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

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.

Deep learning analysis of epicardial adipose tissue to predict cardiovascular risk in heavy smokers

BACKGROUND

Heavy smokers are at increased risk for cardiovascular disease and may benefit from individualized risk quantification using routine lung cancer screening chest computed tomography. We investigated the prognostic value of deep learning-based automated epicardial adipose tissue quantification and compared it to established cardiovascular risk factors and coronary artery calcium.

METHODS

We investigated the prognostic value of automated epicardial adipose tissue quantification in heavy smokers enrolled in the National Lung Screening Trial and followed for 12.3 (11.9-12.8) years. The epicardial adipose tissue was segmented and quantified on non-ECG-synchronized, non-contrast low-dose chest computed tomography scans using a validated deep-learning algorithm. Multivariable survival regression analyses were then utilized to determine the associations of epicardial adipose tissue volume and density with all-cause and cardiovascular mortality (myocardial infarction and stroke).

RESULTS

Here we show in 24,090 adult heavy smokers (59% men; 61 ± 5 years) that epicardial adipose tissue volume and density are independently associated with all-cause (adjusted hazard ratios: 1.10 and 1.38; P < 0.001) and cardiovascular mortality (adjusted hazard ratios: 1.14 and 1.78; P < 0.001) beyond demographics, clinical risk factors, body habitus, level of education, and coronary artery calcium score.

CONCLUSIONS

Our findings suggest that automated assessment of epicardial adipose tissue from low-dose lung cancer screening images offers prognostic value in heavy smokers, with potential implications for cardiovascular risk stratification in this high-risk population.

Epicardial fat volume and its association with cardiac arrhythmias in CT coronary angiography

Purpose

This retrospective study aimed to investigate the epicardial fat volume in cardiac computed tomography (CT), its relationship with cardiac arrhythmias, and its correlation with the coronary artery disease reporting and data system (CAD-RADS) score.

Material and methods

Ninety-six patients who underwent CT coronary angiography (CTCA) were included in this study. Patient data, including demographic information, clinical history, and imaging data were collected retrospectively. Epicardial fat volume was quantified using a standardised algorithm, the CAD-RADS scoring system was applied to assess the extent of coronary artery disease (CAD). Descriptive statistics, correlation analyses, and receiver operating characteristics methods were used.

Results

The study found a significant correlation between epicardial fat volume and CAD-RADS score (r2 = 0.31; p < 0.001), indicating the known influence of epicardial fat on CAD risk. Moreover, patients with higher epicardial fat volumes were more likely to experience cardiac tachyarrhythmia (p < 0.001). Receiver operating characteristic analysis established a threshold value of 123 cm3 for epicardial fat volume to predict tachyarrhythmia with 80% sensitivity (AUC = 0.69).

Conclusions

In this study a volume of at least 123 cm3 epicardial fat in native coronary calcium scans is associated with cardiac tachyarrhythmia. In these patients, careful selection of suitable imaging protocols is advised.

Epicardial Fat Volume as a Good Predictor for Multivessel Coronary Artery Disease

INTRODUCTION

Epicardial adipose tissue may have an important role in the pathogenesis of coronary artery disease (CAD).

AIM

We aimed to study the association between epicardial fat volume (EFV) and presence of obstructive as well as multivessel CAD.

METHODS

A total of 87 adult subjects with suspected CAD who underwent both quantified by multidetector computerized tomography (MDCT) and Invasive Coronary Angiography (ICA) were enrolled in this observational study. EVF was measured by MDCT by calculating the sum of cross- sectional areas of fat multiplied by slice thickness. EFV measurement and its association with the presence of obstructive CAD (defined as coronary artery stenosis > 70%) was evaluated.

RESULTS

Overall, 89.6% patients had obstructive CAD with higher EFV as compared to 10.3% patients with non-obstructive CAD (57 ± 20.14 cm3 vs. 44 ± 7.4 cm3; P < 0.001). Furthermore, EFV was significantly increased in group II as compared with group I (74 ± 24.3 ml vs. 53 ± 16.2 ml; P < 0.003). On the hand, the coronary calcium score (CAC) was insignificantly increased in group II as compared with group I (486.1 vs. 211.2; P = 0.10). Multivariate analysis revealed that, EFV might be an independent risk factor for not only the presence of obstructive CAD (odds ratio [OR], 1.062; 95% CI 1.018- 1.108; P < 0.005) but also in predicting multivessel disease affection.

CONCLUSIONS

Our results demonstrated that, EFV was significantly increased not only with obstructive CAD, independent of other traditional risk factors and CAC score, but also it can be considered a good predictor of multivessel disease occurrence.

