Epicardial adipose tissue and pericoronary fat thickness measured with 64-multidetector computed tomography: potential predictors of the severity of coronary artery disease

Exploring the role of epicardial adipose-tissue-derived extracellular vesicles in cardiovascular diseases

Epicardial adipose tissue (EAT) is a fat depot located between the myocardium and the visceral layer of the epicardium, which, owing to its location, can influence surrounding tissues and can act as a local transducer of systemic inflammation. The mechanisms upon which such influence depends on are however unclear. Given the role EAT undoubtedly has in the scheme of cardiovascular diseases (CVDs), understanding the impact of its cellular components is of upmost importance. Extracellular vesicles (EVs) constitute promising candidates to fill the gap in the knowledge concerning the unexplored mechanisms through which EAT promotes onset and progression of CVDs. Owing to their ability of transporting active biomolecules, EAT-derived EVs have been reported to be actively involved in the pathogenesis of ischemia/reperfusion injury, coronary atherosclerosis, heart failure, and atrial fibrillation. Exploring the precise functions EVs exert in this context may aid in connecting the dots between EAT and CVDs.

AI prediction of cardiovascular events using opportunistic epicardial adipose tissue assessments from CT calcium score

Background

Recent studies have used basic epicardial adipose tissue (EAT) assessments (e.g., volume and mean HU) to predict risk of atherosclerosis-related, major adverse cardiovascular events (MACE).

Objectives

Create novel, hand-crafted EAT features, "fat-omics", to capture the pathophysiology of EAT and improve MACE prediction.

Methods

We segmented EAT using a previously-validated deep learning method with optional manual correction. We extracted 148 radiomic features (morphological, spatial, and intensity) and used Cox elastic-net for feature reduction and prediction of MACE.

Results

Traditional fat features gave marginal prediction (EAT-volume/EAT-mean-HU/BMI gave C-index 0.53/0.55/0.57, respectively). Significant improvement was obtained with 15 fat-omics features (C-index=0.69, test set). High-risk features included volume-of-voxels-having-elevated-HU-[-50, -30-HU] and HU-negative-skewness, both of which assess high HU, which as been implicated in fat inflammation. Other high-risk features include kurtosis-of-EAT-thickness, reflecting the heterogeneity of thicknesses, and EAT-volume-in-the-top-25%-of-the-heart, emphasizing adipose near the proximal coronary arteries. Kaplan-Meyer plots of Cox-identified, high- and low-risk patients were well separated with the median of the fat-omics risk, while high-risk group having HR 2.4 times that of the low-risk group (P<0.001).

Conclusion

Preliminary findings indicate an opportunity to use more finely tuned, explainable assessments on EAT for improved cardiovascular risk prediction.

The relation between pericoronary fat thickness and density quantified by coronary computed tomography angiography with coronary artery disease severity

OBJECTIVE

To study the correlation between epicardial fat thickness (EFT), pericoronary fat thickness (PCFT), and pericoronary fat density (PCFD) with the existence and severity of coronary artery disease (CAD).

METHODS

This cross-sectional study included 210 patients referred for multislice CT angiography. Group I normal CTCA, Group II patients had non-obstructive atherosclerosis, and Group III patients had obstructive atherosclerosis. All patients underwent a clinical examination, history taking, and multislice CT angiography.

RESULTS

The mean EFT was significantly greater in group III (10.43 ± 2.31 mm) compared to groups II (6.30 ± 1.61 mm) and I (5.06 ± 1.14 mm). The mean PCFT was significantly greater in group III (17.96 ± 2.89 mm) compared to group II (11.47 ± 2.51 mm) and group I (9.67 ± 1.99 mm). PCFD was significantly higher adjacent to the lesion (-80.47 ± 29.14) compared to the normal segment (-109.03 ± 35.24), higher in the obstructive group (-59.44 ± 20.10) compared to the non-obstructive group (-101.51 ± 20.23), but lower in calcified lesions (-89.58 ± 28.94) compared to non-calcified (-75.01 ± 29.20), and mixed lesions (-74.83 ± 26.90). EFT and PCFT cut-off values for predicting obstructive CAD were 8.3 and 12.4 mm, respectively, with 87.1% and 92.9% sensitivity and 92.9% and 86.4% specificity, respectively.

CONCLUSION

There is a significant association between epicardial fat thickness, pericoronary fat thickness and density with the severity of coronary artery disease.

