Epicardial adipose tissue thickness as a predictor of impaired microvascular function in patients with non-obstructive coronary artery disease

Epicardial Adipose Tissue and Heart Failure, Friend or Foe?

Heart failure (HF) management guidelines recommend individualized assessments based on HF phenotypes. Adiposity is a known risk factor for HF. Recently, there has been an increased interest in organ-specific adiposity, specifically the role of the epicardial adipose tissue (EAT), in HF risk. EAT is easily assessable through various imaging modalities and is anatomically and functionally connected to the myocardium. In pathological conditions, EAT secretes inflammatory cytokines, releases excessive fatty acids, and increases mechanical load on the myocardium, resulting in myocardial remodeling. EAT plays a pathophysiological role in characterizing both HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). In HFrEF, EAT volume is reduced, reflecting an impaired metabolic reservoir, whereas in HFpEF, the amount of EAT is associated with worse biomarker and hemodynamic profiles, indicating increased EAT activity. Studies have examined the possibility of therapeutically targeting EAT, and recent studies using sodium glucose cotransporter 2 inhibitors have shown potential in reducing EAT volume. However, further research is required to determine the clinical implications of reducing EAT activity in patients with HF.

The Role of Epicardial Adipose Tissue in Acute Coronary Syndromes, Post-Infarct Remodeling and Cardiac Regeneration

Epicardial adipose tissue (EAT) is a fat deposit surrounding the heart and located under the visceral layer of the pericardium. Due to its unique features, the contribution of EAT to the pathogenesis of cardiovascular and metabolic disorders is extensively studied. Especially, EAT can be associated with the onset and development of coronary artery disease, myocardial infarction and post-infarct heart failure which all are significant problems for public health. In this article, we focus on the mechanisms of how EAT impacts acute coronary syndromes. Particular emphasis was placed on the role of inflammation and adipokines secreted by EAT. Moreover, we present how EAT affects the remodeling of the heart following myocardial infarction. We further review the role of EAT as a source of stem cells for cardiac regeneration. In addition, we describe the imaging assessment of EAT, its prognostic value, and its correlation with the clinical characteristics of patients.

Epicardial adipose tissue in patients with systemic sclerosis

Aims

Epicardial adipose tissue (EAT) has emerged as a mediator between systemic inflammatory disorders and cardiovascular disease, and may therefore play a role in the pathophysiology of cardiac involvement in systemic sclerosis (SSc). The aim of this study was to assess the correlation between EAT and left ventricular (LV) function, and to determine the prognostic value of EAT in patients with SSc.

Methods and results

Consecutive patients with SSc who underwent non-contrast thorax computed tomography and echocardiography were included. EAT mass was quantified using dedicated software. The study endpoint was all-cause mortality. A total of 230 SSc patients (age 53 ± 15 years, 14% male) were included. The median value of EAT mass was 67 g (interquartile range: 45-101 g). Patients with increased EAT mass (≥67 g) showed more impaired LV diastolic function as compared with patients with less EAT mass (<67 g), and even after adjusting for age and comorbidities, EAT mass was independently associated with LV diastolic function parameters. During a median follow-up of 8 years, 42 deaths occurred. Kaplan-Meier analysis showed that patients with increased EAT mass had higher all-cause mortality rate as compared with patients with less EAT mass (29% vs. 7%; P < 0.001). In the multivariable analysis, EAT was independently associated with all-cause mortality after adjusting for important covariates (HR: 1.006; 95% CI: 1.001-1.010).

Conclusion

In patients with SSc, EAT is independently associated with LV diastolic dysfunction and higher mortality rate.

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

Background

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

Materials and methods

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

Results

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

Conclusion

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

Impact of Type 2 Diabetes Mellitus on Epicardial Adipose Tissue and Myocardial Microcirculation by MRI in Postmenopausal Women

BACKGROUND

Type 2 diabetes mellitus (T2DM) often occurs conjunctly with the menopausal transition in female patients. In addition, epicardial adipose tissue (EAT) has an unfavorable impact on the myocardium and coronary arteries under the influence of metabolic disorders.

PURPOSE

To investigate the impact of T2DM on EAT and myocardial microvascular function in postmenopausal women.

STUDY TYPE

Retrospective.

POPULATION

One-hundred sixty-one postmenopausal women divided into three groups: newly diagnosed (≤5 years) T2DM (n = 56, 58.6 ± 7.7 years), long-term (>5 years) T2DM (n = 57, 61.9 ± 7.9 years), and healthy controls (n = 48, 59.4 ± 7.4 years).

