The impact of epicardial fat volume on coronary plaque vulnerability: insight from optical coherence tomography analysis

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.

Exploring the Associations Between Non-Traditional Lipid Parameters and Epicardial Adipose Tissue Volume

The aim of this retrospective study was to determine the relationship between non-traditional lipid parameters and epicardial adipose tissue (EAT). A total of 770 patients with coronary computed tomography angiography examinations were included. The non-traditional lipid parameters included the atherogenic index of plasma (AIP), the atherogenic coefficient (AC), monocyte to high-density lipoprotein cholesterol (HDL-C) ratio (MHR), and lipoprotein combined index (LCI). To investigate the association between non-conventional lipid markers and the EAT-volume (EAT-v), a univariate and multivariate analyses were conducted. The receiver operating characteristic (ROC) analysis was used to compare the predictive ability among the four non-traditional lipid parameters. In the univariate analysis, we identified factors that might have effects on EAT-v (all P<.05) and adjusted for these in the multivariate analysis. We found that except for MHR, other non-traditional lipid parameters were still associated with high EAT-v after adjustment (all P<.05). In the ROC analysis, the area under the curve (AUC) of AIP was greater than that of other non-traditional lipid parameters and lipid profiles. There was an association between both non-traditional lipid parameters and EAT-v. After adjustment, the AIP remained an independent predictor of EAT-v and it outperformed other non-traditional lipid parameters.

Pathophysiology of Acute Coronary Syndromes-Diagnostic and Treatment Considerations

Coronary artery disease and acute coronary syndromes are accountable for significant morbidity and mortality, despite the preventive measures and technological advancements in their management. Thus, it is mandatory to further explore the pathophysiology in order to provide tailored and more effective therapies, since acute coronary syndrome pathogenesis is more varied than previously assumed. It consists of plaque rupture, plaque erosion, and calcified nodules. The advancement of vascular imaging tools has been critical in this regard, redefining the epidemiology of each mechanism. When it comes to acute coronary syndrome management, the presence of ruptured plaques almost always necessitates emergent reperfusion, whereas the presence of plaque erosions may indicate the possibility of conservative management with potent antiplatelet and anti-atherosclerotic medications. Calcified nodules, on the other hand, are an uncommon phenomenon that has largely gone unexplored in terms of the best management plan. Future studies should further establish the importance of detecting the underlying mechanism and the role of various treatment plans in each of these distinct entities.

Non-traditional tools for predicting coronary artery disease

Background

The traditional coronary calcium score (CCS) is a time-tested tool for the evaluation of coronary atherosclerosis and predictor of future cardiovascular events. Non-traditional tools can also have a value in predicting and detecting subclinical coronary artery disease (CAD).

Methods

We studied the role of CCS, the traditional CAD risk predictor, and the less-recognized, non-traditional risk factors, i.e. epicardial fat volume (EFV) and thoracic extracoronary calcium (ECC), to assess the degree of subclinical CAD. In this cross-sectional observational study, we included 950 Indian patients (suspected to have CAD). Coronary computed tomography angiography was performed. Estimation of CCS, EFV and thoracic ECC was done.

Results

A CCS of 0 was seen in 583 patients (61.4%). Of these, 492 patients had normal coronary angiogram but 91 patients had CAD. The median values of EFV were statistically significantly higher in the ‘CAD present and CCS 0’ group compared to the ‘CAD absent and CCS 0’ group (p<0.001). The presence of thoracic ECC involving at least a single site was seen in only 6 of these 91 patients. When both EFV and CCS were considered together for the detection of CAD, the sensitivity and negative predictive value (NPV) were improved compared to either of these in isolation. When ECC was taken together with CCS and EFV, no further improvement in sensitivity or NPV was observed.

Conclusion

The combined use of traditional CCS along with non-traditional EFV may guide us in better profiling cardiovascular risk and supplement the various traditional cardiovascular risk factors/scores.

Current Concepts and Future Applications of Non-Invasive Functional and Anatomical Evaluation of Coronary Artery Disease

Over the last decades, significant advances have been achieved in the treatment of coronary artery disease (CAD). Proper non-invasive diagnosis and appropriate management based on functional information and the extension of ischemia or viability remain the cornerstone in the fight against adverse CAD events. Stress echocardiography and single photon emission computed tomography are often used for the evaluation of ischemia. Advancements in non-invasive imaging modalities such as computed tomography (CT) coronary angiography and cardiac magnetic resonance imaging (MRI) have not only allowed non-invasive imaging of coronary artery lumen but also provide additional functional information. Other characteristics regarding the plaque morphology can be further evaluated with the latest modalities achieving a morpho-functional evaluation of CAD. Advances in the utilization of positron emission tomography (PET), as well as software advancements especially regarding cardiac CT, may provide additional prognostic information to a more evidence-based treatment decision. Since the armamentarium on non-invasive imaging modalities has evolved, the knowledge of the capabilities and limitations of each imaging modality should be evaluated in a case-by-case basis to achieve the best diagnosis and treatment decision. In this review article, we present the most recent advances in the noninvasive anatomical and functional evaluation of CAD.

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.

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

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

Cardiac microcalcification burden: Global assessment in high cardiovascular risk subjects with Na[18F]F PET-CT

BACKGROUND

Fluorine-18 sodium fluoride (Na[18F]F) atherosclerotic plaque uptake in positron emission tomography with computed tomography (PET-CT) identifies active microcalcification. We aim to evaluate global cardiac microcalcification activity with Na[18F]F, as a measure of unstable microcalcification burden, in high cardiovascular (CV) risk patients.

