Relationships Between Periventricular Epicardial Adipose Tissue Accumulation, Coronary Microcirculation, and Left Ventricular Diastolic Dysfunction

Correlation between epicardial adipose tissue and myocardial injury in patients with COVID-19

Background: Many people infected with COVID-19 develop myocardial injury. Epicardial adipose tissue (EAT) is among the various risk factors contributing to coronary artery disease. However, its correlation with myocardial injury in patients diagnosed with COVID-19 remains uncertain. Methods: We examined myocardial biomarkers in population affected by COVID-19 during the period from December 2022 to January 2023. The patients without myocardial injury were referred to as group A (n = 152) and those with myocardial injury were referred to as group B (n = 212). Results: 1) The A group and the B group exhibitedstatistically significant differences in terms of age, TC, CRP, Cr, BUN, LDL-C, IL-6, BNP, LVEF and EAT (p < 0.05). 2) EAT volumehad a close relationship with IL-6, LDL-C, cTnI, and CRP (p < 0.05); the corresponding correlation coefficient values were 0.24, 0.21, 0.24, and 0.16. In contrast to those with lower EAT volume, more subjects with a higher volume of EAT had myocardial injury (p < 0.05). Regression analysis showed that EAT, LDL-C, Age and Cr were established as independent risk variables for myocardial injury in subjects affected by COVID-19. 3) In COVID-19 patients, the likelihood of myocardial injury rised notably as EAT levels increase (p < 0.001). Addition of EAT to the basic risk model for myocardial injury resulted in improved reclassification. (Net reclassification index: 58.17%, 95% CI: 38.35%, 77.99%, p < 0.001). Conclusion: Patients suffering from COVID-19 with higher volume EAT was prone to follow myocardial injury and EAT was an independent predictor of heart damage in these individuals.

Pericardial fat volume is related to endothelial-mediated coronary blood flow in women with suspected coronary microvascular dysfunction. A report from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

Background

Coronary microvascular dysfunction is prevalent in women with signs and symptoms of ischemia but no obstructive coronary artery disease (CAD) and is associated with an adverse prognosis. Elevated pericardial fat volume predicts adverse cardiac events, but mechanistic pathways of the association are not well understood.

Methods

118 women enrolled in the NHLBI-sponsored Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction study with suspected coronary microvascular dysfunction but no obstructive CAD underwent adenosine stress 1.5 T cardiovascular magnetic resonance imaging (CMR) imaging and invasive coronary reactivity testing. Semi-quantitative myocardial perfusion reserve index (MPR) index was derived from perfusion images. Pericardial fat volume was measured by manually contouring the cardiac margins and adjacent adipose tissue on a single trans-axial HASTE slice at the level of the left main coronary artery origin and indexed to body surface-area. Simple standard deviation analysis obtained for continuous variables and frequency (percent) for categorical variables. The relationships between pericardial fat volume and coronary reactivity testing parameters were examined by correlation and multivariable regression analyses.

Results

Women with suspected coronary microvascular dysfunction had a mean age of 55 ± 10 years, body mass index (BMI) of 28 ± 7 kg/m2, 44 % had a history of smoking, 63 % hypertension, 8 % diabetes, and 20 % dyslipidemia. CMR imaging-derived pericardial fat volume and coronary blood flow response to intracoronary acetylcholine (Δ CBF) were negatively correlated (r = -0.32, p = 0.0013). After adjustment for age, number of risk factors, high-density lipoprotein (HDL), and cold pressor diameter response, pericardial fat volume remained a significant predictor of Δ coronary blood flow (p = 0.04). There was no association with other coronary reactivity testing measures or CMRI derived MPR index.

Conclusions

Among women with suspected coronary microvascular dysfunction but no obstructive CAD, pericardial fat volume appears to be related in a hypothesized adverse direction to coronary microvascular endothelial function. These results support further work confirming and extending these results to investigate pericardial fat volume as mechanistic pathway and potential treatment target for coronary microvascular dysfunction-related adverse events.Trial registration: clinicaltrials.govNCT00832702.

The Influence of Anthropometrics on Cardiac Mechanics in Healthy Women With Opposite Obesity Phenotypes (Android vs Gynoid)

BACKGROUND

The possible influence exerted by mechanical factors and/or compressive phenomena on myocardial strain parameters in healthy individuals with opposite obesity phenotypes (android vs gynoid) has never been previously investigated. Accordingly, we aimed at evaluating the relationship between anthropometrics, such as the waist-to-hip ratio (WHR), modified Haller index (MHI, the ratio of chest transverse diameter over the distance between sternum and spine), and epicardial adipose tissue (EAT), and left ventricular (LV)-global longitudinal strain (GLS), in healthy women with opposite obesity phenotypes (android vs gynoid).

METHODS

Forty healthy women with obesity (body mass index (BMI) ≥30 Kg/m2) and WHR ≥0.85 ("android group") (52.5±13.2 yrs), 40 age- and BMI-matched healthy women with obesityand WHR <0.78 ("gynoid group") (49.8±13.4 yrs) and 40 age-matched healthy women without obesity (BMI <30 Kg/m2) (controls) (50.3±12.5 yrs) were retrospectively analyzed. All women underwent transthoracic echocardiography implemented with echocardiographic strain analysis of all cardiac chambers. Correlation between LV-GLS and anthropometrics (WHR, MHI, and EAT) was assessed in both groups of obese women. Age, WHR, homeostasis model assessment for insulin resistance (HOMA-IR), and left ventricular mass index (LVMi) were included in the logistic regression analysis performed for evaluating the independent predictors of reduced LV-GLS magnitude (less negative than -20%) in women with android obesity.

RESULTS

Compared to the other groups of women, those with android obesity were found with significantly greater LVMi, higher LV filling pressures, and lower biventricular and biatrial deformation indices. A strong inverse correlation between LV-GLS and all anthropometrics (WHR, MHI, and EAT) was demonstrated in both groups of women with obesity. Univariate logistic regression analysis revealed that WHR (OR 1.58, 95%CI 1.22-2.03, p<0.001) and LVMi (OR 1.09, 95%CI 1.02-1.16, p=0.006) were independently correlated with LV-GLS impairment in women with android obesity. On multivariate logistic regression analysis, the WHR maintained a statistically significant association with the above-mentioned outcome (OR 1.68, 95%CI 1.14-2.48, p=0.009). Receiver operating characteristic (ROC) curve analysis showed that a WHR value ≥1.01 had 93% sensitivity and 100% specificity for detecting LV-GLS impairment in women with android obesity (AUC=0.98; 95%CI 0.96-1.00).

