Epicardial adipose tissue: emerging physiological, pathophysiological and clinical features

Epicardial Adipose Tissue and Diabetic Cardiomyopathy

Diabetes is a long-term chronic disease, and cardiovascular disease is the leading cause of death. Diabetic cardiomyopathy (DCM), one of the cardiovascular complications of diabetes, has many uncertain factors. Epicardial fat, as the heart fat bank, functions as fatty tissue and is the heart's endocrine organ. The existence of diabetes affects the distribution of heart fat and promotes the secretion of adipokine. In different pathological conditions, it can promote the secretion of pro-inflammatory adipokine, reactive oxygen species, oxidative stress, and even autophagy, thus affecting cardiac function. In this paper, we will elaborate on the mechanism of epicardial fat in the pathogenesis of diabetic cardiomyopathy.

Macrophage polarization markers in subcutaneous, pericardial, and epicardial adipose tissue are altered in patients with coronary heart disease

Background

Epicardial and pericardial adipose tissue (EAT and PAT) surround and protect the heart, with EAT directly sharing the microcirculation with the myocardium, possibly presenting a distinct macrophage phenotype that might affect the inflammatory environment in coronary heart disease (CHD). This study aims to investigate the expression of genes in different AT compartments driving the polarization of AT macrophages toward an anti-inflammatory (L-Galectin 9; CD206) or pro-inflammatory (NOS2) phenotype.

Methods

EAT, PAT, and subcutaneous (SAT) biopsies were collected from 52 CHD patients undergoing coronary artery bypass grafting, and from 22 CTRLs undergoing aortic valve replacement. L-Galectin9 (L-Gal9), CD206, and NOS2 AT gene expression and circulating levels were analyzed through RT-PCR and ELISA, respectively.

Results

L-Gal9, CD206, and NOS2 gene expression was similar in all AT compartments in CHD and CTRLs, as were also L-Gal9 and CD206 circulating levels, while NOS2 serum levels were higher in CHD (p = 0.012 vs. CTRLs). In CTRLs, NOS2 expression was lower in EAT vs. SAT (p = 0.007), while in CHD patients CD206 expression was lower in both SAT and EAT as compared to PAT (p = 0.003, p = 0.006, respectively), suggestive of a possible macrophage reprogramming toward a pro-inflammatory phenotype in EAT. In CHD patients, NOS2 expression in SAT correlated to that in PAT and EAT (p = 0.007, both), CD206 expression correlated positively to L-Gal9 (p < 0.001) only in EAT, and CD206 expression associated with that of macrophage identifying markers in all AT compartments (p < 0.001, all). In CHD patients, subjects with LDL-C above 1.8 mmol/L showed significantly higher NOS2 expression in PAT and EAT as compared to subjects with LDL-C levels below (p < 0.05), possibly reflecting increased cardiac AT pro-inflammatory activation. In SAT and PAT, CD206 expression associated with BMI in both CHD and CTRLs (p < 0.05, all), and with L-Gal9 in EAT, however only in CTRLs (p = 0.002).

Conclusion

CHD seems to be accompanied by an altered cardiac, and especially epicardial AT macrophage polarization. This may represent an important pathophysiological mechanism and a promising field of therapy targeting the excessive AT inflammation, in need of further investigation.

Updates on obesity and the obesity paradox in cardiovascular diseases

The prevalence of obesity has reached pandemic proportions worldwide and certainly in the United States. Obesity is a well-established independent risk factor for development of many cardiovascular diseases (CVD), including heart failure, coronary heart disease, atrial fibrillation, and hypertension. Therefore, it is logical to expect obesity would have a strong correlation with CVD mortality. However, a substantial body of literature demonstrates a paradox with improved prognosis of overweight and obese patients with established CVD compared to lean patients with the identical CVD. Surprisingly, similar data has also shown that cardiovascular fitness, rather than weight loss alone, influences the relationship between obesity and mortality in those with established CVD. The impact of fitness, exercise, physical activity (PA), and weight loss and their relationship to the obesity paradox are all reviewed here.

Long-term association of pericardial adipose tissue with incident diabetes and prediabetes: the Coronary Artery Risk Development in Young Adults Study

OBJECTIVES

We examined whether pericardial adipose tissue (PAT) is predictive of prediabetes and type 2 diabetes over time.

METHODS

In total, 2,570 adults without prediabetes/diabetes from the Coronary Artery Risk Development in Young Adults Study were followed up over 15 years. PAT volume was measured by computed tomography scans, and the new onset of prediabetes/diabetes was examined 5 years, 10 years, and 15 years after the PAT measurements. Multivariable Cox regression models were used to examine the association between the tertile of PAT and incident prediabetes/diabetes up to 15 years later. The predictive ability of PAT (vs. waist circumference [WC], body mass index [BMI], waist-to-height ratio [WHtR]) for prediabetes/diabetes was examined by comparing the area under the receiver operating characteristic curve (AUC).

RESULTS

The highest tertile of PAT was associated with a 1.56 times (95% confidence interval [CI], 1.03 to 2.34) higher rate of diabetes than the lowest tertile; however, no association was found between the highest tertile of PAT and prediabetes in the fully adjusted models, including additional adjustment for BMI or WC. In the fully adjusted models, the AUCs of WC, BMI, WHtR, and PAT for predicting diabetes were not significantly different, whereas the AUC of WC for predicting prediabetes was higher than that of PAT.

CONCLUSIONS

PAT may be a significant predictor of hyperglycemia, but this association might depend on the effect of BMI or WC. Additional work is warranted to examine whether novel adiposity indicators can suggest advanced and optimal information to supplement the established diagnosis for prediabetes/diabetes.

Cardiac Hypertrophy and Related Dysfunctions in Cushing Syndrome Patients-Literature Review

The survival rate of adrenal Cushing syndrome patients has been greatly increased because of the availability of appropriate surgical and pharmacological treatments. Nevertheless, increased possibility of a heart attack induced by a cardiovascular event remains a major risk factor for the survival of affected patients. In experimental studies, hypercortisolemia has been found to cause cardiomyocyte hypertrophy via glucocorticoid receptor activation, including the possibility of cross talk among several hypertrophy signals related to cardiomyocytes and tissue-dependent regulation of 11β-hydroxysteroid dehydrogenase type 1. However, the factors are more complex in clinical cases, as both geometric and functional impairments leading to heart failure have been revealed, and their associations with a wide range of factors such as hypertension are crucial. In addition, knowledge regarding such alterations in autonomous cortisol secretion, which has a high risk of leading to heart attack as well as overt Cushing syndrome, is quite limited. When considering the effects of treatment, partial improvement of structural alterations is expected, while functional disorders are controversial. Therefore, whether the normalization of excess cortisol attenuates the risk related to cardiac hypertrophy has yet to be fully elucidated.

Impact of Dysfunctional Adipose Tissue Depots on the Cardiovascular System

Obesity with its associated complications represents a social, economic and health problem of utmost importance worldwide. Specifically, obese patients carry a significantly higher risk of developing cardiovascular disease compared to nonobese individuals. Multiple molecular mechanisms contribute to the impaired biological activity of the distinct adipose tissue depots in obesity, including secretion of proinflammatory mediators and reactive oxygen species, ultimately leading to an unfavorable impact on the cardiovascular system. This review summarizes data relating to the contribution of the main adipose tissue depots, including both remote (i.e., intra-abdominal, hepatic, skeletal, pancreatic, renal, and mesenteric adipose fat), and cardiac (i.e., the epicardial fat) adipose locations, on the cardiovascular system. Finally, we discuss both pharmacological and non-pharmacological strategies aimed at reducing cardiovascular risk through acting on adipose tissues, with particular attention to the epicardial fat.

Shared Mechanisms between Cardiovascular Disease and NAFLD

The burden of nonalcoholic fatty liver disease (NAFLD) is rising globally. Cardiovascular disease is the leading cause of death in patients with NAFLD. Nearly half of individuals with NAFLD have coronary heart disease, and more than a third have carotid artery atherosclerosis. Individuals with NAFLD are at a substantially higher risk of fatal and nonfatal cardiovascular events. NAFLD and cardiovascular disease share multiple common disease mechanisms, such as systemic inflammation, insulin resistance, genetic risk variants, and gut microbial dysbiosis. In this review, we discuss the epidemiology of cardiovascular disease in NAFLD, and highlight common risk factors. In addition, we examine recent advances evaluating the shared disease mechanisms between NAFLD and cardiovascular disease. In conclusion, multidisciplinary collaborations are required to further our understanding of the complex relationship between NAFLD and cardiovascular disease and potentially identify therapeutic targets.