METHODS AND RESULTS

Thirty-four high CV risk individuals without previous CV events were scanned with Na[18F]F PET-CT. Cardiac Na[18F]F uptake was assessed through the global molecular calcium score (GMCS), which was calculated by summing the product of the mean standardized uptake value times the area of the cardiac regions of interest times the slice thickness for all cardiac transaxial slices, divided by the total number of slices. Mean age is 63.5 ± 7.8 years and 62% male. Median GMCS is 320.9 (240.8-402.8). Individuals with more than five CV risk factors (50%) have increased GMCS [356.7 (321.0-409.6) vs. 261.1 (225.6-342.1), P = 0.01], which is positively correlated with predicted fatal CV risk by SCORE (rs = 0.32, P = 0.04). There is a positive correlation between GMCS and weight (rs = 0.61), body mass index (rs = 0.66), abdominal perimeter (rs = 0.74), thoracic fat volume (rs = 0.47), and epicardial adipose tissue (rs = 0.41), all with P ≤ 0.01. There is no correlation between GMCS and coronary calcium score nor coronary artery wall Na[18F]F uptake.

CONCLUSIONS

In a high CV risk group, the global cardiac microcalcification burden is related to CV risk factors, metabolic syndrome variables and cardiac fat. Cardiac GMCS is a promising risk stratification tool, combining a straightforward and objective methodology with a comprehensive analysis of both coronary and valvular microcalcification.

Non-Invasive Modalities in the Assessment of Vulnerable Coronary Atherosclerotic Plaques

Coronary atherosclerosis is a complex, multistep process that may lead to critical complications upon progression, revolving around plaque disruption through either rupture or erosion. Several high-risk features are associated with plaque vulnerability and may add incremental prognostic information. Although invasive imaging modalities such as optical coherence tomography or intravascular ultrasound are considered to be the gold standard in the assessment of vulnerable coronary atherosclerotic plaques (VCAPs), contemporary evidence suggests a potential role for non-invasive methods in this context. Biomarkers associated with deleterious pathophysiologic pathways, including inflammation and extracellular matrix degradation, have been correlated with VCAP characteristics and adverse prognosis. However, coronary computed tomography (CT) angiography has been the most extensively investigated technique, significantly correlating with invasive method-derived VCAP features. The estimation of perivascular fat attenuation as well as radiomic-based approaches represent additional concepts that may add incremental information. Cardiac magnetic resonance imaging (MRI) has also been evaluated in clinical studies, with promising results through the various image sequences that have been tested. As far as nuclear cardiology is concerned, the implementation of positron emission tomography in the VCAP assessment currently faces several limitations with the myocardial uptake of the radiotracer in cases of fluorodeoxyglucose use, as well as with motion correction. Moreover, the search for the ideal radiotracer and the most adequate combination (CT or MRI) is still ongoing. With a look to the future, the possible combination of imaging and circulating inflammatory and extracellular matrix degradation biomarkers in diagnostic and prognostic algorithms may represent the essential next step for the assessment of high-risk individuals.

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

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

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.

Impact of glucose variability on coronary plaque vulnerability in patients with dysglycemia: A whole coronary analysis with multislice computed tomography

BACKGROUND

Dysglycemia is associated with an increased risk of acute coronary syndrome caused by the disruption of vulnerable plaques. The relationship between glycemic variability (GV), which is a component of impaired glucose metabolism, and coronary plaque vulnerability has not been fully elucidated. This study investigated the impact of GV on whole coronary plaque vulnerability using multislice computed tomography (MSCT).

METHODS

We analyzed 88 patients with dysglycemia who underwent 24 h blood glucose monitoring and MSCT. The mean amplitude of glycemic excursion (MAGE) was calculated as an index of the GV. We defined a CT-derived vulnerable plaque as a plaque with a remodeling index > 1.10 and a mean CT density < 30 HU. We calculated the percentage of low-attenuation plaque (% LAP) as the ratio of the low-attenuation component (CT density < 30HU) volume to the total vessel volume.

RESULTS

Vulnerable plaques were detected in 27 patients (31%). Patients with vulnerable plaques had higher MAGE (110.0 ± 40.7 vs. 71.7 ± 21.7, p < 0.01) than patients without vulnerable plaques. A univariate logistic regression analysis showed that vulnerable plaques were associated with the MAGE [odds ratio (OR) 1.04, 95% confidence interval (CI), 1.02-1.07, p < 0.01]. In a multivariate model, the MAGE (OR 1.05, 95% CI 1.02-1.07) remained a significant predictor of vulnerable plaque presence. Patients with multivessel-vulnerable plaques had higher MAGE values than those with single-vessel involvement or no vulnerable plaques (132.3 ± 39.4 vs. 102.2 ± 39.7, vs. 71.7 ± 21.7, p < 0.01). The regression analysis showed a positive correlation between MAGE levels and the % LAP (r = 0.55, p < 0.01). In a multiple linear regression analysis, the MAGE was independently associated with the % LAP (β = 0.42, p < 0.01).

CONCLUSIONS

Increased GV is associated with the presence and extent of vulnerable plaques.