Computed tomography and nuclear medicine for the assessment of coronary inflammation: clinical applications and perspectives

There is increasing evidence that in patients with atherosclerotic cardiovascular disease (ASCVD) under optimal medical therapy, a persisting dysregulation of the lipid and glucose metabolism, associated with adipose tissue dysfunction and inflammation, predicts a substantial residual risk of disease progression and cardiovascular events. Despite the inflammatory nature of ASCVD, circulating biomarkers such as high-sensitivity C-reactive protein and interleukins may lack specificity for vascular inflammation. As known, dysfunctional epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) produce pro-inflammatory mediators and promote cellular tissue infiltration triggering further pro-inflammatory mechanisms. The consequent tissue modifications determine the attenuation of PCAT as assessed and measured by coronary computed tomography angiography (CCTA). Recently, relevant studies have demonstrated a correlation between EAT and PCAT and obstructive coronary artery disease, inflammatory plaque status and coronary flow reserve (CFR). In parallel, CFR is well recognized as a marker of coronary vasomotor function that incorporates the haemodynamic effects of epicardial, diffuse and small-vessel disease on myocardial tissue perfusion. An inverse relationship between EAT volume and coronary vascular function and the association of PCAT attenuation and impaired CFR have already been reported. Moreover, many studies demonstrated that 18F-FDG PET is able to detect PCAT inflammation in patients with coronary atherosclerosis. Importantly, the perivascular FAI (fat attenuation index) showed incremental value for the prediction of adverse clinical events beyond traditional risk factors and CCTA indices by providing a quantitative measure of coronary inflammation. As an indicator of increased cardiac mortality, it could guide early targeted primary prevention in a wide spectrum of patients. In this review, we summarize the current evidence regarding the clinical applications and perspectives of EAT and PCAT assessment performed by CCTA and the prognostic information derived by nuclear medicine.

Epicardial Adipose Tissue in Patients with Coronary Artery Disease: A Meta-Analysis

Objective: The aim of this study is to assess the association between epicardial adipose tissue (EAT) and coronary artery disease (CAD) via meta−analysis. Methods: Specific searches of online databases from January 2000 to May 2022 were conducted. All observational studies evaluating the association between EAT and CAD in PubMed, Web of Science, and the Cochrane Library databases were screened. A meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta−Analyses guidelines (PRISMA). In total, 21 studies encompassing 4975 subjects met the inclusion criteria, including 2377 diagnosed and assigned as the CAD group, while the other 2598 were assigned as the non−CAD group. Subjects in the CAD group were further divided into the severe stenosis group (stenosis ≥ 50%, n = 846) and the mild/moderate stenosis group (stenosis < 50%, n = 577). Results: Both the volume and thickness of EAT in the CAD group were larger compared to the non−CAD group (p < 0.00001). In a subgroup analysis within the CAD group, the severe stenosis group had a larger volume and thickness with respect to EAT when compared to the mild/moderate group (p < 0.001). Conclusions: The enlargement of EAT presented in CAD patients with an association with CAD severity. Although limited by different CAD types and measuring methods for EAT, as well as a smaller sample size, our results suggest that EAT is a novel predictor and a potential therapeutic target for CAD.

Epicardial fat volume is associated with preexisting atrioventricular conduction abnormalities and increased pacemaker implantation rate in patients undergoing transcatheter aortic valve implantation

Epicardial fat tissue (EFT) is a highly metabolically active fat depot surrounding the heart and coronary arteries that is related to early atherosclerosis and adverse cardiac events. We aimed to investigate the relationship between the amount of EFT and preexisting cardiac conduction abnormalities (CCAs) and the need for new postinterventional pacemaker in patients with severe aortic stenosis planned for transcatheter aortic valve implantation (TAVI). A total of 560 consecutive patients (54% female) scheduled for TAVI were included in this retrospective study. EFT volume was measured via a fully automated artificial intelligence software (QFAT) using computed tomography (CT) performed before TAVI. Baseline CCAs [first-degree atrioventricular (AV) block, right bundle branch block (RBBB), and left bundle branch block (LBBB)] were diagnosed according to 12-lead ECG before TAVI. Aortic valve calcification was determined by the Agatston score assessed in the pre-TAVI CT. The median EFT volume was 129.5 ml [IQR 94-170]. Baseline first-degree AV block was present in 17%, RBBB in 10.4%, and LBBB in 10.2% of the overall cohort. In adjusted logistic regression analysis, higher EFT volume was associated with first-degree AV block (OR 1.006 [95% CI 1.002-1.010]; p = 0.006) and the need for new pacemaker implantation after TAVI (OR 1.005 [95% CI 1.0-1.01]; p = 0.035) but not with the presence of RBBB or LBBB. EFT volume did not correlate with the Agatston score of the aortic valve. Greater EFT volume is associated independently with preexisting first-degree AV block and new pacemaker implantation in patients undergoing TAVI. It may play a causative role in degenerative processes and the susceptibility of the AV conduction system.