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

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

Relationship between Epicardial and Coronary Adipose Tissue and the Expression of Adiponectin, Leptin, and Interleukin 6 in Patients with Coronary Artery Disease

Adipose tissue (AT) is an endocrine and paracrine organ that synthesizes biologically active adipocytokines, which affect inflammation, fibrosis, and atherogenesis. Epicardial and perivascular fat depots are of great interest to researchers, owing to their potential effects on the myocardium and blood vessels. The aim of the study was to assess the expression and secretion of adipocytokine genes in the AT of patients with coronary artery disease (CAD) and patients with aortic or mitral valve replacement. This study included 84 patients with CAD and 50 patients with aortic or mitral valve replacement. Adipocytes were isolated from subcutaneous, epicardial (EAT), and perivascular AT (PVAT), and were cultured for 24 h. EAT exhibited the lowest level of adiponectin gene expression and secretion, regardless of nosology, and high expression levels of the leptin gene and interleukin-6 (IL-6). However, EAT adipocytes in patients with CAD were characterized by more pronounced changes in comparison with the group with heart defects. High leptin and IL-6 levels resulted in increased pro-inflammatory activity, as observed in both EAT and PVAT adipocytes, especially in individuals with CAD. Therefore, our results revealed the pathogenetic significance of alterations in the adipokine and cytokine status of adipocytes of EAT and PVAT in patients with CAD.

Epicardial and pericoronary adipose tissue in severe COVID-19 infection

OBJECTIVE

To investigate the association between epicardial and pericoronary adipose tissue thicknesses measured with computed tomography (CT) and severity of COVID-19 infection.

METHODS

We recruited 504 patients admitted with RT-PCR-proven diagnosis of COVID-19 infection and underwent simultaneous Chest CT scanning. Epicardial adipose tissue thickness (EAT) and pericardial adipose tissue thickness (PCAT) were measured by CT. Comparisons were performed between ICU admitting and non-ICU admitting patients were performed.

RESULTS

Of 504 patients, 423 patients were hospitalised in normal wards or followed as outpatient, and 81 patients were admitted to ICU. EAT and PCAT were significantly increased in ICU patients (5.98[5.06-7.13] mm vs. 8.05[6.90-9.89] mm, p < 0.001 and 9.3[7.4-11.5] mm vs. 11.2[10.3-13.2] mm, p < 0.001, respectively). In multiple logistic regression analyses, EAT and PCAT were independent predictors of ICU admission. A cut-off point of 6.64 mm EAT has a sensitivity of 82.7% and a specificity of 66.7% (AUC = 0.789, 95% CI: 0.744-0.833, p < 0.001) and a cut-off point of 9.85 mm PCAT has a sensitivity of 91.4% and a specificity of 61.2% (AUC = 0.744, 95% CI: 0.700-0.788, p < 0.001).

CONCLUSION

We found that both increased EAT and PCAT were associated with the severity of COVID-19 infection defined as the need for ICU admission.

Relationship between epicardial fat volume measured by multi-detector computed tomography and coronary artery disease

Background

The association between epicardial fat thickness and coronary artery disease (CAD) has been evaluated previously using echocardiography. Recently, multidetector computed tomography (MDCT), as a valuable tool in cardiovascular CT imaging, can improve characterization of CAD and give a more accurate volumetric quantitation of EF. The purpose of our study was to evaluate the relationship between the epicardial fat volume and CAD using multi-detector row CT.

Results

Out of the studied 120 patients, 22 patients were negative for CAD, while 98 patients had positive CAD. There was significant difference between both groups as regard epicardial fat volume (p < 0.001), and good relation was found between the amount of epicardial fat volume and coronary calcium score, number of affected vessel, plaque burden and degree of stenosis (p =  < 0.001).

Conclusion

EAT volume was larger in the presence of obstructive CAD and atheromatous plaques. These data suggest that EAT is associated with the development of coronary atherosclerosis and potentially the most dangerous types of plaques.

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

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

Thickness of epicardial and pericoronary adipose tissue measured using 128-slice MSCT as predictors for risk of significant coronary artery diseases

Aim

Determination the relationship between the epicardial adipose tissue thickness (EATT) and pericoronary adipose tissue thickness (PATT) and the risk of significant coronary artery diseases (CAD) using the coronary artery calcium score (CACS).

Materials and methods

The study group consisted of 80 patients. The risk of significant CAD was estimated based on CACS. Adipose tissue thickness was measured based on multiplanar reformation (MPR), left ventricle short axis and mid-chamber level. EATT in the middle of the length of the right ventricular free wall, PATT around the left anterior descending (LAD), around the left circumflex (LCX) and around the right coronary artery in the posterior interventricular sulcus (RCA).

Results

The median (IQR) values of CACS and EATT were 12.00 (97.90) and 8.65 (3.90) mm. It was found that in the subgroup CACS = 0 statistically significantly lower than in the subgroup CACS > 0 were mean values EATT and PATT RCA. Based on the regression analysis, it was demonstrated that higher CACS is associated with higher EATT, independent of older age and higher BMI. On the basis the ROC curve analysis, the highest prediction sensitivity of 98.4% was demonstrated for EATT ≥ 16.7 mm as a predictor of high risk of significant CAD and the highest specificity of 61.5% for the criterion EATT ≤ 8.7 mm as a predictor of practically no risk of significant CAD.