Alternative sites of echocardiographic epicardial fat assessment and coronary artery disease

AIMS

Increasing evidence points towards the use of epicardial fat (EF) as a reliable biomarker of coronary artery disease extent and severity. We aim to assess the different locations of echocardiographic EF thickness measurement and their relation with the presence, extent, and severity of coronary artery disease (CAD) in patients admitted with acute coronary syndromes (ACS).

METHODS

Prospective cohort study including patients admitted for ACS. EF was assessed by transthoracic echocardiography and compared with coronary angiography findings. Spearmen correlation analysis was used to search for EF correlations. Receiver-operating characteristic curve analysis was performed to assess the predictive value of the different sites of measurement of EF thickness for the presence of CAD. To evaluate other potential variables independently associated with CAD, we performed multivariate analysis employing logistic regression.

RESULTS

196 patients were included. Significant CAD was diagnosed in 83.7% of patients. In all views, EF thickness was greater in patients with CAD (p < 0.001). We found a moderate correlation between EF thickness and CAD extent and severity. EF thickness measured at RV basal level showed a good performance in predicting significant CAD in patients with ACS (AUC = 0.885, 95% CI 0.80-0.97, p < 0.001). For a value of mean RV basal region EF thickness ≥ 12.57 mm, sensitivity was 85% and specificity was 80.8%.

CONCLUSION

In patients admitted with ACS, echocardiographic EF thickness predicted the presence of CAD, as well as its extent and severity. We found EF thickness measured at the RV basal region to be the best predictor of significant CAD.

Epicardial Adipose Tissue Volume Is Associated with High Risk Plaque Profiles in Suspect CAD Patients

OBJECTIVE

To explore the association between EAT volume and plaque precise composition and high risk plaque detected by coronary computed tomography angiography (CCTA).

METHODS

101 patients with suspected coronary artery disease (CAD) underwent CCTA examination from March to July 2019 were enrolled, including 70 cases acute coronary syndrome (ACS) and 31 cases stable angina pectoris (SAP). Based on CCTA image, atherosclerotic plaque precise compositions were analyzed using dedicated quantitative software. High risk plaque was defined as plaque with more than 2 high risk features (spotty calcium, positive remolding, low attenuation plaque, napkin-ring sign) on CCTA image. The association between EAT volume and plaque composition was assessed as well as the different of correlation between ACS and SAP was analyzed. Multivariable logistic regression analysis was used to explore whether EAT volume was independent risk factors of high risk plaque (HRP).

RESULTS

EAT volume in the ACS group was significantly higher than that of the SAP group (143.7 ± 49.8 cm3 vs. 123.3 ± 39.2 cm3, P = 0.046). EAT volume demonstrated a significant positive correlation with total plaque burden (r = 0.298, P = 0.003), noncalcified plaque burden (r = 0.245, P = 0.013), lipid plaque burden (r = 0.250, P = 0.012), and homocysteine (r = 0.413, P ≤ 0.001). In ACS, EAT volume was positively correlated with total plaque burden (r = 0.309, P = 0.009), noncalcified plaque burden (r = 0.242, P = 0.044), and lipid plaque burden (r = 0.240, P = 0.045); however, no correlation was observed in SAP. Patients with HRP have larger EAT volume than those without HRP (169 ± 6.2 cm3 vs. 130.6 ± 5.3 cm3, P = 0.002). After adjustment by traditional risk factors and coronary artery calcium score (CACS), EAT volume was an independent risk predictor of presence of HRP (OR: 1.018 (95% CI: 1.006-1.030), P = 0.004).

CONCLUSIONS

With the increasing EAT volume, more dangerous plaque composition burdens increase significantly. EAT volume is a risk predictor of HRP independent of convention cardiovascular risk factors and CACS, which supports the potential impact of EAT on progression of coronary atherosclerotic plaque.

Relationship of epicardial fat volume with coronary plaque characteristics, coronary artery calcification score, coronary stenosis, and CT-FFR for lesion-specific ischemia in patients with known or suspected coronary artery disease

BACKGROUND

We explored the association of epicardial fat volume (EFV) with coronary plaque characteristics, coronary artery calcification (CAC) score, coronary stenosis, lesion-specific ischemia in patients with known or suspected coronary artery disease (CAD).

METHODS

88 controls and 221 patients were analyzed in the study. High-risk plaque was defined as existing≥2 features, including positive remodeling, low attenuation, napkin-ring sign and spotty calcification. EFV, CAC score was measured. The severity of coronary stenosis was quantified using Gensini score. CT-FFR was performed in three major coronary arteries, with a threshold of ≤0.8 considered the presence of ischemia. Univariate and multivariate regression was used to evaluate the association of EFV with CAD, palque characteristics, CAC score, Gensini score, and lesion-specific ischemia derived from CT-FFR.

RESULTS

Median EFV was 104.97 cm³ (85.47-136.09) in controls and 129.28cm³ (101.19-159.44) in patients (P < 0.001). Logistic regression analysis revealed a significant association of EFV with CAD even after adjusting for confounding factors (P < 0.05). At linear regression analysis, EFV was significantly correlated with high-risk plaque and lesion-specific ischemia, but not with non-calcified plaque, mixed plaque, calcified plaque, CAC score and Gensini score (P ≥ 0.05).

CONCLUSION

We found that EFV was associated with CAD, suggesting that it may be a promising marker of CAD. EFV was also correlated with high-risk plaque and lesion-specific ischemia, indicating that EAT was likely to be involved in myocardial ischemia and had the potential to definite patients' risk profile.

