Inflammatory genes in epicardial fat contiguous with coronary atherosclerosis in the metabolic syndrome and type 2 diabetes: changes associated with pioglitazone

Epicardial adipose tissue, metabolic disorders, and cardiovascular diseases: recent advances classified by research methodologies

Epicardial adipose tissue (EAT) is located between the myocardium and visceral pericardium. The unique anatomy and physiology of the EAT determines its great potential in locally influencing adjacent tissues such as the myocardium and coronary arteries. Classified by research methodologies, this study reviews the latest research progress on the role of EAT in cardiovascular diseases (CVDs), particularly in patients with metabolic disorders. Studies based on imaging techniques demonstrated that increased EAT amount in patients with metabolic disorders is associated with higher risk of CVDs and increased mortality. Then, in-depth profiling studies indicate that remodeled EAT may serve as a local mediator of the deleterious effects of cardiometabolic conditions and plays a crucial role in CVDs. Further, in vitro coculture studies provided preliminary evidence that the paracrine effect of remodeled EAT on adjacent cardiomyocytes can promote the occurrence and progression of CVDs. Considering the important role of EAT in CVDs, targeting EAT might be a potential strategy to reduce cardiovascular risks. Several interventions have been proved effective in reducing EAT amount. Our review provides valuable insights of the relationship between EAT, metabolic disorders, and CVDs, as well as an overview of the methodological constructs of EAT-related studies.

Epicardial Fat Volume as a Good Predictor for Multivessel Coronary Artery Disease

INTRODUCTION

Epicardial adipose tissue may have an important role in the pathogenesis of coronary artery disease (CAD).

AIM

We aimed to study the association between epicardial fat volume (EFV) and presence of obstructive as well as multivessel CAD.

METHODS

A total of 87 adult subjects with suspected CAD who underwent both quantified by multidetector computerized tomography (MDCT) and Invasive Coronary Angiography (ICA) were enrolled in this observational study. EVF was measured by MDCT by calculating the sum of cross- sectional areas of fat multiplied by slice thickness. EFV measurement and its association with the presence of obstructive CAD (defined as coronary artery stenosis > 70%) was evaluated.

RESULTS

Overall, 89.6% patients had obstructive CAD with higher EFV as compared to 10.3% patients with non-obstructive CAD (57 ± 20.14 cm3 vs. 44 ± 7.4 cm3; P < 0.001). Furthermore, EFV was significantly increased in group II as compared with group I (74 ± 24.3 ml vs. 53 ± 16.2 ml; P < 0.003). On the hand, the coronary calcium score (CAC) was insignificantly increased in group II as compared with group I (486.1 vs. 211.2; P = 0.10). Multivariate analysis revealed that, EFV might be an independent risk factor for not only the presence of obstructive CAD (odds ratio [OR], 1.062; 95% CI 1.018- 1.108; P < 0.005) but also in predicting multivessel disease affection.

CONCLUSIONS

Our results demonstrated that, EFV was significantly increased not only with obstructive CAD, independent of other traditional risk factors and CAC score, but also it can be considered a good predictor of multivessel disease occurrence.

The cardio-renal-metabolic connection: a review of the evidence

Type 2 diabetes (T2D), cardiovascular disease (CVD) and chronic kidney disease (CKD), are recognized among the most disruptive public health issues of the current century. A large body of evidence from epidemiological and clinical research supports the existence of a strong interconnection between these conditions, such that the unifying term cardio-metabolic-renal (CMR) disease has been defined. This coexistence has remarkable epidemiological, pathophysiologic, and prognostic implications. The mechanisms of hyperglycemia-induced damage to the cardio-renal system are well validated, as are those that tie cardiac and renal disease together. Yet, it remains controversial how and to what extent CVD and CKD can promote metabolic dysregulation. The aim of this review is to recapitulate the epidemiology of the CMR connections; to discuss the well-established, as well as the putative and emerging mechanisms implicated in the interplay among these three entities; and to provide a pathophysiological background for an integrated therapeutic intervention aiming at interrupting this vicious crosstalks.

Echocardiographic Association of Epicardial Adipose Tissue with Ascending Aorta Elasticity in Patients with Type 2 Diabetes Mellitus

Epicardial adipose tissue (EAT) is an emerging cardiovascular risk factor located between the myocardium and visceral pericardium. In order to investigate the association between EAT and ascending aorta elasticity in patients with type 2 diabetes mellitus (T2DM), we prospectively enrolled a total of 135 T2DM patients and 63 age- and gender-matched non-T2DM controls in this study. They all underwent transthoracic echocardiography to measure EAT thickness and ascending aorta inner diameters which were used to calculate ascending aorta elastic parameters: compliance (C), distensibility (D), strain (S), stiffness index (SI), and Peterson's elastic modulus (EM). We found that the values of C, D, and S were significantly lower, while SI, EM, and EAT thickness were significantly higher in T2DM patients compared with non-T2DM controls. Compared with T2DM patients with EAT < 5 mm group, C, D, and S were significantly reduced, SI and EM were significantly increased in T2DM patients with EAT ≥ 5 mm group (all P < .05). Bivariate correlation and multivariate linear regression analysis revealed that EAT was independently associated with ascending aorta elasticity. Our findings suggest that thickened EAT in patients with T2DM is associated with ascending aorta elasticity, independent of blood glucose.

Pioglitazone reduces epicardial fat and improves diastolic function in patients with type 2 diabetes

AIMS

To examine the effect of pioglitazone on epicardial (EAT) and paracardial adipose tissue (PAT) and measures of diastolic function and insulin sensitivity in patients with type 2 diabetes mellitus (T2DM).

METHODS

Twelve patients with T2DM without clinically manifest cardiovascular disease and 12 subjects with normal glucose tolerance (NGT) underwent cardiac magnetic resonance imaging to quantitate EAT and PAT and diastolic function before and after pioglitazone treatment for 24 weeks. Whole-body insulin sensitivity was measured with a euglycaemic insulin clamp and the Matsuda Index (oral glucose tolerance test).

RESULTS

Pioglitazone reduced glycated haemoglobin by 0.9% (P < 0.05), increased HDL cholesterol by 7% (P < 0.05), reduced triacylglycerol by 42% (P < 0.01) and increased whole-body insulin-stimulated glucose uptake by 71% (P < 0.01) and Matsuda Index by 100% (P < 0.01). In patients with T2DM, EAT (P < 0.01) and PAT (P < 0.01) areas were greater compared with subjects with NGT, and decreased by 9% (P = 0.03) and 9% (P = 0.09), respectively, after pioglitazone treatment. Transmitral E/A flow rate and peak left ventricular flow rate (PLVFR) were reduced in T2DM versus NGT (P < 0.01) and increased following pioglitazone treatment (P < 0.01-0.05). At baseline normalized PLVFR inversely correlated with EAT (r = -0.45, P = 0.03) but not PAT (r = -0.29, P = 0.16). E/A was significantly and inversely correlated with EAT (r = -0.55, P = 0.006) and PAT (r = -0.40, P = 0.05). EAT and PAT were inversely correlated with whole-body insulin-stimulated glucose uptake (r = -0.68, P < 0.001) and with Matsuda Index (r = 0.99, P < 0.002).

CONCLUSION

Pioglitazone reduced EAT and PAT areas and improved left ventricular (LV) diastolic function in T2DM. EAT and PAT are inversely correlated (PAT less strongly) with LV diastolic function and both EAT and PAT are inversely correlated with measures of insulin sensitivity.

