Increased subcutaneous and epicardial adipose tissue production of proinflammatory cytokines in cardiac surgery patients: possible role in postoperative insulin resistance

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 Adipose Tissue and Atrial Fibrillation Recurrence following Catheter Ablation: A Systematic Review and Meta-Analysis

(1)Introduction: Catheter ablation has become a cornerstone for the management of patients with atrial fibrillation (AF). Nevertheless, recurrence rates remain high. Epicardial adipose tissue (EAT) has been associated with AF pathogenesis and maintenance. However, the literature has provided equivocal results regarding the relationship between EAT and post-ablation recurrence.(2) Purpose: to investigate the relationship between total and peri-left atrium (peri-LA) EAT with post-ablation AF recurrence. (3) Methods: major electronic databases were searched for articles assessing the relationship between EAT, quantified using computed tomography, and the recurrence of AF following catheter ablation procedures. (4) Results: Twelve studies (2179 patients) assessed total EAT and another twelve (2879 patients) peri-LA EAT. Almost 60% of the included patients had paroxysmal AF and recurrence was documented in 34%. Those who maintained sinus rhythm had a significantly lower volume of peri-LA EAT (SMD: -0.37, 95%; CI: -0.58-0.16, I2: 68%). On the contrary, no significant difference was documented for total EAT (SMD: -0.32, 95%; CI: -0.65-0.01; I2: 92%). No differences were revealed between radiofrequency and cryoenergy pulmonary venous isolation. No publication bias was identified. (5) Conclusions: Only peri-LA EAT seems to be predictive of post-ablation AF recurrence. These findings may reflect different pathophysiological roles of EAT depending on its location. Whether peri-LA EAT can be used as a predictor and target to prevent recurrence is a matter of further research.

Epicardial adipose tissue and cardiac lipotoxicity: A review

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

Cardiac Computed Tomography-Based Epicardial Adipose Tissue Assessment Reveals Association With Electroanatomical Voltage Mapping in Patients With Atrial Fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) around the left atrium (LA) can change the electric conduction of the LA, potentially leading to atrial fibrillation (AF).

AIM

The aim of this study was to evaluate whether an association existed between EAT and the electrophysiological properties of adjacent atrial myocardium in patients with AF.

METHOD

A total of 201 consecutive patients referred for initial AF catheter ablation were prospectively included. A preprocedural computed tomography scan was performed to assess total and LA-EAT parameters. Detailed point-by-point voltage mapping using an electroanatomical mapping system was realised to assess the LA low-voltage zone (LVZ), defined as an area with bipolar electrograms ≤0.5 mV during sinus rhythm.

RESULTS

Ninety-one (91) patients (45.3%) presented at least one LVZ. They had a significantly more severe AF pattern (p=0.04) than patients without LVZ, and little difference existed with regard to other clinical variables. Patients with LVZ presented significantly more total EAT volume (162.4±71.3 mL vs 135.5±57.2 mL; p=0.03) and LA-EAT volume (26.4±15.9 mL vs 20.9±10.5 mL; p<0.01) than no-LVZ patients. Multivariable logistic regression analyses revealed total EAT volume index to be an independent predictor of the presence of LVZ (odds ratio [OR] 1.01; 95% confidence interval [CI] 1.01-1.04; p<0.01) and LA-EAT percentage to be an independent predictor of severe LVZ (OR 1.34; 95% CI 1.18-1.64; p<0.001).

CONCLUSIONS

The EAT volume and its distribution around the LA may indicate the presence and severity of LVZ. The assessment of the volume of EAT and its distribution may lead to better risk stratification in patients with AF.

Left atrial epicardial adipose tissue is closely associated with left atrial appendage flow velocity in patients with nonvalvular atrial fibrillation

Epicardial adipose tissue (EAT) can play an important role in the occurrence and development of atrial fibrillation and stroke. In this study, we explored the relationship between left atrial epicardial adipose tissue (LA-EAT) and left atrial appendage flow velocity (LAA-FV) in patients with nonvalvular atrial fibrillation (NV-AF). A total of 145 patients with NV-AF who underwent their first radiofrequency ablation were enrolled. They underwent left aortopulmonary vein computed tomography angiography (CTA) and transesophageal echocardiography (TEE) before AF ablation. Left atrial (LA) electroanatomical mapping was performed intraoperatively to assess left atrial voltage. Univariate regression analysis showed that LAA-FV was lower in patients with a low voltage zone (LAA-FV; 35.02 ± 10.78 cm/s vs. 50.60 ± 12.17 cm/s, P < 0.001). A multiple linear regression model showed that the left atrial low voltage zone (β = − 0.311 P < 0.001), LA-EAT volume (β = − 0.256 P < 0.001), left atrial appendage shape (β = − 0.216 P = 0.041), LAVI (β = − 0.153 P = 0.041), and type of atrial fibrillation (paroxysmal vs. persistence) (β = − 0.146 P < 0.048) were independent predictors of LAA-FV. In NV-AF patients, the increase in LA-EAT volume is related to the decrease in LAA-FV.

Epicardial adipose tissue in contemporary cardiology

Interest in epicardial adipose tissue (EAT) is growing rapidly, and research in this area appeals to a broad, multidisciplinary audience. EAT is unique in its anatomy and unobstructed proximity to the heart and has a transcriptome and secretome very different from that of other fat depots. EAT has physiological and pathological properties that vary depending on its location. It can be highly protective for the adjacent myocardium through dynamic brown fat-like thermogenic function and harmful via paracrine or vasocrine secretion of pro-inflammatory and profibrotic cytokines. EAT is a modifiable risk factor that can be assessed with traditional and novel imaging techniques. Coronary and left atrial EAT are involved in the pathogenesis of coronary artery disease and atrial fibrillation, respectively, and it also contributes to the development and progression of heart failure. In addition, EAT might have a role in coronavirus disease 2019 (COVID-19)-related cardiac syndrome. EAT is a reliable potential therapeutic target for drugs with cardiovascular benefits such as glucagon-like peptide 1 receptor agonists and sodium–glucose co-transporter 2 inhibitors. This Review provides a comprehensive and up-to-date overview of the role of EAT in cardiovascular disease and highlights the translational nature of EAT research and its applications in contemporary cardiology.

In this Review, Iacobellis provides a comprehensive overview of the role of epicardial adipose tissue (EAT) in cardiovascular disease, including coronary artery disease, heart failure and atrial fibrillation, discusses imaging techniques for EAT assessment and highlights the therapeutic potential of targeting EAT in cardiovascular disease.

Epicardial adipose tissue (EAT) has anatomical and functional interactions with the heart owing to the shared circulation and the absence of muscle fascia separating the two organs.

EAT can be clinically measured with cardiac imaging techniques that can help to predict and stratify cardiovascular risk.

Regional distribution of EAT is important because pericoronary EAT and left atrial EAT differently affect the risk of coronary artery diseases and atrial fibrillation, respectively.

EAT has a role in the development of several cardiovascular diseases through complex mechanisms, including gene expression profile, pro-inflammatory and profibrotic proteome, neuromodulation, and glucose and lipid metabolism.

EAT could be a potential therapeutic target for novel cardiometabolic medications that modulate adipose tissue such as glucagon-like peptide 1 receptor agonists and sodium–glucose co-transporter 2 inhibitors.

EAT might be a reservoir of severe acute respiratory syndrome coronavirus 2 and an amplifier of coronavirus disease 2019 (COVID-19)-related cardiac syndrome.

