At baseline and after 12 months, EF was 318.6 (275.2–392.6) ml and 329.5 (271.7–384.8) ml, respectively (p = 0.03). When compared to patients who EF decreased (n = 33), those with EF gain (n = 65) had a greater increase of body mass index, abdominal circumference and blood glucose. These patients also had a lower reduction of LVM index. However in the multivariate analysis, there was no difference in LVM index change between groups (interaction p = 0.565), even after adjustment for hypertension, glucose and coronary calcium score (interaction p = 0.538).

Conclusion

The impact of EF gain on ventricular mass after KTX could not be definitely confirmed. Further prospective studies in a large sample of KTX patients should be considered to address a possible causal relationship between EF gain and cardiac hypertrophy in this population.

Expression of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Human Epicardial and Intramyocardial Coronary Arteries of Male Patients Undergoing Coronary Artery Bypass Grafting

OBJECTIVES

Atherosclerosis is almost absent in intramyocardial coronary arteries, while epicardial coronary arteries may show extensive occlusive disease. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression has been implicated in atherogenesis. We aimed to investigate differences in arterial wall LOX-1 expression between human epicardial and intramyocardial coronary arteries.

METHODS

Epicardial and intramyocardial total artery wall specimens were obtained from 13 male patients (aged 61.9 ± 10.3 years) undergoing coronary artery bypass graft surgery due to 3-vessel coronary artery disease. LOX-1 expression was examined by reverse transcription-polymerase chain reaction.

RESULTS

LOX-1 expression was significantly higher in the arterial wall of epicardial coronary arteries compared to intramyocardial coronary arteries. The LOX-1/GAPDH ratio was 0.48 ± 0.07 vs. 0.35 ± 0.03 (p < 0.001).

CONCLUSIONS

Our findings may partially explain the atheroprotective effect of the intramyocardial course since arterial wall LOX-1 expression was lower in intramyocardial arteries and higher in epicardial coronary arteries.

Investigating interactions between epicardial adipose tissue and cardiac myocytes: what can we learn from different approaches?

Heart disease is a major cause of morbidity and mortality throughout the world. Some cardiovascular conditions can be modulated by lifestyle factors such as increased exercise or a healthier diet, but many require surgical or pharmacological interventions for their management. More targeted and less invasive therapies would be beneficial. Recently, it has become apparent that epicardial adipose tissue plays an important role in normal and pathological cardiac function, and it is now the focus of considerable research. Epicardial adipose tissue can be studied by imaging of various kinds, and these approaches have yielded much useful information. However, at a molecular level, it is more difficult to study as it is relatively scarce in animal models and, for practical and ethical reasons, not always available in sufficient quantities from patients. What is needed is a robust model system in which the interactions between epicardial adipocytes and cardiac myocytes can be studied, and physiologically relevant manipulations performed. There are drawbacks to conventional culture methods, not least the difficulty of culturing both cardiac myocytes and adipocytes, each of which has special requirements. We discuss the benefits of a three-dimensional co-culture model in which in vivo interactions can be replicated.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Epicardial adipose tissue: at the heart of the obesity complications

In recent years, the anatomic and functional contiguity of epicardial adipose tissue (EAT) to myocardium and coronary arteries has gained increasing interest for its potential pathogenetic role in obesity-related cardiac diseases. Besides its known and attributed biochemical cardioprotective properties, it is becoming evident that, in metabolic disease states, EAT-secreted bioactive molecules may play an important role in the pathogenesis of coronary artery disease and cardiac arrhythmias. EAT-derived inflammatory cytokines and reactive oxidative species may, indeed, play a part in the development of a local proatherogenic milieu by paracrine and vasocrine mechanisms of interaction. In addition, initial clinical and in vitro studies have pointed out that EAT could be a determinant of the substrate of atrial fibrillation by contributing to the structural and electrical remodeling of myocardium. This article reviews the current state of knowledge on the association of EAT with cardiac dysfunction and the potential factors mediating the cross talk between this fat depot and the underlying cardiac structures.

Epicardial, pericardial and total cardiac fat and cardiovascular disease in type 2 diabetic patients with elevated urinary albumin excretion rate