Effects of treatment of non-alcoholic fatty liver disease on heart failure with preserved ejection fraction

In the past few decades, non-alcoholic fatty liver disease (NAFLD) and heart failure with preserved ejection fraction (HFpEF) have become the most common chronic liver disease and the main form of heart failure (HF), respectively. NAFLD is closely associated with HFpEF by sharing common risk factors and/or by boosting systemic inflammation, releasing other secretory factors, and having an expansion of epicardial adipose tissue (EAT). Therefore, the treatments of NAFLD may also affect the development and prognosis of HFpEF. However, no specific drugs for NAFLD have been approved by the Food and Drug Administration (FDA) and some non-specific treatments for NAFLD are applied in the clinic. Currently, the treatments of NAFLD can be divided into non-pharmacological and pharmacological treatments. Non-pharmacological treatments mainly include dietary intervention, weight loss by exercise, caloric restriction, and bariatric surgery. Pharmacological treatments mainly include administering statins, thiazolidinediones, glucagon-like peptide-1 receptor agonists, sodium-glucose cotransporter 2 inhibitors, and metformin. This review will mainly focus on analyzing how these treatments may affect the development and prognosis of HFpEF.

Epicardial fat and atrial fibrillation: the perils of atrial failure

Obesity is a heterogeneous condition, characterized by different phenotypes and for which the classical assessment with body mass index may underestimate the real impact on cardiovascular (CV) disease burden. An epidemiological link between obesity and atrial fibrillation (AF) has been clearly demonstrated and becomes even more tight when ectopic (i.e. epicardial) fat deposition is considered. Due to anatomical and functional features, a tight paracrine cross-talk exists between epicardial adipose tissue (EAT) and myocardium, including the left atrium (LA). Alongside-and even without-mechanical atrial stretch, the dysfunctional EAT may determine a pro-inflammatory environment in the surrounding myocardial tissue. This evidence has provided a new intriguing pathophysiological link with AF, which in turn is no longer considered a single entity but rather the final stage of atrial remodelling. This maladaptive process would indeed include structural, electric, and autonomic derangement that ultimately leads to overt disease. Here, we update how dysfunctional EAT would orchestrate LA remodelling. Maladaptive changes sustained by dysfunctional EAT are driven by a pro-inflammatory and pro-fibrotic secretome that alters the sinoatrial microenvironment. Structural (e.g. fibro-fatty infiltration) and cellular (e.g. mitochondrial uncoupling, sarcoplasmic reticulum fragmentation, and cellular protein quantity/localization) changes then determine an electrophysiological remodelling that also involves the autonomic nervous system. Finally, we summarize how EAT dysfunction may fit with the standard guidelines for AF. Lastly, we focus on the potential benefit of weight loss and different classes of CV drugs on EAT dysfunction, LA remodelling, and ultimately AF onset and recurrence.

Epicardial Adipose Tissue and Cardiac Arrhythmias: Focus on Atrial Fibrillation

Atrial Fibrillation (AF) is the most frequent cardiac arrhythmia and its prevalence increases with age. AF is strongly associated with an increased risk of stroke, heart failure and cardiovascular mortality. Among the risk factors associated with AF onset and severity, obesity and inflammation play a prominent role. Numerous recent evidence suggested a role of epicardial adipose tissue (EAT), the visceral fat depot of the heart, in the development of AF. Several potential arrhythmogenic mechanisms have been attributed to EAT, including myocardial inflammation, fibrosis, oxidative stress, and fat infiltration. EAT is a local source of inflammatory mediators which potentially contribute to atrial collagen deposition and fibrosis, the anatomical substrate for AF. Moreover, the close proximity between EAT and myocardium allows the EAT to penetrate and generate atrial myocardium fat infiltrates that can alter atrial electrophysiological properties. These observations support the hypothesis of a strong implication of EAT in structural and electrical atrial remodeling, which underlies AF onset and burden. The measure of EAT, through different imaging methods, such as echocardiography, computed tomography and cardiac magnetic resonance, has been proposed as a useful prognostic tool to predict the presence, severity and recurrence of AF. Furthermore, EAT is increasingly emerging as a promising potential therapeutic target. This review aims to summarize the recent evidence exploring the potential role of EAT in the pathogenesis of AF, the main mechanisms by which EAT can promote structural and electrical atrial remodeling and the potential therapeutic strategies targeting the cardiac visceral fat.

Effect of glucagon-like peptide-1 (GLP-1) analogues on epicardial adipose tissue: A meta-analysis

BACKGROUND AND AIMS

Glucagon-like peptide-1 (GLP-1) analogues reduce body fat and cardiovascular events in patients with type 2 diabetes. Accumulation of epicardial adipose tissue (EAT) is associated with increased cardio-metabolic risks and coronary events in type 2 diabetes.

METHODS

A systematic review and meta-analysis were performed from Glucagon-like peptide-1 analogues therapy on type 2 diabetes patients, reporting data from changes in EAT, after searching the PubMed/MEDLINE, Embase, Science Direct, Scopus, Google Scholar, and Cochrane databases.

RESULTS

It has been found a limited number of studies, a total of 4 studies (n = 160 patients with GLP-1 analogues therapy) were included in the final analysis. Pooled analysis revealed that GLP-1 analogues reduce EAT (MD: 1.83 mm [-2.50; -1.10]; P < 0.01). Compared with the patients before the treatment, the patients after the treatment had a smaller HbA1c (MD -1.10%[-1.80; -0.30]; p = 0.0143) and body mass index was reduced (MD -2.20 kg/m²[-3.70; -0.60]; p = 0.0058), GLP-1 therapy reduced low-density lipoprotein levels (MD-13.53 mg/dL [-21.74; -5.31]; p = 0.001) and reduced triglycerides levels significantly (MD -18.32 -28.20 mg/dL; -8.50); p = 0.0003).

CONCLUSIONS

This meta-analysis suggests that the amount of EAT is significantly reduced in T2D patients with Glucagon-like peptide-1 analogues.

Epicardial Adipose Tissue as an Independent Cardiometabolic Risk Factor for Coronary Artery Disease

During the last decades, visceral adiposity has been at the forefront of scientific research because of its complex role in the pathogenesis of cardiovascular diseases. Epicardial adipose tissue (EAT) is the visceral lipid compartment between the myocardium and the visceral pericardium. Due to their unobstructed anatomic vicinity, epicardial fat and myocardium are nourished by the same microcirculation. It is widely known that EAT serves as an energy lipid source and thermoregulator for the human heart. In addition to this, epicardial fat exerts highly protective effects since it releases a great variety of anti-inflammatory molecules to the adjacent cardiac muscle. Taking into account the unique properties of human EAT, it is undoubtedly a key factor in cardiac physiology since it facilitates complex heart functions. Under pathological circumstances, however, epicardial fat promotes coronary atherosclerosis in a variety of ways. Therefore, the accurate estimation of epicardial fat thickness and volume could be utilized as an early detecting method and future medication target for coronary artery disease (CAD) elimination. Throughout the years, several therapeutic approaches for dysfunctional human EAT have been proposed. A balanced healthy diet, aerobic and anaerobic physical activity, bariatric surgery, and pharmacological treatment with either traditional or novel antidiabetic and antilipidemic drugs are some of the established medical approaches. In the present article, we review the current knowledge regarding the anatomic and physiological characteristics of epicardial fat. In addition to this, we describe the pathogenic mechanisms which refer to the crosstalk between epicardial fat alteration and coronary arterial atherosclerosis development. Lastly, we present both lifestyle and pharmacological methods as possible treatment options for EAT dysfunction. 

Association between epicardial adipose tissue and left ventricular function in type 2 diabetes mellitus: Assessment using two-dimensional speckle tracking echocardiography

BACKGROUND AND AIMS

Epicardial adipose tissue (EAT) is the visceral fat between the myocardium and the visceral pericardium. Dysfunctional EAT can cause cardiovascular diseases. The aim of this study was to investigate the association between EAT and left ventricular function in type 2 diabetes mellitus (T2DM) patients by two-dimensional speckle tracking echocardiography (2D-STE).

METHODS

We prospectively enrolled 116 T2DM patients who were divided into two groups according to their left ventricular global longitudinal strain (GLS): 53 with GLS <18% and 63 with GLS ≥18%. The thickness of EAT was measured as the echo-free space between the free wall of the right ventricle and the visceral layer of pericardium at end-systole. LV systolic function was evaluated by GLS measured by 2D-STE. LV diastolic function was defined as the ratio of the early diastolic transmitral flow velocity (E) to average mitral annular velocity (e¯).