Functions and origins of cardiac fat

Triglyceride droplets can be stored within cardiac adipocytes (CAs) and cardiomyocytes in the heart. Cardiac adipocytes reside in three distinct regions: pericardial, epicardial, and intramyocardial adipose tissues. In healthy individuals, cardiac adipose tissues modulate cardiovascular functions and energy partitioning, which are, thus, protective. However, ectopic deposition of cardiac adipose tissues turns them into adverse lipotoxic, prothrombotic, and pro-inflammatory tissues with local and systemic contribution to the development of cardiovascular disorders. Accumulation of triglyceride droplets in cardiomyocytes may lead to lipotoxic injury of cardiomyocytes and contribute to the development of cardiac hypertrophy and dysfunction. Here, we summarize the roles of CAs and myocardial triglyceride droplets under physiological and pathological conditions and review the cellular sources of CAs in heart development and diseases. Understanding the functions and cellular origins of cardiac fat will provide clues for future studies on pathophysiological processes and treatment of cardiovascular diseases.

Adipokine gene expression in adipocytes isolated from different fat depots of coronary artery disease patients

To compare DPP4, LCN2, NAMPT, ITLN1, APLN mRNA levels in adipocytes isolated from the biopsies of subcutaneous, epicardial and perivascular fat obtained from 25 patients with coronary artery disease. Gene expression signature was determined by RT-qPCR with hydrolysis probes. We found DPP4 and APLN mRNA was higher expressed only in adipocytes isolated from epicardial adipose tissue compared to the subcutaneous fat. The ITLN1 gene was overexpressed in epicardial adipose tissue compared to both subcutaneous and perivascular tissues. APLN mRNA expression was positively correlated with total and LDL cholesterol plasma level, and DPP4 mRNA expression - with VLDL cholesterol concentration. Thus, adipocytes isolated from different adipose depots are characterised by differential gene expression of adipokines. Epicardial adipose tissue is of particular interest in the context of its function, molecular and genetic mechanisms of regulation of the cardiovascular system and as a therapeutic target for correction of adipose tissue-induced effects on health.

Characteristics of adipocytokine expression by local fat depots of the heart: Relationship with the main risk factors for cardio-vascular diseases

In our study we investigated the relationships between adipocytokines in adipose tissue (AT) and cardiovascular disease (CVD) risk factors; (2) Methods: fat tissue biopsies were obtained from 134 patients with stable CAD undergoing coronary artery bypass grafting and 120 patients undergoing aortic or mitral valve replacement. Adipocytes were isolated from subcutaneous (SAT), epicardial (EAT), and perivascular AT (PVAT) samples, and cultured for 24 h, after which gene expression of adipocytokines in the culture medium was determined; (3) Results: men showed reduced ADIPOQ expression in EAT and PVAT, LEP expression in PVAT, and LEPR expression in SAT and PVAT compared to women. Men also exhibited higher SAT and lower PVAT IL6 than women. Meanwhile, dyslipidemia associated with decreased ADIPOQ expression in EAT and PVAT, LEPR in EAT, and IL6 in PVAT. Arterial hypertension (AH) associated with low EAT and PVAT ADIPOQ, and high EAT LEP, SAT, as well as PVAT LEPR, and IL6 in SAT and EAT. ADIPOQ expression decreased with increased AH duration over 20 years against an increased LEP background in ATs. Smoking increased ADIPOQ expression in all ATs and increased LEP in SAT and EAT, however, decreased LEPR in PVAT. Patients 51-59 years old exhibited the highest EAT and PVAT LEP, IL-6, and LEPR expression compared to other age groups; (4) Conclusions: decreased EAT ADIPOQ expression against an increased pro-inflammatory IL6 background may increase atherogenesis and contribute to CAD progression in combination with risk factors including male sex, dyslipidemia, and AH.

Epicardial adipose tissue is a robust measure of increased risk of myocardial infarction - a meta-analysis on over 6600 patients and rationale for the EPIC-ACS study

BACKGROUND

Epicardial adipose tissue (EAT) surrounds the heart and the coronary vessels. EAT produces pro- and anti-inflammatory cytokines. Several studies have already documented the association of EAT and cardiovascular risk factors as well as coronary artery disease manifestations. Currently computed tomography (CT) is considered the gold standard for measurement of 3-dimensional volume of EAT. In addition, echocardiography might be an easy accessible alternative in particular in an emergency setting.

METHODS

We performed a metaanalysis of existing studies describing the differences of EAT in patients with and without myocardial infarction. We used established databases and were searching for "epicardial adipose tissue" or "pericardial adipose tissue" and "myocardial infarction", "coronary events", or "acute coronary syndrome". We included over 6600 patients from 7 studies. Random effect models were calculated and all analyses were performed by using the Review Manager 5.3.

RESULTS

Patients with myocardial infarction had 37% (confidence interval [0.21-0.54], P value <.001)] higher measures of EAT compared to patients without myocardial infarction. Comparing studies using echocardiography vs CT for assessment of EAT thickness, similar relative differences in EAT with wide overlap of confidence intervals were observed (for echocardiography: 0.4 [0.04-0.76], for CT: 0.36 [0.16-0.57], P value <.001 for both).

CONCLUSIONS

Patients with myocardial infarction have more EAT as compared to patients without myocardial infarction independently of the used imaging modality. Further prospective studies are needed to evaluate, how quantification of EAT in clinical routine can improve patients management.

A histological study of the atria in patients with isolated rheumatic mitral regurgitation with and without atrial fibrillation

BACKGROUND

There is a high incidence of atrial fibrillation (AF) in patients with isolated rheumatic mitral regurgitation (MR). The histopathologic changes in the atria of patients with isolated rheumatic MR with and without AF are unknown.

OBJECTIVES

We aimed to determine the histological findings in patients with isolated severe rheumatic MR with and without AF.

METHODS

Patients with severe isolated rheumatic MR undergoing valve replacement surgeries underwent endocardial biopsies from right atrial appendage, left atrial appendage, right free wall, left free wall, left posterior wall, and mitral valve. Group I consisted of patients in sinus rhythm (SR), and Group II included patients with AF. We analyzed and compared these 10 histological features in the biopsies of patients in Groups I and II.

RESULTS

Of the 25 patients, 12 were in Group I and 13 in Group II. In Group I, patients had severe myocyte hypertrophy (60% vs. 18%, p = .04) that was significantly more in the right atrium (22.7% vs. 11.4%, p = .059). Interstitial adipose tissue deposition was more common in Group I (30% vs. 25%, p = .06). Interstitial fibrosis was evenly distributed at all sites without significant difference between the two groups. Group II patients had a higher prevalence and severity of vacuolar degeneration (91% vs. 60%, p = .09).

CONCLUSIONS

Patients with isolated severe rheumatic MR and AF have more vacuolar degeneration in the atrial tissue. Patients with SR have myocyte hypertrophy and interstitial adipose tissue deposition. Interstitial fibrosis is uniformly distributed in patients in SR and AF.

The Emerging Role of CT-Based Imaging in Adipose Tissue and Coronary Inflammation

A large body of evidence arising from recent randomized clinical trials demonstrate the association of vascular inflammatory mediators with coronary artery disease (CAD). Vascular inflammation localized in the coronary arteries leads to an increased risk of CAD-related events, and produces unique biological alterations to local cardiac adipose tissue depots. Coronary computed tomography angiography (CTA) provides a means of mapping inflammatory changes to both epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) as independent markers of coronary risk. Radiodensity or attenuation of PCAT on coronary CTA, notably, provides indirect quantification of coronary inflammation and is emerging as a promising non-invasive imaging implement. An increasing number of observational studies have shown robust associations between PCAT attenuation and major coronary events, including acute coronary syndrome, and 'vulnerable' atherosclerotic plaque phenotypes that are associated with an increased risk of the said events. This review outlines the biological characteristics of both EAT and PCAT and provides an overview of the current literature on PCAT attenuation as a surrogate marker of coronary inflammation.