Pericardial adiposity is independently linked to adverse cardiovascular phenotypes: a CMR study of 42 598 UK Biobank participants

AIMS

We evaluated independent associations of cardiovascular magnetic resonance (CMR)-measured pericardial adipose tissue (PAT) with cardiovascular structure and function and considered underlying mechanism in 42 598 UK Biobank participants.

METHODS AND RESULTS

We extracted PAT and selected CMR metrics using automated pipelines. We estimated associations of PAT with each CMR metric using linear regression adjusting for age, sex, ethnicity, deprivation, smoking, exercise, processed food intake, body mass index, diabetes, hypertension, height cholesterol, waist-to-hip ratio, impedance fat measures, and magnetic resonance imaging abdominal visceral adiposity measures. Higher PAT was independently associated with unhealthy left ventricular (LV) structure (greater wall thickness, higher LV mass, more concentric pattern of LV hypertrophy), poorer LV function (lower LV global function index, lower LV stroke volume), lower left atrial ejection fraction, and lower aortic distensibility. We used multiple mediation analysis to examine the potential mediating effect of cardiometabolic diseases and blood biomarkers (lipid profile, glycaemic control, inflammation) in the PAT-CMR relationships. Higher PAT was associated with cardiometabolic disease (hypertension, diabetes, high cholesterol), adverse serum lipids, poorer glycaemic control, and greater systemic inflammation. We identified potential mediation pathways via hypertension, adverse lipids, and inflammation markers, which overall only partially explained the PAT-CMR relationships.

CONCLUSION

We demonstrate association of PAT with unhealthy cardiovascular structure and function, independent of baseline comorbidities, vascular risk factors, inflammatory markers, and multiple non-invasive and imaging measures of obesity. Our findings support an independent role of PAT in adversely impacting cardiovascular health and highlight CMR-measured PAT as a potential novel imaging biomarker of cardiovascular risk.

The Importance of the Assessment of Epicardial Adipose Tissue in Scientific Research

Epicardial adipose tissue (EAT) exhibits morphological similarities with pericardial adipose tissue, however, it has different embryological origin and vascularization. EAT is a metabolically active organ and a major source of anti-inflammatory and proinflammatory adipokines, which have a significant impact on cardiac function and morphology. Moreover, it can regulate vascular tone by releasing various molecules. The relationship between EAT and cardiovascular disease and diseases of other organ systems is now considered a common discussion subject. The present clinical review article summarizes the epidemiological findings based on imaging techniques in studies conducted so far. In conclusion, evaluation of the epicardial adipose tissue constitutes a helpful scientific parameter, which can be assessed by means of different diagnostic imaging examinations.

Correlation analysis of epicardial adipose tissue and ventricular myocardial strain in Chinese amateur marathoners using cardiac magnetic resonance

Background

The volume of epicardial adipose tissue (EAT) is associated with an increased incidence of cardiovascular disease (CVD); however, only a few studies have examined its effect on the myocardial function of endurance in athletes. The association between the EAT and the variation of myocardial function is still unclear in amateur marathoners. Consequently, by using some sedentary individuals as the control, this study aims to evaluate the correlation between the EAT volume and the myocardial strain in the left and right ventricles of Chinese amateur marathoners by cardiac magnetic resonance (CMR).

Methods

A total of 30 amateur marathoners were included as the exercise group and 20 sedentary people as a control group. All participants received the cardiac magnetic resonance (CMR) to measure the left and right ventricular end-diastolic volume, end-systolic volume and volume index, stroke volume and index, cardiac output index, ejection fraction and myocardial mass, the EAT volume, global radial, circumferential, and longi-tudinal strains, and the strain rates of left and right ventricular myocardium.

Results

There was a significant difference in the EAT volume (EATV) index between the exercise group and the control group (26.82±11.76ml/m² vs 37.82±17.15ml/m², P = 0.01). Results from the multivariate linear regression analysis showed that BMI (standardized β = 0.458; P < 0.001) had an independent positive correlation with the EATV index. The EATV index was negatively correlated with the left ventricular global radial strain (GRS) (r = -0.505; P = 0.004) in the exercise group, while it is negatively correlated with right ventricular GRS (r = -0.492; P = 0.027) and positively correlated with global longitudinal strain (GLS) (r = 0.601; P = 0.005) in the control group. In the exercise group, the multivariate linear regression analysis showed that the EATV index (standardized β = -0.429; P = 0.021) was an independent determinant of the left ventricular GRS, and being a male (standardized β = 0.396; P = 0.029) was an independent determinant of the right ventricular GLS.

Conclusion

The EATV index is independently correlated with the left ventricular GRS in the amateur Chinese marathoners, also, the amateur marathon reduces the EATV index and increases the left ventricular myocardial mass, which consequently reduces the adverse effects on myocardial function.

Systematic Review and Meta-Analysis of the Usefulness of Epicardial Fat Thickness as a Non-Invasive Marker of the Presence and Severity of Nonalcoholic Fatty Liver Disease

We performed a systematic review and meta-analysis to assess the association between epicardial fat thickness (EFT) and nonalcoholic fatty liver disease (NAFLD). This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) and was based on a registered protocol (CRD 4201809 5493). We searched Medline and Embase until December 2021 for studies reporting on the association between EFT and NAFLD. Qualitative reviews, meta-analyses and meta-regressions were performed to explore this association. Effect sizes are reported as standardized mean differences. We included 12 studies, comprising 3610 individuals. EFT was evaluated with trans-thoracic echocardiography in nine studies, two studies using cardiac computed tomography and one study using magnetic resonance imaging (MRI). The presence of NAFLD was evaluated using transabdominal liver ultrasound in nine studies. Other studies used histology, magnetic resonance spectroscopy and MRI-derived proton density fat fraction. Liver biopsy was performed to assess the severity of NAFLD in four studies. The random-effects meta-analysis indicated that, as compared to control patients with lean livers, patients with NAFLD displayed significantly higher EFT (standardized mean difference 0.61, 95% confidence interval: 0.47−0.75, p < 0.0001, I2 = 72%). EFT was further significantly higher in patients with severe liver steatosis versus patients with mild−moderate liver steatosis (standardized mean difference 1.21 95% confidence interval: 0.26−2.16, p < 0.001, I2 S = 96%). Through the meta-regression analysis, we found that patients with increasingly higher blood levels of aspartate aminotransferase displayed an increasingly higher depth of association. The current meta-analysis suggests that EFT may represent a useful surrogate for assessing the presence and severity of NAFLD in a non-invasive manner.

The correlation of pericoronary adipose tissue with coronary artery disease and left ventricular function

Objective

We sought to investigate the correlation of pericoronary adipose tissue with coronary artery disease and left ventricular (LV) function.

Methods

Participants with clinically suspected coronary artery disease were enrolled. All participants underwent coronary computed tomography angiography (CCTA) and echocardiography followed by invasive coronary angiography (ICA) within 6 months. Pericoronary adipose tissue (PCAT) was extracted to analyze the correlation with the Gensini score and LV function parameters, including IVS, LVPW, LVEDD, LVESD, LVEDV, LVESV, FS, LVEF, LVM, and LVMI. The correlation between PCAT and the Gensini score was assessed using Spearman’s correlation analysis, and that between the PCAT volume or FAI and LV function parameters was determined using partial correlation analysis.