Background We evaluated the association of cardiac adipose tissue including epicardial adipose tissue and pericardial adipose tissue with incident cardiovascular disease and mortality, coronary artery calcium, carotid intima media thickness and inflammatory markers. Design A prospective study of 200 patients with type 2 diabetes and elevated urinary albumin excretion rate (UAER). Methods Cardiac adipose tissue was measured from baseline echocardiography. The composite endpoint comprised incident cardiovascular disease and all-cause mortality. Coronary artery calcium, carotid intima media thickness and inflammatory markers were measured at baseline. Cardiac adipose tissue was investigated as continuous and binary variable. Analyses were performed unadjusted (model 1), and adjusted for age, sex (model 2), body mass index, low-density lipoprotein cholesterol, smoking, glycated haemoglobin, and systolic blood pressure (model 3). Results Patients were followed-up after 6.1 years for non-fatal cardiovascular disease ( n = 29) or mortality ( n = 23). Cardiac adipose tissue ( p = 0.049) and epicardial adipose tissue ( p = 0.029) were associated with cardiovascular disease and mortality in model 1. When split by the median, patients with high cardiac adipose tissue had a higher risk of cardiovascular disease and mortality than patients with low cardiac adipose tissue in unadjusted (hazard ratio 1.9, confidence interval: 1.1; 3.4, p = 0.027) and adjusted (hazard ratio 2.0, confidence interval: 1.1; 3.7, p = 0.017) models. Cardiac adipose tissue ( p =  0.033) was associated with baseline coronary artery calcium (model 1) and interleukin-8 (models 1-3, all p < 0.039). Conclusions In type 2 diabetes patients without coronary artery disease, high cardiac adipose tissue levels were associated with increased risk of incident cardiovascular disease or all-cause mortality even after accounting for traditional cardiovascular disease risk factors. High cardiac adipose tissue amounts were associated with subclinical atherosclerosis (coronary artery calcium) and with the pro-atherogenic inflammatory marker interleukin-8.

Role of Epicardial Adipose Tissue in Health and Disease: A Matter of Fat?

Epicardial adipose tissue (EAT) is a small but very biologically active ectopic fat depot that surrounds the heart. Given its rapid metabolism, thermogenic capacity, unique transcriptome, secretory profile, and simply measurability, epicardial fat has drawn increasing attention among researchers attempting to elucidate its putative role in health and cardiovascular diseases. The cellular crosstalk between epicardial adipocytes and cells of the vascular wall or myocytes is high and suggests a local role for this tissue. The balance between protective and proinflammatory/profibrotic cytokines, chemokines, and adipokines released by EAT seem to be a key element in atherogenesis and could represent a future therapeutic target. EAT amount has been found to predict clinical coronary outcomes. EAT can also modulate cardiac structure and function. Its amount has been associated with atrial fibrillation, coronary artery disease, and sleep apnea syndrome. Conversely, a beiging fat profile of EAT has been identified. In this review, we describe the current state of knowledge regarding the anatomy, physiology and pathophysiological role of EAT, and the factors more globally leading to ectopic fat development. We will also highlight the most recent findings on the origin of this ectopic tissue, and its association with cardiac diseases. © 2017 American Physiological Society. Compr Physiol 7:1051-1082, 2017.

Pericardial fat volume and incident atrial fibrillation in the Multi-Ethnic Study of Atherosclerosis and Jackson Heart Study

OBJECTIVE

To determine whether greater pericardial fat volume would be associated with increased risk of incident atrial fibrillation (AF).

METHODS

In the Multi-Ethnic Study of Atherosclerosis and Jackson Heart Study, pericardial fat volume was quantified by computed tomography. Incident AF was identified from discharge diagnosis codes, study electrocardiograms, and Medicare claims.

RESULTS

Among 7,991 participants, 40% were African American, 32% white, 18% Hispanic, and 10% Chinese American; mean age was 62 years; 55% were women. During an average of 10.0 years of follow-up in the Multi-Ethnic Study of Atherosclerosis and 4.5 years in the Jackson Heart Study, 756 incident AF cases were identified. After adjustment for age, sex, study, race/ethnicity, height, glucose status, systolic blood pressure, treated hypertension, and BMI, greater pericardial fat volume was associated with higher AF risk in Hispanics (hazard ratio 1.24 per SD, 95% confidence interval 1.05-1.46) but not overall (hazard ratio 1.06, 95% confidence interval 0.97-1.15). In mediation analysis, pericardial fat volume partially mediated the association of BMI with incident AF in Hispanics.

CONCLUSIONS

After adjustment for BMI, greater pericardial fat volume was associated with incident AF in Hispanics but not overall. Additional research is needed on the mechanisms by which pericardial fat volume is related to increased AF risk and possible differences by race/ethnicity.

Original research. The Assessment of Epicardial Adipose Tissue in Acute Coronary Syndrome Patients. A Systematic Review