Different Expression of Mitochondrial and Endoplasmic Reticulum Stress Genes in Epicardial Adipose Tissue Depends on Coronary Atherosclerosis

The aim of our study was to analyze mitochondrial and endoplasmic reticulum (ER) gene expression profiles in subcutaneous (SAT) and epicardial (EAT) adipose tissue, skeletal muscle, and myocardium in patients with and without CAD undergoing elective cardiac surgery. Thirty-eight patients, 27 with (CAD group) and 11 without CAD (noCAD group), undergoing coronary artery bypass grafting and/or valvular surgery were included in the study. EAT, SAT, intercostal skeletal muscle, and right atrium tissue and blood samples were collected at the start and end of surgery; mRNA expression of selected mitochondrial and ER stress genes was assessed using qRT-PCR. The presence of CAD was associated with decreased mRNA expression of most of the investigated mitochondrial respiratory chain genes in EAT, while no such changes were seen in SAT or other tissues. In contrast, the expression of ER stress genes did not differ between the CAD and noCAD groups in almost any tissue. Cardiac surgery further augmented mitochondrial dysfunction in EAT. In our study, CAD was associated with decreased expression of mitochondrial, but not endoplasmic reticulum stress genes in EAT. These changes may contribute to the acceleration of coronary atherosclerosis.

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.

Major elective abdominal surgery acutely impairs lower limb muscle pyruvate dehydrogenase complex activity and mitochondrial function

BACKGROUND & AIMS

This post hoc study aimed to determine whether major elective abdominal surgery had any acute impact on mitochondrial pyruvate dehydrogenase complex (PDC) activity and maximal mitochondrial ATP production rates (MAPR) in a large muscle group (vastus lateralis -VL) distant to the site of surgical trauma.

METHODS

Fifteen patients undergoing major elective open abdominal surgery were studied. Muscle biopsies were obtained after the induction of anesthesia from the VL immediately before and after surgery for the determination of PDC and maximal MAPR (utilizing a variety of energy substrates).

RESULTS

Muscle PDC activity was reduced by >50% at the end of surgery compared with pre-surgery (p < 0.05). Muscle MAPR were comprehensively suppressed by surgery for the substrate combinations: glutamate + succinate; glutamate + malate; palmitoylcarnitine + malate; and pyruvate + malate (all p < 0.05), and could not be explained by a lower mitochondrial yield.

CONCLUSIONS

PDC activity and mitochondrial ATP production capacity were acutely impaired in muscle distant to the site of surgical trauma. In keeping with the limited data available, we surmise these events resulted from the general anesthesia procedures employed and the surgery related trauma. These findings further the understanding of the acute dysregulation of mitochondrial function in muscle distant to the site of major surgical trauma in patients, and point to the combination of general anesthesia and trauma related inflammation as being drivers of muscle metabolic insult that warrants further investigation.

CLINICAL TRIAL REGISTRATION

Registered at (NCT01134809).

Epicardial adipose tissue affects the efficacy of left atrial posterior wall isolation for persistent atrial fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) contributes to atrial fibrillation (AF). However, its impact on the efficacy of left atrial posterior wall isolation (LAPWI) is unclear.

METHODS

Forty-four nonparoxysmal AF patients underwent LAPWI after pulmonary vein isolation. EAT overlap on LAPWI was assessed by fusing computed tomography images with electro-anatomical mapping.

RESULTS

During the 21 ± 7 months of follow-up, AF recurred in 10 patients (23%). The total and left atrial EAT volumes were 113 ± 36 and 33 ± 12 cm3, respectively. No differences were found between the AF-free and AF-recurrent groups regarding EAT volume. The EAT overlaps on LAPWI lines and LAPWI area were 1.2 ± 1.0 and 0.5 ± 0.9 cm2 respectively. Although no difference was found between groups regarding the EAT overlap on LAPWI area, the AF-free group had a significantly larger EAT overlap on LAPWI lines (1.4 ± 1.0 vs 0.6 ± 0.6 cm2, P = .014). Multivariate analysis identified EAT overlap on LAPWI lines as an independent predictor of AF recurrence (hazard ratio: 0.399, 95% confidence interval: 0.178-0.891, P = .025). Kaplan-Meier analysis revealed that, during follow-up, 92% of the large EAT overlap group (≥1.0 cm2) and 58% of the small EAT overlap group (<1.0 cm2) remained AF-free (P = .008).

CONCLUSIONS

EAT overlap on LAPWI lines is related to a high AF freedom rate. Direct radiofrequency application to EAT overlap may be necessary to suppress AF.

Epicardial adipose tissue characteristics and CT high-risk plaque features: correlation with coronary thin-cap fibroatheroma determined by intravascular ultrasound

To investigate the correlation of epicardial adipose tissue (EAT) characteristics and high-risk plaque features characterized by coronary CT angiography (CCTA) for identifying the presence of thin-cap fibroatheroma (TCFA). Patients who underwent both CCTA and intravascular ultrasound (IVUS) within 4 weeks were retrospectively included. CT-derived quantitative and qualitative parameters, including diameter stenosis, low attenuation plaque (LAP), napkin-ring sign (NRS), positive remodeling and spotty calcification, were recorded. EAT volume and density were also measured. TCFA lesions and non-TCFA lesions were determined by IVUS. Multivariate regression analysis was used to determine the independent predictors of TCFA lesions. Sixty-eight patients (mean age: 68.6 ± 9.7 years; 40 males) with 91 lesions were finally included in our study. For CT-derived plaque features, LAP (77.8% versus 25%, p < 0.001) and NRS (40.7% versus 9.4%, p < 0.001) was more frequently presented in TCFA lesions than was in non-TCFA lesions. For EAT characteristics, EAT volume (110 ± 14 cm³ versus 98 ± 12 cm³, p < 0.001) was significantly larger whereas EAT density (-77 ± 4 HU versus -80 ± 5, p = 0.003) was markedly higher in TCFA lesions. According to multivariate logistic regression analysis, LAP, EAT volume and EAT density were significant predictors (odds ratio: 9.758, 1.095 and 1.202, all p value < 0.05) for the presence of TCFA lesions. EAT volume and density was greater in patients with TCFA lesions whereas LAP and NRS was more frequently presented. In addition, EAT characteristics and LAP were independent predictors of vulnerable plaques as determined by IVUS.

The association of systemic inflammatory markers with indicators of stress and cardiac necrosis in patients undergoing aortic valve replacement and revascularization surgeries

The aim was to investigate: changes of inflammatory, stress and cardiac response in patients undergoing open heart surgeries up to five days after the procedure; the association between inflammatory, stress and cardiac response and whether changes in a certain marker can predict short-term patient outcome. Ninety patients were divided into three groups, 30 participants each (on-pump,off-pump revascularization and valve replacement group). The following markers were measured:complete blood count, CRP, IL-6, IL-10, leptin, resistin, monocyte chemoattractant protein-1 (MCP-1), cortisol, CK and hsTnT in 5 points. Resistin increased in all three groups. Lower IL-10 levels were found after the surgery and higher levels of leptin and MCP-1 in the off-pump than in the on-pump group. Off-pump group had higher values of IL-6, IL-10, leptin, resistin and MCP-1 and lower levels of CK and hsTnT 24 after surgery than the on-pump group. We found significant correlation between MCP-1 and resistin. The difference between resistin at time points 2 and 3 significantly predicted transfusion needs; while the difference between CRP and resistin before and at the end of the surgery together with the difference between leukocytes at the end and 24 hours after the surgery predicted the use of inotropic agents/vasopressors. Cardiac surgeries cause an increase of inflammatory, stress and cardiac markers. Only resistin correlated with MCP-1 which confirms the link between resistin secreted form infiltrated macrophages and enhanced release of MCP-1.