Results

One hundred and fifty-nine participants (mean age, 64.55 ± 10.64 years; men, 65.4% [104/159]) were included in the final analysis. Risk factors for coronary artery disease, such as hypertension, diabetes, dyslipidemia, and a history of smoking or drinking, had no significant association with PCAT (P > 0.05), and there was also no correlation between PCAT and the Gensini score. However, the LAD-FAI was positively correlated with the IVS (r = 0.203, P = 0.013), LVPW (r = 0.218, P = 0.008), LVEDD (r = 0.317, P < 0.001), LVESD (r = 0.298, P < 0.001), LVEDV (r = 0.317, P < 0.001), LVESV (r = 0.301, P < 0.001), LVM (r = 0.371, P < 0.001), and LVMI (r = 0.304, P < 0.001). Also, the LCX-FAI was positively correlated with the LVEDD (r = 0.199, P = 0.015), LVESD (r = 0.190, P = 0.021), LVEDV (r = 0.203, P = 0.013), LVESV (r = 0.197, P = 0.016), LVM (r = 0.220, P = 0.007), and LVMI (r = 0.172, P = 0.036), and the RCA-FAI was positively correlated with the LVEDD (r = 0.258, P = 0.002), LVESD (r = 0.238, P = 0.004), LVEDV (r = 0.266, P = 0.001), LVESV (r = 0.249, P = 0.002), LVM (r = 0.237, P = 0.004), and LVMI (r = 0.218, P = 0.008), respectively. Finally, the total volume was positively correlated with FS (r = 0.167, P = 0.042).

Conclusion

The FAI was positively correlated with the LV function but was not associated with the severity of coronary artery disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02843-y.

A significant correlation exists between the fat attenuation index (FAI) and left ventricular function parameters.

Our results suggest that cardiac mortality caused by an increased FAI may be due to changes in the left ventricular function.

Pericoronary adipose tissue did not correlate with the body mass index or risk factors of coronary heart disease.

Big gamma-glutamyltransferase is associated with epicardial fat volume and cardiovascular outcome in the general population

AIMS

Gamma-glutamyltransferase (GGT) has been recognized as a cardiovascular risk factor, and its highest molecular weight fraction [big GGT (b-GGT)] is found in vulnerable atherosclerotic plaques. We explored the relationship between b-GGT, computed tomography findings, and long-term outcomes in the general population.

METHODS AND RESULTS

Between May 2010 and October 2011, subjects aged 45-75 years living in a Tuscan city and without known cardiac disease were screened. The primary endpoint was a composite of cardiovascular death or acute coronary syndrome requiring urgent coronary revascularization. Gamma-glutamyltransferase fractions were available in 898 subjects [median age 65 years (25th-75th percentile 55-70), 46% men]. Median plasma GGT was 20 IU (15-29), and b-GGT was 2.28 (1.28-4.17). Coronary artery calcium (CAC) score values were 0 (0-60), and the volume of pro-atherogenic epicardial fat was 155 mL (114-204). In a model including age, sex, low-density lipoprotein (LDL) cholesterol, current or previous smoking status, hypertension, diabetes, obesity, b-GGT independently predicted epicardial fat volume (EFV) (r = 0.162, P < 0.001), but not CAC (P = 0.198). Over a 10.3-year follow-up (9.6-10.8), 27 subjects (3%) experienced the primary endpoint. We evaluated couples of variables including b-GGT and a cardiovascular risk factor, CAC or EFV. Big GGT yielded independent prognostic significance from age, LDL cholesterol, current or previous smoking status, hypertension, diabetes, obesity, but not CAC or EFV. Conversely, GGT predicted the primary endpoint even independently from CAC and EFV.

CONCLUSION

Big GGT seemed at least as predictive as the commonly available GGT assay; therefore, the need for b-GGT rather than GGT measurement should be carefully examined.

The Role and Implications of Epicardial Fat in Coronary Atherosclerotic Disease

The current minireview aims to assess the implications of epicardial fat secretory function in the development of coronary artery disease. The epicardial adipose tissue (EAT) is a visceral fat depot that has been described as a cardiovascular risk factor. In addition to its mechanical protection role and physiological secretory function, it seems that various secretion products of the epicardial fat are responsible for metabolic disturbances at the level of the cardiac muscle when in association with pre-existing pathological conditions, such as metabolic syndrome. There is a pathological reduction in sarcomere shortening, abnormal cytosolic Ca²⁺ fluxes, reduced expression of sarcoplasmic endoplasmic reticulum ATPase 2a and decreased insulin-mediated Akt-Ser473-phosphorylation in association with abnormal levels of epicardial fat tissue. Activin A, angiopoietin-2, and CD14-positive monocytes selectively accumulate in the diseased myocardium, resulting in reduced cardiomyocyte contractile function. At the same time, it is believed that these alterations in secretory products directly decrease the myocyte function via molecular changes, thus contributing to the development of coronary disease when certain comorbidities are associated.

Epicardial Adipose Tissue in Patients with Coronary Artery Disease: A Meta-Analysis

Objective: The aim of this study is to assess the association between epicardial adipose tissue (EAT) and coronary artery disease (CAD) via meta−analysis. Methods: Specific searches of online databases from January 2000 to May 2022 were conducted. All observational studies evaluating the association between EAT and CAD in PubMed, Web of Science, and the Cochrane Library databases were screened. A meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta−Analyses guidelines (PRISMA). In total, 21 studies encompassing 4975 subjects met the inclusion criteria, including 2377 diagnosed and assigned as the CAD group, while the other 2598 were assigned as the non−CAD group. Subjects in the CAD group were further divided into the severe stenosis group (stenosis ≥ 50%, n = 846) and the mild/moderate stenosis group (stenosis < 50%, n = 577). Results: Both the volume and thickness of EAT in the CAD group were larger compared to the non−CAD group (p < 0.00001). In a subgroup analysis within the CAD group, the severe stenosis group had a larger volume and thickness with respect to EAT when compared to the mild/moderate group (p < 0.001). Conclusions: The enlargement of EAT presented in CAD patients with an association with CAD severity. Although limited by different CAD types and measuring methods for EAT, as well as a smaller sample size, our results suggest that EAT is a novel predictor and a potential therapeutic target for CAD.

Evaluation of subclinical cardiovascular risk and cardiac function in children with vesicoureteral reflux: a prospective study

BACKGROUND

Vesicoureteral reflux is a prominent congenital anomaly of the kidney and the urinary tract. Further, renal scarring is known to be related to chronic inflammation. However, there have been limited studies to date regarding the cardiovascular consequences of vesicoureteral reflux.

OBJECTIVE

The aim of this study is to evaluate the possible subclinical atherosclerosis and cardiovascular complications in children with vesicoureteral reflux.

METHODS

Patients with vesicoureteral reflux and age matched healthy controls were prospectively included in this case-control study. Patients were divided into two groups concerning renal scarring status. To assess cardiac functions, carotid artery intima media, epicardial adipose tissue, and periaortic adipose tissue thicknesses were evaluated.

RESULTS

There were 50 patients with vesicoureteral reflux; 26 patients without renal scarring and 24 patients with renal scarring, as well as 40 healthy controls. Myocardial performance indexes (Tei indexes) measured by tissue Doppler echocardiography from septum and left ventricle were significantly increased in study group (for all, p < 0.001). Also, intima media, epicardial adipose tissue, and periaortic adipose tissue thicknesses of the study groups were significantly higher than the control group (for all, p < 0.001). However, no statistical difference was observed between renal scarring (-) and renal scarring (+) groups.

CONCLUSIONS

Results of our study showed early deterioration of cardiac systolic and diastolic functions in children with vesicoureteral reflux regardless of renal scarring. Also, diagnosis of vesicoureteral reflux is an important risk factor for subclinical atherosclerosis, independent of renal scarring, which should be considered in the follow-up of these patients.