CONCLUSIONS

Anthropometrics may strongly influence cardiac mechanics in healthy women with obesity. The WHR is associated with reduced LV-GLS magnitude in healthy women with android obesity, independent of age, glycometabolic status, and LV size.

The immunology of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) now accounts for the majority of new heart failure diagnoses and continues to increase in prevalence in the United States. Importantly, HFpEF is a highly morbid, heterogeneous syndrome lacking effective therapies. Inflammation has emerged as a potential contributor to the pathogenesis of HFpEF. Many of the risk factors for HFpEF are also associated with chronic inflammation, such as obesity, hypertension, aging, and renal dysfunction. A large amount of preclinical evidence suggests that immune cells and their associated cytokines play important roles in mediating fibrosis, oxidative stress, metabolic derangements, and endothelial dysfunction, all potentially important processes in HFpEF. How inflammation contributes to HFpEF pathogenesis, however, remains poorly understood. Recently, a variety of preclinical models have emerged which may yield much needed insights into the causal relationships between risk factors and the development of HFpEF, including the role of specific immune cell subsets or inflammatory pathways. Here, we review evidence in animal models and humans implicating inflammation as a mediator of HFpEF and identify gaps in knowledge requiring further study. As the understanding between inflammation and HFpEF evolves, it is hoped that a better understanding of the mechanisms underlying immune cell activation in HFpEF can open up new therapeutic avenues.

Extent of coronary atherosclerosis is associated with deterioration of left ventricular global longitudinal strain in patients with preserved ejection fraction undergoing coronary computed tomography angiography

Background

This study aimed to investigate the association between the extent and severity of coronary atherosclerosis, epicardial adipose tissue (EAT) accumulation, and left ventricular (LV) global longitudinal strain (GLS) in patients with preserved LV ejection fraction (LVEF) and without LV regional wall motion abnormalities.

Methods

This study included 169 preserved LVEF patients without LV wall motion abnormalities who underwent coronary computed tomography (CT) angiography for the assessment of suspected coronary artery disease (CAD). The segment stenosis score (SSS) and segment involvement score (SIS) were calculated to evaluate CAD extent. The EAT volume was defined as CT attenuation values ranging from -250 to -30 HU within the pericardial sac. LVGLS was measured using echocardiography to assess subclinical LV dysfunction.

Results

All patients had preserved LVEF of ≥50%, and the mean LVGLS was -18.7% (-20.5% to -16.9%). Mean SSS and SIS were 2.0 (0-5) and 4.0 (0-36), respectively, while mean EAT volume was 116.1 mL (22.9-282.5 mL). Multivariate analysis using linear regression model demonstrated that LVEF (β, -17.0; 95% CI, -20.9 - -13.1), LV mass index (β, 0.03; 95% CI, 0.01-0.06), and EAT volume (β, 0.010; 95% CI, 0.0020-0.0195) were independently associated with LVGLS; however, obstructive CAD was not. The multivariate models demonstrated that SSS (Î, 0.12; 95% CI, 0.05-0.18) and SIS (Î, 0.27; 95% CI, 0.10-0.44) were correlated with deterioration of LVGLS, independent of other parameters.

Conclusion

This study demonstrates that EAT volume and CAD extent are associated with the deterioration of LVGLS in this population.

Epicardial fat accumulation and left heart remodelling in patients with chronic coronary syndrome

AIMS

Patients with chronic coronary syndrome (CCS) suffer from subsequent cardiovascular events, even after complete revascularization; thus, elucidation of the underlying pathophysiological mechanisms is required. Epicardial adipose tissue (EAT) is increasingly recognized as a metabolically active organ with a key role in the pathogenesis of metabolic-related cardiac diseases. The present study investigated the association between EAT burden and left heart remodelling in patients with CCS.

METHODS AND RESULTS

We studied 267 CCS patients (210 men; 71 ± 9 years) with complete revascularization and normal left ventricular (LV) ejection fraction who underwent follow-up echocardiography. All patients underwent the measurement of EAT thickness and speckle-tracking analysis to evaluate LV global longitudinal strain (LVGLS) and left atrial (LA) phasic strain. The mean EAT thickness was 5.0 ± 1.8 mm. Age, sex, body mass index, and diabetes mellitus were independently associated with EAT thickness (all P < 0.05). Multivariable linear regression analysis demonstrated that EAT thickness was significantly associated with LV mass index, early diastolic mitral annular velocity, and LA conduit strain independent of age, sex, and cardiovascular risk factors (all P < 0.05). On the other hand, there was no relationship between EAT thickness and LV systolic parameters including LV ejection fraction and LVGLS.

CONCLUSION

CCS patients with increased EAT thickness had unfavourable left heart remodelling. The assessment of EAT thickness by echocardiography may have clinical utility as a simple surrogate to aid in risk stratification for impaired left heart function in CCS patients.

Empagliflozin inhibits coronary microvascular dysfunction and reduces cardiac pericyte loss in db/db mice

Background

Coronary microvascular dysfunction (CMD) is a pathophysiological feature of diabetic heart disease. However, whether sodium-glucose cotransporter 2 (SGLT2) inhibitors protect the cardiovascular system by alleviating CMD is not known.

Objective

We observed the protective effects of empagliflozin (EMPA) on diabetic CMD.

Materials and methods

The mice were randomly divided into a db/db group and a db/db + EMPA group, and db/m mice served as controls. At 8 weeks of age, the db/db + EMPA group was given empagliflozin 10 mg/(kg⋅d) by gavage for 8 weeks. Body weight, fasting blood glucose and blood pressure were dynamically observed. Cardiac systolic and diastolic function and coronary flow reserve (CFR) were detected using echocardiography. The coronary microvascular structure and distribution of cardiac pericytes were observed using immunofluorescence staining. Picrosirius red staining was performed to evaluate cardiac fibrosis.