Epicardial adipose tissue thickness is not associated with adverse cardiovascular events in patients undergoing haemodialysis

In non-haemodialysis (HD) patients, increased epicardial adipose tissue (EAT) thickness was significantly associated with adverse cardiovascular (CV) events. This study was designed to investigate whether EAT thickness was a useful parameter in the prediction of adverse CV events in HD patients. In addition, we also evaluated the major correlates of EAT thickness in these patients. In 189 routine HD patients, we performed a comprehensive transthoracic echocardiographic examination with assessment of EAT thickness. The definition of CV events included CV death, non-fatal stroke, non-fatal myocardial infarction, peripheral artery disease, and hospitalization for heart failure. The follow-up period for CV events was 2.5 ± 0.7 years. Thirty-one CV events were documented. The multivariable analysis demonstrated that older age, smoking status, the presence of diabetes mellitus and coronary artery disease, and low albumin levels were independently correlated with adverse CV events. However, increased EAT thickness was not associated with adverse CV events (P = 0.631). Additionally, older age, female sex, low haemoglobin, and low early diastolic mitral annular velocity were correlated with high EAT thickness in the univariable analysis. In the multivariable analysis, older age and female sex were still correlated with high EAT thickness. In conclusion, high EAT thickness was associated with older age and female sex in the multivariable analysis in our HD patients. However, EAT thickness was not helpful in predicting adverse CV events in such patients. Further large-scale studies are necessary to verify this finding.

Myocardium Metabolism in Physiological and Pathophysiological States: Implications of Epicardial Adipose Tissue and Potential Therapeutic Targets

The main energy substrate of adult cardiomyocytes for their contractility are the fatty acids. Its metabolism generates high ATP levels at the expense of high oxygen consumption in the mitochondria. Under low oxygen supply, they can get energy from other substrates, mainly glucose, lactate, ketone bodies, etc., but the mitochondrial dysfunction, in pathological conditions, reduces the oxidative metabolism. In consequence, fatty acids are stored into epicardial fat and its accumulation provokes inflammation, insulin resistance, and oxidative stress, which enhance the myocardium dysfunction. Some therapies focused on improvement the fatty acids entry into mitochondria have failed to demonstrate benefits on cardiovascular disorders. Oppositely, those therapies with effects on epicardial fat volume and inflammation might improve the oxidative metabolism of myocardium and might reduce the cardiovascular disease progression. This review aims at explain (a) the energy substrate adaptation of myocardium in physiological conditions, (b) the reduction of oxidative metabolism in pathological conditions and consequences on epicardial fat accumulation and insulin resistance, and (c) the reduction of cardiovascular outcomes after regulation by some therapies.

Impact of epicardial adipose tissue volume upon left ventricular dysfunction in patients with mild-to-moderate aortic stenosis: A post-hoc analysis

Background

Aortic stenosis (AS) may lead to diastolic dysfunction and later on heart failure (HF) with preserved left ventricular ejection fraction (HFpEF) via increased afterload and left-ventricular (LV) hypertrophy. Since epicardial adipose tissue (EAT) is a metabolically active fat depot that is adjacent to the myocardium and can influence cardiomyocytes and LV function via secretion of proinflammatory cytokines, we hypothesized that high amounts of EAT, as assessed by computed tomography (CT), may aggravate the development and severity of LV hypertrophy and diastolic dysfunction in the context of AS.

Methods

We studied 50 patients (mean age 71 ± 9 years; 9 women) in this preliminary study with mild or moderate AS and mild to severe LV diastolic dysfunction (LVDD), diagnosed by echocardiography, who underwent non-contrast cardiac CT and echocardiography. EAT parameters were measured on 2nd generation dual source CT. Conventional two-dimensional echocardiography and Tissue Doppler Imaging (TDI) was performed to assess LV function and to derive myocardial straining parameter. All patients had a preserved LV ejection fraction > 50%. Data was analysed using Pearson’s correlation.

Results

Only weak correlation was found between EAT volume or density and E/é ratio as LVDD marker (r = -.113 p = .433 and r = .260, p = .068 respectively). Also, EAT volume or density were independent from Global Strain Parameters (r = 0.058 p = .688 and r = -0.207 p = .239). E/é ratio was strongly associated with LVDD (r = .761 p≤0.0001) and Strain Parameters were moderately associated with LV Ejection Fraction (r = -.669 p≤0.001 and r = -.454 P≤0.005).

Conclusions

In this preliminary study in patients with AS, the EAT volume and density as assessed by CT correlated only weakly with LVDD, as expressed by the commonly used E/é ratio, and with LV strain function. Hence, measuring EAT volume and density may neither contribute to the prediction nor upon the severity of LVDD, respectively.

Altered mitochondrial metabolism in the insulin-resistant heart

Obesity-induced insulin resistance and type 2 diabetes mellitus can ultimately result in various complications, including diabetic cardiomyopathy. In this case, cardiac dysfunction is characterized by metabolic disturbances such as impaired glucose oxidation and an increased reliance on fatty acid (FA) oxidation. Mitochondrial dysfunction has often been associated with the altered metabolic function in the diabetic heart, and may result from FA-induced lipotoxicity and uncoupling of oxidative phosphorylation. In this review, we address the metabolic changes in the diabetic heart, focusing on the loss of metabolic flexibility and cardiac mitochondrial function. We consider the alterations observed in mitochondrial substrate utilization, bioenergetics and dynamics, and highlight new areas of research which may improve our understanding of the cause and effect of cardiac mitochondrial dysfunction in diabetes. Finally, we explore how lifestyle (nutrition and exercise) and pharmacological interventions can prevent and treat metabolic and mitochondrial dysfunction in diabetes.

Relationship Between Epicardial Adipose Tissue and Body Composition as Determined by Multi-Frequency Bioelectrical Impedance Analysis in Patients with Stage 5 Chronic Kidney Disease

Background

The main cause of mortality among chronic kidney disease (CKD) patients is cardiovascular disease (CVD). Epicardial adipose tissue (EAT) is considered to be novel cardiovascular risk factor. We assessed EAT in non-dialyzed stage 5 CKD patients and explored the association of EAT with body composition as determined by multi-frequency BIA.

Material/Methods

The present included 70 stage 5 CKD patients who had not undergone dialysis and 40 healthy control subjects. EAT thickness was assessed by echocardiography. Hydration status and body composition were evaluated by multi-frequency bioelectrical impedance analysis.

Results

Stage 5 CKD patients had significantly higher EAT thickness than healthy subjects (6.56±1.18 vs. 4.05±1.45, p<0.001). Fat tissue mass, systolic blood pressure (SBP), age, fat tissue index, and body mass index were positively correlated with EAT thickness in the CKD patient group (p<0.05). Lean tissue mass, lean tissue index (LTI), and high-density lipoprotein (HDL) were negatively correlated with EAT thickness in the CKD patient group (p<0.05). Stepwise multiple regression analysis showed that age, SBP, and LTI were independently associated with EAT thickness in CKD patients.

Conclusions

We found significantly higher EAT thickness in stage 5 CKD patients who were not on dialysis compared to healthy controls. EAT was significantly associated with age, SBP, and LTI in CKD patients. Interventions to reduce the risk factors associated with EAT thickness might protect against CVD disease in CKD patients.