RESULTS

Compared with patients with GLS ≥18% group, the age, body mass index (BMI), waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), low-density lipoprotein cholesterol (LDL-C), glycosylated hemoglobinA1c (HbA1c), E/e¯, and thickness of EAT were higher in patients with GLS <18% group (all P < 0.05). Multivariate linear regression analysis revealed that the thickness of EAT was independently associated with left ventricular GLS and E/e¯.

CONCLUSIONS

Thickened EAT is associated with impaired left ventricular function in T2DM patients. To investigate the association between EAT and left ventricular function can help us gain a deeper understanding of the pathogenesis of impaired cardiac function in T2DM patients.

Browning Epicardial Adipose Tissue: Friend or Foe?

The epicardial adipose tissue (EAT) is the visceral fat depot of the heart which is highly plastic and in direct contact with myocardium and coronary arteries. Because of its singular proximity with the myocardium, the adipokines and pro-inflammatory molecules secreted by this tissue may directly affect the metabolism of the heart and coronary arteries. Its accumulation, measured by recent new non-invasive imaging modalities, has been prospectively associated with the onset and progression of coronary artery disease (CAD) and atrial fibrillation in humans. Recent studies have shown that EAT exhibits beige fat-like features, and express uncoupling protein 1 (UCP-1) at both mRNA and protein levels. However, this thermogenic potential could be lost with age, obesity and CAD. Here we provide an overview of the physiological and pathophysiological relevance of EAT and further discuss whether its thermogenic properties may serve as a target for obesity therapeutic management with a specific focus on the role of immune cells in this beiging phenomenon.

Role of Epicardial Adipose Tissue in Cardiovascular Diseases: A Review

Simple Summary

Cardiovascular diseases (CVDs) are the leading causes of death worldwide. Epicardial adipose tissue (EAT) is one of the most important risk factors for cardiovascular events and a promising new therapeutic target in CVDs. Here, we summarize the currently available evidence regarding the role of EAT in the development of CVDs, including coronary artery disease, heart failure and atrial fibrillation; compile data regarding the association between EAT’s function and the course of COVID-19; and present new potential therapeutic possibilities, aiming at modifying EAT’s function. The development of novel therapies specifically targeting EAT could revolutionize the prognosis in CVDs.

Abstract

Cardiovascular diseases (CVDs) are the leading causes of death worldwide. Epicardial adipose tissue (EAT) is defined as a fat depot localized between the myocardial surface and the visceral layer of the pericardium and is a type of visceral fat. EAT is one of the most important risk factors for atherosclerosis and cardiovascular events and a promising new therapeutic target in CVDs. In health conditions, EAT has a protective function, including protection against hypothermia or mechanical stress, providing myocardial energy supply from free fatty acid and release of adiponectin. In patients with obesity, metabolic syndrome, or diabetes mellitus, EAT becomes a deleterious tissue promoting the development of CVDs. Previously, we showed an adverse modulation of gene expression in pericoronary adipose tissue in patients with coronary artery disease (CAD). Here, we summarize the currently available evidence regarding the role of EAT in the development of CVDs, including CAD, heart failure, and atrial fibrillation. Due to the rapid development of the COVID-19 pandemic, we also discuss data regarding the association between EAT and the course of COVID-19. Finally, we present the potential therapeutic possibilities aiming at modifying EAT’s function. The development of novel therapies specifically targeting EAT could revolutionize the prognosis in CVDs.

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.

Dysregulated Epicardial Adipose Tissue as a Risk Factor and Potential Therapeutic Target of Heart Failure with Preserved Ejection Fraction in Diabetes

Cardiovascular (CV) disease and heart failure (HF) are the leading cause of mortality in type 2 diabetes (T2DM), a metabolic disease which represents a fast-growing health challenge worldwide. Specifically, T2DM induces a cluster of systemic metabolic and non-metabolic signaling which may promote myocardium derangements such as inflammation, fibrosis, and myocyte stiffness, which represent the hallmarks of heart failure with preserved ejection fraction (HFpEF). On the other hand, several observational studies have reported that patients with T2DM have an abnormally enlarged and biologically transformed epicardial adipose tissue (EAT) compared with non-diabetic controls. This expanded EAT not only causes a mechanical constriction of the diastolic filling but is also a source of pro-inflammatory mediators capable of causing inflammation, microcirculatory dysfunction and fibrosis of the underlying myocardium, thus impairing the relaxability of the left ventricle and increasing its filling pressure. In addition to representing a potential CV risk factor, emerging evidence shows that EAT may guide the therapeutic decision in diabetic patients as drugs such as metformin, glucagon-like peptide‑1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 inhibitors (SGLT2-Is), have been associated with attenuation of EAT enlargement.

Targeting Epicardial Fat in Obesity and Diabetes Pharmacotherapy

Epicardial adipose tissue surrounds and infiltrates the heart. Epicardial fat displays unique anatomic, genetic, and biomolecular properties. People with obesity and in particular, those with abdominal obesity and associated type 2 diabetes mellitus, have an increased amount of epicardial adipose tissue (EAT). Epicardial fat works well as therapeutic target due to its fast-responding metabolism, organ fat specificity, and easy measurability. Epicardial fat responds to thiazolidinediones (TZD), glucagon-like peptide 1-receptor agonists (GLP1A), sodium-glucose cotransporter 2 inhibitors (SGLT2i), dipeptidyl peptidase-4 inhibitors (DPP4i), and statins. Modulating epicardial fat morphology and genetic profile with targeted pharmacological agents suggests novel strategies in the pharmacotherapy of diabetes and obesity.

Beneficial effects of a plant-fish oil, slow carbohydrate diet on cardio-metabolic health exceed the correcting effects of metformin-pioglitazone in diabetic pigs fed a fast-food diet

Background

Lifestyle influences endocrine, metabolic and cardiovascular homeostasis. This study investigated the impact of diet and oral anti-diabetic medication on cardio-metabolic health in human-sized diabetic pigs.

Methods

After a growing pre-phase from ~30 to ~69 kg during which domestic pigs were fed either a low fat, low sucrose diet (group A) or a fast food-type diet elevated in lard (15%) and sucrose (40%) (group B), the pigs were subdivided in 5 groups (n = 7–8 pigs per group). Group 1, normal pigs from group A on a low fat, low sugar (L) pig diet and group 2, normal pigs from group B on a high lard (25%), sucrose-fructose (40%), cholesterol (1%) fast food-type (F) diet. Diabetes (D) was induced in group B pigs by streptozotocin and group 3 received the F diet (DF), group 4 received the F diet with Anti-diabetic medication metformin (2 g.day^-1)-pioglitazone (40 mg.day^-1) (DFA) and group 5 switched to a Plant-Fish oil (25%), Slowly digestible starch (40%) diet (DPFS). The F and PFS diets were identical for fat, carbohydrate and protein content but only differed in fat and carbohydrate composition. The 5 pig groups were followed up for 7 weeks until reaching ~120 kg.

Results

In normal pigs, the F diet predisposed to several abnormalities related to metabolic syndrome. Diabetes amplified the inflammatory and cardiometabolic abnormalities of the F diet, but both oral FA medication and the PFS diet partially corrected these abnormalities (mean±SEM) as follows: Fasting plasma TNF-ɑ (pg.ml^-1) and NEFA (mmol.l^-1) concentrations were high (p<0.02) in DF (193±55 and 0.79±0.16), intermediate in DFA (136±40 and 0.57±012) and low in DPFS pigs (107±31 and 0.48±0.19). Meal intolerance (response over fasting) for glucose and triglycerides (area under the curve, mmol.h^-1) and for lactate (3-h postprandial, mmol.l^-1) was high (p<0.03) in DF (489±131, 8.6±4.8 and 2.2±0.6), intermediate in DFA (276±145, 1.4±1.1 and 1.6±0.4) and low in DPFS (184±62, 0.7±1.8 and 0.1±0.1). Insulin-mediated glucose disposal (mg.kg^-1.min^-1) showed a numerical trend (p = NS): low in DF (6.9±2.2), intermediate in DFA (8.2±1.3) and high in DPFS pigs (10.4±2.7). Liver weight (g.kg^-1 body weight) and liver triglyceride concentration (g.kg^-1 liver) were high (p<0.001) in DF (23.8±2.0 and 69±14), intermediate in DFA (21.1±2.0 and 49±15) and low in DPFS pigs (16.4±0.7 and 13±2.0). Aorta fatty streaks were high (p<0.01) in DF (16.4±5.7%), intermediate in DFA (7.4±4.5%) and low in DPFS pigs (0.05±0.02%).