Association between abdominal fat distribution and coronary plaque instability in patients with acute coronary syndrome

BACKGROUND AND AIMS

This study aimed to assess possible association of detailed abdominal fat profiles with coronary plaque characteristics in patients with acute coronary syndrome (ACS).

METHODS AND RESULTS

In 60 patients with ACS, culprit arteries were evaluated at 1-mm intervals (length analyzed: 66 ± 28 mm) by grayscale and integrated backscatter intravascular ultrasound (IB-IVUS) before percutaneous coronary intervention. Standard IVUS indexes (as a volume index: volume/length), plaque components (as percent tissue volume) and fibrous cap thickness (FCT) were assessed by IB-IVUS. Plain abdominal computed tomography was performed to evaluate subcutaneous adipose tissue (SAT) area, visceral adipose tissue (VAT) area, and VAT/SAT ratio. While SAT area only correlated with vessel volume (r = 0.27, p = 0.04), VAT area correlated positively with vessel (r = 0.30, p = 0.02) and plaque (r = 0.33, p = 0.01) volumes and negatively with FCT (r = -0.26, p = 0.049), but not with percent plaque volume and plaque tissue components. In contrast, higher VAT/SAT ratio significantly correlated with higher percent lipid (r = 0.34, p = 0.008) and lower percent fibrous (r = -0.34, p = 0.007) volumes with a trend toward larger percent plaque volume (r = 0.19, p = 0.15), as well as thinner FCT (r = -0.53, p < 0.0001). In the multiple regression analysis, higher VAT/SAT ratio was independently associated with higher percent lipid with lower percent fibrous volumes (p = 0.03 for both) and thinner fibrous cap thickness (p = 0.0001).

CONCLUSION

Coronary plaque vulnerability, defined as increased lipid content with thinner fibrous cap thickness, appears to be more related to abnormal abdominal fat distribution, or so-called hidden obesity, compared with visceral or subcutaneous fat amount alone in patients with ACS.

Difference in epicardial adipose tissue distribution between paroxysmal atrial fibrillation and coronary artery disease

BACKGROUND

An increase in epicardial adipose tissue (EAT) volume is associated with the development of atrial fibrillation (AF) and coronary artery disease (CAD), but little is known about differences in its distribution.

METHODS AND RESULTS

We included 50 patients with paroxysmal AF (PAF), 50 patients with CAD, and 50 control patients. Using multidetector computed tomography, EAT volumes surrounding the whole heart (total EAT), the atrium (atrial-EAT), and the ventricle (ventricular-EAT) were measured. EAT atrial/ventricular (A/V) ratio was calculated by dividing atrial- by ventricular-EAT volume. The total EAT volume indexes in the PAF and CAD groups were significantly larger than those in the control group. The atrial-EAT volume index in the PAF group was significantly larger than that in the CAD and control groups, whereas the ventricular-EAT volume index in the CAD group was significantly larger than that in the PAF and control groups. Thus, EAT A/V ratio was smaller in the CAD and control group than that in the PAF group (0.28 ± 0.12 vs. 0.38 ± 0.13 vs. 0.54 ± 0.33, P < .001). Univariate and multivariate linear regression analysis showed EAT A/V ratio to be independently associated with cardiovascular disease type (PAF vs. CAD; P < .001, β = .463).

CONCLUSIONS

Atrial- and ventricular-dominant distribution of EAT was observed in the PAF and CAD groups, respectively. Uneven distribution of EAT may imply the direct contribution of EAT-related inflammation to the pathogenesis of AF or CAD.

Epicardial adipose tissue volume and annexin A2/fetuin-A signalling are linked to coronary calcification in advanced coronary artery disease: Computed tomography and proteomic biomarkers from the EPICHEART study

BACKGROUND & AIMS

The role of epicardial adipose tissue (EAT) in the pathophysiology of late stage-coronary artery disease (CAD) has not been investigated. We explored the association of EAT volume and its proteome with advanced coronary atherosclerosis.

METHODS

The EPICHEART Study prospectively enrolled 574 severe aortic stenosis patients referred to cardiac surgery. Before surgery, EAT volume was quantified by computed tomography (CT). During surgery, epicardial, mediastinal (MAT) and subcutaneous (SAT) adipose tissue samples were collected to explore fat phenotype by analyzing the proteomic profile using SWATH-mass spectrometry; pericardial fluid and peripheral venous blood were also collected. CAD presence was defined as coronary artery stenosis ≥50% in invasive angiography and by CT-derived Agatston coronary calcium score (CCS).

RESULTS

EAT volume adjusted for body fat was associated with higher CCS, but not with the presence of coronary stenosis. In comparison with mediastinal and subcutaneous fat depots, EAT exhibited a pro-calcifying proteomic profile in patients with CAD characterized by upregulation of annexin-A2 and downregulation of fetuin-A; annexin-A2 protein levels in EAT samples were also positively correlated with CCS. We confirmed that the annexin-A2 gene was overexpressed in EAT samples of CAD patients and positively correlated with CCS. Fetuin-A gene was not detected in EAT samples, but systemic fetuin-A was higher in CAD than in non-CAD patients, suggesting that fetuin-A was locally downregulated.

CONCLUSIONS

In an elderly cohort of stable patients, CCS was associated with EAT volume and annexin-A2/fetuin-A signaling, suggesting that EAT might orchestrate pro-calcifying conditions in the late phases of CAD.