Background: This systematic review seeks to evaluate the role of epicardial adipose tissue (EAT), quantified either by thickness, assessed by transthoracic echocardiography, or by volume, assessed by cardiac computed tomography (CT), in the follow-up of patients with acute coronary syndromes (ACS). Method: One-hundred forty-four articles were screened, from which 56 were reviewed in full-text. From those, 47 studies were excluded for the following reasons: they did not meet the inclusion criteria; they were either reviews or meta-analyses; the study cohorts included only stable coronary artery disease patients; they did not state a clear and concise study design, endpoints, or follow-up. The final draft included nine studies for systematic evaluation. Results: Of the 2,306 patients included in the review, 170 underwent cardiac CT while the remaining 2,136 underwent transthoracic echocardiography for the measurement of EAT. The analysis found that the EAT thickness was significantly associated with major adverse cardiovascular events (MACE) rates during hospitalization (OR: -1.3, 95% CI: 1.05-1.62, p = 0.020) and at three years (HR: 1.524, 95% CI: 1.0-2.2, p = 0.038). The included studies found that EAT was correlated with the following clinical and angiographic risk scores for ACS: GRACE (r = 0.438, p <0.001), TIMI risk score (r = 0.363, p = 0.001), SYNTAX score (r = 0.690, p <0.0001; r = 0.610, p <0.01), and Gensini score (r = 0.438, p = 0.001). There was an inverse correlation between ST-segment resolution of <70% after revascularization and EAT (r = −0.414, p = 0.01), and the myocardial blush grade (r = −0.549, p <0.001). The EF aggregation ranged between 2.65 mm and 4.7 mm within the included studies. Conclusions: EAT, evaluated either by echocardiography or cardiac CT, correlates with the severity of coronary lesions, with the clinical and angiographic risk scores for acute coronary syndromes, with indicators for coronary reperfusion, and with short- and long-term MACE rates. Further studies are required to fully elucidate the role of this extensively studied but still novel cardiovascular biomarker as part of a risk prediction tool.

Relation of Epicardial Adipose Tissue Radiodensity to Coronary Artery Calcium on Cardiac Computed Tomography in Patients at High Risk for Cardiovascular Disease

Adipose tissue radiodensity detected by computed tomography (CT) is hypothesized to be associated with differences in adipose tissue composition which may contribute to the development of coronary atherosclerosis independent of epicardial adipose tissue volume. The aim of the present study is to quantify the relation between epicardial adipose tissue radiodensity and presence, distribution, and density of coronary artery calcium (CAC) in patients at high risk for cardiovascular disease. A total of 140 patients of the Secondary Manifestations of ARTerial disease (SMART) study underwent cardiac-CT angiography. Ordinal logistic and linear regression was used to quantify the relation between epicardial adipose tissue radiodensity (in Hounsfield Units, HU) and CAC. One SD lower attenuation (5 HU) was associated with a 1.90 (95% confidence interval [CI] 1.14 to 3.19) higher odds for men and a 1.07 (95% CI 0.41 to 2.75) higher odds for women of being in a higher CAC class (0, 1 to 100, 101 to 400, and >400), independent of age, coronary artery bypass graft history, epicardial adipose tissue volume, and body mass index. One SD lower attenuation was not associated with more diffuse distribution of CAC, but increased the odds of being in a higher tertile of CAC density per plaque (odds ratio 1.77, 95% CI 1.18 to 2.66). In conclusion, low epicardial adipose tissue CT attenuation is associated with higher CAC scores in men at high risk for cardiovascular disease, independent of epicardial depot volume and body mass index. Present results suggest a potential role for epicardial adipose tissue radiodensity as a measure of adipose tissue composition and may inform on the contribution of epicardial adipose tissue composition to coronary atherosclerosis.

Epicardial Adipose Tissue Removal Potentiates Outward Remodeling and Arrests Coronary Atherogenesis

BACKGROUND

Pericoronary epicardial adipose tissue (cEAT) serves as a metabolic and paracrine organ that contributes to inflammation and is associated with macrovascular coronary artery disease (CAD) development. Although there is a strong correlation in humans between cEAT volume and CAD severity, there remains a paucity of experimental data demonstrating a causal link of cEAT to CAD. The current study tested the hypothesis that surgical resection of cEAT attenuates inflammation and CAD progression.

METHODS

Female Ossabaw miniature swine (n = 12) were fed an atherogenic diet for 8 months and randomly allocated into sham (n = 5) or adipectomy (n = 7) groups. Both groups underwent a thoracotomy, opening of the pericardial sac, and placement of radioopaque clips to mark the proximal left anterior descending artery. Adipectomy swine underwent removal of 1 to 1.5 cm2 of cEAT from the proximal artery. After sham or adipectomy, CAD severity was assessed with intravascular ultrasonography. Swine recovered for an additional 3 months on an atherogenic diet, and CAD was assessed immediately before euthanasia. Artery sections were processed for histologic and immunohistochemical analysis.

RESULTS

Severity of CAD as assessed by percent stenosis was reduced in the adipectomy cohort compared with shams; however, plaque size remained unaltered, whereas larger plaque sizes developed in sham-operated swine. Adipectomy resulted in an expanded arterial diameter, similar to the Glagov phenomenon of positive outward remodeling. No differences in inflammatory marker expression were observed.

CONCLUSIONS

These data indicate that cEAT resection did not alter inflammatory marker expression, but arrested CAD progression through increased positive outward remodeling and arrest of atherogenesis.