Epicardial adipose tissue volume is associated with abdominal aortic aneurysm expansion

BACKGROUND

Epicardial adipose tissue volume (EATV) is associated with cardiovascular diseases such as coronary artery disease. However, no information is available regarding the relationship between EATV and abdominal aortic aneurysm (AAA) expansion. This study aimed to evaluate the association between EATV and the growth of AAA, and to identify predictors of AAA expansion.

METHODS

Between June 2009 and December 2019, a total of 906 patients underwent endovascular or open repair of AAA at our institution. Patients with previous cardiac surgery, previous ascending thoracic aortic surgery, ruptured AAA, infected AAA, inflammatory AAA, saccular aneurysm, solitary iliac aneurysm, or reintervention after treatment for AAA were excluded. Two hundred and thirty-seven patients with at least two preoperative computed tomography (CT) scans performed more than 180 days apart were included in this study. EATV within the pericardium was retrospectively quantified from preoperative non-contrast CT images using a 3D workstation. The EATV index was defined as EATV divided by body surface area. The AAA expansion rate was defined as the increase in AAA diameter per year, and patients were divided into the slow-expansion group, with an expansion rate < 5 mm/year, and the fast-expansion group, with an expansion rate ≥ 5 mm/year. The correlation between expansion rate and the EATV index was analyzed, and the cut-off value of the EATV index was determined using a receiver operating characteristics curve. Multivariate analysis was used to assess predictors of the AAA expansion rate.

RESULTS

The expansion rate of AAA was positively correlated with the EATV index (R = .237, P < .001). The initial aneurysm diameter (P < .001) and EATV index (P = .009) differed significantly between the two groups. The cut-off value of the EATV index was 60.3 cm³/m² (area under the curve, .658; 95% confidence interval [CI], .568-.749; sensitivity, 1.000; specificity, .309). Multivariate analysis revealed that the initial aneurysm diameter and an EATV index > 60.3 cm³/m² were significantly associated with the AAA expansion rate.

CONCLUSIONS

This study demonstrated that the EATV index was associated with AAA expansion.

Association of Epicardial Fat Volume With Increased Risk of Obstructive Coronary Artery Disease in Chinese Patients With Suspected Coronary Artery Disease

Background Epicardial adipose tissue may be associated with the pathogenesis of coronary artery disease (CAD), but its effect on obstructive CAD risk is uncertain. Therefore, we aimed to examine the relationship between epicardial adipose tissue and obstructive CAD in Chinese patients with suspected CAD. Methods and Results The present study enrolled 194 consecutive inpatients with suspected CAD who underwent both noncontrast computed tomography and coronary angiography. We measured epicardial fat volume (EFV) and evaluated its association with obstructive CAD, which was defined as coronary stenosis severity ≥70%. Overall, 44.3% patients had obstructive CAD and tend to have higher EFV. Age, body mass index, triglycerides, incidence of hypertension, and hyperlipidemia were higher across tertiles of EFV (P for trend <0.05). In univariate regression analysis, a per-SD increase in EFV was independently associated with obstructive CAD (odds ratio [OR], 2.31; 95% CI, 1.61-3.32; P<0.001). Consistent with these findings, EFV was still significantly related to obstructive CAD as continuous variable after adjustment for all traditional risk factors and coronary artery calcium (OR per SD, 2.82; 95% CI, 1.68-4.74; P<0.001). Generalized additive model indicated that EFV was linearly associated with risk of obstructive CAD. E-value analysis suggested robustness to unmeasured confounding. Conclusions Our results suggested that in Chinese patients with suspected CAD, EFV was significantly and positively associated with the risk of obstructive CAD, independent of traditional risk factors and coronary artery calcium.

Association of Epicardial Fat Volume With the Extent of Coronary Atherosclerosis and Cardiovascular Adverse Events in Asymptomatic Patients With Diabetes

Epicardial adipose tissue has a paracrine effect, enhancing coronary artery atherosclerotic plaque development. This study evaluated epicardial fat volume (EFV), adipokines, coronary atherosclerosis, and adverse cardiovascular events in a cohort of asymptomatic patients with type 2 diabetes mellitus (T2DM). Epicardial fat volume was calculated using data from computed tomography coronary angiograms. Adipokines and inflammatory cytokines were also assayed and correlated with EFV. Epicardial fat volume was also assessed as a predictor of coronary artery calcium (CAC) score, number of coronary artery plaques, and significant plaque (>50% luminal stenosis). Data from the EFV analysis were available for 221 (85.7%) participants. Median EFV was 97.4 cm³, mean body mass index was 28.1 kg/m², and mean duration of T2DM was 13 years. Statistically significant, but weak, correlations were observed between several adipokines, inflammatory cytokines, and EFV. Epicardial fat volume was a significant univariate (P = .01), but not multivariate, predictor of the number of coronary plaques, but not of CAC score or significant plaque. After a mean follow-up of 22.8 months, 12 adverse cardiovascular events were reported, exclusively in participants with EFV >97.4 cm³. Epicardial fat volume has limited utility as a marker of coronary artery plaque in patients with T2DM and is weakly correlated with adipokine expression.