Conclusion

This translational study using pigs with induced type 2 diabetes provides evidence that a change in nutritional life style from fast food to a plant-fish oil, slowly digestible starch diet can be more effective than sole anti-diabetic medication.

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.

Potential role of epicardial adipose tissue in coronary artery endothelial cell dysfunction in type 2 diabetes

Cardiovascular disease is the most prevalent cause of morbidity and mortality in diabetes. Epicardial adipose tissue (EAT) lies in direct contact with the myocardium and coronary arteries and can influence cardiac (patho) physiology through paracrine signaling pathways. This study hypothesized that the proteins released from EAT represent a critical molecular link between the diabetic state and coronary artery endothelial cell dysfunction. To simulate type 2 diabetes-associated metabolic and inflammatory status in an ex vivo tissue culture model, human EAT samples were treated with a cocktail composed of high glucose, high palmitate, and lipopolysaccharide (gplEAT) and were compared with control EAT (conEAT). Compared to conEAT, gplEAT showed a markedly increased gene expression profile of proinflammatory cytokines, corroborating EAT inflammation, a hallmark feature observed in patients with type 2 diabetes. Luminex assay of EAT-secretome identified increased release of various proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), interferon-alpha 2 (IFNA2), interleukin 1 beta (IL1B), interleukin 5 (IL5), interleukin 13 (IL13), and CCL5, among others, in response to high glucose, high palmitate, and lipopolysaccharide. Conditioned culture media was used to collect the concentrated proteins (CPs). In response to gplEAT-CPs, human coronary artery endothelial cells (HCAECs) exhibited an inflammatory endothelial cell phenotype, featuring a significantly increased gene expression of proinflammatory cytokines and cell surface expression of VCAM-1. Moreover, gplEAT-CPs severely decreased Akt-eNOS signaling, nitric oxide production, and angiogenic potential of HCAECs, when compared with conEAT-CPs. These findings indicate that EAT inflammation may play a key role in coronary artery endothelial cell dysfunction in type 2 diabetes.

Epicardial adipose tissue characteristics, obesity and clinical outcomes in COVID-19: A post-hoc analysis of a prospective cohort study

BACKGROUND AND AIMS

Obesity-related cardiometabolic risk factors associate with COVID-19 severity and outcomes. Epicardial adipose tissue (EAT) is associated with cardiometabolic disturbances, is a source of proinflammatory cytokines and a marker of visceral adiposity. We investigated the relation between EAT characteristics and outcomes in COVID-19 patients.

METHODS AND RESULTS

This post-hoc analysis of a large prospective investigation included all adult patients (≥18 years) admitted to San Raffaele University Hospital in Milan, Italy, from February 25th to April 19th, 2020 with confirmed SARS-CoV-2 infection who underwent a chest computed tomography (CT) scan for COVID-19 pneumonia and had anthropometric data available for analyses. EAT volume and attenuation (EAT-At, a marker of EAT inflammation) were measured on CT scan. Primary outcome was critical illness, defined as admission to intensive care unit (ICU), invasive ventilation or death. Cox regression and regression tree analyses were used to assess the relationship between clinical variables, EAT characteristics and critical illness. One-hundred and ninety-two patients were included (median [25th-75th percentile] age 60 years [53-70], 76% men). Co-morbidities included overweight/obesity (70%), arterial hypertension (40%), and diabetes (16%). At multivariable Cox regression analysis, EAT-At (HR 1.12 [1.04-1.21]) independently predicted critical illness, while increasing PaO₂/FiO₂ was protective (HR 0.996 [95% CI 0.993; 1.00]). CRP, plasma glucose on admission, EAT-At and PaO₂/FiO₂ identified five risk groups that significantly differed with respect to time to death or admission to ICU (log-rank p < 0.0001).

CONCLUSION

Increased EAT attenuation, a marker of EAT inflammation, but not obesity or EAT volume, predicts critical COVID-19.

TRIAL REGISTRATION

NCT04318366.

Cardiorenal Fat: A Cardiovascular Risk Factor With Implications in Chronic Kidney Disease

There is a growing interest in the potential role of adipose tissues in cardiac and renal pathophysiology, and determining the mechanisms by which fat compartments around the heart and kidneys influence cardiovascular disease is of clinical importance in both general and high-risk populations. Epicardial fat and perirenal fat have been associated with adverse outcomes in chronic kidney disease (CKD) patients. Epicardial fat is a rich source of free fatty acids and is capable of secreting inflammatory and pro-atherogenic cytokines that promote atherosclerosis through a local paracrine effect. Recent evidence has demonstrated that perirenal fat has a closer correlation with kidney diseases than other visceral fat deposits in obesity or metabolic disturbances. Moreover, perirenal fat has been reported as an independent risk factor for CKD progression and even associated with cardiorenal dysfunction. Accordingly, these forms of organ-specific fat deposits may act as a connecter between vascular and cardiorenal disease. This review explores the possible links between epicardial and perirenal fat and its significant role as a modulator of cardiorenal dysfunction in CKD patients.

Can We Decrease Epicardial and Pericardial Fat in Patients With Diabetes?

Diabetes mellitus (DM) is a chronic and complex metabolic disorder and also an important cause of cardiovascular (CV) disease (CVD). Patients with type 2 DM (T2DM) and obesity show a greater propensity for visceral fat deposition (and excessive fat deposits elsewhere) and the link between adiposity and CVD risk is greater for visceral than for subcutaneous (SC) adipose tissue (AT). There is growing evidence that epicardial AT (EAT) and pericardial AT (PAT) play a role in the development of DM-related atherosclerosis, atrial fibrillation (AF), myocardial dysfunction, and heart failure (HF). In this review, we will highlight the importance of PAT and EAT in patients with DM. We also consider therapeutic interventions that could have a beneficial effect in terms of reducing the amount of AT and thus CV risk. EAT is biologically active and a likely determinant of CV morbidity and mortality in patients with DM, given its anatomical characteristics and proinflammatory secretory pattern. Consequently, modification of EAT/PAT may become a therapeutic target to reduce the CV burden. In patients with DM, a low calorie diet, exercise, antidiabetics and statins may change the quantity of EAT, PAT or both, alter the secretory pattern of EAT, improve the metabolic profile, and reduce inflammation. However, well-designed studies are needed to clearly define CV benefits and a therapeutic approach to EAT/PAT in patients with DM.

Pathogenic gene expression of epicardial adipose tissue in patients with coronary artery disease

Background & objectives:

Coronary artery disease (CAD), a leading cause of mortality and morbidity worldwide has multifactorial origin. Epicardial adipose tissue (EAT) has complex mechanical and thermogenic functions and paracrine actions via various cytokines released by it, which can have both pro- and anti-inflammatory actions on myocardium and adjacent coronaries. The alteration of EAT gene expression in CAD is speculated, but poorly understood. This study was undertaken to find out the difference in gene expression of epicardial fat in CAD and non-CAD patients.