Results

Empagliflozin lowered the increased fasting blood glucose levels of the db/db group. The left ventricular ejection fraction, left ventricular fractional shortening, E/A ratio and E/e' ratio were not significantly different between the three groups. CFR was decreased in the db/db group, but EMPA significantly improved CFR. In contrast to the sparse and abnormal expansion of coronary microvessels observed in the db/db group, the number of coronary microvessels was increased, and the capillary diameter was decreased in the db/db + EMPA group. The number and microvascular coverage of cardiac pericytes were reduced in the db/db mice but were improved by EMPA. The cardiac fibrosis was increased in db/db group and may alleviate by EMPA.

Conclusion

Empagliflozin inhibited CMD and reduced cardiac pericyte loss in diabetic mice.

Cardiovascular protection by SGLT2 inhibitors - Do anti-inflammatory mechanisms play a role?

BACKGROUND

Metabolic syndrome and related metabolic disturbances represent a state of low-grade inflammation, which accelerates insulin resistance, type 2 diabetes (T2D) and cardiovascular disease (CVD) progression. Among antidiabetic medications, sodium glucose co-transporter (SGLT) 2 inhibitors are the only agents which showed remarkable reductions in heart failure (HF) hospitalizations and major cardiovascular endpoints (MACE) as well as renal endpoints regardless of diabetes status in large randomized clinical outcome trials (RCTs). Although the exact mechanisms underlying these benefits are yet to be established, growing evidence suggests that modulating inflammation by SGLT2 inhibitors may play a key role.

SCOPE OF REVIEW

In this manuscript, we summarize the current knowledge on anti-inflammatory effects of SGLT2 inhibitors as one of the mechanisms potentially mediating their cardiovascular (CV) benefits. We introduce the different metabolic and systemic actions mediated by these agents which could mitigate inflammation, and further present the signalling pathways potentially responsible for their proposed direct anti-inflammatory effects. We also discuss controversies surrounding some of these mechanisms.

MAJOR CONCLUSIONS

SGLT2 inhibitors are promising anti-inflammatory agents by acting either indirectly via improving metabolism and reducing stress conditions or via direct modulation of inflammatory signalling pathways. These effects were achieved, to a great extent, in a glucose-independent manner which established their clinical use in HF patients with and without diabetes.

Inflammation and Cardiovascular Diseases in the Elderly: The Role of Epicardial Adipose Tissue

Human aging is a complex phenomenon characterized by a wide spectrum of biological changes which impact on behavioral and social aspects. Age-related changes are accompanied by a decline in biological function and increased vulnerability leading to frailty, thereby advanced age is identified among the major risk factors of the main chronic human diseases. Aging is characterized by a state of chronic low-grade inflammation, also referred as inflammaging. It recognizes a multifactorial pathogenesis with a prominent role of the innate immune system activation, resulting in tissue degeneration and contributing to adverse outcomes. It is widely recognized that inflammation plays a central role in the development and progression of numerous chronic and cardiovascular diseases. In particular, low-grade inflammation, through an increased risk of atherosclerosis and insulin resistance, promote cardiovascular diseases in the elderly. Low-grade inflammation is also promoted by visceral adiposity, whose accumulation is paralleled by an increased inflammatory status. Aging is associated to increase in epicardial adipose tissue (EAT), the visceral fat depot of the heart. Structural and functional changes in EAT have been shown to be associated with several heart diseases, including coronary artery disease, aortic stenosis, atrial fibrillation, and heart failure. EAT increase is associated with a greater production and secretion of pro-inflammatory mediators and neuro-hormones, so that thickened EAT can pathologically influence, in a paracrine and vasocrine manner, the structure and function of the heart and is associated to a worse cardiovascular outcome. In this review, we will discuss the evidence underlying the interplay between inflammaging, EAT accumulation and cardiovascular diseases. We will examine and discuss the importance of EAT quantification, its characteristics and changes with age and its clinical implication.

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.

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.

Deep-Learning Segmentation of Epicardial Adipose Tissue Using Four-Chamber Cardiac Magnetic Resonance Imaging

In magnetic resonance imaging (MRI), epicardial adipose tissue (EAT) overload remains often overlooked due to tedious manual contouring in images. Automated four-chamber EAT area quantification was proposed, leveraging deep-learning segmentation using multi-frame fully convolutional networks (FCN). The investigation involved 100 subjects-comprising healthy, obese, and diabetic patients-who underwent 3T cardiac cine MRI, optimized U-Net and FCN (noted FCNB) were trained on three consecutive cine frames for segmentation of central frame using dice loss. Networks were trained using 4-fold cross-validation (n = 80) and evaluated on an independent dataset (n = 20). Segmentation performances were compared to inter-intra observer bias with dice (DSC) and relative surface error (RSE). Both systole and diastole four-chamber area were correlated with total EAT volume (r = 0.77 and 0.74 respectively). Networks' performances were equivalent to inter-observers' bias (EAT: DSCInter = 0.76, DSCU-Net = 0.77, DSCFCNB = 0.76). U-net outperformed (p < 0.0001) FCNB on all metrics. Eventually, proposed multi-frame U-Net provided automated EAT area quantification with a 14.2% precision for the clinically relevant upper three quarters of EAT area range, scaling patients' risk of EAT overload with 70% accuracy. Exploiting multi-frame U-Net in standard cine provided automated EAT quantification over a wide range of EAT quantities. The method is made available to the community through a FSLeyes plugin.

Inflammation in Metabolic Cardiomyopathy

Overlapping pandemics of lifestyle-related diseases pose a substantial threat to cardiovascular health. Apart from coronary artery disease, metabolic disturbances linked to obesity, insulin resistance and diabetes directly compromise myocardial structure and function through independent and shared mechanisms heavily involving inflammatory signals. Accumulating evidence indicates that metabolic dysregulation causes systemic inflammation, which in turn aggravates cardiovascular disease. Indeed, elevated systemic levels of pro-inflammatory cytokines and metabolic substrates induce an inflammatory state in different cardiac cells and lead to subcellular alterations thereby promoting maladaptive myocardial remodeling. At the cellular level, inflammation-induced oxidative stress, mitochondrial dysfunction, impaired calcium handling, and lipotoxicity contribute to cardiomyocyte hypertrophy and dysfunction, extracellular matrix accumulation and microvascular disease. In cardiometabolic patients, myocardial inflammation is maintained by innate immune cell activation mediated by pattern recognition receptors such as Toll-like receptor 4 (TLR4) and downstream activation of the NLRP3 inflammasome and NF-κB-dependent pathways. Chronic low-grade inflammation progressively alters metabolic processes in the heart, leading to a metabolic cardiomyopathy (MC) phenotype and eventually to heart failure with preserved ejection fraction (HFpEF). In accordance with preclinical data, observational studies consistently showed increased inflammatory markers and cardiometabolic features in patients with HFpEF. Future treatment approaches of MC may target inflammatory mediators as they are closely intertwined with cardiac nutrient metabolism. Here, we review current evidence on inflammatory processes involved in the development of MC and provide an overview of nutrient and cytokine-driven pro-inflammatory effects stratified by cell type.