Connecting the dots between inflammatory cascades of obesity and COVID-19 in light of mortal consequences-a review

Obesity is a term that has recently been referred to describe a condition in which a person has become a diseased vessel. Obesity's internal pathology is too mysterious as it has a close resemblance with fatal diseases pathology. Obesity and coronavirus disease 2019 (COVID-19) are simultaneous epidemics declared by many organizations after observing their rampage in the recent world. Oxidative stress, cytokine storm, interleukin, and their contribution to the internal adipocyte environment implicated in the cascades of inflammatory pathology are portrayed here. Major determinants like angiotensin-converting enzyme 2 (ACE2) and renin-angiotensin-aldosterone system (RAAS) axis are highly sensitive molecular factors. Data from various countries suggested a clinical overview of how greater body mass index (BMI) is related to greater COVID-19 risk. It also gives insight into how obese individuals are obligately getting admitted and combating COVID-19 in intensive care unit including children less than 13 years of age under ultimate therapeutic options. There are numerous studies currently taking place for finding a cure for obesity which are mainly focused on natural resources and novel therapies like photobiomodulation (PBM) consisting of laser treatment, infrared treatment, etc. as current pharmacological treatments are reported to have fatal adverse effects. Finally, it is discussed how attenuating obesity will be a solution for future combat strategy. This review gives light on the areas of coagulation, inflammatory parameters, cardiometabolic complications, endothelial dysfunctions, immunological infirmity due to COVID-19 in obese individuals. A conceptual outline about correlation between the inflammatory pathophysiological steps triggering the aggravation of fatal consequences has been drawn in this review.

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.

Identification of genes and key pathways underlying the pathophysiological association between nonalcoholic fatty liver disease and atrial fibrillation

Background

Atrial fibrillation (AF) is one of the most prevalent sustained cardiac arrhythmias. The latest studies have revealed a tight correlation between nonalcoholic fatty liver disease (NAFLD) and AF. However, the exact molecular mechanisms underlying the association between NAFLD and AF remain unclear. The current research aimed to expound the genes and signaling pathways that are related to the mechanisms underlying the association between these two diseases.

Materials and methods

NAFLD- and AF- related differentially expressed genes (DEGs) were identified via bioinformatic analysis of the Gene Expression Omnibus (GEO) datasets GSE63067 and GSE79768, respectively. Further enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), the construction of a protein–protein interaction (PPI) network, the identification of significant hub genes, and receiver operator characteristic curve analysis were conducted. The gene-disease interactions were analyzed using the Comparative Toxicogenomics Database. In addition, the hub genes were validated by quantitative Real-Time PCR (qRT-PCR) in NAFLD cell model.

Results

A total of 45 co-expressed differentially expressed genes (co-DEGs) were identified between the NAFLD/AF and healthy control individuals. GO and KEGG pathway analyses revealed that the co-DEGs were mostly enriched in neutrophil activation involved in the immune response and cytokine-cytokine receptor interactions. Moreover, eight hub genes were selected owing to their high degree of connectivity and upregulation in both the NAFLD and AF datasets. These genes included CCR2, PTPRC, CXCR2, MNDA, S100A9, NCF2, S100A12, and S100A8.

Conclusions

In summary, we conducted the gene differential expression analysis, functional enrichment analysis, and PPI analysis of DEGs in AF and NAFLD, which provides novel insights into the identification of potential biomarkers and valuable therapeutic leads for AF and NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01300-1.

Higher epicardial fat in older adults living with HIV with viral suppression and relationship with liver steatosis, coronary calcium and cardiometabolic risks

OBJECTIVES

HIV infection is associated with ectopic fat deposition, which leads to chronic inflammation and cardiometabolic dysregulation. We assessed the epicardial adipose tissue (EAT) volume and its associated factors among people with HIV (PWH).

DESIGN

A cross-sectional study.

METHODS

We conducted a cross-sectional study among PWH aged at least 50 years and age-matched and sex-matched HIV-negative older individuals in Bangkok, Thailand. Participants underwent a noncontrast, cardiac computed tomography (CT) scan to assess coronary artery calcium (CAC) score and EAT between March 2016 and June 2017. Multivariate linear regression analyses were used to investigate HIV-related factors, cardiac and metabolic markers associated with EAT volume.

RESULTS

Median age was 55 years [interquartile range (IQR) 52-60] and 63% were men. Median duration of antiretroviral therapy (ART) was 16 years with 97% had HIV-1 RNA less than 50 copies/ml and median CD4 + cell count of 617 cells/μl. Median EAT volume was significantly higher in PWH [99 (IQR 75-122) cm 3 ] than HIV-negative individuals [93 (IQR 69-117) cm 3 ], P  = 0.022. In adjusted model, factors associated with EAT volume included male sex ( P  = 0.045), older age ( P  < 0.001), abnormal waist circumference ( P  < 0.001) and HOMA-IR ( P  = 0.01). In addition, higher CAC score was independently associated with EAT volume. Higher mean EAT volume was seen in PWH with severe liver steatosis than those without steatosis ( P  = 0.018). In adjusted PWH-only model, duration of HIV was significantly associated with higher EAT volume ( P  = 0.028).

CONCLUSION

In an aging cohort, PWH had higher EAT volume than HIV-negative controls. EAT was also independently associated with central fat accumulation, insulin resistance, liver steatosis and CAC score.

Recent advances in potential of Fisetin in the management of myocardial ischemia-reperfusion injury-A systematic review

BACKGROUND

The primary therapeutic strategy in managing ischemic heart diseases is to restore the perfusion of the myocardial ischemic area by surgical methods that often result in an unavoidable injury called ischemia-reperfusion injury (IR). Fisetin is an effective flavonoid with antioxidant and anti-inflammatory properties, proven to be cardioprotective against IR injury in both in-vitro and invivo models, apart from its promising health benefits against cancer, diabetes, and neurodegenerative ailments.

PURPOSE

The potential of fisetin in attenuating myocardial IR is inconclusive as the effectiveness of fisetin needs more understanding in terms of its possible target sites and underlying different mechanisms. Considering the surge in recent scientific interests in fisetin as a pharmacological agent, this review not only updates the existing preclinical and clinical studies with fisetin and its underlying mechanisms but also summarizes its possible targets during IR protection.

METHODS

We performed a literature survey using search engines Pubmed, PMC, Science direct, Google, and research gate published across the years 2006-2021. The relevant studies were extracted from the databases with the combinations of the following keywords and summarized: myocardial ischemia-reperfusion injury, natural products, flavonoid, fisetin, PI3K, JAK-STAT, Nrf2, PKC, JNK, autophagy.

RESULTS

Fisetin is reported to be effective in attenuating IR injury by delaying the clotting time, preserving the mitochondrial function, reducing oxidative stress, and inhibiting GSK 3β. But it failed to protect diseased cardiomyocytes challenged to IR. As discussed in the current review, fisetin not only acts as a conventional antioxidant and anti-inflammatory agent to exert its biological effect but may also exert modulatory action on the cellular metabolism and adaptation via direct action on various signalling pathways that comprise PI3K, JAK-STAT, Nrf2, PKC, JNK, and autophagy. Moreover, the dosage of fisetin and co-morbidities like diabetes and obesity are found to be detrimental factors for cardioprotection.

CONCLUSION

For further evaluation and smooth clinical translation of the fisetin molecule in IR treatment, researchers should pay close attention to the potential of fisetin to possibly alter the key cardioprotective pathways and dosage, as the efficacy of fisetin is tissue and cell type-specific and varies with different doses.

Putative protective effects of sodium-glucose cotransporter 2 inhibitors on atrial fibrillation through risk factor modulation and off-target actions: potential mechanisms and future directions

Atrial fibrillation, the most common cardiac arrhythmia, results in substantial morbidity and mortality related to its increased risks of stroke, heart failure, and impaired cognitive function. The incidence and prevalence of atrial fibrillation in the general population is rising, making atrial fibrillation treatment and management of its risk factors highly relevant clinical targets. One well-studied risk factor for the development of atrial fibrillation is diabetes mellitus. Inhibitors of sodium-glucose cotransporter 2 (SGLT2), common medications used to treat diabetes mellitus, have been observed to decrease the incidence of atrial fibrillation. This review discusses the SGLT2 and its role in glucose homeostasis, molecules inhibiting the transporter, possible physiological mechanisms responsible for the decreased incident atrial fibrillation in patients treated with SGLT2 inhibitors and proposes mechanistic studies to further our understanding of the biological processes involved.

Accelerated fatty acid composition MRI of epicardial adipose tissue: Development and application to eplerenone treatment in a mouse model of obesity-induced coronary microvascular disease

Purpose

To develop an accelerated MRI method to quantify the epicardial adipose tissue (EAT) fatty acid composition (FAC) and test the hypothesis that eplerenone (EPL) shifts the EAT FAC toward unsaturation in obese mice.