Regional differences of fat depot attenuation using non-contrast, contrast-enhanced, and delayed-enhanced cardiac CT

BACKGROUND

Regional fat density assessed by computed tomography (CT) has been suggested as a marker of perivascular adipose tissue inflammation. Dual energy CT (DECT) allows improved tissue characterization compared to conventional CT.

PURPOSE

To explore whether DECT might aid regional fat density discrimination.

MATERIAL AND METHODS

We included patients who had completed a non-enhanced cardiac CT scan, CT coronary angiography (CTCA), and a delayed enhancement CT. Attenuation levels (Hounsfield units [HU]) were assessed at the epicardial, paracardial, visceral, and subcutaneous fat. The number of coronary segments with disease (SIS) was calculated.

RESULTS

A total of 36 patients were included in the analysis. Twenty-six (72%) patients had evidence of obstructive disease at CCTA and 25 (69%) patients had evidence of previous myocardial infarction. At non-contrast CT, we did not identify significant attenuation differences between epicardial, paracardial, subcutaneous, and visceral fat depots (-110.8 ± 9 HU, vs. -113.7 ± 9 HU, vs. -114.7 ± 8 HU, vs. -113.8 ± 11 HU, P = 0.36). Significant attenuation differences were detected between fat depots at mid and low energy levels, both at CTCA and delayed-enhancement scans ( P < 0.05 for all). Epicardial fat showed the least negative attenuation, irrespective of the acquisition mode; epicardial fat evaluated at 40 keV was related to the SIS (r = 0.37, P = 0.03).

CONCLUSIONS

In this study, regional fat depots amenable to examination during thoracic CT scans have distinctive regional attenuation values. Furthermore, such differences were better displayed using contrast-enhanced monochromatic imaging at low energy levels.

Epicardial Adipose Tissue and Renal Disease

Epicardial adipose tissue (EAT) is derived from splanchnic mesoderm, localized anatomically between the myocardium and pericardial visceral layer, and surrounds the coronary arteries. Being a metabolically active organ, EAT secretes numerous cytokines, which moderate cardiovascular morphology and function. Through its paracrine and vasocrine secretions, EAT may play a prominent role in modulating cardiac function. EAT protects the heart in normal physiological conditions by secreting a variety of adipokines with anti-atherosclerotic properties, and in contrast, secretes inflammatory molecules in pathologic conditions that may play a dynamic role in the pathogenesis of cardiovascular diseases by promoting atherosclerosis. Considerable research has been focused on comparing the anatomical and biochemical features of EAT in healthy people, and a variety of disease conditions such as cardiovascular diseases and renal diseases. The global cardiovascular morbidity and mortality in renal disease are high, and there is a paucity of concrete evidence and societal guidelines to detect early cardiovascular disease (CVD) in this group of patients. Here we performed a clinical review on the existing evidence and knowledge on EAT in patients with renal disease, to evaluate its application as a reliable, early, noninvasive biomarker and indicator for CVD, and to assess its significance in cardiovascular risk stratification.

Correlation of epicardial fat quantification with severity of coronary artery disease: A study in Indian population

Objective

We studied the correlation of quantified epicardial fat with severity of coronary artery disease in patients [suspected cases of coronary artery disease (CAD)] referred for computed tomography (CT) coronary angiography and established cutoffs for epicardial fat volume (EFV) for the presence of CAD and obstructive CAD.

Methods

A prospective cum retrospective cross-sectional observational study was carried out on 950 Indian subjects (suspected cases of CAD) who were referred for coronary CT in the year 2013–2016. EFV was quantified using semiautomatic technique on multidetector coronary CT angiography. The presence of atherosclerotic plaques and degree of stenosis was assessed on coronary CT angiography scans. The correlation between quantified EFV and degree of stenosis was assessed. Multivariate analysis was also performed.

Results

A higher quantity of epicardial fat is found in patients with increasing severity of coronary artery stenosis. The EFV cutoff for the presence of CAD and obstructive CAD are 49.75 and 67.69 mL with area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 0.68, 81%, 45.9%,58.24%, 72.2%, and 62.84% and 0.709, 64.9%, 66.4%, 35.84%, 86.55%, and 66%, respectively. EFV correlates with age, weight, and body mass index (BMI). Multivariate analysis revealed EFV to be an independent risk factor for the presence of CAD.

Conclusions

Higher quantities of EFV are found in patients with greater degree of coronary artery stenosis. EFV correlates with age, weight, and BMI. EFV is an independent risk factor for CAD.

Is there relationship between epicardial fat and cardiovascular parameters in incident kidney transplant patients? A post-hoc analysis

Background

Epicardial fat (EF) has been related to increased cardiovascular risk in chronic kidney disease patients. Kidney transplantation is associated with weight gain, especially within the first 12 months. Recently an association between EF and left ventricular mass (LVM) has been suggested in kidney transplant (KTX) recipients.

Objective

Evaluate the EF in KTX recipients and its association with cardiovascular parameters in a 12-month follow-up study.

Methods

EF volume was determined using thoracic computed tomography. The EF progressor group (EF gain) was defined by any increment in EF after 12 months. LVM and LVM index were calculated by echocardiography.