FIELD STRENGTH/SEQUENCE

3.0 T; balanced steady-state free precession and inversion recovery prepared echo-planar sequences.

ASSESSMENT

EAT volume was quantified by delineating the epicardial border and the visceral layer of pericardium on the short-axis cine stacks. Perfusion parameters including upslope, maximum signal intensity (MaxSI) and time to maximum signal intensity (TTM) were derived from the first-pass perfusion signal intensity-time curves.

STATISTICAL TESTS

One-way analysis of variance, Pearson's and Spearman correlation, and multivariable linear regression. Two-sided P < 0.05 was considered statistically significant.

RESULTS

EAT volume was significantly increased in diabetic postmenopausal women compared to the controls (48.4 ± 13.4 mL/m² [newly diagnosed T2DM] vs. 58.4 ± 17.3 mL/m² [long-term T2DM] vs. 35.8 ± 12.3 mL/m² [controls]). Regarding perfusion parameters, upslope and MaxSI were significantly reduced (2.6 ± 1.0 [newly diagnosed T2DM] vs. 2.1 ± 0.8 [long-term T2DM] vs. 3.6 ± 1.3 [controls]; and 21.4 ± 6.9 [newly diagnosed T2DM] vs. 18.7 ± 6.4 [long-term T2DM] vs. 28.4 ± 8.6 [controls]), whereas TTM was significantly increased in the T2DM groups compared to the control group (23.6 ± 8.7 [newly diagnosed T2DM] vs. 27.1 ± 9.4 [long-term T2DM] vs. 21.4 ± 6.0 [controls]). Multivariable analysis (adjusted coefficient of determination [R² ] = 0.489) showed that EAT volume (β = -0.610) and menopausal age (β = 0.433) were independently correlated with decreased perfusion upslope.

DATA CONCLUSION

Diabetic postmenopausal women had significantly higher EAT volume and more impaired microcirculation compared to the controls. Increased EAT volume and earlier menopausal age were independently associated with microvascular dysfunction in these patients.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 3.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

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Epicardial adipose tissue 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.

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

Background and Aim

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

Methods

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

Results

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

Conclusions

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

Epicardial adipose tissue in obesity-related cardiac dysfunction

Obesity is associated with the development of heart failure and is a major risk factor for heart failure with preserved ejection fraction (HFpEF). Epicardial adipose tissue (EAT) is a unique visceral fat in close proximity to the heart and is of particular interest to the study of cardiac disease. Small poorly differentiated adipocytes with altered lipid:water content are associated with a proinflammatory secretome and may contribute to the pathophysiology observed in HFpEF. Multimodality imaging approaches can be used to quantify EAT volume and characterise EAT composition. Current research studies remain unclear as to the magnitude of effect that EAT plays on myocardial dysfunction and further work using multimodality imaging techniques is ongoing. Pharmacological interventions, including glucagon-like peptide 1 receptor agonists and sodium-dependent glucose linked transporter 2 inhibitors have shown promise in attenuating the deleterious metabolic and inflammatory changes seen in EAT. Clinical studies are ongoing to explore whether these therapies exert their beneficial effects by modifying this unique adipose deposit.

Metformin: Expanding the Scope of Application-Starting Earlier than Yesterday, Canceling Later

Today the area of application of metformin is expanding, and a wealth of data point to its benefits in people without carbohydrate metabolism disorders. Already in the population of people leading an unhealthy lifestyle, before the formation of obesity and prediabetes metformin smooths out the adverse effects of a high-fat diet. Being prescribed at this stage, metformin will probably be able to, if not prevent, then significantly reduce the progression of all subsequent metabolic changes. To a large extent, this review will discuss the proofs of the evidence for this. Another recent important change is a removal of a number of restrictions on its use in patients with heart failure, acute coronary syndrome and chronic kidney disease. We will discuss the reasons for these changes and present a new perspective on the role of increasing lactate in metformin therapy.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Research Progress of Imaging Methods for Detection of Microvascular Angina Pectoris in Diabetic Patients