Methods:

Twenty seven patients undergoing coronary artery bypass graft (CABG) and 16 controls (non-CAD patients undergoing valvular heart surgeries) were included in the study and their EAT samples were obtained. Gene expressions of uncoupling protein-1, monocyte chemoattractant protein-1 (MCP-1), adiponectin, adenosine A1 receptor (ADORA-1), vascular cell adhesion molecule-1 (VCAM-1) and tumour necrosis factor-alpha (TNF-α) were studied by real-time reverse transcription-polymerase chain reaction. Glucose, insulin, lipid profile, high-sensitivity C-reactive protein, homocysteine, vitamin D, TNF-α and leptin levels were estimated in fasting blood samples and analyzed.

Results:

Leptin levels were significantly higher in CABG group as compared to controls (P<0.05), whereas other metabolic parameters were not significantly different between the two groups. MCP-1, VCAM-1 and TNF-α were upregulated in the CABG group as compared to controls. Further, multivariate analysis showed significantly reduced adjusted odds ratio for MCP-1 [0.27; 95% confidence interval: 0.08-0.91] in the CABG group as compared to controls (P<0.05).

Interpretation & conclusions:

Our findings showed an alteration in EAT gene expression in CAD patients with significant upregulation of MCP-1. Further studies with a large sample need to be done to confirm these findings.

Epicardial Adipose Tissue as a New Target of Therapeutic Interventions

There is evidence of a correlation between epicardial adipose tissue and the presence and severity of coronary heart disease, the development of hypertrophy, impaired diastolic and systolic function of the left ventricle, enlargement, fibrosis and electrophysiological remodeling of the atria, the occurrence and severity of supraventricular arrhythmias. There is also a lot of evidence of the influence of both non-drug methods and drugs on the severity and functional activity of epicardial adipose tissue, which can be considered as a potentially modifiable factor of cardiovascular risk, the various therapeutic interventions target and a criterion for their effectiveness. Its unique characteristics suggest the advisability of pharmacological strategies aimed at regulating the expression of genes encoding the secretion of adipocytokines and adipocyte function, and a dynamic assessment of the severity of epicardial fat during therapy can be a tool to evaluate its effectiveness in various cardiovascular diseases.

Epicardial adipose tissue deposition in patients with diabetes and renal impairment: Analysis of the literature

Diabetes mellitus (DM) is defined as a chronic disease of disordered metabolism with an ongoing increase in prevalence and incidence rates. Renal disease in patients with diabetes is associated with increased morbidity and premature mortality, particularly attributed to their very high cardiovascular risk. Since this group of patients frequently lacks specific symptomatology prior to the adverse events, a screening tool for the identification of high-risk patients is necessary. The epicardial adipose tissue (EAT) is a biologically active organ having properties similar to visceral adipose tissue and has been associated with metabolic diseases and coronary artery disease. Superior to conventional cardiovascular risk factors and anthropometric measures, including body mass index and waist circumference, the EAT can early predict the development of coronary artery disease. Assessment of EAT can be performed by two-dimensional echocardiography, magnetic resonance imaging or computer tomography. However, its role and significance in patients with DM and nephropathy has not been thoroughly evaluated. The aim of the current editorial is to evaluate all available evidence regarding EAT in patients with DM and renal impairment. Systematic search of the literature revealed that patients with DM and nephropathy have increased EAT measurements, uncontrolled underlying disease, high body mass index and raised cardiovascular risk markers. Acknowledging the practical implications of this test, EAT assessment could serve as a novel and non-invasive biomarker to identify high-risk patients for cardiovascular adverse events.

Epicardial Adipose Tissue, Adiponectin and Leptin: A Potential Source of Cardiovascular Risk in Chronic Kidney Disease

The importance of cardiometabolic factors in the inception and progression of atherosclerotic cardiovascular disease is increasingly being recognized. Beyond diabetes mellitus and metabolic syndrome, other factors may be responsible in patients with chronic kidney disease (CKD) for the high prevalence of cardiovascular disease, which is estimated to be 5- to 20-fold higher than in the general population. Although undefined uremic toxins are often blamed for part of the increased risk, visceral adipose tissue, and in particular epicardial adipose tissue (EAT), have been the focus of intense research in the past two decades. In fact, several lines of evidence suggest their involvement in atherosclerosis development and its complications. EAT may promote atherosclerosis through paracrine and endocrine pathways exerted via the secretion of adipocytokines such as adiponectin and leptin. In this article we review the current knowledge of the impact of EAT on cardiovascular outcomes in the general population and in patients with CKD. Special reference will be made to adiponectin and leptin as possible mediators of the increased cardiovascular risk linked with EAT.

Epicardial adipose tissue: an emerging biomarker of cardiovascular complications in type 2 diabetes?

Type 2 diabetes (T2D) is associated with an increased risk of cardiovascular disease and heart failure, which highlights the need for improved understanding of factors contributing to the pathophysiology of these complications as they are the leading cause of mortality in T2D. Patients with T2D have high levels of epicardial adipose tissue (EAT). EAT is known to secrete inflammatory factors, lipid metabolites, and has been proposed to apply mechanical stress on the cardiac muscle that may accelerate atherosclerosis, cardiac remodeling, and heart failure. High levels of EAT in patients with T2D have been associated with atherosclerosis, diastolic dysfunction, and incident cardiovascular events, and this fat depot has been suggested as an important link coupling diabetes, obesity, and cardiovascular disease. Despite this, the predictive potential of EAT in general, and in patients with diabetes, is yet to be established, and, up until now, the clinical relevance of EAT is therefore limited. Should this link be established, importantly, studies show that this fat depot can be modified both by pharmacological and lifestyle interventions. In this review, we first introduce the role of adipose tissue in T2D and present mechanisms involved in the pathophysiology of EAT and pericardial adipose tissue (PAT) in general, and in patients with T2D. Next, we summarize the evidence that these fat depots are elevated in patients with T2D, and discuss whether they might drive the high cardiometabolic risk in patients with T2D. Finally, we discuss the clinical potential of cardiac adipose tissues, address means to target this depot, and briefly touch upon underlying mechanisms and future research questions.

Inflammaging as a common ground for the development and maintenance of sarcopenia, obesity, cardiomyopathy and dysbiosis

Sarcopenia, obesity and their coexistence, obese sarcopenia (OBSP) as well as atherosclerosis-related cardio-vascular diseases (ACVDs), including chronic heart failure (CHF), are among the greatest public health concerns in the ageing population. A clear age-dependent increased prevalence of sarcopenia and OBSP has been registered in CHF patients, suggesting mechanistic relationships. Development of OBSP could be mediated by a crosstalk between the visceral and subcutaneous adipose tissue (AT) and the skeletal muscle under conditions of low-grade local and systemic inflammation, inflammaging. The present review summarizes the emerging data supporting the idea that inflammaging may serve as a mutual mechanism governing the development of sarcopenia, OBSP and ACVDs. In support of this hypothesis, various immune cells release pro-inflammatory mediators in the skeletal muscle and myocardium. Subsequently, the endothelial structure is disrupted, and cellular processes, such as mitochondrial activity, mitophagy, and autophagy are impaired. Inflamed myocytes lose their contractile properties, which is characteristic of sarcopenia and CHF. Inflammation may increase the risk of ACVD events in a hyperlipidemia-independent manner. Significant reduction of ACVD event rates, without the lowering of plasma lipids, following a specific targeting of key pro-inflammatory cytokines confirms a key role of inflammation in ACVD pathogenesis. Gut dysbiosis, an imbalanced gut microbial community, is known to be deeply involved in the pathogenesis of age-associated sarcopenia and ACVDs by inducing and supporting inflammaging. Dysbiosis induces the production of trimethylamine-N-oxide (TMAO), which is implicated in atherosclerosis, thrombosis, metabolic syndrome, hypertension and poor CHF prognosis. In OBSP, AT dysfunction and inflammation induce, in concert with dysbiosis, lipotoxicity and other pathophysiological processes, thus exacerbating sarcopenia and CHF. Administration of specialized, inflammation pro-resolving mediators has been shown to ameliorate the inflammatory manifestations. Considering all these findings, we hypothesize that sarcopenia, OBSP, CHF and dysbiosis are inflammaging-oriented disorders, whereby inflammaging is common and most probably the causative mechanism driving their pathogenesis.