Perivascular Adipose Tissue and Coronary Atherosclerosis: from Biology to Imaging Phenotyping

PURPOSE OF REVIEW

Perivascular adipose tissue (PVAT) has a complex, bidirectional relationship with the vascular wall. In disease states, PVAT secretes pro-inflammatory adipocytokines which may contribute to atherosclerosis. Recent evidence demonstrates that pericoronary adipose tissue (PCAT) may also function as a sensor of coronary inflammation. This review details PVAT biology and its clinical translation to current imaging phenotyping.

RECENT FINDINGS

PCAT attenuation derived from routine coronary computed tomography (CT) angiography is a novel noninvasive imaging biomarker of coronary inflammation. Pro-inflammatory cytokines released from the arterial wall diffuse directly into the surrounding PCAT and inhibit adipocyte lipid accumulation in a paracrine manner. This can be detected as an increased PCAT CT attenuation, a metric which associates with high-risk plaque features and independently predicts cardiac mortality. There is also evidence that PCAT attenuation relates to coronary plaque progression and is modified by systemic anti-inflammatory therapies. Due to its proximity to the coronary arteries, PCAT has emerged as an important fat depot in cardiovascular research. PCAT CT attenuation has the potential to improve cardiovascular risk stratification, and future clinical studies should examine its role in guiding targeted medical therapy.

Effects of dapagliflozin on human epicardial adipose tissue: modulation of insulin resistance, inflammatory chemokine production, and differentiation ability

Aims

In patients with cardiovascular disease, epicardial adipose tissue (EAT) is characterized by insulin resistance, high pro-inflammatory chemokines, and low differentiation ability. As dapagliflozin reduces body fat and cardiovascular events in diabetic patients, we would like to know its effect on EAT and subcutaneous adipose tissue (SAT).

Methods and results

Adipose samples were obtained from 52 patients undergoing heart surgery. Sodium-glucose cotransporter 2 (SGLT2) expression was determined by real-time polymerase chain reaction (n = 20), western blot, and immunohistochemistry. Fat explants (n = 21) were treated with dapagliflozin and/or insulin and glucose transporters expression measured. Glucose, free fatty acid, and adipokine levels (by array) were measured in the EAT secretomes, which were then tested on human coronary endothelial cells using wound healing assays. Glucose uptake was also measured using the fluorescent glucose analogue (6NBDG) in differentiated stromal vascular cells (SVCs) from the fat pads (n = 11). Finally, dapagliflozin-induced adipocyte differentiation was assessed from the levels of fat droplets (AdipoRed staining) and of perilipin. SGLT2 was expressed in EAT. Dapagliflozin increased glucose uptake (20.95 ± 4.4 mg/dL vs. 12.97 ± 4.1 mg/dL; P < 0.001) and glucose transporter type 4 (2.09 ± 0.3 fold change; P < 0.01) in EAT. Moreover, dapagliflozin reduced the secretion levels of chemokines and benefited wound healing in endothelial cells (0.21 ± 0.05 vs. 0.38 ± 0.08 open wound; P < 0.05). Finally, chronic treatment with dapagliflozin improved the differentiation of SVC, confirmed by AdipoRed staining [539 ± 142 arbitrary units (a.u.) vs. 473 ± 136 a.u.; P < 0.01] and perilipin expression levels (121 ± 10 vs. 84 ± 11 a.u.).

Conclusions

Dapagliflozin increased glucose uptake, reduced the secretion of pro-inflammatory chemokines (with a beneficial effect on the healing of human coronary artery endothelial cells), and improved the differentiation of EAT cells. These results suggest a new protective pathway for this drug on EAT from patients with cardiovascular disease.

Impact of Obesity on Postoperative Outcomes following cardiac Surgery (The OPOS study): rationale and design of an investigator-initiated prospective study

INTRODUCTION

Increasing levels of obesity worldwide have led to a rise in the prevalence of obesity-related complications including cardiovascular risk factors such as diabetes, hypertension and dyslipidaemia. Healthcare providers believe that overweight and obese cardiac surgery patients are more likely to experience adverse postoperative outcomes. The body mass index (BMI) is the primary measure of obesity in clinical practice, without accounting for a patient's level of cardiopulmonary fitness or muscle mass. The objective of this study is to determine whether fitness capacity of obese cardiac surgical patients and biomarkers, alone or in combination, will help identify patients at risk for adverse outcomes when undergoing cardiac surgery.

METHODS AND ANALYSIS

Patients between the ages of 18 and 75 years undergoing elective cardiac surgery are consented to participate in this prospective observational study. Patients will be invited to participate in measures of obesity, functional capacity and exercise capacity assessments, quality of life questionnaires, and blood and tissue sampling for biomarker analysis. The endpoints evaluated are measures other than BMI that could be predictive of short-term and long-term postoperative outcomes. Clinical outcomes of interest are prolonged ventilation, hospital length of stay, renal failure and all-cause mortality. Biomarkers of interest will largely focus on metabolism (lipids, amino acids) and inflammation (adipokines, cytokines and chemokines).

ETHICS AND DISSEMINATION

This study has been approved by the institutional review board at the Horizon Health Network. On completion of the study, the results shall be disseminated through conference presentations and publications in peer-reviewed journals. Additionally, the report shall also be diffused more broadly to the general public and the cardiovascular community.

TRIAL REGISTRATION NUMBER

NCT03248921.

Coronary Artery Disease Is Associated with an Increased Amount of T Lymphocytes in Human Epicardial Adipose Tissue

Immunocompetent cells including lymphocytes play a key role in the development of adipose tissue inflammation and obesity-related cardiovascular complications. The aim of the study was to explore the relationship between epicardial adipose tissue lymphocytes and coronary artery disease (CAD). To this end, we studied the content and phenotype of lymphocytes in peripheral blood, subcutaneous adipose tissue (SAT), and epicardial adipose tissue (EAT) in subjects with and without CAD undergoing elective cardiac surgery. Eleven subjects without CAD (non-CAD group) and 22 age-, BMI-, and HbA_1C-matched individuals with CAD were included into the study. Blood, SAT, and EAT samples were obtained at the beginning of surgery. Lymphocyte populations were quantified as % of CD45+ cells using flow cytometry. Subjects with CAD had a higher total lymphocyte amount in EAT compared with SAT (32.24 ± 7.45 vs. 11.22 ± 1.34%, p = 0.025) with a similar trend observed in non-CAD subjects (29.68 ± 7.61 vs. 10.13 ± 2.01%, p = 0.067). T (CD3+) cells were increased (75.33 ± 2.18 vs. 65.24 ± 4.49%, p = 0.032) and CD3- cells decreased (21.17 ± 2.26 vs. 31.64 ± 4.40%, p = 0.028) in EAT of CAD relative to the non-CAD group. In both groups, EAT showed an elevated percentage of B cells (5.22 ± 2.43 vs. 0.96 ± 0.21%, p = 0.039 for CAD and 12.49 ± 5.83 vs. 1.16 ± 0.19%, p = 0.016 for non-CAD) and reduced natural killer (NK) cells (5.96 ± 1.32 vs. 13.22 ± 2.10%, p = 0.012 for CAD and 5.32 ± 1.97 vs. 13.81 ± 2.72%, p = 0.022 for non-CAD) relative to SAT. In conclusion, epicardial adipose tissue in subjects with CAD shows an increased amount of T lymphocytes relative to non-CAD individuals as well as a higher number of total and B lymphocytes and reduced NK cells as compared with corresponding SAT. These changes could contribute to the development of local inflammation and coronary atherosclerosis.