Diabetes is a complex metabolic disease characterized by hyperglycemia. Its complications are various, often involving the heart, brain, kidney, and other essential organs. At present, the number of diabetic patients in the world is growing day by day. The cardiovascular disease caused by diabetes has dramatically affected the quality of life of diabetic patients. It is the leading cause of death of diabetic patients. Diabetic patients often suffer from microvascular angina pectoris without obstructive coronary artery disease. Still, there are typical ECG ischemia and angina pectoris, that is, chest pain and dyspnea under exercise. Unlike obstructive coronary diseases, nitrate does not affect chest pain caused by coronary microvascular angina in most cases. With the increasing emphasis on diabetic microvascular angina, the need for accurate diagnosis of the disease is also increasing. We can use SPECT, PET, CMR, MCE, and other methods to evaluate coronary microvascular function. SPECT is commonly used in clinical practice, and PET is considered the gold standard for non-invasive detection of myocardial blood flow. This article mainly introduces the research progress of these imaging methods in detecting microvascular angina in diabetic patients.

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.

Impact of atherosclerotic extent on clinical outcome for diabetic patients with non-obstructive coronary artery disease

Background and aims

The prognostic impact of non-obstructive coronary artery disease (CAD) has long been underestimated due to its mild stenosis (<50% stenosis). We aim to investigate the prognostic value of atherosclerotic extent in DM patients with non-obstructive CAD.

Methods

The analysis was based on a single center cohort of DM patients referred for coronary computed tomography angiography (CCTA) due to suspect CAD in 2015-2017. Based on coronary stenosis combined with segment involvement score (SIS), the study population were divided into four groups: normal (0% stenosis), non-obstructive SIS<3, non-obstructive SIS≥3 and obstructive (≥50% stenosis). The intra-class correlation (ICC) was used to test the inter-and intra-reviewer agreement. Multivariate Cox model and Kaplan-Meier method were used to evaluate the effect size of atherosclerotic extent on the prognosis.

Results

In total, 1241 patients (age 60.2 ± 10.4 years, 54.1% male) were included, of which 50.2% were non-obstructive. During a median follow-up of 2.6 years, 131 MACEs (10.6%) were adjudicated, including 17 cardiovascular deaths, 28 non-fatal myocardial infarctions, 64 unstable anginas requiring hospitalization and 22 strokes. Incremental event rates could be observed across the four groups. After adjustment for age, gender, hyperlipidemia and presence of high-risk plaque, Hazard Ratio (HR) for non-obstructive SIS<3, non-obstructive SIS≥3 and the obstructive group was 1.84 (95%CI: 0.70-4.79), 3.71 (95%CI: 1.37-10.00) and 5.46 (95%CI: 2.18-13.69), respectively. Compared with non-obstructive SIS<3, non-obstructive SIS≥3 showed a significantly higher risk (HR:2.02 95%CI:1.11-3.68, p = 0.021). Similar results were demonstrated when Leiden risk score was used for sensitivity analysis.

Conclusion

In DM patients with non-obstructive CAD, atherosclerotic extent was associated with higher risk of major adverse cardiac events at long-term follow-up. Efforts should be made to determine risk stratification for the management of DM patients with non-obstructive CAD.

Epicardial adipose tissue differentiates in patients with and without coronary microvascular dysfunction

BACKGROUND/OBJECTIVES

Coronary microvascular dysfunction (CMD) is a common disorder, leading to symptoms similar to obstructive coronary artery disease and bears important prognostic implications. Local inflammation is suggested to promote development of CMD. Epicardial adipose tissue (EAT) is a local visceral fat depot surrounding the heart and the coronary arteries, modifying the inflammatory environment of the heart. We compared EAT in patients with and without CMD.

METHODS

We retrospectively included consecutive patients undergoing diagnostic coronary angiography as well as transthoracic echocardiography between March and October 2016. EAT thickness was defined as space between the epicardial wall of the myocardium and the visceral layer of the pericardium and EAT index was calculated as EAT thickness/body surface area. Logistic regression analysis was used to determine the association of EAT index with the presence of CMD.

RESULTS

Overall, 399 patients (mean age 60.2 ± 14.0 years, 46% male) were included. EAT thickness was significantly higher in patients with CMD compared to patients without CMD (EAT thickness 4.4 ± 1.8 vs. 4.9 ± 2.4 mm, p = 0,048 for patients without and with CMD, respectively). In univariate regression analysis, EAT index was associated with a 30% higher frequency of CMD (odds ratio [95% confidence interval]: 1.30 [1.001-1.69], p = 0.049). Effect sizes remained stable upon adjustment for body mass index (BMI, 1.30 [1.003-1.70], p = 0.048), but were attenuated when ancillary adjusting for age and gender (1.17 [0.90-1.54, p = 0.25). The effect was more pronounced in patients >65 years of age and independent of BMI and sex (1.85 [1.14-3.00], p = 0.013).