Methods

Undersampled multi‐echo gradient echo imaging employing a dictionary‐based compressed‐sensing reconstruction and iterative decomposition with echo asymmetry and least‐squares–based mapping (IDEAL) was developed, validated, and used to study EAT in obese mice scanned at 7T. Fully sampled and rate 2, 2.5, 3, and 3.5 undersampled image data were acquired, reconstructed, and assessed using RMSE and structural similarity (SSIM). Two groups of mice were studied: untreated (control, n = 10) and EPL‐treated (n = 10) mice fed a high‐fat high‐sucrose diet. MRI included imaging of EAT FAC, EAT volume, and myocardial perfusion reserve.

Results

Rate 3 acceleration provided RMSE <5% and structural similarity >0.85 for FAC MRI. After 6 weeks of diet, EPL‐treated compared to untreated mice had a reduced EAT saturated fatty acid fraction (0.27 ± 0.09 vs. 0.39 ± 0.07, P < 0.05) and increased EAT unsaturation degree (4.37 ± 0.32 vs. 3.69 ± 0.58, P < 0.05). Also, EAT volume in EPL‐treated compared to untreated mice was reduced (8.1 ± 0.6 mg vs. 11.4 ± 0.7 mg, P < 0.01), and myocardial perfusion reserve was improved (1.83 ± 0.15 vs. 1.61 ± 0.17, P < 0.05).

Conclusion

Rate 3 accelerated FAC MRI enabled accurate quantification of EAT FAC in mice. EPL treatment shifted the EAT FAC toward increased unsaturation and was associated with improvement of coronary microvascular function.

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Epicardial adipose tissue is associated with higher recurrence risk after catheter ablation in atrial fibrillation patients: a systematic review and meta-analysis

OBJECTIVE

Our study aimed to investigate the association between epicardial adipose tissue (EAT) and atrial fibrillation (AF) recurrence risk after catheter ablation.

METHODS

We searched PubMed, Embase, and Cochrane Library databases up to November 30, 2021 without language restrictions. Outcome was the relative risk (RR) of EAT contributes to AF recurrence after catheter ablation. The RR and 95% confidence interval (CI) was pooled by the random-effect model.

RESULTS

10 studies that contained 1840 AF patients were included in our study. The result of this study showed that EAT amount was associated with higher risk of AF recurrence after catheter ablation (RR = 1.06, 95% CI 1.02-1.11, P = 0.005) and EAT related thickness was a risk factor for AF recurrence after catheter ablation (RR = 1.73, 95% CI 1.04-2.87, P = 0.040). Sub-analysis showed that EAT was strongly associated with higher risk of AF recurrence common in Asian population (RR = 1.25, 95% CI 1.10-1.43, P < 0.001), patients aged ≤ 60 years old (RR = 2.01, 95% CI 1.18-3.44, P = 0.010), and follow-up more than 1 year (RR = 1.06, 95% CI 1.01-1.11, P = 0.020).

CONCLUSION

The meta-analysis demonstrated that EAT related thickness seems to be the marker most strongly associated with a greater risk of AF recurrences after catheter ablation. It should be included into risk stratification for predicting AF recurrent before catheter ablation.

Association of Epicardial Fat with Diastolic and Vascular Functions in Children with Type 1 Diabetes

We aimed to examine the relationship between epicardial fat thickness (EFT) measured by echocardiography and cardiovascular functional parameters in children with type 1 diabetes mellitus (T1DM). The study included 50 type 1 diabetic children and 50 healthy subjects matched by sex, age, and body mass index. In addition to laboratory tests, all participants underwent transthoracic echocardiography for EFT, cardiac dimensions and left ventricular functions, and ultrasonographic examination for brachial artery flow-mediated dilation (FMD) response and carotid intima-media thickness (CIMT). Multivariate linear regression was used to analyze the relationship between EFT and CIMT, FMD, lateral mitral E' velocity, and mitral E/E' ratio. EFT was significantly increased in diabetic children compared with controls (P < 0.001). In comparison with controls diabetic children had significantly increased mitral A, decreased lateral mitral E', decreased mitral E/A ratio, decreased lateral mitral E'/A' ratio, and increased mitral E/E' ratio (P < 0.001). FMD response was significantly lower in diabetic group versus controls (P < 0.001) and CIMT was significantly increased in diabetics versus controls (P = 0.03). EFT was negatively correlated with lateral mitral E' velocity (r =  - 0.613, P < 0.001), positively correlated with mitral E/E' ratio (r = 0.60, P < 0.001), positively correlated with CIMT (r = 0.881, P < 0.001), and negatively correlated with FMD (r =  - 0.533, P < 0.001). By multivariate regression analysis, the EFT was independently and positively associated with CIMT mean and E/E' mean and negatively associated with FMD mean and E' mean. The cut-off point for EFT as predictor of endothelial dysfunction was 6.95 mm. Our findings suggest that children with T1DM have subclinical LV diastolic and vascular endothelial dysfunctions associated with increased EFT.

Epicardial fat volume is associated with preexisting atrioventricular conduction abnormalities and increased pacemaker implantation rate in patients undergoing transcatheter aortic valve implantation

Epicardial fat tissue (EFT) is a highly metabolically active fat depot surrounding the heart and coronary arteries that is related to early atherosclerosis and adverse cardiac events. We aimed to investigate the relationship between the amount of EFT and preexisting cardiac conduction abnormalities (CCAs) and the need for new postinterventional pacemaker in patients with severe aortic stenosis planned for transcatheter aortic valve implantation (TAVI). A total of 560 consecutive patients (54% female) scheduled for TAVI were included in this retrospective study. EFT volume was measured via a fully automated artificial intelligence software (QFAT) using computed tomography (CT) performed before TAVI. Baseline CCAs [first-degree atrioventricular (AV) block, right bundle branch block (RBBB), and left bundle branch block (LBBB)] were diagnosed according to 12-lead ECG before TAVI. Aortic valve calcification was determined by the Agatston score assessed in the pre-TAVI CT. The median EFT volume was 129.5 ml [IQR 94-170]. Baseline first-degree AV block was present in 17%, RBBB in 10.4%, and LBBB in 10.2% of the overall cohort. In adjusted logistic regression analysis, higher EFT volume was associated with first-degree AV block (OR 1.006 [95% CI 1.002-1.010]; p = 0.006) and the need for new pacemaker implantation after TAVI (OR 1.005 [95% CI 1.0-1.01]; p = 0.035) but not with the presence of RBBB or LBBB. EFT volume did not correlate with the Agatston score of the aortic valve. Greater EFT volume is associated independently with preexisting first-degree AV block and new pacemaker implantation in patients undergoing TAVI. It may play a causative role in degenerative processes and the susceptibility of the AV conduction system.

Cardiorespiratory Fitness in Adults Aged 18 to 34 Years and Long-Term Pericardial Adipose Tissue (from the Coronary Artery Risk Development in Young Adults Study)

Pericardial adipose tissue (PAT), an ectopic adipose depot surrounding the coronary arteries, is a pathogenic risk marker for cardiometabolic disease; however, the association between cardiorespiratory fitness (CRF) and PAT is unclear. Young adults (n = 2,614, mean age 25.1 years, 55.8% women, and 43.8% Black at baseline [1985 to 1986]) from the Coronary Artery Risk Development in Young Adults study were included. Maximal CRF was estimated at baseline, examination year 7 (1992 to 1993) and year 20 (2005 to 2006), using a symptom-limited maximal treadmill exercise test (duration in minutes) among those achieving ≥85% of age-predicted maximal heart rate. PAT volume (ml) was quantified at examination year 15 (2000 to 2001) and year 25 (2010 to 2011) using computed tomography. Multivariable linear and linear mixed regressions with covariates (sociodemographics, cardiovascular disease risk factors, inflammation, waist circumference) from baseline, year 7, and/or year 20 were used. Separate multivariable regression models revealed inverse associations of CRF at baseline, year 7, or year 20 with PAT at year 25 in fully adjusted models (all p <0.001). The linear mixed model showed that a 1-minute increase in treadmill exercise test duration over 20 years was associated with 1.49 ml lower subsequent PAT volume (p <0.001). In conclusion, findings suggest that higher CRF is inversely associated with subsequent PAT volume. Strategies to optimize CRF may be preventive against excessive PAT accumulation with age.