Differential Pathophysiological Mechanisms in Heart Failure With a Reduced or Preserved Ejection Fraction in Diabetes

Diabetes promotes the development of both heart failure with a reduced ejection fraction and heart failure with a preserved ejection fraction through diverse mechanisms, which are likely mediated through hyperinsulinemia rather than hyperglycemia. Diabetes promotes nutrient surplus signaling (through Akt and mammalian target of rapamycin complex 1) and inhibits nutrient deprivation signaling (through sirtuin-1 and its downstream effectors); this suppresses autophagy and promotes endoplasmic reticulum and oxidative stress and mitochondrial dysfunction, thereby undermining the health of diabetic cardiomyocytes. The hyperinsulinemia of diabetes may also activate sodium-hydrogen exchangers in cardiomyocytes (leading to injury and loss) and in the proximal renal tubules (leading to sodium retention). Diabetes may cause epicardial adipose tissue expansion, and the resulting secretion of proinflammatory adipocytokines onto the adjoining myocardium can lead to coronary microcirculatory dysfunction and myocardial inflammation and fibrosis. Interestingly, sodium-glucose cotransporter 2 (SGLT2) inhibitors-the only class of antidiabetic medication that reduces serious heart failure events-may act to mitigate each of these mechanisms. SGLT2 inhibitors up-regulate sirtuin-1 and its downstream effectors and autophagic flux, thus explaining the actions of these drugs to reduce oxidative stress, normalize mitochondrial structure and function, and mute proinflammatory pathways in the stressed myocardium. Inhibition of SGLT2 may also lead to a reduction in the activity of sodium-hydrogen exchangers in the kidney (leading to diuresis) and in the heart (attenuating the development of cardiac hypertrophy and systolic dysfunction). Finally, SGLT2 inhibitors reduce the mass and mute the adverse biology of epicardial adipose tissue (and reduce the secretion of leptin), thus explaining the capacity of these drugs to mitigate myocardial inflammation, microcirculatory dysfunction, and fibrosis, and improve ventricular filling dynamics. The pathophysiological mechanisms by which SGLT2 inhibitors may benefit heart failure likely differ depending on ejection fraction, but each represents interference with distinct pathways by which hyperinsulinemia may adversely affect cardiac structure and function.

Expression profile of circular RNAs in epicardial adipose tissue in heart failure

Background

Recent studies have reported circular RNA (circRNA) expression profiles in various tissue types; however, circRNA expression profile in human epicardial adipose tissue (EAT) remains undefined. This work aimed to compare circRNA expression patterns in EAT between the heart failure (HF) and non-HF groups.

Methods

RNA-sequencing was carried out to compare circRNA expression patterns in EAT specimens from coronary artery disease cases between the HF and non-HF groups. Quantitative real-time polymerase chain reaction was performed for validation. Comparisons of patient characteristics between the two groups were using t test, Mann-Whitney U test, and Chi-squared test.

Results

A total of 141 circRNAs substantially different between the HF and non-HF groups (P < 0.05; fold change >2) were detected, including 56 up-regulated and 85 down-regulated. Among them, hsa_circ_0005565 stood out, for it had the highest fold change and was significantly increased in HF patients in quantitative real-time polymerase chain reaction validation. The top highly expressed EAT circRNAs corresponded to genes involved in cell proliferation and inflammatory response, including GSE1, RHOBTB3, HIPK3, UBXN7, PCMTD1, N4BP2L2, CFLAR, EPB41L2, FCHO2, FNDC3B, and SPECC1. The top enriched Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway were positive regulation of metabolic processes and insulin resistance, respectively.

Conclusion

These data indicate EAT circRNAs may contribute to the pathogenesis of metabolic disorders causing HF.

Targeting perivascular and epicardial adipose tissue inflammation: therapeutic opportunities for cardiovascular disease

Major shifts in human lifestyle and dietary habits toward sedentary behavior and refined food intake triggered steep increase in the incidence of metabolic disorders including obesity and Type 2 diabetes. Patients with metabolic disease are at a high risk of cardiovascular complications ranging from microvascular dysfunction to cardiometabolic syndromes including heart failure. Despite significant advances in the standards of care for obese and diabetic patients, current therapeutic approaches are not always successful in averting the accompanying cardiovascular deterioration. There is a strong relationship between adipose inflammation seen in metabolic disorders and detrimental changes in cardiovascular structure and function. The particular importance of epicardial and perivascular adipose pools emerged as main modulators of the physiology or pathology of heart and blood vessels. Here, we review the peculiarities of these two fat depots in terms of their origin, function, and pathological changes during metabolic deterioration. We highlight the rationale for pharmacological targeting of the perivascular and epicardial adipose tissue or associated signaling pathways as potential disease modifying approaches in cardiometabolic syndromes.

Microvascular and lymphatic dysfunction in HFpEF and its associated comorbidities

Heart failure with preserved ejection fraction (HFpEF) is a complex heterogeneous disease for which our pathophysiological understanding is still limited and specific prevention and treatment strategies are lacking. HFpEF is characterised by diastolic dysfunction and cardiac remodelling (fibrosis, inflammation, and hypertrophy). Recently, microvascular dysfunction and chronic low-grade inflammation have been proposed to participate in HFpEF development. Furthermore, several recent studies demonstrated the occurrence of generalized lymphatic dysfunction in experimental models of risk factors for HFpEF, including obesity, hypercholesterolaemia, type 2 diabetes mellitus (T2DM), hypertension, and aging. Here, we review the evidence for a combined role of coronary (micro)vascular dysfunction and lymphatic vessel alterations in mediating key pathological steps in HFpEF, including reduced cardiac perfusion, chronic low-grade inflammation, and myocardial oedema, and their impact on cardiac metabolic alterations (oxygen and nutrient supply/demand imbalance), fibrosis, and cardiomyocyte stiffness. We focus primarily on HFpEF caused by metabolic risk factors, such as obesity, T2DM, hypertension, and aging.