Rationale, Design for the ASSET Study: A Prospective Randomized Study Comparing Empagliflozin's Effect to Sitagliptin on Cardiac Fat Accumulation/Function in Patients with Type 2 Diabetes

INTRODUCTION

Ectopic fat accumulation has been found to play a pathophysiological role in insulin resistance, type 2 diabetes (T2DM), and coronary artery diseases. Findings from a number of previous studies suggest that sodium glucose cotransporter 2 (SGLT2) inhibitors reduce lipid accumulation, including myocardial and pericardial fat, while dipeptidyl peptidase 4 (DPP4) inhibitors suppress ectopic lipid accumulation and improve cardiac function. However, a clinical study that precisely explains and compares the efficacy of SGLT2 inhibitors and DPP4 inhibitors on cardiac fat accumulation has not been performed. Moreover, the association between cardiac fat accumulation and cardiac function or metabolic changes, such as tissue-specific insulin resistance, remains unclear. It is our intention to conduct the first study to assess the effects of empagliflozin compared to sitagliptin in reducing ectopic fat accumulation, specifically pericardial fat, and its association with improvement in cardiac function and tissue-specific insulin sensitivity.

METHODS

We have designed a prospective, randomized open-label, and blinded-endpoint study with the intention to enroll 44 Japanese patients with T2DM. The patients are to be divided them into two groups, an empagliflozin group and an sitagliptin group, with the former to be supplemented with empagliflozin 10 mg and the latter to be supplemented with sitagliptin 100 mg, both groups for 12 weeks. The primary endpoint of the study is the change in the amount of pericardial fat. The secondary endpoints are the changes in the amount of intracellular fat in the myocardium, cardiac function, tissue-specific insulin sensitivity, fatty acid metabolism in myocardial tissue, assessed by parameters of iodine-123-β-methyl-iodophenyl pentadecanoic acid myocardial scintigraphy, blood and urine biomarkers, and lifestyle evaluation.

PLANNED OUTCOMES

The results of this study will be available in 2020. The aim of this study is to provide an effective treatment strategy for patients with T2DM by considering cardiac fat accumulation, cardiac function, and insulin resistance.

FUNDING

Boehringer Ingelheim & Eli Lilly and Company Diabetes Alliance.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trial Registry: UMIN000026340.

Epicardial fat thickness is significantly increased and related to LDL cholesterol level in patients with familial hypercholesterolemia

PURPOSE

Increased epicardial fat thickness (EFT) is accepted as a risk factfcardiovascular diseases in some studies. There are conflicting results about the relation between plasma low-density lipoprotein cholesterol (LDL-C) level and EFT. As well, the relation between EFT and familial hypercholesterolemia is not clearly documented in the literature. Our aim was to investigate EFT in familial hypercholesterolemia patients and to determine which parameters were related to EFT increase.

METHODS

A total of 150 subjects enrolled in our study. Subjects were separated into two groups: 75 hypercholesterolemia patients (16 men, mean age 52.8 ± 7.4 years) and 75 familial hypercholesterolemia patients (26 men, mean age 50.7 ± 9.2 years). Medical history assessments and complete physical examinations were done. Routine laboratory tests and echocardiographic measurements were performed.

RESULTS

Coronary artery disease frequency was significantly higher in the familial hypercholesterolemia group (p < 0.001). This group had significantly higher TC and LDL-C levels than the hypercholesterolemia group (p < 0.05 for all). EFT values were higher in the familial hypercholesterolemia group, and were significantly different than in the other group (p < 0.001). LDL-C was found to be independently related to EFT in the linear regression analysis.

CONCLUSIONS

Epicardial fat thickness increased in the familial hypercholesterolemia patients. In addition, LDL-C levels were significantly crelated with increased EFT.

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.

Correlation of epicardial fat quantification with severity of coronary artery disease: A study in Indian population

Objective

We studied the correlation of quantified epicardial fat with severity of coronary artery disease in patients [suspected cases of coronary artery disease (CAD)] referred for computed tomography (CT) coronary angiography and established cutoffs for epicardial fat volume (EFV) for the presence of CAD and obstructive CAD.

Methods

A prospective cum retrospective cross-sectional observational study was carried out on 950 Indian subjects (suspected cases of CAD) who were referred for coronary CT in the year 2013–2016. EFV was quantified using semiautomatic technique on multidetector coronary CT angiography. The presence of atherosclerotic plaques and degree of stenosis was assessed on coronary CT angiography scans. The correlation between quantified EFV and degree of stenosis was assessed. Multivariate analysis was also performed.

Results

A higher quantity of epicardial fat is found in patients with increasing severity of coronary artery stenosis. The EFV cutoff for the presence of CAD and obstructive CAD are 49.75 and 67.69 mL with area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 0.68, 81%, 45.9%,58.24%, 72.2%, and 62.84% and 0.709, 64.9%, 66.4%, 35.84%, 86.55%, and 66%, respectively. EFV correlates with age, weight, and body mass index (BMI). Multivariate analysis revealed EFV to be an independent risk factor for the presence of CAD.

Conclusions

Higher quantities of EFV are found in patients with greater degree of coronary artery stenosis. EFV correlates with age, weight, and BMI. EFV is an independent risk factor for CAD.

Inflammation of brown/beige adipose tissues in obesity and metabolic disease

Many of the comorbidities of obesity, including type 2 diabetes and cardiovascular diseases, are related to the low-grade chronic inflammation of white adipose tissue. Under white adipocyte stress, local infiltration of immune cells and enhanced production of pro-inflammatory cytokines together reduce metabolic flexibility and lead to insulin resistance in obesity. Whereas white adipocytes act in energy storage, brown and beige adipocytes specialize in energy expenditure. Brown and beige activity protects against obesity and associated metabolic disorders, such as hyperglycaemia and hyperlipidaemia. Compared to white fat, brown adipose tissue depots are less susceptible to developing local inflammation in response to obesity; however, strong obesogenic insults ultimately induce a locally pro-inflammatory environment in brown fat. This condition directly alters the thermogenic activity of brown fat by impairing its energy expenditure mechanism and uptake of glucose for use as a fuel substrate. Pro-inflammatory cytokines also impair beige adipogenesis, which occurs mainly in subcutaneous adipose tissue. There is evidence that inflammatory processes occurring in perivascular adipose tissues alter their brown-versus-white plasticity, impair the extent of browning in these depots and favour the local release of vasculature damaging signals. In summary, the targeting of brown and beige adipose tissues by pro-inflammatory signals and the subsequent impairment of their thermogenic and metabolite draining activities appears to represent obesity-driven disturbances that contribute to metabolic syndrome and cardiovascular alterations in obesity.

Effects of antidiabetic drugs on epicardial fat

Epicardial adipose tissue is defined as a deposit of adipocytes with pathophysiological properties similar to those of visceral fat, located in the space between the myocardial muscle and the pericardial sac. When compared with subcutaneous adipose tissue, visceral adipocytes show higher metabolic activity, lipolysis rates, increased insulin resistance along with more steroid hormone receptors. The epicardial adipose tissue interacts with numerous cardiovascular pathways via vasocrine and paracrine signalling comprised of pro- and anti-inflammatory cytokines excretion. Both the physiological differences between the two tissue types, as well as the fact that fat distribution and phenotype, rather than quantity, affect cardiovascular function and metabolic processes, establish epicardial fat as a biomarker for cardiovascular and metabolic syndrome. Numerous studies have underlined an association of altered epicardial fat morphology, type 2 diabetes mellitus (T2DM) and adverse cardiovascular events. In this review, we explore the prospect of using the epicardial adipose tissue as a therapeutic target in T2DM and describe the underlying mechanisms by which the antidiabetic drugs affect the pathophysiological processes induced from adipose tissue accumulation and possibly allow for more favourable cardiovascular outcomes though epicardial fat manipulation.