CONCLUSION

EAT thickness is independently associated with CMD and can differentiate between patients with and without CMD especially in older age groups. Our results support the hypothesis that modulation of local inflammation by epicardial fat is involved in the development of CMD.

Characterization of the inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction: a hypothesis to explain influence of sex on the evolution and potential treatment of the disease

Accumulating evidence points to the existence of an inflammatory-metabolic phenotype of heart failure with a preserved ejection fraction (HFpEF), which is characterized by biomarkers of inflammation, an expanded epicardial adipose tissue mass, microvascular endothelial dysfunction, normal-to-mildly increased left ventricular volumes and systolic blood pressures, and possibly, altered activity of adipocyte-associated inflammatory mediators. A broad range of adipogenic metabolic and systemic inflammatory disorders - e.g. obesity, diabetes and metabolic syndrome as well as rheumatoid arthritis and psoriasis - can cause this phenotype, independent of the presence of large vessel coronary artery disease. Interestingly, when compared with men, women are both at greater risk of and may suffer greater cardiac consequences from these systemic inflammatory and metabolic disorders. Women show disproportionate increases in left ventricular filling pressures following increases in central blood volume and have greater arterial stiffness than men. Additionally, they are particularly predisposed to epicardial and intramyocardial fat expansion and imbalances in adipocyte-associated proinflammatory mediators. The hormonal interrelationships seen in inflammatory-metabolic phenotype may explain why mineralocorticoid receptor antagonists and neprilysin inhibitors may be more effective in women than in men with HFpEF. Recognition of the inflammatory-metabolic phenotype may improve an understanding of the pathogenesis of HFpEF and enhance the ability to design clinical trials of interventions in this heterogeneous syndrome.

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.

Relationship between epicardial adipose tissue and coronary vascular function in patients with suspected coronary artery disease and normal myocardial perfusion imaging

Aims

We evaluated the relationship between epicardial adipose tissue (EAT) and coronary vascular function assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) in patients with suspected coronary artery disease (CAD).

Methods and results

The study population included 270 patients with suspected CAD and normal myocardial perfusion at stress–rest 82Rb PET/CT. Coronary artery calcium (CAC) score and EAT volume were measured. Absolute myocardial blood flow (MBF) was computed in mL/min/ from the dynamic rest and stress imaging. Myocardial perfusion reserve (MPR) was defined as the ratio of hyperaemic to baseline MBF and it was considered reduced when <2. MPR was normal in 177 (65%) patients and reduced in 93 (35%). Patients with impaired MPR were older (P < 0.001) and had higher CAC score values (P = 0.033), EAT thickness (P = 0.009), and EAT volume (P < 0.001). At univariable logistic regression analysis, age, heart rate reserve (HRR), CAC score, EAT thickness, and EAT volume resulted significant predictors of reduced MPR, but only age (P = 0.002), HRR (P = 0.021), and EAT volume (P = 0.043) were independently associated with reduced MPR, at multivariable analysis. In patients with CAC score 0 (n = 114), a significant relation between EAT volume and MPR (P = 0.014) was observed, while the relationship was not significant (P = 0.21) in patients with CAC score >0 (n = 156).

Conclusion

In patients with suspected CAD and normal myocardial perfusion, EAT volume predicts hyperaemic MBF and reduced MPR, confirming that visceral pericardium fat may influence coronary vascular function. Thus, EAT evaluation has a potential role in the early identification of coronary vascular dysfunction.