Epicardial fat tissue in patients with diabetes mellitus: a systematic review and meta-analysis

Background

Epicardial fat tissue (EFT) is the visceral fat distributed along the coronary arteries between the pericardium and the myocardium. Increases in EFT are closely related to the occurrence of diabetes mellitus (DM) and cardiovascular disease. To further understand the link between EFT and DM, we conducted a meta-analysis of the relevant literature.

Methods

We systematically searched electronic databases for studies on EFT performed in DM patients and published up to 30 September 2018. We included data on EFT in a DM patient group and a non-DM control group. We then assessed the effect of DM on EFT by meta-analysis and trial sequential analysis (TSA). All statistical analyses were performed using Stata 12.0 and TSA software.

Results

A total of 13 studies (n = 1102 patients) were included in the final analysis. Compared with the control group, DM patients had significantly higher EFT (SMD: 1.23; 95% CI 0.98, 1.48; P = 0.000; TSA-adjusted 95% CI 0.91, 2.13; P < 0.0001). The TSA indicated that the available samples were sufficient and confirmed that firm evidence was reached. According to the regression analysis and subgroup analyses, DM typing, EFT ultrasound measurements, total cholesterol (TC) and triglyceride (TG) levels were confounding factors that significantly affected our results.

Conclusions

Our meta-analysis suggests that the amount of EFT is significantly higher in DM patients than in non-DM patients.

Dynamics of Epicardiac Fat and Heart Function in Type 2 Diabetic Patients Initiated with SGLT-2 Inhibitors

PURPOSE

The aim of this study was to assess the dynamics of epicardiac adipose tissue (EAT) thickness and total volume as well as that of systolic and diastolic dysfunction in a group of patients with type 2 diabetes (T2D) after initiation of sodium glucose co-transporter 2 (SGLT 2) inhibitors therapy.

PATIENTS AND METHODS

This prospective, observational study included 53 patients with T2D who received SGLT-2 inhibitors for 24 weeks. In all patients, echocardiographic screening for EAT, systolic and diastolic dysfunction and non-contrast computed tomography scans were performed, both before and after 24 weeks of SGLT-2 inhibition. Imagistic evaluation was followed by the association's analysis between the dynamics of EAT and heart function, as well as the patient's clinical and biological parameters. We considered a decrease or increase of more than 10% in EAT as being clinically significant.

RESULTS

The mean volume of EAT decreased significantly after SGLT 2 inhibition (37.8±17.2 vs. 20.7±7 cm³; p<0.001). Median values of EAT thickness also decreased significantly (5.95 vs. 3.01 mm; p<0.001). Most patients, 75.4% (40/53), presented more than 10% decrease in EAT volume, 9.5% (5/53) had stable EAT volume values, while in 15.1% (8/53) the means of EAT volume increased. 73.5% of the patients had diastolic dysfunction type 1 (DD 1) at baseline. No significant change was observed in the left ventricular ejection fraction or diastolic dysfunction after 24 weeks of treatment. Although not statistically significant, an improvement in cardiac function has been noticed throughout the duration of 1 year of treatment with SGLT 2 inhibitors.

CONCLUSION

This study showed the beneficial effect of SGLT 2 inhibitors on EAT after a short period of treatment, but there were no significant changes in the systolic function during the 1st year of study. However, reducing epicardial fat has led to remission of diastolic dysfunction.

Local enrichment of fatty acid-binding protein 4 in the pericardial cavity of cardiovascular disease patients

BACKGROUND

The pericardial fluid may be representative of the interstitium of the heart. The aim of this study was to discriminate in cardiovascular disease patients between adipocytokines that are produced locally by the heart and those supplied by the circulation.

METHODS

Enzyme-linked immunosorbent assays (ELISA) were used to determine levels of N-terminal pro-brain natriuretic peptide (NT-pBNP), fatty acid-binding protein 4 (FABP4), leptin, lipocalin-2, neutrophil elastase, proteinase-3, high sensitivity C-reactive protein (hsCRP) and adiponectin in venous plasma and pericardial fluid harvested during elective cardio-thoracic surgery (n = 132-152).

RESULTS

In pericardial fluid compared to plasma, the levels were significantly smaller (p < 0.001) for leptin, lipocalin-2, neutrophil elastase, proteinase-3, hsCRP and adiponectin. For these biomarkers, the ratio of pericardial fluid-to-plasma level ([PF]/[P], median (interquartile range)) was 0.65 (0.47-1.01), 0.78 (0.56-1.09), 0.23 (0.11-0.60), 0.17 (0.09-0.36), 0.14 (0.08-0.35), and 0.25 (0.15-0.34), respectively. In contrast, pericardial fluid was significantly enriched (p < 0.001) in NT-pBNP ([PF]/[P]: 1.9 (1.06-2.73)) and even more so for FABP4 ([PF]/[P]: 3.90 (1.47-9.77)). Moreover, in pericardial fluid, the adipocytokines interrelated all significantly positive and correlated negative to hsCRP, whereas for NT-pBNP only a significantly positive correlation with adiponectin was found. These interrelations were distinct from those in the plasma, as were the correlations of the pericardial biomarkers with patient characteristics compared to plasma.

CONCLUSIONS

In cardiovascular disease patients, the pericardial cavity is a distinct adipocytokine microenvironment in which especially FABP4 is mainly derived from the heart.

Changes in omentin levels and its mRNA expression in epicardial adipose tissue in patients undergoing elective cardiac surgery: the influence of type 2 diabetes and coronary heart disease

Omentin is a protein produced by numerous tissues including adipose tissue. Its concentrations are decreased in patients with obesity, type 2 diabetes mellitus (DM) and coronary artery disease (CAD). Experimental studies suggest that omentin may have anti-inflammatory and insulin-sensitizing properties. In the present study, we measured circulating omentin levels and its mRNA expression in epicardial and subcutaneous fat, intercostal and heart muscle before and after elective cardiac surgery in patients with CAD (CAD+, DM-, n=18), combination of CAD and DM (CAD+, DM+, n=9) or with none of these conditions (CAD-, DM-, n=11). The groups did not differ in baseline anthropometric and biochemical characteristics with the exception of higher blood glucose and HBA(1c) in CAD+, DM+ group. Baseline circulating omentin levels tended to be lower in CAD+, DM- and CAD+, DM+ groups as compared to CAD-, DM- group and cardiac surgery increased its concentration only in CAD-, DM- group. The change in serum omentin levels during surgery inversely correlated with epicardial fat thickness. While baseline omentin mRNA expression did not differ among the groups in any of the studied tissues, its increase after surgery was present only in subcutaneous fat in CAD-, DM- and CAD+, DM- groups, but not in CAD+, DM+ group. Intercostal muscle omentin mRNA expression increased after surgery only in CAD-, DM- group. In conclusion, cardiac surgery differentially affects omentin levels and subcutaneous fat and skeletal muscle mRNA expression in patients without coronary artery disease and diabetes as compared to patients with these conditions.