Epicardial adipose tissue feeding and overfeeding the heart

Epicardial adipose tissue is a particular visceral fat depot with unique anatomic, biomolecular, and genetic features. Epicardial fat displays both physiological and pathological properties. Epicardial fat expresses genes and secretes cytokines actively involved in the thermogenesis and regulation of lipid and glucose metabolism of the adjacent myocardium. A disequilibrium between epicardial fat feeding and overfeeding the myocardium with free fatty acids leads to intramyocardial fat infiltration causing organ damage and clinical consequences. The upregulation of epicardial fat proinflammatory and lipogenic genes contributes to the fat build up in the proximal coronary arteries. Epicardial fat is a measurable and modifiable risk factor that can serve as a novel and additional tool for cardiovascular risk stratification. Pharmacologically targeting epicardial fat with drugs such as glucagon peptide-like 1 analogs or sodium glucose transport 2 inhibitors reduces the epicardial fat burden and induces beneficial cardiometabolic effects. Assessment and manipulation of epicardial fat transcriptome might open new avenues in the prevention of cardiometabolic diseases.

Interplay between epicardial adipose tissue, metabolic and cardiovascular diseases

Cardiovascular disease is the primary cause of death in obese and diabetic patients. In these groups of patients, the alterations of epicardial adipose tissue (EAT) contribute to both vascular and myocardial dysfunction. Therefore, it is of clinical interest to determine the mechanisms by which EAT influences cardiovascular disease. Two key factors contribute to the tight intercommunication among EAT, coronary arteries and myocardium. One is the close anatomical proximity between these tissues. The other is the capacity of EAT to secrete cytokines and other molecules with paracrine and vasocrine effects on the cardiovascular system. Epidemiological studies have demonstrated that EAT thickness is associated with not only metabolic syndrome but also atherosclerosis and heart failure. The evaluation of EAT using imaging modalities, although effective, presents several disadvantages including radiation exposure, limited availability and elevated costs. Therefore, there is a clinical interest in EAT as a source of new biomarkers of cardiovascular and endocrine alterations. In this review, we revise the mechanisms involved in the protective and pathological role of EAT and present the molecules released by EAT with greater potential to become biomarkers of cardiometabolic alterations.

Epicardial Adipose Tissue May Mediate Deleterious Effects of Obesity and Inflammation on the Myocardium

Epicardial adipose tissue has unique properties that distinguish it from other depots of visceral fat. Rather than having distinct boundaries, the epicardium shares an unobstructed microcirculation with the underlying myocardium, and in healthy conditions, produces cytokines that nourish the heart. However, in chronic inflammatory disorders (especially those leading to heart failure with preserved ejection fraction), the epicardium becomes a site of deranged adipogenesis, leading to the secretion of proinflammatory adipokines that can cause atrial and ventricular fibrosis. Accordingly, in patients at risk of heart failure with preserved ejection fraction, drugs that promote the accumulation or inflammation of epicardial adipocytes may lead to heart failure, whereas treatments that ameliorate the proinflammatory characteristics of epicardial fat may reduce the risk of heart failure. These observations suggest that epicardial adipose tissue is a transducer of the adverse effects of systemic inflammation and metabolic disorders on the heart, and thus, represents an important target for therapeutic interventions.

The effect of dapagliflozin treatment on epicardial adipose tissue volume

BACKGROUND

Glycosuria produced by sodium-glucose co-transporter-2 (SGLT-2) inhibitors is associated with weight loss. SGLT-2 inhibitors reportedly might reduce the occurrence of cardiovascular events. Epicardial adipose tissue (EAT) is a pathogenic fat depot that may be associated with coronary atherosclerosis. The present study evaluated the relationship between an SGLT-2 inhibitor (dapagliflozin) and EAT volume.

METHODS

In 40 diabetes mellitus patients with coronary artery disease (10 women and 30 men; mean age of all 40 patients was 67.2 ± 5.4 years), EAT volume was compared prospectively between the dapagliflozin treatment group (DG; n = 20) and conventional treatment group (CTG; n = 20) during a 6-month period. EAT was defined as any pixel that had computed tomography attenuation of - 150 to - 30 Hounsfield units within the pericardial sac. Metabolic parameters, including HbA1c, tumor necrotic factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1) levels, were measured at both baseline and 6-months thereafter.

RESULTS

There were no significant differences at baseline of EAT volume and HbA1c, PAI-1, and TNF-α levels between the two treatment groups. After a 6-month follow-up, the change in HbA1c levels in the DG decreased significantly from 7.2 to 6.8%, while body weight decreased significantly in the DG compared with the CTG (- 2.9 ± 3.4 vs. 0.2 ± 2.4 kg, p = 0.01). At the 6-month follow-up, serum PAI-1 levels tended to decline in the DG. In addition, the change in the TNF-α level in the DG was significantly greater than that in the CTG (- 0.5 ± 0.7 vs. 0.03 ± 0.3 pg/ml, p = 0.03). Furthermore, EAT volume significantly decreased in the DG at the 6-month follow-up compared with the CTG (- 16.4 ± 8.3 vs. 4.7 ± 8.8 cm³, p = 0.01). Not only the changes in the EAT volume and body weight, but also those in the EAT volume and TNF-α level, showed significantly positive correlation.

CONCLUSION

Treatment with dapagliflozin might improve systemic metabolic parameters and decrease the EAT volume in diabetes mellitus patients, possibly contributing to risk reduction in cardiovascular events.

Novel atherogenic pathways from the differential transcriptome analysis of diabetic epicardial adipose tissue

BACKGROUND AND AIM

To evaluate the epicardial adipose tissue (EAT) transcriptome in comparison to subcutaneous fat (SAT) in coronary artery disease (CAD) and type 2 diabetes (T2DM).

METHODS AND RESULTS

SAT and EAT samples were obtained from subjects with T2DM and CAD (n = 5) and those without CAD with or without T2DM (=3) undergoing elective cardiac surgery. RNA-sequencing analysis was performed in both EAT and SAT. Gene enrichment analysis was conducted to identify pathways affected by the differentially expressed genes. Changes of top genes were verified by quantitative RT-PCR (qRT-PCR), western blot, and immunofluorescence. A total of 592 genes were differentially expressed in diabetic EAT, whereas there was no obvious changes in SAT transcriptome between diabetics and non-diabetics. Diabetic EAT was mainly enriched in inflammatory genes, such as Colony Stimulating Factor 3 (CSF3), Interleukin-1b (IL-1b), IL-6. KEGG pathway analysis confirmed that upregulated genes were involved in inflammatory pathways, such as Tumor Necrosis Factor (TNF), Nuclear Factor-κB (NF-κB) and advanced glycation end-products-receptor advanced glycation end products (AGE-RAGE). The overexpression of inflammatory genes in diabetic EAT was largely correlated with upregulated transcription factors such as NF-κB and FOS.

CONCLUSIONS

Diabetic EAT transcriptome is significantly different when compared to diabetic SAT and highly enriched with genes involved in innate immune response and endothelium, like Pentraxin3 (PTX3) and Endothelial lipase G (LIPG). EAT inflammatory genes expression could be induced by upregulated transcription factors, mainly NF-kB and FOSL, primarily activated by the overexpressed AGE-RAGE signaling. This suggests a unique and novel atherogenic pathway in diabetes.

Ipragliflozin Reduces Epicardial Fat Accumulation in Non-Obese Type 2 Diabetic Patients with Visceral Obesity: A Pilot Study

INTRODUCTION

Epicardial fat (EF) was reported to be independently associated with cardiovascular disease regardless of obesity. We have previously reported that a sodium-glucose co-transporter-2 (SGLT2) inhibitor, luseogliflozin, reduces the EF volume (EFV) in parallel with the reduction of body weight in obese patients (BMI ≥25 kg/m²) with type 2 diabetes. However, it is unknown whether SGLT2 inhibitors could reduce EFV in non-obese patients (BMI <25 kg/m²) with type 2 diabetes. Therefore, we evaluated the effect of SGLT2 inhibitors on the EFV in non-obese type 2 diabetic patients with visceral obesity in this pilot study.