Detecting human coronary inflammation by imaging perivascular fat

Early detection of vascular inflammation would allow deployment of targeted strategies for the prevention or treatment of multiple disease states. Because vascular inflammation is not detectable with commonly used imaging modalities, we hypothesized that phenotypic changes in perivascular adipose tissue (PVAT) induced by vascular inflammation could be quantified using a new computerized tomography (CT) angiography methodology. We show that inflamed human vessels release cytokines that prevent lipid accumulation in PVAT-derived preadipocytes in vitro, ex vivo, and in vivo. We developed a three-dimensional PVAT analysis method and studied CT images of human adipose tissue explants from 453 patients undergoing cardiac surgery, relating the ex vivo images with in vivo CT scan information on the biology of the explants. We developed an imaging metric, the CT fat attenuation index (FAI), that describes adipocyte lipid content and size. The FAI has excellent sensitivity and specificity for detecting tissue inflammation as assessed by tissue uptake of 18F-fluorodeoxyglucose in positron emission tomography. In a validation cohort of 273 subjects, the FAI gradient around human coronary arteries identified early subclinical coronary artery disease in vivo, as well as detected dynamic changes of PVAT in response to variations of vascular inflammation, and inflamed, vulnerable atherosclerotic plaques during acute coronary syndromes. Our study revealed that human vessels exert paracrine effects on the surrounding PVAT, affecting local intracellular lipid accumulation in preadipocytes, which can be monitored using a CT imaging approach. This methodology can be implemented in clinical practice to noninvasively detect plaque instability in the human coronary vasculature.

Epicardial fat thickness is associated with aortic intima-media thickness in patients without clinical manifestation of atherosclerotic cardiovascular disease

BACKGROUND

Although the relationship between epicardial fat thickness (EFTh) and coronary atherosclerosis is well established, this relation in the early periods of atherosclerosis has not been fully demonstrated. On the other hand, thoracic aortic intima-media thickness (IMT) rather than carotid IMT was reported as an earlier marker of preclinical atherosclerosis.

OBJECTIVE

We aimed to assess the relationship between thoracic aortic IMT and EFTh in patients undergoing transesophageal echocardiography (TEE) examination for different indications.

METHODS

We included 104 patients (mean age 38±11.4 years), who underwent TEE for various indications. The patients were divided into two groups according to the median thoracic aortic IMT values (IMT normal group<10 mm and IMT abnormal group≥10 mm). EFTh was obtained using two-dimensional transthoracic echocardiography on the right ventricular free wall during systole and diastole.

RESULTS

The highest EFTh values (3.3±0.96 mm vs. 4.51±0.66 mm, P<.001) were observed in the abnormal aortic IMT group. Multivariate linear regression analysis showed that aortic IMT was independently correlate with EFTh (β=0.423, P<.001). Moreover, EFTh was found to be associated with history of transient ischemic attack (r=.403, P<.001) and abnormal IMT (r=.643, P<.001) in bivariate analysis.

CONCLUSION

Epicardial fat thickness is independently related to the extent of subclinical thoracic aortic atherosclerosis. Increase in EFTh may be crucial marker for initial atherosclerosis.

Obesity Related Coronary Microvascular Dysfunction: From Basic to Clinical Practice

Obesity related coronary microvascular disease is a medical entity which is not yet fully elucidated. The pathophysiological basis of coronary microcirculatory dysfunction consists of a heterogeneous group of disorders with individual morphologic/functional/clinical presentation and prognosis. Coronary microcirculatory changes include mechanisms connected with vascular dysfunction, as well as extravascular and vasostructural changes in responses to neural, mechanical, and metabolic factors. Cardiometabolic changes that include obesity, dyslipidemia, diabetes mellitus type II, and hypertension are associated with atherosclerosis of epicardial coronary arteries and/or microvascular coronary dysfunction, with incompletely understood underlying mechanisms. In obesity, microvascular disease is mediated via adipokines/cytokines causing chronic, subclinical inflammation with (a) reduced NO-mediated dilatation, (b) changed endothelial- and smooth muscle-dependent vasoregulating mechanisms, (c) altered vasomotor control with increased sympathetic activity, and (d) obesity related hypertension with cardiomyocytes hypertrophy and impaired cardiac vascular adaptation to metabolic needs. From a clinical point of view it can present itself in acute or chronic form with different prognosis, as a practice problem for real-life diagnosis and treatment.

Evaluation oF Epicardial Fat and Carotid Intima-Media Thickness in Obese Children

Background:

Epicardial fat has a role in cardiovascular diseases.

Objectives:

To assess epicardial fat and its relation with carotid intima-media thickness (IMT) in obese adolescents with metabolic syndrome (MetS).

Patients and Methods:

The study included 60 obese adolescents and 25 control subjects. According to the presence or absence of MetS, obese subjects were divided into two subgroups. We measured weight, height, calculated Body Mass Index, waist circumference, hip circumference, systolic blood pressure, diastolic blood pressure and biochemical parameters (fasting glucose, total cholesterol, triglycerides, high density lipoprotein cholesterol, and low density lipoprotein cholesterol, High sensitivity C-reactive protein, fasting insulin, a homeostasis model assessment index of insulin resistance. plus an echocardiographic examination with measurement of epicardial adipose tissue thickness (EATT).