Conclusion

There is a positive relationship between the risk of a significant CAD estimated based on the coronary artery calcium score and the epicardial adipose tissue thickness.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Maximal pericoronary adipose tissue thickness is associated with hypertension in nonobese patients with acute or chronic illness

BACKGROUND/AIMS

Recent studies have shown an association of epicardial fat thickness with diabetes and hypertension (HTN) in asymptomatic populations. However, there is lack of information as to whether there is similar association between pericoronary adipose tissue (PAT) and HTN in the patients who have acute or chronic illness.

METHODS

This study included 214 nonobese patients hospitalized with acute or chronic noncardiogenic illness. PAT thicknesses were measured from fat tissues surrounding left and right coronary arteries in enhanced, chest computed tomography scans, yielding the maximal PAT value from left and right coronary arteries was used for analysis. Baseline data from hypertensive (n = 81) and normotensive (n = 133) patients were collected and compared.

RESULTS

PAT is positively correlated with age (r = 0.377, p <0.001), body mass index (BMI; r = 0.305, p < 0.001), systolic blood pressure (r = 0.216, p = 0.001), and total cholesterol (r = 0.200, p = 0.006). The hypertensive group was older (69.58 ± 11.69 years vs. 60.29 ± 14.98 years), and had higher PAT content (16.30 ± 5.37 mm vs. 13.06 ± 5.58 mm) and BMI (23.14 ± 3.32 kg/m² vs. 20.96 ± 3.28 kg/m) than the normotensive group (all p < 0.001). Multivariate analysis showed that age (odds ratio [OR], 2.193; p = 0.016), PAT thickness (OR, 1.065; p = 0.041), and BMI (25 ≤ BMI < 30 kg/m² ; OR, 6.077; p = 0.001) were independent risk factors for HTN.

CONCLUSIONS

In nonobese patients with noncardiogenic acute or chronic illness, PAT thickness is independently correlated with HTN, age, and BMI.

Fat deposition in the left ventricle: descriptive and observacional study in autopsy

BACKGROUND

The human heart contains varying amounts of fat deposits. Cardiac physiological fat occurs predominantly in the right ventricle (RV). The discovery and characterization of adipose tissue along the left ventricle (LV) has been rarely reported. This study aimed to determine the occurrence of fatty deposits in epicardial, pericoronay and myocardial compartments in the LV, and to trace the epidemiological profile and clinical associations with this finding.

METHODS

Epidemiological and morphological data and heart samples were collected from corpses submitted to necropsy. Cardiac samples were fixed, embedded in paraffin and subjected to hematoxylin-eosin for microscopic study.

RESULTS

The research was based on 40 samples of cardiac tissue, 21 male cadavers and 19 female ones with mean age of 68.2 years. 52.2% of the subjects had a history of smoking, 20% of them had alcohol consumption and 43.59% showed cardiac cause as a cause of death (acute myocardial infarction - AMI - was the most frequent immediate cause of death). 82.5% of the subjects showed atherosclerotic disease in the ascending aorta (ADAA). The fat deposition in the left ventricule (FDLV) was observed in 95% of cases. Epicardial fat (EF) and pericoronary adipose tissue (PAT) are the most frequent topographies in fat accumulation in the left heart chamber and the EF deposition is associated with myocardial adiposity (MA) (Fisher test [FT] 0.019; odds ratio [OR] 0.097 [95% CI 0.033 to 0.284]; p < 0.05). FDLV was associated with alcoholism (FT 0.04, OR 0.161 [95% CI 0.072 to 0.36]; p < 0.05); smoking (FT 0.508; OR 0581 [95% CI 0.431 to 0.73]; p < 0.05), presence of Frank's sign (FT 0.502; OR 0.567 [95% CI 0.414 to 0.775]; p < 0.05); ADAA (0.774 OR [95% CI 0.6405 to 0.936]; p < 0.05); AMI (OR 0.730 [95% CI 0.600 to 0.888]; p < 0.05) and macroscopic finding of cardiac hypertrophy (OR 0.700 [95% CI 0.525 to 0.933]; p < 0.05). FDLV is related with the thickness of the abdominal fat cushion.

CONCLUSIONS

FDLV is common and associated with cardiovascular disease risk factors. Cardiac adiposity cannot be considered a random autopsy finding, requiring diagnostic research and more studies to investigate the clinical implications.