METHODS

Nine of type 2 diabetic patients (mean age 66 ± 8 years; 33% female) with HbA_1c 6.5-9.0%, body mass index (BMI, kg/m²) <25.0, and visceral fat area (VFA, cm²) ≥100 were enrolled. Participants were administered ipragliflozin 50 mg daily. EFV [median (interquartile range), cm³] was measured by magnetic resonance imaging. Primary endpoint was the change in EFV at 12 weeks. VFA and liver attenuation index (LAI), skeletal muscle index (SMI), and body fat (%) were also assessed at baseline and at 12 weeks.

RESULTS

The EFV was significantly reduced from 102 (79-126) cm³ to 89 (66-109) cm³ by ipraglifrozin (p = 0.008). The body weight, BMI, HbA_1c, fasting plasma glucose, insulin, homeostasis model assessment-insulin resistance, triglycerides, leptin, body fat, android, gynoid, and VFA were significantly reduced and high-density lipoprotein cholesterol was significantly increased by ipraglifrozin at 12 weeks, whereas SFA and LAI were unchanged. The change in EFV was significantly correlated with the change in BMI.

CONCLUSIONS

A12-week intervention of ipragliflozin reduced the EFV in non-obese type 2 diabetic patients with visceral adiposity.

CLINICAL TRIAL REGISTRATION

UMIN Clinical Trial Registry: UMIN000019071.

FUNDING

Astellas Pharma Inc. and the Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

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.

Re: "Plasminogen Activator Inhibitor-1 and Pericardial Fat in Individuals with Type 2 Diabetes Mellitus" by Bayomi et al. (Metab Syndr Relat Disord 2017;15:269-275)

Plasminogen activator inhibitor-1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily, which inactivates tissue plasminogen activator (tPA); therefore, increased level of PAI-1 antigen counteracts the anticoagulant effect of tPA and facilitates the fibrin clot formation. Plasma PAI-1 antigen and activity levels are associated with increased body mass index and with features of the insulin resistance syndrome like obesity and diabetes. Visceral adipose tissue produces more PAI-1 than subcutaneous adipose tissue: This increased production of PAI-1 from the visceral adipose tissue is one important link between visceral obesity and cardiovascular disease. Besides visceral adipose tissue, there is mounting evidence that epicardial adipose tissue may be an important source of PAI-1, especially in patients with type 2 diabetes.

Regulation of visceral and epicardial adipose tissue for preventing cardiovascular injuries associated to obesity and diabetes

Nowadays, obesity is seriously increasing in most of the populations all over the world, and is associated with the development and progression of high-mortality diseases such as type-2 diabetes mellitus (T2DM) and its subsequent cardiovascular pathologies. Recent data suggest that both body fat distribution and adipocyte phenotype, can be more determinant for fatal outcomes in obese patients than increased general adiposity. In particular, visceral adiposity is significantly linked to long term alterations on different cardiac structures, and in developed forms of myocardial diseases such as hypertensive and ischaemic heart diseases, and diabetic cardiomyopathy. Interestingly, this depot may be also related to epicardial fat accumulation through secretion of lipids, adipokines, and pro-inflammatory and oxidative factors from adipocytes. Thus, visceral adiposity and its white single-lipid-like adipocytes, are risk factors for different forms of heart disease and heart failure, mainly in higher degree obese subjects. However, under specific stimuli, some of these adipocytes can transdifferentiate to brown multi-mitochondrial-like adipocytes with anti-inflammatory and anti-apoptotic proprieties. Accordingly, in order to improve potential cardiovascular abnormalities in obese and T2DM patients, several therapeutic strategies have been addressed to modulate the visceral and epicardial fat volume and phenotypes. In addition to lifestyle modifications, specific genetic manipulations in adipose tissue and administration of PPARγ agonists or statins, have improved fat volume and phenotype, and cardiovascular failures. Furthermore, incretin stimulation reduced visceral and epicardial fat thickness whereas increased formation of brown adipocytes, alleviating insulin resistance and associated cardiovascular pathologies.

Luseogliflozin reduces epicardial fat accumulation in patients with type 2 diabetes: a pilot study

BACKGROUND

Accumulation of epicardial fat (EF) is associated with increased cardio-metabolic risks and coronary events, independently of traditional cardiovascular risk factors. Therefore, the reduction of EF volume (EFV) may be associated with reduced cardio-metabolic risks and future cardiovascular events. Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce body fat including visceral fat and cardiovascular events in patients with type 2 diabetes. However, it has still been unknown whether SGLT2 inhibitors can reduce EFV.

METHODS

Type 2 diabetic patients with HbA1c 6.5-9.0% and body mass index (BMI, kg/m2) ≥25.0 were enrolled in this single arm pilot study. Participants were administered luseogliflozin 2.5 mg daily and the dosage was tolerated to be increased up to 5.0 mg daily. EFV [median (interquartile range), cm3] was measured by magnetic resonance imaging. Primary endpoint was the decrease in EFV at 12 weeks. Visceral fat area (VFA, cm2) and liver attenuation index (LAI) measured by the abdominal computed tomography, and skeletal muscle index (SMI) and body fat (%) measured by the whole body dual-energy X-ray absorptiometry were also determined at baseline and at 12 weeks.

RESULTS

Nineteen patients (mean age: 55 ± 12 years; 26% female) completed this study. Luseogliflozin treatment significantly reduced EFV at 12 weeks [117 (96-136) to 111 (88-134), p = 0.048]. The body weight, BMI, systolic and diastolic blood pressure, HbA1c, fasting plasma glucose, insulin, homeostasis model assessment-insulin resistance (HOMA-IR), triglycerides, SMI, and body fat were significantly reduced by luseogliflozin at 12 weeks. The reduction of EFV was significantly correlated with the reduction of C-reactive protein (r = 0.493, p = 0.019). Neither VFA nor LAI were significantly reduced by the luseogliflozin treatment. No severe adverse events were observed.

CONCLUSIONS

Our data suggest that luseogliflozin could reduce the EFV in parallel with the improvement of systemic micro-inflammation and the reduction of body weight in Japanese patients with type 2 diabetes. The reduction of muscle mass after the administration of SGLT2 inhibitors may require a particular attention. Trial registration umin.ac.jp, UMIN000019072.

The ratio of epicardial to body fat improves the prediction of coronary artery disease beyond calcium and Framingham risk scores

The association between epicardial fat and coronary artery disease (CAD) might be affected by general adiposity. We aimed to determine whether the percentage of epicardial adipose tissue (%EAT), defined as the mass ratio of epicardial fat to body fat, could improve prediction of asymptomatic CAD. We consecutively enrolled 846 adults who underwent coronary computed tomography angiography as part of a health check-up and assessed their coronary stenosis severity and epicardial fat mass. Body fat mass was measured by bioelectrical impedance analysis. Subjects with CAD history, hyperthyroidism, pitting edema, or subjects taking diuretics or thiazolidinedione were excluded. Obstructive CAD was defined as at least one coronary artery with 50 % or greater obstruction, and severe CAD was defined as 70 % or greater obstruction. The %EAT had the maximum area under the curve for predicting the presence of CAD and superior discriminative performance to EAT and other EAT-indexed parameters. Multivariable logistic regression analysis revealed that %EAT >0.41 % was a predictor of obstructive CAD [odds ratio 3.59 (95 % confidence interval 2.28-5.64)], and %EAT >0.47 % was a predictor of severe CAD [4.01 (2.01-7.99)] after adjustment for calcium score and Framingham risk score. This prediction was more pronounced in subjects with higher body fat percentage (≥25 % for men and ≥35 % for women), Framingham risk score (≥10 %), or calcium score (≥100). A spillover of body fat at epicardium over a critical threshold is associated with significant coronary stenosis. This association was independent of obesity, coronary calcium burden, and Framingham risk factors.