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

Background

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

Material/Methods

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

Results

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

Conclusions

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

Association between histological features of epicardial adipose tissue and coronary plaque characteristics on computed tomography angiography

The means by which epicardial adipose tissue (EAT) could influence coronary plaque progression biologically remain unclear. We investigated the association between the histological findings of EAT and coronary plaque characteristics assessed by coronary computed tomography angiography (CCTA). We enrolled 34 patients in whom one or more coronary plaques containing non-calcified components were detected on CCTA before cardiac surgery [coronary artery bypass graft (CABG) or non-CABG]. We evaluated visceral adipose tissue (VAT) area, EAT volume, and coronary plaque characteristics including minimum computed tomography density (CTD) and vascular Remodeling Index (RI). Lower CTD and higher RI were considered as high-risk characteristics, and coronary plaque with both CTD < 39 Hounsfield units and RI > 1.05 was defined as two-characteristic plaque (2-CP). The numbers of CD68⁺ macrophages and CD31⁺ microvessels were assessed in six random high-power fields (400×) of EAT samples obtained during cardiac surgery. The entire cohort showed a wide range of EAT volume, which were similar between patients with 2-CP and those without. Patients with 2-CP had more amounts of EAT macrophages (85 ± 38 versus 45 ± 22, p = 0.0005) and vascularity (62 ± 33 versus 37 ± 19, p = 0.013) than those without. On multivariate analyses adjusted for age, sex, coronary risk factors, statin use, type of surgery, VAT area, EAT volume, and coronary calcium score, the presence of 2-CP showed significant correlation with increased EAT macrophages (β = 0.65, p = 0.014) and vascularity (β = 0.74, p = 0.0053). Our findings support the hypothesis that EAT biologic activities are associated with coronary plaque vulnerability.

Tumor Necrosis Factor-α Gene Expression in Epicardial Adipose Tissue is Related to Coronary Atherosclerosis Assessed by Computed Tomography

Aims: Tumor necrosis factor (TNF)-α reportedly has key pro-inflammatory properties in both atherosclerosis and adipocytes. To further investigate the biologic impact of epicardial adipose tissue (EAT) on coronary atherosclerosis, we evaluated the relationship between TNF-α gene expression in EAT and clinically-assessed coronary atherosclerosis on computed tomography (CT).

Methods: We studied 47 patients before cardiac surgery (coronary artery bypass grafting [CABG], n = 26; non-CABG, n = 21), assessing visceral adipose tissue (VAT) area, EAT volume, coronary calcium score (CCS), and the presence of non- and/or partially-calcified coronary plaque (NCP) on CT angiography. EAT and subcutaneous adipose tissue (SAT) samples were obtained during cardiac surgery. TNF-α mRNA in EAT was measured using quantitative real-time PCR, and normalized to that of SAT as control adipose tissue.

Results: There was no difference in the TNF-α expression level between patients scheduled for CABG and non-CABG surgery (p = 0.23), or among the subgroups based on CCS (p = 0.68), while patients with NCP had the higher TNF-α expression level than those without NCP (median [interquartile range], 2.50 [1.01–5.53] versus. 1.03 [0.64–2.16], p = 0.022). On multivariate analysis adjusted for age, sex, coronary risk factors, statin therapy, CABG versus non-CABG, VAT area, and EAT volume, the presence of NCP had close correlation with the elevated TNF-α expression level (β= 0.79, p = 0.003).

Conclusions: TNF-α expressed regionally in EAT may exert potent effects on the progression of coronary atherosclerosis, suggesting a contribution of EAT to coronary artery disease through behavior of molecule.

Epicardial Fat in the Maintenance of Cardiovascular Health

Epicardial fat is a unique adipose tissue located between the myocardium and the visceral layer of pericardium. This tissue is characterized by highly active fatty acid metabolism and highly expressed thermogenic genes. Epicardial fat and the underlying myocardium share the same microcirculation, suggesting a close and strong interaction between these two structures. Under physiological conditions, epicardial fat protects and supports the heart to exert its normal function. Many clinical studies have shown significant associations between increased amounts of epicardial fat and coronary artery disease (CAD). In patients with CAD, increased epicardial fat becomes inflammatory and may promote plaque development through secretion of proinflammatory cytokines and other mechanisms. Therefore, epicardial fat is a biomarker of cardiovascular risk and a potential therapeutic target for cardiovascular disease. Weight loss and pharmaceuticals can reduce epicardial fat and improve its protective physiological functions.

Association of epicardial adipose tissue with serum level of cystatin C in type 2 diabetes

Objective

Accumulation of epicardial adipose tissue (EAT) is considered to be a cardiovascular risk factor independent from visceral adiposity, obesity, hypertension and diabetes. We explored the parameters related to EAT accumulation, aiming to clarify the novel pathophysiological roles of EAT in subjects with type 2 diabetes (T2DM).

Methods

We examined the laboratory values, including cystatinC, and surrogate markers used for evaluating atherosclerosis. EAT was measured as the sum of the adipose tissue area, obtained by plain computed tomography scans in 208 subjects with T2DM but no history of coronary artery disease.

Results

EAT correlated positively with age, body mass index (BMI), visceral fat area, leptin, cystatin C and C-peptide, while correlating negatively with adiponectin, estimated glomerular filteration rate (eGFR) and the liver-to-spleen ratio. Multiple linear regression analysis revealed serum cystatin C (β = 0.175), leptin (β = 0.536), BMI (β = 0.393) and age (β = 0.269) to be the only parameters showing independent statistically significant associations with EAT. When cystatin C was replaced with eGFR, eGFR showed no significant correlation with EAT. In reverse analysis, serum cystatin C was significantly associated with EAT after adjustment in multivariate analysis.

Discussion

EAT accumulation and elevated cystatin C have been independently regarded as risk factors influencing atherosclerosis. The strong association between EAT and cystatin C demonstrated herein indicates that EAT accumulation may play an important role in Cystatin C secretion, possibly contributing to cardiometabolic risk in T2DM patients.

Aberrant Epicardial Adipose Tissue Extracellular Matrix Remodeling in Patients with Severe Ischemic Cardiomyopathy: Insight from Comparative Quantitative Proteomics

There is ample evidence indicating that epicardial adipose tissue (EAT) volume and thickness is positively associated with coronary artery disease (CAD). However, the exact pathological changes in the human EAT after myocardial ischemia remains largely unclear. In the current study, we applied a comparative quantitative proteomics to elucidate the altered biological processes in the EAT of ischemic cardiomyopathy (ICM) patients. A total of 1649 proteins were successfully quantified in our study, among which 165 proteins were significantly changed (ratio <0.8 or >1.2 fold and p < 0.05 in both repetitions) in EAT of ICM individuals. Gene ontology (GO) enrichment analysis revealed that cardiac structure and cellular metabolism were over-represented among these regulated proteins. The hypertrophic cardiomyopathy, adrenergic signaling in cardiomyocytes, extracellular matrix (ECM)-receptor interaction, phagosome, Glycolysis/Gluconeogenesis, and PPAR signaling pathway were highlighted by the KEGG PATHWAY analysis. More importantly, we found that the proteins responsible for extracellular matrix organization were dramatically increased in EAT of ICM patients. In addition, the picrosirius red (PSR) staining results showed that the collagen fiber content was prominently increased, which indicated the EAT of ICM individuals underwent extracellular matrix remodeling and ERK1/2 activation maybe responsible for these pathological changes partially.

Neutrophil-to-lymphocyte ratio as a possible indicator of epicardial adipose tissue in patients undergoing hemodialysis

INTRODUCTION

Chronic inflammation is a major risk factor in the pathogenesis of cardiovascular disease in end-stage renal disease (ESRD) patients. Epicardial adipose tissue (EAT) is the true visceral fat depot of the heart. The relationship between coronary artery disease and EAT was shown in healthy subjects and ESRD patients. In the present study we aimed to investigate the relationship between EAT and inflammation parameters including neutrophil-to-lymphocyte ratio (NLR) in hemodialysis (HD) patients.

MATERIAL AND METHODS

Forty-three HD patients (25 females, 18 males; mean age: 64.1 ±11.9 years) receiving HD and 30 healthy subjects (15 females, 15 males; mean age: 59.1 ±10.8 years) were enrolled in the study. Epicardial adipose tissue measurements were performed by echocardiography.