Results

Ninety-eight incident KTX patients [57% men, 41.2 ± 10.1 years, mean dialysis time prior to transplant of 24 (11–60) months] were analyzed. At baseline and after 12 months, EF was 318.6 (275.2–392.6) ml and 329.5 (271.7–384.8) ml, respectively (p = 0.03). When compared to patients who EF decreased (n = 33), those with EF gain (n = 65) had a greater increase of body mass index, abdominal circumference and blood glucose. These patients also had a lower reduction of LVM index. However in the multivariate analysis, there was no difference in LVM index change between groups (interaction p = 0.565), even after adjustment for hypertension, glucose and coronary calcium score (interaction p = 0.538).

Conclusion

The impact of EF gain on ventricular mass after KTX could not be definitely confirmed. Further prospective studies in a large sample of KTX patients should be considered to address a possible causal relationship between EF gain and cardiac hypertrophy in this population.

Association of Epicardial Adipose Tissue and High-Risk Plaque Characteristics: A Systematic Review and Meta-Analysis

Background

Epicardial adipose tissue (EAT) is hypothesized to alter atherosclerotic plaque composition, with potential development of high‐risk plaque (HRP). EAT can be measured by volumetric assessment (EAT‐v) or linear thickness (EAT‐t). We performed a systematic review and random‐effects meta‐analysis to assess the association of EAT with HRP and whether this association is dependent on the measurement method used.

Methods and Results

Electronic databases were systematically searched up to October 2016. Studies reporting HRP by computed tomography or intracoronary imaging and studies measuring EAT‐v or EAT‐t were included. Odds ratios were extracted from multivariable models reporting the association of EAT with HRP and described as pooled estimates with 95% confidence intervals (CIs). Analysis was stratified by EAT measurement method. Nine studies (n=3772 patients) were included with 7 measuring EAT‐v and 2 measuring EAT‐t. Increasing EAT was significantly associated with the presence of HRP (odds ratio: 1.26 [95% CI, 1.11–1.43]; P<0.001). Patients with HRP had higher EAT‐v than those without (weighted mean difference: 28.3 mL [95% CI, 18.8–37.8 mL]; P<0.001). EAT‐v was associated with HRP (odds ratio: 1.19 [95% CI, 1.06–1.33]; P<0.001); however, EAT‐t was not (odds ratio: 3.09 [95% CI, 0.56–17]; P=0.2). Estimates remained significant when adjusted for small‐study effect bias (odds ratio: 1.13 [95% CI, 1.03–1.28]; P=0.04).

Conclusions

Increasing EAT is associated with the presence of HRP, and patients with HRP have higher quantified EAT‐v. The association of EAT‐v with HRP is significant compared with EAT‐t; however, a larger scale study is still required, and further evaluation is needed to assess whether EAT may be a potential therapeutic target for novel pharmaceutical agents.

Clinical Trial Registration

URL: https://www.crd.york.ac.uk/. Unique identifier: CRD42017055473.

Clinical importance of epicardial adipose tissue

Different visceral fat compartments have several systemic effects and may play a role in the development of both insulin resistance and cardiovascular diseases. In the last couple of years special attention has been paid to the epicardial adipose tissue (EAT), which can be quantified by non-invasive cardiac imaging techniques. The epicardial fat is a unique fat compartment between the myocardium and the visceral pericardium sharing a common embryologic origin with the visceral fat depot. Epicardial adipose tissue has several specific roles, and its local effects on cardiac function are incorporated in the complex pathomechanism of coronary artery disease. Importantly, EAT may produce several adipocytokines and chemokines that may influence - through paracrine and vasocrine effects - the development and progression of coronary atherosclerosis. Epicardial adipose tissue volume has a relatively strong genetic dependence, similarly to other visceral fat depots. In this article, the anatomical and physiological as well as pathophysiological characteristics of the epicardial fat compartment are reviewed.

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."

Measurement of epicardial fat thickness by transthoracic echocardiography for predicting high-risk coronary artery plaques

Epicardial adipose tissue (EAT) volume is reported to be associated with coronary plaques. We evaluated whether non-invasive measurement of EAT thickness by echocardiography can predict high-risk coronary plaque characteristics determined independently by coronary computed tomography (CT) angiography. We enrolled 406 patients (mean age 63 years, 57 % male) referred for 64-slice CT. EAT was measured on the right ventricle free wall from a parasternal long-axis view at the end of systole. High-risk coronary plaques were defined as low-density plaques (<30 Hounsfield units) with positive remodeling (remodeling index >1.05). Patients were divided into thin or thick EAT groups using a cutoff value derived from receiver operator characteristic curve analysis for discriminating high-risk plaques. The receiver operator characteristic cutoff value was 5.8 mm with a sensitivity of 83 % and specificity of 64 % (area under the curve 0.77, 95 % confidence interval 0.70-0.83, p < 0.01). Compared with the thin EAT group, the thick EAT group had a high prevalence of low-density plaques (4 vs. 24 %, p < 0.01), positive remodeling (39 vs. 60 %, p < 0.01), and high-risk plaques (3 vs. 17 %, p < 0.01). Multiple logistic analysis revealed that thick EAT was a significant predictor of high-risk plaques (odds ratio 7.98, 95 % confidence interval 2.77-22.98, p < 0.01) after adjustment for covariates, including conventional risk factors, visceral adipose tissue area, and medications. The measurement of EAT thickness by echocardiography may provide a non-invasive option for predicting high-risk coronary plaques.

Segmental peri-coronary epicardial adipose tissue volume and coronary plaque characteristics

AIMS

Epicardial adipose tissue (EAT) has been proposed to modulate underlying coronary plaque features. The study aimed to determine the relation between segmental EAT (sEAT) volume, assessed by cardiac magnetic resonance (CMR), and underlying coronary plaque characteristics, as estimated by multidetector computed tomography (CT) (MDCT).