Cross-Sectional and Longitudinal Associations of Lifestyle Behaviors with Pericardial Adipose Tissue: The MESA Study

PURPOSE

We examined associations of sedentary behavior (SB), light-intensity physical activity (LPA), and moderate-to-vigorous intensity physical activity (MVPA) with pericardial adipose tissue (PAT).

METHODS

Adults from the Multi-Ethnic Study of Atherosclerosis were included from exam years 1 (2000-2002; N = 6057; mean age, 62.2 yr; 52.9% female, 38.0% White; 12.8% Chinese American, 26.7% African American, 22.5% Hispanic American), 2 (2002-2004), and 3 (2004-2005). Weekly volume of SB, LPA, and MVPA (in MET-hours per week) was reported using a questionnaire. PAT volume (in cubic centimeters) was quantified using computed tomography, analysis of covariance, and repeated-measures linear mixed models with adjustment for covariates (sociodemographics, cardiovascular disease risk factors, inflammation, waist circumference) tested cross-sectional and longitudinal associations, respectively.

RESULTS

In cross-sectional analysis, the highest tertile of SB (β = 2.71; 95% confidence interval (CI), 0.69 to 4.73; P < 0.01) and the middle tertile of MVPA (β = -1.97; 95% CI, -3.92 to -0.02; P < 0.05) were associated with PAT, whereas no association was observed for LPA in fully adjusted models. In longitudinal models, SB, LPA, and MVPA were not associated with PAT in the full study sample; however, LPA was inversely associated with PAT among Whites in stratified analysis (β = -0.54; 95% CI, -0.95 to -0.13; P < 0.05).

CONCLUSIONS

Lower SB and higher LPA (among Whites only) and MVPA may be associated with lower PAT, but additional longitudinal research is needed.

MicroRNA Expression Profiles of Epicardial Adipose Tissue-Derived Exosomes in Patients with Coronary Atherosclerosis

Background and Aims

Epicardial adipose tissue, exosomes, and miRNAs have important activities in atherosclerosis. The purpose of this study was to establish miRNA expression profiles of epicardial adipose tissue-derived exosomes in patients with coronary atherosclerosis.

Methods

Biopsies of epicardial adipose tissue were obtained from patients with and without coronary artery disease (CAD, n = 12 and NCAD, n = 12) during elective open-heart surgeries. Tissue was incubated with DMEM-F12 for 24 hours. Exosomes were isolated, then nanoparticle tracking analysis, transmission electron microscopy, and immunoblotting were performed to confirm the existence of exosomes. Total RNA in exosomes was subjected to high-throughput sequencing to identify differentially expressed miRNAs. MicroRNA target gene prediction was performed, and target genes were analyzed by Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG), and mirPath to identify function. Reverse transcription quantitative PCR was performed to confirm the differentially expressed miRNAs.

Results

Fifty-three unique miRNAs were identified (adjusted p < 0.05, fold of change > 2), among which 32 miRNAs were upregulated and 21 miRNAs were downregulated in coronary artery disease patients. Reverse transcription quantitative PCR validated the results for seven miRNAs including miR-141-3p, miR-183-5p, miR-200a-5p, miR-205-5p, miR-429, miR-382-5p and miR-485-3p, with the last two downregulated. GO and KEGG analysis by mirPath indicated that these differentially expressed miRNAs were enriched in cell survival, apoptosis, proliferation, and differentiation.

Conclusions

Coronary artery disease patients showed differential epicardial adipose tissue exosomal miRNA expression compared with patients without coronary artery disease. The results provide clues for further studies of mechanisms of atherosclerosis.

Epicardial adipose tissue, obesity and the occurrence of atrial fibrillation: an overview of pathophysiology and treatment methods

INTRODUCTION

Obesity is a chronic disease, which has significant health consequences and is a staggering burden to health care systems. Obesity can have harmful effects on the cardiovascular system, including heart failure, hypertension, coronary heart disease, and atrial fibrillation (AF). One of the possible substrates might be epicardial adipose tissue (EAT), which can be the link between AF and obesity. EAT is a fat deposit located between the myocardium and the visceral pericardium. Numerous studies have demonstrated that EAT plays a pivotal role in this relationship regarding atrial fibrillation.

AREAS COVERED

This review will focus on the role of obesity and the occurrence of atrial fibrillation (AF) and examine the connection between these and epicardial adipose tissue (EAT). The first part of this review will explain the pathophysiology of EAT and its association with the occurrence of AF. Secondly, we will review bariatric and metabolic surgery and its effects on EAT and AF.

EXPERT COMMENTARY

In this review, the epidemiology, pathophysiology, and treatments methods of AF are explained. Secondly the effects on EAT were elucidated. Due to the complex pathophysiological link between EAT, AF, and obesity, it is still uncertain which treatment strategy is superior.

Ectopic Fat Depots: Physiological Role And Impact On Cardiovascular Disease Continuum

Obesity is a non-infectious pandemic. The visceral distribution of adipose tissue is a significant factor in the development of cardiovascular diseases and their complications. Along with the visceral abdominal depot in omentum and subcutaneous tissue, there are other ectopic adipose tissue depots: epicardial adipose tissue (EAT), perivascular adipose tissue (PVAT) and perirenal adipose tissue. This article presents a review of the physiological role and molecular basis of the PVAT and EAT function in healthy, as well as in pathological, conditions; the interaction of adipokines and cytokines, their contribution to the development and progression of cardiovascular diseases. The review discusses well-known facts and controversial issues in this field. Comprehensive investigation of the mechanisms of vascular and myocardial pathology in obese people, along with identification of biomarkers for early prediction of cardiovascular complications, would contribute to the development of targeted preventive measures and choice of therapeutic strategies, which is consistent with the contemporary concept of personalized medicine. We have analyzed domestic and foreign literature sources in eLIBRARY and PubMed scientific libraries for the period of 2001-2020.

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.

Incremental Prognostic Value of Pericoronary Adipose Tissue Thickness Measured Using Cardiac Magnetic Resonance Imaging After Revascularization in Patients With ST-Elevation Myocardial Infarction

Background and Aim

Pericoronary adipose tissue (PCAT) reflects pericoronary inflammation and is associated with coronary artery disease. We aimed to identify the association between local PCTA thickness using cardiac magnetic resonance (CMR) and prognosis of patients with ST-elevation myocardial infarction (STEMI), and to investigate the incremental prognostic value of PCAT thickness in STEMI after reperfusion.

Methods

A total of 245 patients with STEMI (mean age, 55.61 ± 10.52 years) who underwent CMR imaging within 1 week of percutaneous coronary intervention therapy and 35 matched controls (mean age, 53.89 ± 9.45 years) were enrolled. PCAT thickness indexed to body surface area at five locations, ventricular volume and function, infarct-related parameters, and global strain indices were evaluated using CMR. Associations between PCAT thickness index and 1-year major adverse cardiovascular events (MACE) after STEMI were calculated. The prognostic value of the standard model based on features of clinical and CMR and updated model including PACT thickness index were further assessed.

Results

Patients with MACE had a more significant increase in PCAT thickness index at superior interventricular groove (SIVGi) than patients without MACE. The SIVGi was significantly associated with left ventricular ejection fraction (LVEF), infarct size, and global deformation. SIVGi &gt; 4.98 mm/m2 was an independent predictor of MACE (hazard ratio, 3.2; 95% CI: 1.6–6.38; p &lt; 0.001). The updated model significantly improved the power of prediction and had better discrimination ability than that of the standard model for predicting 1-year MACE (areas under the ROC curve [AUC] = 0.8 [95% CI: 0.74–0.87] vs. AUC = 0.76 [95% CI: 0.68–0.83], p &lt; 0.05; category-free net reclassification index [cfNRI] = 0.38 [95% CI: 0.1–0.53, p = 0.01]; integrated discrimination improvement [IDI] = 0.09 [95% CI: 0.01–0.18, p = 0.02]).

Conclusions

This study demonstrated SIVGi as an independent predictor conferred incremental value over standard model based on clinical and CMR factors in 1-year MACE predictions for STEMI.