Results:

Left ventricular mass index measurements were significantly higher in MetS group than both non-MS and control groups. The MetS and non-MetS obese patients had significantly higher carotid IMT in comparison to the control group. Carotid IMT measurements were significantly higher in MetS group had than both non-MetS and control groups. Also, EATT was significantly increased in patients with MetS compared to control group. Among MetS obese group, EATT was positively correlated with body mass index-standard deviation score, waist circumference, fasting glucose, fasting insulin, insulin resistance, triglyceride levels, left ventricular thickness, left ventricular mass index and myocardial performance index. EATT was found to be the only predictor of carotid IMT.

Conclusions:

EATT is closely related to carotid IMT and early cardiac dysfunction in obese adolescents with MetS.

The impact of obesity on the relationship between epicardial adipose tissue, left ventricular mass and coronary microvascular function

Purpose

Epicardial adipose tissue (EAT) has been linked to coronary artery disease (CAD) and coronary microvascular dysfunction. However, its injurious effect may also impact the underlying myocardium. This study aimed to determine the impact of obesity on the quantitative relationship between left ventricular mass (LVM), EAT and coronary microvascular function.

Methods

A total of 208 (94 men, 45 %) patients evaluated for CAD but free of coronary obstructions underwent quantitative [¹⁵O]H₂O hybrid positron emission tomography (PET)/CT imaging. Coronary microvascular resistance (CMVR) was calculated as the ratio of mean arterial pressure to hyperaemic myocardial blood flow.

Results

Obese patients [body mass index (BMI) > 25, n = 133, 64 % of total] had more EAT (125.3 ± 47.6 vs 93.5 ± 42.1 cc, p < 0.001), a higher LVM (130.1 ± 30.4 vs 114.2 ± 29.3 g, p < 0.001) and an increased CMVR (26.6 ± 9.1 vs 22.3 ± 8.6 mmHg×ml⁻¹×min⁻¹×g⁻¹, p < 0.01) as compared to nonobese patients. Male gender (β = 40.7, p < 0.001), BMI (β = 1.61, p < 0.001), smoking (β = 6.29, p = 0.03) and EAT volume (β = 0.10, p < 0.01) were identified as independent predictors of LVM. When grouped according to BMI status, EAT was only independently associated with LVM in nonobese patients. LVM, hypercholesterolaemia and coronary artery calcium score were independent predictors of CMVR.

Conclusion

EAT volume is associated with LVM independently of BMI and might therefore be a better predictor of cardiovascular risk than BMI. However, EAT volume was not related to coronary microvascular function after adjustments for LVM and traditional risk factors.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-015-3087-5) contains supplementary material, which is available to authorized users.

Local and systemic effects of the multifaceted epicardial adipose tissue depot

Epicardial adipose tissue is a unique and multifaceted fat depot with local and systemic effects. This tissue is distinguished from other visceral fat depots by a number of anatomical and metabolic features, such as increased fatty acid metabolism and a unique transcriptome enriched in genes that are associated with inflammation and endothelial function. Epicardial fat and the heart share an unobstructed microcirculation, which suggests these tissues might interact. Under normal physiological conditions, epicardial fat has metabolic, thermogenic (similar to brown fat) and mechanical (cardioprotective) characteristics. Development of pathological conditions might drive the phenotype of epicardial fat such that it becomes harmful to the myocardium and the coronary arteries. The equilibrium between protective and detrimental effects of this tissue is fragile. Expression of the epicardial-fat-specific transcriptome is downregulated in the presence of severe and advanced coronary artery disease. Improved local vascularization, weight loss and targeted medications can restore the protective physiological functions of epicardial fat. Measurements of epicardial fat have several important applications in the clinical setting: accurate measurement of its thickness or volume is correlated with visceral adiposity, coronary artery disease, the metabolic syndrome, fatty liver disease and cardiac changes. On account of this simple clinical assessment, epicardial fat is a reliable marker of cardiovascular risk and an appealing surrogate for assessing the efficacy of drugs that modulate adipose tissues.

Relationship of epicardial fat volume from noncontrast CT with impaired myocardial flow reserve by positron emission tomography

BACKGROUND

Impaired myocardial flow reserve (MFR) is a marker of coronary vascular dysfunction with prognostic significance.