Coronary perivascular epicardial adipose tissue and major adverse cardiovascular events after ST segment-elevation myocardial infarction

BACKGROUND AND AIMS

Perivascular epicardial adipose tissue (pEAT) plays a key role in the progression of atherosclerosis, plaque rupture, and thrombosis. However, the relationship between pEAT and prognosis after revascularization of ST-segment elevation myocardial infarction (STEMI) is unknown. This study aimed to investigate the relationship between pEAT thickness and prognosis after STEMI.

METHODS

We studied 180 STEMI patients (mean age 59.4 ± 13.3 years, 78.9% male) who underwent cardiac magnetic resonance (CMR) imaging within 1 week of prompt infarct-related artery revascularization and 52 age/sex/body mass index-matched controls (mean age 59.9 ± 13.5 years, 78.9% male). pEAT thickness indexed to body surface area at five locations, infarct size, left ventricular ejection fraction (LVEF), and coronary microvascular obstruction (MVO) were evaluated by CMR. Associations between pEAT index and 1-year composite major adverse cardiovascular events (MACE), infarct size, LVEF, and MVO were analyzed.

RESULTS

Mean pEAT indices were significantly higher in STEMI patients than controls. In STEMI patients, higher pEAT indices at the superior and inferior interventricular groove (SIVG and IIVG, respectively) were significantly associated with larger infarct size, higher prevalence of MVO, and inversely correlated with post-infarct LVEF. SIVG pEAT index was an independent predictor of composite MACE in post-STEMI patients with an odds ratio of 2.26 (95% confidence interval 1.63-3.13; p < 0.0001) after adjustment for age, sex, LVEF, and 2.71 (95% confidence interval 1.93-3.80; p < 0.0001) after adjustment for age, sex, previous myocardial infarction, diabetes mellitus, and renal function.

CONCLUSIONS

STEMI patients have significantly higher pEAT indices than controls. SIVG pEAT index independently predicts composite MACE in revascularized STEMI patients, underscoring the potentially prognostic value of this variable.

Metabolic syndrome - Evidence-based strategies for patient optimization

With the increasing prevalence of obesity worldwide, it is inevitable that anesthesiologists will encounter patients with metabolic syndrome. Metabolic syndrome encompasses multiple diseases, which include central obesity, hypertension, dyslipidemia, and hyperglycemia. Given the involvement of multiple diseases, metabolic syndrome involves numerous complex pathophysiological processes that negatively impact several organ systems. Some of the organ systems that have been well-documented to be adversely affected include the cardiovascular, pulmonary, and endocrine systems. Metabolic syndrome also leads to prolonged hospital stays, increased rates of infections, a greater need for care after discharge, and overall increased healthcare costs. Several interventions have been suggested to mitigate these negative outcomes ranging from lifestyle modifications to surgeries. Therefore, anesthesiologists should understand metabolic syndrome and formulate management strategies that may modify perianesthetic and surgical risks.

The Role of Adipose Triglyceride Lipase and Cytosolic Lipolysis in Cardiac Function and Heart Failure

Heart failure is one of the leading causes of death worldwide. New therapeutic concepts are urgently required to lower the burden of heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), the two major forms of heart failure. Lipolytic processes are induced during the development of heart failure and occur in adipose tissue and multiple organs, including the heart. Increasing evidence suggests that cellular lipolysis, in particular, adipose triglyceride lipase (ATGL) activity, has an important function in cardiac (patho)physiology. This review summarizes the crucial role of cellular lipolysis for normal cardiac function and for the development of HFrEF and HFpEF. We discuss the most relevant pre-clinical studies and elaborate on the cardiac consequences of non-myocardial and myocardial lipolysis modulation. Finally, we critically analyze the therapeutic importance of pharmacological ATGL inhibition as a potential treatment option for HFrEF and/or HFpEF in the future.

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.

Association of Local Epicardial Adipose Tissue Depots and Left Ventricular Diastolic Performance in Patients With Preserved Left Ventricular Ejection Fraction

BACKGROUND

Although full-volume quantification of epicardial adipose tissue (EAT) is a predictor of LV diastolic dysfunction (LVDD), how localized EAT depots are linked to LVDD remains unclear. We evaluated the effect of local EAT depots on LV diastolic function parameters in patients with preserved LV ejection fraction (LVEF).Methods and Results:From 423 consecutive patients who underwent cardiac CT angiography, we recruited 252 with sinus rhythm and normal LVEF. The EAT volume index (EATV/body surface area) and the localized EAT thickness around the right coronary artery (EAT_RCA), left anterior descending artery (EAT_LAD), left circumflex artery (EAT_LCX), right ventricle (EAT_RV), left ventricle (EAT_LV), right atrium (EAT_RA), and left atrium (EAT_LA) were measured using cardiac CT. In the LVDD group (n=71), the EATV index (75±30 vs. 64±28 mL/m², P=0.010), EAT_LCX(10.7±3.8 vs. 9.4±3.4 mm, P=0.008), and EAT_LV(2.6±1.6 vs. 2.1±1.4 mm, P=0.024) were greater than in the non-LVDD group (n=181). In contrast, EAT_LCXand EAT_LVwere markedly associated with decreased lateral e' and increased lateral E/e'. Multiple regression analysis indicated that EAT_LCXand EAT_LVwere strongly associated with LV diastolic function parameters.

CONCLUSIONS

Localized EAT depots are linked to altered mitral annular motion. Further study is warranted to clarify whether localized EAT depots are functionally linked to the clinical manifestations of LVDD.

Influence of visceral adiposity accumulation on adverse left and right ventricular mechanics in the community

AIMS

Obesity carries significant risk for unfavorable ventricular remodeling and subsequent heart failure (HF) development, although the association between abdominal fat distribution and subclinical ventricular dysfunction is unclear. This study aimed to compare the subcutaneous and visceral abdominal adiposity with the risk of decreased ventricular strain.