Cardiovascular risk reduction throughout GLP-1 receptor agonist and SGLT2 inhibitor modulation of epicardial fat

Epicardial adipose tissue is a novel cardiovascular risk factor. It plays a role in the progression of coronary artery disease, heart failure and atrial fibrillation. Given its rapid metabolism, clinical measurability, and modifiability, epicardial fat works well as therapeutic target of drugs modulating the adipose tissue. Epicardial fat responds to glucagon-like peptide 1 receptor agonists (GLP1A) and sodium glucose co-transporter 2 inhibitors (SGLT2i). GLP-1A and SGLT2i provide weight loss and cardiovascular protective effects beyond diabetes control, as recently demonstrated. The potential of modulating the epicardial fat morphology and genetic profile with targeted pharmacological agents can open new avenues in the pharmacotherapy of diabetes and obesity, with particular focus on cardiovascular risk reduction.

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.

The endocrine role of brown adipose tissue: An update on actors and actions

In recent years, brown adipose tissue (BAT) has been recognized not only as a main site of non-shivering thermogenesis in mammals, but also as an endocrine organ. BAT secretes a myriad of regulatory factors. These so-called batokines exert local autocrine and paracrine effects, as well as endocrine actions targeting tissues and organs at a distance. The endocrine batokines include peptide factors, such as fibroblast growth factor-21 (FGF21), neuregulin-4 (NRG4), phospholipid transfer protein (PLTP), interleukin-6, adiponectin and myostatin, and also lipids (lipokines; e.g., 12,13-dihydroxy-9Z-octadecenoic acid [12,13-diHOME]) and miRNAs (e.g., miR-99b). The liver, heart, and skeletal muscle are the most commonly reported targets of batokines. In response to BAT thermogenic activation, batokines such as NRG4 and PLTP are released and act to reduce hepatic steatosis and improve insulin sensitivity. Stress-induced interleukin-6-mediated signaling from BAT to liver favors hepatic glucose production through enhanced gluconeogenesis. Batokines may act on liver to induce the secretion of regulatory hepatokines (e.g. FGF21 and bile acids in response to miR-99b and PLTP, respectively), thereby resulting in a systemic expansion of BAT-originating signals. Batokines also target extrahepatic tissues: FGF21 and 12,13-diHOME are cardioprotective, whereas BAT-secreted myostatin and 12,13-diHOME influence skeletal muscle development and performance. Further research is needed to ascertain in humans the role of batokines, which have been identified mostly in experimental models. The endocrine role of BAT may explain the association between active BAT and a healthy metabolism in the human system, which is characterized by small amounts of BAT and a likely moderate BAT-mediated energy expenditure.

Role of anatomical location, cellular phenotype and perfusion of adipose tissue in intermediary metabolism: A narrative review

It is well-established that adipose tissue accumulation is associated with insulin resistance through multiple mechanisms. One major metabolic link is the classical Randle cycle: enhanced release of free fatty acids (FFA) from hydrolysis of adipose tissue triglycerides impedes insulin-mediated glucose uptake in muscle tissues. Less well studied are the different routes of this communication. First, white adipose tissue depots may be regionally distant from muscle (i.e., gluteal fat and diaphragm muscle) or contiguous to muscle but separated by a fascia (Scarpa's fascia in the abdomen, fascia lata in the thigh). In this case, released FFA outflow through the venous drainage and merge into arterial plasma to be transported to muscle tissues. Next, cytosolic triglycerides can directly, i.e., within the cell, provide FFA to myocytes (but also pancreatic ß-cells, renal tubular cells, etc.). Finally, adipocyte layers or lumps may be adjacent to, but not anatomically segregated, from muscle, as is typically the case for epicardial fat and cardiomyocytes. As regulation of these three main delivery paths is different, their separate contribution to substrate competition at the whole-body level is uncertain. Another important link between fat and muscle is vascular. In the resting state, blood flow is generally higher in adipose tissue than in muscle. In the insulinized state, fat blood flow is directly related to whole-body insulin resistance whereas muscle blood flow is not; consequently, fractional (i.e., flow-adjusted) glucose uptake is stimulated in muscle but not fat. Thus, reduced blood supply is a major factor for the impairment of in vivo insulin-mediated glucose uptake in both subcutaneous and visceral fat. In contrast, the insulin resistance of glucose uptake in resting skeletal muscle is predominantly a cellular defect.

Postoperative atrial fibrillation and atrial epicardial fat: Is there a link?

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Detailed local EAT analysis does not differ between POAF and non-POAF.

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General rather than local effects of EAT play a role in the onset of early POAF.

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The dominance of surgical induced factors may obscure the potential role of EAT.

Background

Atrial Epicardial Adipose Tissue (EAT) is presumably involved in the pathogenesis of atrial fibrillation (AF). The transient nature of postoperative AF (POAF) suggests that surgery-induced triggers provoke an unmasking of a pre-existent AF substrate. The aim is to investigate the association between the volume of EAT and the occurrence of POAF. We hypothesise that the likelihood of developing POAF is higher in patients with high compared to low left atrial (LA) EAT volumes.

Methods

Quantification of LA EAT based on the Hounsfield Units using custom made software was performed on pre-operative coronary computed tomography angiography scans of patients who underwent cardiac surgery between 2009 and 2019. Patients with mitral valve disease were excluded.

Results

A total of 83 patients were included in this study (CABG = 34, aortic valve = 33, aorta ascendens n = 7, combination n = 9), of which 43 patients developed POAF. The EAT percentage in the LA wall nor indexed EAT volumes differed between patients with POAF and with sinus rhythm (all P > 0.05). In multivariable analysis, age and LA volume index (LAVI) were the only independent predictors for early POAF (OR: 1.076 and 1.056, respectively).

Conclusions

As expected, advanced age and LAVI were independent predictors of POAF. However, the amount of local EAT was not associated with the occurrence of AF after cardiac surgery. This suggests that the role of EAT in POAF is rather limited, or that the association of EAT in the early phase of POAF is obscured by the dominance of surgical-induced triggers.

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.

Expression profiles of long noncoding and messenger RNAs in epicardial adipose tissue derived from patients with coronary atherosclerosis

BACKGROUND

Given its close anatomical location to the heart and its endocrine properties, attention on epicardial adipose tissue (EAT) has increased.

OBJECTIVE

This study investigated the expression profiles of long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) in EAT derived from patients with coronary artery disease (CAD).

METHODS

EAT samples from 8 CAD and 8 non-CAD patients were obtained during open-heart surgery. The expression of lncRNAs and mRNAs in each EAT sample was investigated using microarray analysis and further verified using reverse transcription-quantitative polymerase chain reaction.

RESULTS

Overall, 1,093 differentially expressed mRNAs and 2,282 differentially expressed lncRNAs were identified in EAT from CAD vs non-CAD patients. Analysis using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes showed that these differentially expressed genes were mainly enriched in various inflammatory, immune, and metabolic processes. They were also involved in osteoclast differentiation, B cell receptor and adipocytokine signaling, and insulin resistance pathways. Additionally, lncRNA-mRNA and lncRNA-target pathway networks were built to identify potential core genes (e.g. Lnc-CCDC68-2:1, AC010148.1, NONHSAT104810) involved in atherosclerosis pathogenesis.

CONCLUSION

In summary, lncRNA and mRNA profiles in EAT were markedly different between CAD and non-CAD patients. Our study identifies several potential key genes and pathways that may participate in atherosclerosis development.

Spectral analysis of ultrasound radiofrequency backscatter for the identification of epicardial adipose tissue

Purpose: The coronary arteries are embedded in a layer of fat known as epicardial adipose tissue (EAT). The EAT influences the development of coronary artery disease (CAD), and increased EAT volume can be indicative of the presence and type of CAD. Identification of EAT using echocardiography is challenging and only sometimes feasible on the free wall of the right ventricle. We investigated the use of spectral analysis of the ultrasound radiofrequency (RF) backscatter for its potential to provide a more complete characterization of the EAT. Approach: Autoregressive (AR) models facilitated analysis of the short-time signals and allowed tuning of the optimal order of the spectral estimation process. The spectra were normalized using a reference phantom and spectral features were computed from both normalized and non-normalized data. The features were used to train random forests for classification of EAT, myocardium, and blood. Results: Using an AR order of 15 with the normalized data, a Monte Carlo cross validation yielded accuracies of 87.9% for EAT, 84.8% for myocardium, and 93.3% for blood in a database of 805 regions-of-interest. Youden's index, the sum of sensitivity, and specificity minus 1 were 0.799, 0.755, and 0.933, respectively. Conclusions: We demonstrated that spectral analysis of the raw RF signals may facilitate identification of the EAT when it may not otherwise be visible in traditional B-mode images.