METHODS AND RESULTS

The study included 32 male patients with stable angina pectoris and 11 age-matched healthy controls. For each CAD patient, sEAT volume around 8 coronary segments (3 in left anterior descending artery, 3 in right coronary artery, and 2 in left circumflex artery) was quantified by CMR. By MDCT, plaques in each coronary segment were characterized in terms of plaque volume, type, CT attenuation, and severity of luminal stenosis. Serum levels of adipokines were measured. Total EAT volume was significantly higher in CAD patients than in control group. Serum resistin showed significant correlation with EAT volume (r = 0.69, P < 0.001). Analysis of 256 coronary segments showed larger sEAT volume with increasing luminal stenosis of the corresponding segment (mild: 8.2 cm(3); moderate: 11 cm(3); severe: 11.8 cm(3), P < 0.001). sEAT volume was larger in segments with mixed than those with calcified or non-calcified plaques (12.1 vs. 10.2 vs. 9.5 cm(3), respectively, P = 0.015). sEAT volume was larger in segments with low CT attenuation non-calcified plaques compared with non-calcified plaques with CT attenuation >30 HU (10.5 vs. 8.2 mm(3), P < 0.001).

CONCLUSION

Peri-coronary epicardial adipose tissue volume is significantly associated with the extent and severity of coronary atherosclerosis and may be a determinant of plaque vulnerability.

The correlation of epicardial adipose tissue on postmortem CT with coronary artery stenosis as determined by autopsy

The goal of this study was to assess whether epicardial and paracardial adipose tissue volumes, as determined by computed tomography (CT), correlate with coronary artery stenosis as determined by autopsy. The postmortem CT data and autopsy findings of 116 adult human decedents were retrospectively compared. Subjects were classified into three groups according to their degree of coronary artery stenosis: ≥50, <50%, and no stenosis. Epicardial and paracardial adipose tissue volumes were calculated based on manual segmentation after threshold based masking. In addition, epicardial adipose tissue thickness was measured using a caliper. All three parameters (thickness of epicardial fat and volumes of both epicardial and paracardial fat) were compared among the three groups and correlated with the degree of coronary artery stenosis. The group with no coronary artery stenosis showed the lowest mean values of epicardial adipose tissue volume, while the coronary artery stenosis ≥50 % group showed the highest volume. All measured variables (thickness of epicardial fat and volumes of both epicardial and paracardial fat) correlated significantly with the grade of coronary artery stenosis, even after controlling for BMI, however, epicardial adipose tissue volume exhibited the strongest correlation. This study reveals that there is an association between the degree of coronary artery stenosis and the amount of epicardial fat tissue: The larger the volume of epicardial fat, the higher the degree of coronary artery stenosis.

[Epicardial fat: Imaging and implications for diseases of the cardiovascular system]

Since the discovery of the obese (ob) gene product leptin, fat has been considered an endocrine organ. Especially epicardial fat has gained increasing attention in recent years. The epicardial fat plays a major role in fat metabolism; however, harmful properties have also been reported. Echocardiography, computed tomography and cardiac magnetic resonance imaging are the non-invasive tools used to measure epicardial fat volume. This review briefly introduces the basic physiological and pathophysiological considerations concerning epicardial fat. The main issue of this review is the presentation of non-invasive measurement techniques of epicardial fat using various imaging modalities and a literature overview of associations between epicardial fat and common cardiovascular diseases.

Epicardial fat and vascular risk: a narrative review

PURPOSE OF REVIEW

We comment on the associations between epicardial adiposity and cardiovascular disease (CVD) and associated risk factors. The effects of lifestyle measures and CVD drugs on cardiac adipose tissue are also discussed.

RECENT FINDINGS

Epicardial adipose tissue exerts cardioprotective properties; however, in cases of pathological enlargement, epicardial fat can lead to myocardial inflammation and dysfunction as well as left ventricular hypertrophy and coronary artery disease (CAD) due to paracrine actions that include increased production of reactive oxygen species, atherogenic and inflammatory cytokines. Cardiac adiposity is associated with CAD, obesity, type 2 diabetes, metabolic syndrome, nonalcoholic fatty liver disease, and chronic kidney disease, as well as with CVD risk factors such as lipids, hypertension, obesity markers, and carotid atherosclerosis.

SUMMARY

Due to its anatomical and functional proximity to the coronary circulation, epicardial adipose tissue may represent an even more direct CVD risk marker than central adiposity. Lifestyle measures and certain drugs may affect its thickness, although there are limited data currently available. The clinical implications of epicardial fat in daily practice remain to be established in future studies.

Epicardial fat: definition, measurements and systematic review of main outcomes

Epicardial fat (EF) is a visceral fat deposit, located between the heart and the pericardium, which shares many of the pathophysiological properties of other visceral fat deposits, It also potentially causes local inflammation and likely has direct effects on coronary atherosclerosis. Echocardiography, computed tomography and magnetic resonance imaging have been used to evaluate EF, but variations between methodologies limit the comparability between these modalities.

We performed a systematic review of the literature finding associations of EF with metabolic syndrome and coronary artery disease. The summarization of these associations is limited by the heterogeneity of the methods used and the populations studied, where most of the subjects were at high cardiovascular disease risk.