METHODS

We included 340 participants without overt cardiac disease who underwent laboratory testing, abdominal computed tomographic examination, and speckle-tracking echocardiography. Abdominal adiposity was quantitatively assessed as visceral fat area (VFA) and subcutaneous fat area (SFA) at the level of the umbilicus. Speckle-tracking echocardiography was performed to assess left ventricular global longitudinal strain (LVGLS) and right ventricular free-wall longitudinal strain (RVLS).

RESULTS

Mean age was 56 ± 9 years, and 244 of the participants (72%) were male. The mean LVGLS and RVLS were -19.1 ± 3.0% and -25.0 ± 4.1%, respectively. Both VFA and SFA correlated with LVGLS (r = 0.46 and r = 0.15, both p < 0.01) and RVLS (r = 0.38 and r = 0.12, both p < 0.05), demonstrating a stronger correlation between VFA and ventricular strain. Multivariable analysis showed that VFA was significantly associated with LVGLS and RVLS, independent of traditional cardiovascular risk factors as well as pertinent laboratory and echocardiographic parameters (both p < 0.05), whereas SFA was not. Serum adiponectin level was correlated with LVGLS (r = -0.34, p < 0.001) and RVLS (r = -0.25, p < 0.001), although it lost statistical significance following multivariable adjustment.

CONCLUSION

In a sample of the general population, VFA, but not SFA, accumulation was significantly associated with decreased LV and RV strain, an association that may be involved in the increased risk of HF in obese individuals.

Proteomics of epicardial adipose tissue in patients with heart failure

Epicardial adipose tissue (EAT) is a metabolically active visceral fat depot closely linked to the pathogenesis of heart failure (HF). But the molecular signatures related to the mechanism of HF have not been systematically explored. Here, we present comprehensive proteomic analysis of EAT in HF patients and non‐HF patients as controls. A total of 771 proteins were identified in liquid chromatography‐tandem mass spectrometry experiments. Amongst them, 17 increased in abundance in HF and seven decreased. They were involved in HF‐related processes including inflammation and oxidative stress response and lipid metabolism. Of these proteins, serine proteinase inhibitor A3 (Serpina3) levels in EAT were highly up‐regulated in HF, with HF/non‐HF ratio of 4.63 (P = .0047). Gene expression of Serpina3 via quantitative polymerase chain reaction was significantly increased in the HF group. ELISA analysis confirmed a significant increase in circulating plasma Serpina3 levels in the HF group (P = .004). In summary, for the first time, we describe that parts of EAT proteome may be reactive and work as modulators of HF. Our profiling provides a comprehensive basis for linking EAT with pathogenesis of HF. Understanding the role of EAT may offer new insights into the treatment of HF.

Increased epicardial adipose tissue in young adults with congenital heart disease comorbid with major depressive disorder

OBJECTIVE

Congenital heart disease is the most common congenital malformation. In adult congenital heart disease (ACHD), the prevalence of major depressive disorder (MDD) is increased. Beyond its immanent health risks, increased epi‑ and paracardial adipose tissue has been described in MDD. Epicardial adipose tissue (EAT) is a fat depot surrounding the heart, and it is hypothesized to be associated with coronary artery disease, left-ventricular dysfunction and atrial fibrillation, being frequent problems in ACHD long-term management. We here examined whether EAT is increased in depressed patients with ACHD.

METHODS

Two-hundred and ten ACHD outpatients (mean age 35.5y, 43% female) were included. MDD was diagnosed according to DSM-IV criteria using expert interviews. EAT was measured using echocardiography. Further assessments comprised NT-proBNP, left and right ventricular end-diastolic diameter, left-ventricular ejection fraction, smoking behavior and physical activity.

RESULTS

Of 210 patients, 53 (25.2%) were diagnosed with MDD. EAT was increased in depressed ACHD (F = 5.04; df = 1; p = 0.026). Depressed male patients were less physically active (p < 0.05) and smoked more cigarettes (p < 0.05). EAT was positively predicted by depression severity (p = 0.039), body mass index (p < 0.001), and negatively predicted by physical activity (p = 0.019).

CONCLUSIONS

The presence of MDD is associated with an increased amount of EAT in ACHD, and is dependent on depression severity. Further, the amount of EAT is at least in part mediated by a more sedentary lifestyle. Given the long-term health risks associated with increased EAT, interventions aiming at increased physical activity, smoking cessation and early identification of comorbid MDD may be recommended in ACHD.

[Epicardial adipose tissue as a marker of visceral obesity and its association with metabolic parameters and remodeling of the left chambers of the heart in young people with abdominal obesity]

AIM

to study the correlation of epicardial adipose tissue (EAT) with metabolic parameters, 24-hours profile of blood pressure (BP) and left ventricular remodeling, with the volume of intraabdominal adipose tissue (IAAT), measured by multislice computed tomography (MSCT) in patients with abdominal obesity and metabolic syndrome.

MATERIALS AND METHODS

the study included 80 participants with abdominal obesity (waist circumference > 80 cm in women and >94 cm in men) and without cardiovascular diseases and diabetes. Within this study the following examinations were performed: waist circumference and the body mass index measurement, blood sampling and measurements of lipid levels, uric acid, fasting glucose, insulin, HOMA index, 24-hour ambulatory blood pressure monitoring. Left ventricular (LV) mass index, relative wall thickness, LV mass/height index were estimated from echocardiographic data. EAT volume and IAAT was measured by MSCT. All patients was devided in two groups for analysis: 1 (n=28) - patients with isolated abdominal obesity, without metabolic syndrome, age was 37.5±6.43 years; 2 (n=52) - patients with metabolic syndrome, age - 38.8±5.88 years. The control group 0 included healthy individuals (n=13) without obesity, age was 30.5±5.97 years.

RESULTS

A positive correlation was found between the volume of EAT with the level of insulin in the blood (r=0.2937, p.

Patients With Obesity Exhibit a Plateau Pattern of the Right Ventricular Waveform

Background

Ventricular waveforms are characterized by a dip-and-plateau pattern during diastole owing to an abrupt termination of ventricular filling because of pericardial constraint under conditions such as constrictive pericarditis (CP). However, constrictive hemodynamics is not specifically caused by CP. Therefore, this study aimed to evaluate whether patients with obesity exhibited constrictive hemodynamics.