OBJECTIVES

We aimed to investigate the relationship between epicardial fat volume (EFV) measured from noncontrast CT and impaired MFR derived from rest-stress Rb-82 positron emission tomography (PET).

METHODS

We retrospectively studied 85 consecutive patients without known coronary artery disease who underwent rest-stress Rb-82 myocardial PET/CT and were subsequently referred for invasive coronary angiography. EFV was computed from noncontrast CT by validated software and indexed to body surface area (EFVi, cm3/m2). Global stress and rest MFR were automatically derived from PET. Patient age, sex, cardiovascular risk factors, coronary calcium score (CCS), and EFVi were combined by boosted ensemble machine learning algorithm into a novel composite risk score, using 10-fold cross-validation, to predict impaired global MFR (MFR ≤2.0) by PET.

RESULTS

Patients with impaired MFR (44 of 85; 52%) were older (71 vs. 65 years; P = .03) and had higher frequency of CCS (≥400; P = .02) with significantly higher EFVi (63.1 ± 20.4 vs. 51.3 ± 14.1 cm3/m2; P = .003). On multivariate logistic regression (with age, sex, number of risk factors, CCS, and EFVi), EFVi was the only independent predictor of impaired MFR (odds ratio, 7.39; P = .02). The machine learning composite risk score significantly improved risk reclassification of impaired MFR compared to CCS or EFVi alone (integrated discrimination improvement = 0.19; P = .007 and IDI = 0.22; P = .002, respectively).

CONCLUSIONS

Increased EFVi and composite risk score combining EFVi and CCS significantly improve identification of impaired global MFR by PET.

Increased Epicardial Adipose Tissue Thickness is Associated With Angiographic Thrombus Burden in the Patients With Non-ST-Segment Elevation Myocardial Infarction

We aimed to evaluate the relation among epicardial adipose tissue (EAT) thickness, angiographic presence of thrombus, and the no-reflow in the patients with non-ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. The study population consisted of 229 patients. The EAT thickness and neutrophil to lymphocyte ratio (NLR) were significantly higher in the patients with coronary thrombus than in those without coronary thrombus (6.1 ± 1.1 vs 5.1 ± 1.3 mm, P < .001 and 3.4 ± 0.9 vs 2.5 ± 0.7, P < .001, respectively) and in the patients with no-reflow compared to patients with reflow. The EAT thickness was found to be correlated positively with the degree of the thrombus burden, NLR, and waist circumference and negatively with high-density lipoprotein cholesterol. Multivariate logistic regression analysis demonstrated that EAT thickness and NLR independently predicted coronary thrombus formation and no-reflow. We have suggested that EAT can play an important role in the pathophysiology of coronary thrombus formation and the no-reflow.

Increased intrathoracic and hepatic visceral adipose tissue independently correlates with coronary artery calcification in asymptomatic patients

BACKGROUND

Visceral adipose tissue (VAT) is associated with cardiac events, but it is not clear which, if any of the various measures of VAT independently correlate with coronary artery disease (CAD).

METHODS

We studied 400 patients undergoing computed tomography to determine coronary artery calcium (CAC) score. VAT was measured in the form of epicardial adipose tissue (EAT) volume and thickness, intrathoracic adipose tissue volume (ITAV), and hepatic steatosis.

RESULTS

Of the 400 subjects, the average CAC score was 112.2 ± 389.3. When each measure of VAT (EAT volume and thickness, ITAV, hepatic steatosis) was added to the traditional model (they were independently associated with greater risk of CAC score ≥100 AU as measured by IDI/NRI (P < .05). On univariable logistic regression analysis, each of the 4 measures of VAT showed association with greater risk of a CAC score of ≥100 AU (OR > 1).

CONCLUSIONS

Each measure of VAT is a strong correlate of CAC score ≥100 AU in asymptomatic subjects-these VAT assessments correlate more significantly than do traditional CAD risk factors. This incremental power in the predictive models is likely the result of measurement of a fundamental expression of the metabolic syndrome and consequent proatherogenic derangements.