'Browning' the cardiac and peri-vascular adipose tissues to modulate cardiovascular risk

Excess visceral adiposity, in particular that located adjacent to the heart and coronary arteries is associated with increased cardiovascular risk. In the pathophysiological state, dysfunctional adipose tissue secretes an array of factors modulating vascular function and driving atherogenesis. Conversely, brown and beige adipose tissues utilise glucose and lipids to generate heat and are associated with improved cardiometabolic health. The cardiac and thoracic perivascular adipose tissues are now understood to be composed of brown adipose tissue in the healthy state and undergo a brown-to-white transition i.e. during obesity which may be a driving factor of cardiovascular disease. In this review we discuss the risks of excess cardiac and vascular adiposity and potential mechanisms by which restoring the brown phenotype i.e. “re-browning” could potentially be achieved in clinically relevant populations.

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Epicardial, paracardial and thoracic perivascular adipose tissues resemble BAT at birth.

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Despite ‘whitening’ in early life these depots remain metabolically active and potentially thermogenic into adulthood.

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Obesity induces further ‘whitening’ and inflammation in these depots likely driving the atherogenesis.

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Maintaining or inducing the brown phenotype in these depots could prevent atherosclerotic disease.

Epicardial Fat: Physiological, Pathological, and Therapeutic Implications

Epicardial fat is closely related to blood supply vessels, both anatomically and functionally, which is why any change in this adipose tissue's behavior is considered a potential risk factor for cardiovascular disease development. When proinflammatory adipokines are released from the epicardial fat, this can lead to a decrease in insulin sensitivity, low adiponectin production, and an increased proliferation of vascular smooth muscle cells. These adipokines move from one compartment to another by either transcellular passing or diffusion, thus having the ability to regulate cardiac muscle activity, a phenomenon called vasocrine regulation. The participation of these adipokines generates a state of persistent vasoconstriction, increased stiffness, and weakening of the coronary wall, consequently contributing to the formation of atherosclerotic plaques. Therefore, epicardial adipose tissue thickening should be considered a risk factor in the development of cardiovascular disease, a potential therapeutic target for cardiovascular pathology and a molecular point of contact for "endocrine-cardiology."

Myocardial fat as a part of cardiac visceral adipose tissue: physiological and pathophysiological view

Thoracic fat includes extra-pericardial (outside the visceral pericardium) and intra-pericardial (inside the visceral pericardium) adipose tissue. It is called ectopic adipose tissue although it is a normal anatomical structure. Intra-pericardial adipose tissue, which is predominantly composed of epicardial and pericoronary adipose tissue, has a significant role in cardiovascular system function. It provides metabolic-mechanical support to the heart and blood vessels in physiological conditions, while it represents metabolic-cardiovascular risk in case of qualitative and quantitative structural changes in the tissue: it correlates with coronary atherosclerotic disease, left ventricular mass, left atrium enlargement and atrial fibrillation presence. In the last decade there has been mounting evidence of fat cells presence in the myocardium of healthy (non-diseased) persons as well as in persons with both cardiovascular and non-cardiovascular diseases. Thus, it is necessary to clarify the incidence, aetiology, physiological role of fat cells in the myocardium, as well as the clinical significance of pathological fatty infiltration of the myocardium.

Incremental diagnostic value of epicardial adipose tissue for the detection of functionally relevant coronary artery disease

BACKGROUND AND AIM

To determine the incremental diagnostic value of epicardial adipose tissue (EAT) volume in addition to the coronary artery calcium (CAC) score for detecting hemodynamic significant coronary artery disease (CAD).

METHODS AND RESULTS

122 patients (mean age 61 ± 10 years, 61% male) without a previous cardiac history underwent a non-contrast CT scan for calcium scoring and EAT volume measurements. Subsequently all patients underwent invasive coronary angiography (ICA) in conjunction with fractional flow reserve (FFR) measurements. A stenosis >90% and/or a FFR ≤0.80 were considered significant. Mean EAT volume and CACscore were 128 ± 51 cm(3) and 418 ± 704, respectively. The correlation between EAT volume and the CACscore was poor (r = 0.11, p = 0.24). Male gender (odds ratio [OR] 2.86, p = 0.01), CACscore ([cut-off value 100] OR 3.31, p = 0.003, and EAT volume ([cut-off value 92 cm(3)] OR 4.28, p = 0.01) were associated with flow-limiting disease. The multivariate model revealed that only male gender (OR 2.50, p = 0.045), CAC score (OR 3.60, p = 0.005), and EAT volume (OR 4.95, p = 0.02) were independent predictors of myocardial ischemia. Using the cut-off values of 100 (CAC score) and 92 cm(3) (EAT volume), sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for detecting functionally relevant CAD as indicated by FFR were 71, 57, 77, 50 and 63% and 91, 29, 85, 44 and 52% for the CACscore and EAT volume, respectively. Adding EAT volume to the CAC score and cardiovascular risk factors did not enhance diagnostic performance for the detection of significant CAD (p = 0.57).

CONCLUSION

EAT volume measurements have no diagnostic value beyond calcium scoring and cardiovascular risk factors in the detection of hemodynamic significant CAD.