Methods

Overall, 60 consecutive Japanese patients (mean age, 69.5 years; 45% women) who underwent right heart catheterization at the Japan Community Healthcare Organization Osaka Hospital from July 2016 to September 2018 were examined. Two-dimensional echocardiography was used to measure the epicardial adipose tissue (EAT) in the standard parasternal long-axis view during end-diastole. Because patients who underwent open-heart surgery were highly likely to have CP, they were excluded.

Results

Among the 60 patients, 11 (18%) exhibited a plateau pattern of the right ventricular waveform and had a mean EAT value of 4.2 mm, which was significantly higher than that of patients without such a pattern (2.1 mm, P < 0.001). Similarly, the mean body mass index (BMI) values were significantly higher in patients with a plateau pattern than in those without it (27.2 vs. 21.8 kg/m², P < 0.001). EAT was significantly correlated with the BMI (r = 0.72, P < 0.001). In patients with a plateau pattern, the triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels were significantly higher (TG: 150 vs. 100 mg/dL, LDL-C: 121 vs. 95 mg/dL, P < 0.05) and the left atrial diameter (52.8 vs. 44.7 mm, P < 0.01) and left atrial volume index (58.7 vs. 47.6 mL/m², P < 0.05) were significantly greater than those in the patients without it. The EAT was also significantly correlated with the TG level (r = 0.37, P < 0.01).

Conclusions

Obese patients may present with constrictive hemodynamics, suggesting left ventricular diastolic dysfunction. EAT was significantly correlated with metabolic syndrome components, namely obesity and TG levels.

Cholesterol-Lowering Gene Therapy Prevents Heart Failure with Preserved Ejection Fraction in Obese Type 2 Diabetic Mice

Hypercholesterolemia may be causally related to heart failure with preserved ejection fraction (HFpEF). We aimed to establish a HFpEF model associated with hypercholesterolemia and type 2 diabetes mellitus by feeding a high-sucrose/high-fat (HSHF) diet to C57BL/6J low-density lipoprotein receptor (LDLr)^−/− mice. Secondly, we evaluated whether cholesterol-lowering adeno-associated viral serotype 8 (AAV8)-mediated LDLr gene transfer prevents HFpEF. AAV8-LDLr gene transfer strongly (p < 0.001) decreased plasma cholesterol in standard chow (SC) mice (66.8 ± 2.5 mg/dl versus 213 ± 12 mg/dl) and in HSHF mice (84.6 ± 4.4 mg/dl versus 464 ± 25 mg/dl). The HSHF diet induced cardiac hypertrophy and pathological remodeling, which were potently counteracted by AAV8-LDLr gene transfer. Wet lung weight was 19.0% (p < 0.001) higher in AAV8-null HSHF mice than in AAV8-null SC mice, whereas lung weight was normal in AAV8-LDLr HSHF mice. Pressure–volume loop analysis was consistent with HFpEF in AAV8-null HSHF mice and showed a completely normal cardiac function in AAV8-LDLr HSHF mice. Treadmill exercise testing demonstrated reduced exercise capacity in AAV8-null HSHF mice but a normal capacity in AAV8-LDLr HSHF mice. Reduced oxidative stress and decreased levels of tumor necrosis factor-α may mediate the beneficial effects of cholesterol lowering. In conclusion, AAV8-LDLr gene therapy prevents HFpEF.

Hypoxia-inducible factor 1-alpha (HIF-1α) as a factor mediating the relationship between obesity and heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF), a common condition with an increased mortality, is strongly associated with obesity and the metabolic syndrome. The latter two conditions are associated with increased epicardial fat that can extend into the heart. This review advances the proposition that hypoxia-inhibitory factor-1α (HIF-1α) maybe a key factor producing HFpEF. HIF-1α, a highly conserved transcription factor that plays a key role in tissue response to hypoxia, is increased in adipose tissue in obesity. Increased HIF-1α expression leads to expression of a potent profibrotic transcriptional programme involving collagen I, III, IV, TIMP, and lysyl oxidase. The net effect is the formation of collagen fibres leading to fibrosis. HIF-1α is also responsible for recruiting M1 macrophages that mediate obesity-associated inflammation, releasing IL-6, MCP-1, TNF-α, and IL-1β with increased expression of thrombospondin, pro α2 (I) collagen, transforming growth factor β, NADPH oxidase, and connective tissue growth factor. These factors can accelerate cardiac fibrosis and impair cardiac diastolic function. Inhibition of HIF-1α expression in adipose tissue of mice fed a high-fat diet suppressed fibrosis and reduces inflammation in adipose tissue. Delineation of the role played by HIF-1α in obesity-associated HFpEF may lead to new potential therapies.

Epicardial Adipose Tissue and Cardiovascular Disease

PURPOSE OF REVIEW

Epicardial adipose tissue has been associated with the development/progression of cardiovascular disease. We appraise the strength of the association between epicardial adipose tissue and development/progression of cardiovascular diseases like coronary artery disease, atrial fibrillation, and heart failure with preserved ejection fraction.

RECENT FINDINGS

Cross-sectional clinical and translational correlative studies have established an association between epicardial adipose tissue and progression of coronary artery disease. Recent studies question this association and underline the need for longitudinal studies. Epicardial adipose tissue also plays a definite role in the pathobiology of atrial fibrillation and its recurrence after ablation. In contrast to an early paradigm, epicardial adipose tissue does not appear to play a key role in the pathogenesis of heart failure with preserved ejection fraction in obese patients. The association of epicardial adipose tissue with atrial fibrillation is robust. In contrast, the association of epicardial adipose tissue with coronary artery disease and heart failure with preserved ejection fraction is tenuous. Additional research, including longitudinal studies, is needed to confirm or refute these proposed associations.

The relationship between epicardial adipose tissue and coronary artery stenosis by sex and menopausal status in patients with suspected angina

Background

Evidence suggests that epicardial adipose tissue (EAT) is closely related to coronary artery stenosis (CAS). However, sexual dimorphism may be present in adipose tissue, and its influence on CAS between men and women is controversial. We assessed the relationship between EAT and CAS by sex and menopausal status in patients with suspected angina.