EF is also associated with other known factors, such as obesity, diabetes mellitus, age and hypertension, which makes the interpretation of its role as an independent risk marker intricate. Based on these data, we conclude that EF is a visceral fat deposit with potential implications in coronary artery disease. We describe the reference values of EF for the different imaging modalities, even though these have not yet been validated for clinical use. It is still necessary to better define normal reference values and the risk associated with EF to further evaluate its role in cardiovascular and metabolic risk assessment in relation to other criteria currently used.

Visceral adipose tissue as a source of inflammation and promoter of atherosclerosis

The current epidemic of obesity with the associated increasing incidence of insulin resistance, diabetes mellitus and atherosclerosis affecting a large proportion of the North American and Western populations, has generated a strong interest in the potential role of visceral adipose tissue in the development of atherosclerosis and its complications. The intra-abdominal and epicardial space are two compartments that contain visceral adipose tissue with a similar embryological origin. These visceral fats are highly inflamed in obese patients, patients with the metabolic syndrome and in those with established coronary artery disease; additionally they are capable of secreting large quantities of pro-inflammatory cytokines and free fatty acids. There is accumulating evidence to support a direct involvement of these regional adipose tissue deposits in the development of atherosclerosis and its complicating events, as will be reviewed in this article.

The year 2012 in the European Heart Journal-Cardiovascular Imaging: Part I

The new multi-modality cardiovascular imaging journal, European Heart Journal - Cardiovascular Imaging, was started in 2012. During its first year, the new Journal has published an impressive collection of cardiovascular studies utilizing all cardiovascular imaging modalities. We will summarize the most important studies from its first year in two articles. The present 'Part I' of the review will focus on studies in myocardial function, myocardial ischaemia, and emerging techniques in cardiovascular imaging.

Relationship of epicardial fat volume to coronary plaque, severe coronary stenosis, and high-risk coronary plaque features assessed by coronary CT angiography

BACKGROUND

Associations of epicardial fat volume (EFV) measured on noncontrast cardiac CT (NCT) include coronary plaque, myocardial ischemia, and adverse cardiac events.

OBJECTIVES

This study aimed to define the relationship of EFV to coronary plaque type, severe coronary stenosis, and the presence of high-risk plaque features (HRPFs).

METHODS

We retrospectively evaluated 402 consecutive patients, with no prior history of coronary artery disease, who underwent same day NCT and coronary CT angiography (CTA). EFV was measured on NCT with the use of validated, semiautomated software. The coronary arteries were evaluated for coronary plaque type (calcified [CP], noncalcified [NCP], or partially calcified [PCP]) and coronary stenosis severity ≥70% with the use of coronary CTA. For patients with NCP and PCP, 2 high-risk plaque features were evaluated: low-attenuation plaque and positive remodeling.

RESULTS

There were 402 patients with a median age of 66 years (range, 23-92 years) of whom 226 (56%) were men. The EFV was greater in patients with CP (112 ± 55 cm(3) vs 89 ± 39 cm(3)), PCP (110 ± 57 cm(3) vs 98 ± 45 cm(3)), and NCP (115 ± 44 cm(3) vs EFV 100 ± 52 cm(3)). In the 192 patients with PCP or NCP, on multivariable analysis, after adjusting for conventional cardiovascular risk factors, EFV was an independent predictor of ≥70% coronary artery stenosis (odds ratio [OR], 3.0; 95% CI, 1.3-6.6; P = 0.008), any high-risk plaque features (OR, 1.7; 95% CI, 0.9-3.4; P = 0.04), and low attention plaque (OR, 2.4; 95% CI, 1.1-5.1; P = 0.02) but not of positive remodeling.

CONCLUSIONS

EFV is greater in patients with CP, PCP, and NCP. In patients with NCP and PCP, EFV is significantly associated with severe coronary stenosis, high-risk plaque features, and low attenuation plaque.

The Association between Epicardial Adipose Tissue and Coronary Artery Disease: an Echocardiographic Cut-off Point

INTRODUCTION

EAT is an independent factor in coronary artery disease (CAD). The objective of the current study was to define an echocardiographic cut-off point for EAT and to determine its diagnostic value in predicting the increase in CAD risk.

METHODS

Two hundred patients underwent coronary artery angiography for diagnosis of CAD and transthoracic echocardiography for measurement of EAT on the right ventricle (RV), RV apex and RV outlet tract. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the EAT cut-off points in the three above-mentioned areas for predicting the severity of CAD were measured. The relation between the EAT and CAD risk factors was evaluated as well.

RESULTS

EAT was independent from gender, height, hypertension, diabetes, HDL, total cholesterol, ejection fraction, acute coronary syndrome, and the location of the coronary artery stenosis in the coronary artery in all three anatomical areas. EAT on RV and RV apex had a significant relation with CAD (P ≤ 0.05). Overall, RV EAT≥ 10 mm and RV apex EAT ≥ 8 mm had sensitivity and PPV of more than 70% in predicting coronary stenosis ≥ 50% and acute coronary syndrome (ACS) and RVOT EAT ≥ 13 mm is of PPV=83.5% for predicting coronary stenosis ≥ 50%.

CONCLUSION

EAT thickness has an acceptable diagnostic value for predicting severe coronary artery stenosis and ACS. Therefore, non-invasive EAT thickness measurement could be of great assistance to clinicians for detecting the patients at risk and helping them to undergo supplementary evaluations with invasive approaches.