Adipose tissue and vascular inflammation in coronary artery disease

Obesity has become an important public health issue in Western and developing countries, with well known metabolic and cardiovascular complications. In the last decades, evidence have been growing about the active role of adipose tissue as an endocrine organ in determining these pathological consequences. As a consequence of the expansion of fat depots, in obese subjects, adipose tissue cells develope a phenotypic modification, which turns into a change of the secretory output. Adipocytokines produced by both adipocytes and adipose stromal cells are involved in the modulation of glucose and lipid handling, vascular biology and, moreover, participate to the systemic inflammatory response, which characterizes obesity and metabolic syndrome. This might represent an important pathophysiological link with atherosclerotic complications and cardiovascular events. A great number of adipocytokines have been described recently, linking inflammatory mileu and vascular pathology. The understanding of these pathways is crucial not only from a pathophysiological point of view, but also to a better cardiovascular disease risk stratification and to the identification of possible therapeutic targets. The aim of this paper is to review the role of Adipocytokines as a possible link between obesity and vascular disease.

Epicardial adipose tissue thickness and plasma homocysteine in patients with metabolic syndrome and normal coronary arteries

BACKGROUND

Increased epicardial adipose tissue thickness and plasma homocysteine levels are associated with Metabolic Syndrome (MS) and coronary artery disease. The majority of patients with MS have subclinical or manifest coronary artery disease. The aim of this study was to evaluate the relationship between MS and plasma homocysteine levels and epicardial adipose tissue thickness in subjects without epicardial coronary artery disease.

METHODS

Patients who underwent coronary angiography due to angina or equivocal symptoms and/or abnormal stress test results and were found to have normal coronary arteries were evaluated for the presence of MS. The study group comprised 75 patients with normal coronary arteries and MS, and the control group included 75 age-gender matched subjects without coronary artery disease or MS.

RESULTS

Epicardial adipose tissue thickness (5.8 ± 1.9 mm vs. 4.3 ± 1.6 mm, p <0.001) and plasma homocysteine levels (21.6 ± 6.1 μmol/L vs. 15.1 ± 5.8 μmol/L, p <0.001) were significantly higher in the MS group. Body mass index, triglyceride level, weight, age and waist circumference were positively and HDL cholesterol level were negatively correlated with both epicardial adipose tissue thickness and plasma homocysteine level. Epicardial adipose tissue thickness had the strongest correlation with plasma homocysteine level (r = 0.584, p < 0.001). For each 1 mm increase in epicardial adipose tissue thickness, an increase of 3.51 μmol/L (95% CI: 2.24-4.79) in plasma homocysteine level was expected.

CONCLUSIONS

We observed a close relationship between MS and epicardial adipose tissue thickness and plasma homocysteine levels, even in the absence of overt coronary artery disease.

Epicardial adipose tissue thickness is associated with myocardial infarction and impaired coronary perfusion

Objective:

Epicardial adipose tissue (EAT) is associated with the presence, severity and extent of atherosclerotic coronary artery disease (CAD) in addition to subclinical atherosclerosis. We investigated if EAT thickness is related to acute myocardial infarction in patients with CAD. We also searched for the association between EAT thickness and objective coronary flow and myocardial perfusion parameters such as Thrombolysis in Myocardial Infarction Frame count (TFC) and myocardial blush grade (MBG).

Methods:

Two-hundred consecutive patients with stable angina pectoris or acute coronary syndrome who were admitted to Ufuk University Faculty of Medicine, Dr Ridvan Ege Hospital cardiology department were included in this observational, cross-sectional study. EAT thickness was evaluated by conventional transthoracic echocardiography. Coronary angiography was performed to determine the coronary involvement and perfusion.

Results:

Mean EAT thicknesses were 5.4±1.9 mm, 6.3±1.8 mm, and 8.5±1.4 mm in the stable angina pectoris (SAP), unstable angina pectoris (USAP) and acute myocardial infarction groups, respectively (p<0.001). With increasing EAT thickness, TFC increases whereas mean MBG values decrease (for EAT thickness <5 mm, 5-7 mm, >7 mm; mean TFC: 21.6±2.2, 25.3±3.3 and 35.2±7.7; and MBG values: 2.98±0.14, 2.83±0.57 and 1.7±1.16, respectively; both p<0.001). Cut-off EAT value to predict AMI was identified as 7.8 mm (ROC analysis AUC: 0.876; p<0.001, 95% CI: 0.822-0.927). Sensitivity and specificity of EAT cut-off value 7.8 mm to predict AMI were 81.8% and 82.5% respectively.

Conclusion:

Increased EAT is associated with AMI and it may prove beneficial for choosing patients who would need more aggressive approach in terms of risk reduction using echocardiography which is a relatively cheap and readily available tool as a follow-up parameter.