Methods

Six hundred twenty-eight consecutive patients (men/women n = 257/371; mean age = 59.9 ± 10.2 years) who had chest pain for angina and underwent coronary angiography were included. CAS was defined as > 50% luminal narrowing of at least one epicardial coronary artery. EAT thickness was measured by transthoracic echocardiography.

Results

Of the 628 patients, 52.1% (n = 134) of men and 35.3% (n = 131) of women had CAS. The mean EAT thickness was not different between men and women and was larger in patients with CAS (8.04 ± 2.39 vs 6.58 ± 1.88 mm, P < 0.001). EAT thickness was independently associated with CAS in both sexes (P < 0.001). The odds ratio (OR) of EAT for the presence of CAS was higher in men (OR = 1.43, 95% confidence interval [CI] 1.21–1.69) than in women (OR = 1.24, 95% CI 1.10–1.40). EAT thickness was larger in postmenopausal women than in premenopausal women (7.59 ± 2.25 vs 5.80 ± 1.57 mm, P < 0.001) and was independently related with CAS (OR = 1.24, 95% CI 1.09–1.41). This was not the case in premenopausal women.

Conclusion

In patients with suspected angina, an increase in EAT thickness was independently related to the presence of CAS in both men and women, with it being stronger in men. According to menopausal status in women, EAT thickness is significantly associated with CAS only in postmenopausal women.

Epicardial adipose tissue and cardiovascular diseases

Obesity is a heterogeneous disease with different degrees of cardiovascular (CV) and metabolic manifestations. Certain ectopic fat depots may contribute to obesity-related CV risk and may explain part of the risk differential observed in metabolically healthy obese and the so called "obesity paradox". The growing interest towards the potential impact of epicardial adipose tissue (EAT) in cardiovascular (CV) risk has led to deepen its biological function. Genetic, epigenetic and environmental factors may drive the shift towards a dysfunctional EAT characterized by a pro-inflammatory and pro-fibrotic phenotype. Due to the close anatomic proximity to coronary arteries, a thicker and dysfunctional EAT actively contribute to development and progression of coronary atherosclerosis. Beside classical paracrine transmission, EAT may directly release mediators into the vasa vasorum of the coronary arterial wall, a mechanism referred to as "vasocrine". Similarly, the pro-inflammatory and pro-fibrotic secretome characterizing dysfunctional EAT may impair cardiac structure and function, thus being implicated in the pathogenesis of diastolic heart failure and atrial fibrillation. The development of 3D imaging techniques have paved the way for clarifying the causative role of EAT in CV pathophysiology, the use of EAT volume/thickness in CV risk stratification and potential cardio-protective effects of EAT reduction. The aim of this narrative review is to update current knowledge on the pathophysiological functions of EAT, focusing on basic mechanisms and potential clinical implications.

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

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

Epicardial Adipose Tissue Is Associated With Left Atrial Dysfunction in People Without Obstructive Coronary Artery Disease or Atrial Fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) is a metabolically active visceral fat depot. Although EAT volume is associated with the incidence and burden of atrial fibrillation (AF), its role in subclinical left atrial (LA) dysfunction is unclear. This study aims to evaluate the relationships between EAT volumes, LA function, and LA global longitudinal strain.

METHODS

One hundred and thirty people without obstructive coronary artery disease or AF were prospectively recruited into the study in Australia and underwent cardiac computed tomography and echocardiography. EAT volume was quantified from cardiac computed tomography. Echocardiographic 3-dimensional (3D) volumetric measurements and 2D speckle-tracking analysis were performed.

RESULTS

Using the overall median body surface area-indexed total EAT volume (EATi), the study cohort was divided into 2 groups of larger and smaller EATi volume. Subjects with larger EATi volume had significantly impaired LA reservoir function (3D LA ejection fraction, 46.1% ± 8.9% vs 49.0% ± 7.0%, P = 0.044) and reduced LA global longitudinal strain (37.6% ± 10.2% vs 44.1% ± 10.7%, P < 0.001). Total EATi volume was a predictor of impaired 2D LA global longitudinal strain (standardized β = -0.204, P = 0.034), reduced 3D LA ejection fraction (standardized β = -0.208, P = 0.036), and reduced 3D active LA ejection fraction (standardized β = -0.211, P = 0.017). Total EATi volume, rather than LA EATi volume, was the more important predictor of LA dysfunction.

CONCLUSIONS

Indexed EAT volume is independently associated with subclinical LA dysfunction and impaired global longitudinal strain in people without obstructive coronary artery disease or a history of AF.

Are the effects of drugs to prevent and to treat heart failure always concordant? The statin paradox and its implications for understanding the actions of antidiabetic medications

Most treatments for chronic heart failure are effective both in preventing its onset and reducing its progression. However, statins prevent the development of heart failure, but they do not decrease morbidity and mortality in those with established heart failure. This apparent discordance cannot be explained by an effect to prevent interval myocardial infarctions. Instead, it seems that the disease that statins were preventing in trials of patients with a metabolic disorder was different from the disease that they were treating in trials of chronic heart failure. The most common phenotype of heart failure in patients with obesity and diabetes is heart failure with a preserved ejection fraction (HFpEF). In this disorder, the anti-inflammatory effects of statins might ameliorate myocardial fibrosis and cardiac filling abnormalities, but these actions may have little relevance to patients with heart failure and a reduced ejection fraction (HFrEF), whose primary derangement is cardiomyocyte loss and stretch. These distinctions may explain why statins were ineffective in trials that focused on HFrEF, but have been reported to produce favourable effects in observational studies of HFpEF. Similarly, selective cytokine antagonists were ineffective in HFrEF, but have been associated with benefits in HFpEF. These observations may have important implications for our understanding of the effects of antihyperglycaemic medications. Glucagon-like peptide-1 receptor agonists have had neutral effects on heart failure events in people at risk for HFpEF, but have exerted deleterious actions in HFrEF. Similarly, sodium-glucose co-transporter 2 inhibitors, which exert anti-inflammatory effects and reduce heart failure events in patients who are prone to HFpEF, may not be effective in HFrEF. The distinctions between HFrEF and HFpEF may explain why the effects of drugs on heart failure events in diabetes trials may not be relevant to their use in patients with systolic dysfunction.