RESULTS

Neutrophil-to-lymphocyte ratio levels were significantly higher in HD patients than in the healthy control group. Hemodialysis patients were separated into two groups according to their median value of NLR (group 1, NLR < 3.07 (n = 21) and group 2, NLR ≥ 3.07 (n = 22)). Group 2 patients had significantly higher EAT, C-reactive protein and ferritin levels, while albumin levels were significantly lower in this group. In the bivariate correlation analysis, EAT was positively correlated with NLR (r = 0.600, p < 0.001) and ferritin (r = 0.485, p = 0.001) levels.

CONCLUSIONS

Neutrophil-to-lymphocyte ratio was found to be an independent predictor of EAT in HD patients (odds ratio = 3.178; p = 0.008). We concluded that this relationship might be attributed to increased inflammation in uremic patients.

Impact of cardiopulmonary bypass surgery on cytokines in epicardial adipose tissue: comparison with subcutaneous fat

BACKGROUND

Cardiac surgery and cardiopulmonary bypass (CPB) have been shown to stimulate a systemic inflammatory response which has been associated with adverse postoperative outcomes. Adipose tissue, both epicardial (EAT) and subcutaneous (SAT), is a known source of inflammatory cytokines, but its role in the pathophysiology of surgery- and CPB-induced systemic inflammatory response has not been fully elucidated. Therefore, we conducted a study to establish levels of selected cytokines in EAT and SAT prior to and after surgery with CPB.

METHODS

Adipose tissue samples were obtained from patients undergoing planned cardiac surgery on CPB. Samples from EAT and SAT were collected before and immediately after CPB. Levels of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), adipocyte fatty acid-binding protein (AFABP), leptin and adiponectin were determined by ELISA, which were adjusted for a total concentration of proteins in the individual samples.

RESULTS

Samples from 77 patients (mean age 67.68 ± 11.5 years) were obtained and analysed. Leptin, adiponectin, TNF-α and AFABP were shown to decrease their concentrations statistically significantly in the EAT after CPB while no statistically significant drop was observed in the SAT. On the contrary, IL-6 showed only a slight and statistically insignificant decrease in the EAT after CPB and it was in the SAT where a statistically significant drop was observed.

DISCUSSION

One of the most relevant findings of this study was the marked decrease in EAT levels of TNF-α, AFABP, leptin and adiponectin after the CPB termination. Our results suggest that EAT might serve as a pool of cytokines which are released into the circulation in reaction to surgery with CPB. Should these novel findings be confirmed, new strategies to assess and possibly reduce EAT contribution on adverse outcomes of cardiac surgery may be developed.

Epicardial Adipose Tissue (EAT) Thickness Is Associated with Cardiovascular and Liver Damage in Nonalcoholic Fatty Liver Disease

Background and Aims

Epicardial adipose tissue (EAT) has been proposed as a cardiometabolic and hepatic fibrosis risk factor in patients with non alcoholic fatty liver disease (NAFLD). Aim of this study was to evaluate the role of EAT in NAFLD by analyzing 1) the association between EAT, the other metabolic parameters and the severity of steatosis 2) the relationship between cardiovascular (cIMT, cplaques, E/A), liver (presence of NASH and significant fibrosis) damage and metabolic risk factors including EAT 3) the relationship between EAT and genetic factors strongly influencing liver steatosis.

Methods

In a cross-sectional study, we considered 512 consecutive patients with NAFLD (confirmed by biopsy in 100). EAT, severity of steatosis, carotid intima-media thickness (cIMT) and plaques were evaluated by ultrasonography and results analysed by multiple linear and logistic regression models. Variables independently associated with EAT (mm) were female gender (p = 0.003), age (p = 0.001), BMI (p = 0.01), diastolic blood pressure (p = 0.009), steatosis grade 2 (p = 0.01) and 3 (p = 0.04), fatty liver index (p = 0.001) and statin use (p = 0.03). Variables independently associated with carotid IMT were age (p = 0.0001), hypertension (p = 0.009), diabetes (p = 0.04), smoking habits (p = 0.04) and fatty liver index (p = 0.02), with carotid plaques age (p = 0.0001), BMI (p = 0.03), EAT (p = 0.02),) and hypertension (p = 0.02), and with E/A age (p = 0.0001), diabetes (p = 0.005), hypertension (p = 0.04) and fatty liver index (p = 0.004). In the 100 patients with available liver histology non alcoholic steatohepatitis (NASH) was independently associated with EAT (p = 0.04) and diabetes (p = 0.054) while significant fibrosis with EAT (p = 0.02), diabetes (p = 0.01) and waist circumference (p = 0.05). No association between EAT and PNPLA3 and TM6SF2 polymorphisms was found.

Conclusion

In patients with NAFLD, EAT is associated with the severity of liver and vascular damage besides with the known metabolic risk factors.

Role of miRNAs in Epicardial Adipose Tissue in CAD Patients with T2DM

Background. Epicardial adipose tissue (EAT) is identified as an atypical fat depot surrounding the heart with a putative role in the involvement of metabolic disorders, including obesity, type-2 diabetes mellitus, and atherosclerosis. We profiled miRNAs in EAT of metabolic patients with coronary artery disease (CAD) and type-2 diabetes mellitus (T2DM) versus metabolically healthy patients by microarray. Compared to metabolically healthy patients, we identified forty-two miRNAs that are differentially expressed in patients with CAD and T2DM from Xinjiang, China. Eleven miRNAs were selected as potential novel miRNAs according to P value and fold change. Then the potential novel miRNAs targeted genes were predicted via TargetScan, PicTar, and miRTarbase, and the function of the target genes was predicted via Gene Ontology (GO) analysis while the enriched KEGG pathway analyses of the miRNAs targeted genes were performed by bioinformatics software DAVID. Then protein-protein interaction networks of the targeted gene were conducted by online software STRING. Finally, using microarray, bioinformatics approaches revealed the possible molecular mechanisms pathogenesis of CAD and T2DM. A total of 11 differentially expressed miRNAs were identified and among them, hsa-miR-4687-3p drew specific attention. Bioinformatics analysis revealed that insulin signaling pathway is the central way involved in the progression of metabolic disorders. Conclusions. The current findings support the fact that miRNAs are involved in the pathogenesis of metabolic disorders in EAT of CAD patients with T2DM, and validation of the results of these miRNAs by independent and prospective study is certainly warranted.

Lipid signaling and lipotoxicity in metaflammation: indications for metabolic disease pathogenesis and treatment

Lipids encompass a wide variety of molecules such as fatty acids, sterols, phospholipids, and triglycerides. These molecules represent a highly efficient energy resource and can act as structural elements of membranes or as signaling molecules that regulate metabolic homeostasis through many mechanisms. Cells possess an integrated set of response systems to adapt to stresses such as those imposed by nutrient fluctuations during feeding-fasting cycles. While lipids are pivotal for these homeostatic processes, they can also contribute to detrimental metabolic outcomes. When metabolic stress becomes chronic and adaptive mechanisms are overwhelmed, as occurs during prolonged nutrient excess or obesity, lipid influx can exceed the adipose tissue storage capacity and result in accumulation of harmful lipid species at ectopic sites such as liver and muscle. As lipid metabolism and immune responses are highly integrated, accumulation of harmful lipids or generation of signaling intermediates can interfere with immune regulation in multiple tissues, causing a vicious cycle of immune-metabolic dysregulation. In this review, we summarize the role of lipotoxicity in metaflammation at the molecular and tissue level, describe the significance of anti-inflammatory lipids in metabolic homeostasis, and discuss the potential of therapeutic approaches targeting pathways at the intersection of lipid metabolism and immune function.