Can EAT be an INOCA goalkeeper

Ischemia with non-obstructive coronary artery (INOCA) is a blind spot of coronary artery disease (CAD). Such patients are often reassured but offered no specific care, that lead to a heightened risk of adverse cerebrovascular disease (CVD) outcomes. Epicardial adipose tissue (EAT) is proven to correlate independently with CAD and its severity, but it is unknown whether EAT is a specific and sensitive indicator of INOCA. This review focuses on the INOCA epidemiology and related factors, as well as the association between EAT.

Epicardial adipose tissue and risk of arrhythmia in nephrotic syndrome

BACKGROUND

Patients with nephrotic syndrome (NS) are at a high risk of cardiovascular disease, obesity, and dyslipidemia. The aim of this study was to evaluate the formation of epicardial adipose tissue (EAT) and investigate electrocardiographic (ECG) parameters in patients.

METHODS

Thirty-two patients aged 0-18 years and 15 control patients were compared. In the patient group, physical examination and laboratory parameters were recorded. Atrial depolarization and ventricular repolarization parameters in ECG were compared between the groups. EAT was evaluated with M-mode measurements on echocardiography.

RESULTS

There was no difference between the groups in terms of sex, age, body mass index, systolic and diastolic BP. EAT was found to be significantly higher in the patient group. In ECG evaluations it was determined that atrial depolarization and ventricular repolarization parameters increased in the patient group.

CONCLUSIONS

Cardiovascular morbidity and mortality are high in kidney diseases. Measurement and follow-up of EAT and ECG findings as a noninvasive parameter can provide information in NS.

[Heart failure with preserved ejection fraction as a model disease for the cardio-pulmonary-renal syndrome : Importance of visceral fat expansion as central pathomechanism]

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with diverse underlying etiologies and pathophysiological factors. Obesity and type 2 diabetes mellitus (T2DM), diseases which frequently coexist, induce a cluster of metabolic and nonmetabolic signaling derangements, which promote induction of inflammation, fibrosis and myocyte stiffness, all representing hallmarks of HFpEF. In contrast to other HFpEF risk factors, obesity and T2DM are often associated with the formation of an enlarged visceral adipose tissue (VAT), which is a highly active endocrine organ that can sustainably exacerbate inflammation and fibrotic remodeling of myocardial, renal, and vascular tissues via various paracrine and vasocrine signals. An abnormally large epicardial adipose tissue (EAT) thus not only causes a mechanical constriction of the diastolic filling procedure of the heart but is also associated with an increased release of proinflammatory adipokines that trigger atrial fibrillation and impaired left ventricular contraction parameters. Obese patients with HFpEF therefore belong to a unique HFpEF phenotype with a particularly poor prognosis that could benefit from an EAT-oriented phenotype-specific intervention. In addition to statins and antidiabetic drugs such as metformin, glucagon-like peptide‑1 (GLP-1) receptor agonists and sodium-glucose transporter 2 (SGLT-2) inhibitors could also play an important role.

Epicardial Fat Expansion in Diabetic and Obese Patients With Heart Failure and Preserved Ejection Fraction-A Specific HFpEF Phenotype

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with diverse etiologies and pathophysiological factors. Obesity and type 2 diabetes mellitus (T2DM), conditions that coexist frequently, induce a cluster of metabolic and non-metabolic signaling derangements which are in favor to induce inflammation, fibrosis, myocyte stiffness, all hallmarks of HFpEF. In contrast to other HFpEF risk factors, obesity and T2DM are often associated with the generation of enlarged epicardial adipose tissue (EAT). EAT acts as an endocrine tissue that may exacerbate myocardial inflammation and fibrosis via various paracrine and vasocrine signals. In addition, an abnormally large EAT poses mechanical stress on the heart via pericardial restrain. HFpEF patients with enlarged EAT may belong to a unique phenotype that can benefit from specific EAT-targeted interventions, including life-style modifications and pharmacologically via statins and fat modifying anti-diabetics drugs; like metformin, sodium-glucose cotransporter 2 inhibitors, or glucagon-like peptide-1 receptor agonists, respectively.

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.

COVID-19 and Obesity: Role of Ectopic Visceral and Epicardial Adipose Tissues in Myocardial Injury

In March 2020, the WHO declared coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a global pandemic. Obesity was soon identified as a risk factor for poor prognosis, with an increased risk of intensive care admissions and mechanical ventilation, but also of adverse cardiovascular events. Obesity is associated with adipose tissue, chronic low-grade inflammation, and immune dysregulation with hypertrophy and hyperplasia of adipocytes and overexpression of pro-inflammatory cytokines. However, to implement appropriate therapeutic strategies, exact mechanisms must be clarified. The role of white visceral adipose tissue, increased in individuals with obesity, seems important, as a viral reservoir for SARS-CoV-2 via angiotensin-converting enzyme 2 (ACE2) receptors. After infection of host cells, the activation of pro-inflammatory cytokines creates a setting conducive to the "cytokine storm" and macrophage activation syndrome associated with progression to acute respiratory distress syndrome. In obesity, systemic viral spread, entry, and prolonged viral shedding in already inflamed adipose tissue may spur immune responses and subsequent amplification of a cytokine cascade, causing worse outcomes. More precisely, visceral adipose tissue, more than subcutaneous fat, could predict intensive care admission; and lower density of epicardial adipose tissue (EAT) could be associated with worse outcome. EAT, an ectopic adipose tissue that surrounds the myocardium, could fuel COVID-19-induced cardiac injury and myocarditis, and extensive pneumopathy, by strong expression of inflammatory mediators that could diffuse paracrinally through the vascular wall. The purpose of this review is to ascertain what mechanisms may be involved in unfavorable prognosis among COVID-19 patients with obesity, especially cardiovascular events, emphasizing the harmful role of excess ectopic adipose tissue, particularly EAT.

Relationship of Pericardial Fat Tissue With Cardiovascular Risk Factors in Patients Without Cardiovascular Diseases

Background: Obesity and related cardiovascular diseases (CVDs) are important public health problems. The role of visceral ectopic fat remains contested. We studied the relationship between pericardial fat tissue (PFT) volume and CVD risk factors. Methods: We examined 320 patients (average age 63.8 ± 19.9 years) without manifested CVD. Anthropometric indicators were measured, and body mass index (BMI) was calculated. The total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglycerides were assessed. Cardiovascular (CV) risk was calculated using the SCORE system. All patients underwent chest computed tomography with detection of PFT volume using specialized semiautomatic software. Results: Among study participants with normal body mass, the PFT volume was 1.95 cm³ [2.1; 3.9], while it was 3.0 cm³ [2.0; 3.7] in overweight patients and 3.6 cm³ [2.7; 4.7] in obese patients (P < 0.001). Patients with hypertension (HTN) also had significantly higher PFT volumes compared with individuals without HTN: 3.1 cm³ [2.3; 4.15] versus 1.8 cm³ [1.0; 2.5] (P < 0.001). Patients with higher CV risk had significantly higher PFT volume, categorized as follows: 1.6 cm³ [1.0; 2.4], low risk; 2.24 cm³ [2.0; 3.1], moderate risk; 3.1 cm³ [2.4; 3.7], high risk; and 3.9 cm³ [3.0; 5.1], very high risk, respectively (P < 0.001). Results of multiple regression demonstrated that waist circumference and HDL-C were significantly associated with PFT volume. Another model revealed a significant association of BMI and PFT volume with the level of CV risk. Conclusions: This study demonstrates the association of PFT volume with the major diagnostic criteria of obesity, HTN, lipid disorders, and CV risk measured by the SCORE system.