Epicardial fat attenuation, not volume, predicts obstructive coronary artery disease and high risk plaque features in patients with atypical chest pain

OBJECTIVE

This study sought to investigate the association between volume and attenuation of epicardial fat and presence of obstructive coronary artery disease (CAD) and high-risk plaque features (HRPF) on CT angiography (CTA) in patients with atypical chest pain and whether the association, if any, is independent of conventional cardiovascular risk factors and coronary artery calcium score (CACS).

METHODS

Patients referred for coronary CTA with atypical chest pain and clinical suspicion of CAD were included in the study. Quantification of CACS, epicardial fat volume (EFV) and epicardial fat attenuation (EFat) was performed on non-contrast images. CTA was evaluated for presence of obstructive CAD and presence of HRPF.

RESULTS

255 patients (median age [interquartile range; IQR]: 51[41-60] years, 51.8% males) were included. On CTA, CAD, obstructive CAD (≥50% stenosis) and CTA-derived HRPFs was present in 133 (52.2%), 37 (14.5%) and 82 (32.2%) patients respectively. A significantly lower EFat was seen in patients with obstructive CAD than in those without (-86HU [IQR:-88 to -82 HU] vs -84 [IQR:-87 HU to -82 HU]; p = 0.0486) and in patients with HRPF compared to those without (-86 HU [IQR:-88 to -83 HU] vs -83 HU [-86 HU to -81.750 HU]; p < 0.0001). EFat showed significant association with obstructive CAD (unadjusted Odd's ratio (OR) [95% CI]: 0.90 [0.81-0.99];p = 0.0248) and HRPF (unadjusted OR [95% CI]: 0.83 [0.76-0.90];p < 0.0001) in univariate analysis, which remained significant in multivariate analysis. However, EFV did not show any significant association with neither obstructive CAD nor HRPF in multivariate analysis. Adding EFat to conventional coronary risk factors and CACS in the pre-test probability models increased the area-under curve (AUC) for prediction of both obstructive CAD (AUC[95% CI]: 0.76 [0.70-0.81] vs 0.71 [0.65-0.77)) and HRPF (AUC [95% CI]: 0.92 [0.88-0.95] vs 0.89 [0.85-0.93]), although not reaching statistical significance.

CONCLUSION

EFat, but not EFV, is an independent predictor of obstructive CAD and HRPF. Addition of EFat to traditional cardiovascular risk factors and CACS improves estimation for pretest probability of obstructive CAD and HRPF.

ADVANCES IN KNOWLEDGE

EFat is an important attribute of epicardial fat as it reflects the "quality" of fat, taking into account the effects of brown-white fat transformation and fibrosis, as opposed to mere evaluation of "quantity" of fat by EFV. Our study shows that EFat is a better predictor of obstructive CAD and HRPF than EFV and can thus explain the inconsistent association of increased EFV alone with CAD.

Segmentation of cardiac fats based on Gabor filters and relationship of adipose volume with coronary artery disease using FP-Growth algorithm in CT scans

Heart mediastinal and epicardial fat tissues are related to several adverse metabolic effects and cardiovascular risk factors, especially coronary artery disease (CAD). The manual segmentation of those fats is that the high dependence on user intervention and time-consuming analyzes. As a result, the automated measurement of cardiac fats could be considered as one of the most important biomarkers for cardiovascular risks in imaging and medical visualization by physicians. In this paper, we validate an automatic approach for the cardiac fat segmentation in non-contrast CT images then investigate the correlation between cardiac fat volume and CAD using the association rule mining algorithm. The pre-processing step includes threshold and contrast enhancement, the feature extraction step includes Gabor filter bank based on GLCM, the cardiac fat segmentation step is predicated on pattern recognition classification algorithms, and eventually, the step of investigating the relationship between cardiac fat volume and CAD is using FP-Growth algorithm. Experimental validation using CT images of two databases points to a good performance in cardiac fat segmentation. Experiments showed that the accuracy of the designed algorithm using the ensemble classifier with the best performance over other classifiers for the cardiac fat segmentation was 99.2%, with a sensitivity of 96.3% and a specificity of 99.8%. The results of using the FP-Growth algorithm showed that the low volume of epicardial (Confidence = 0.6818, Lift = 1.0626) and mediastinal (Confidence = 0.6696, Lift = 1.0436) fat are associated with healthy individuals and the high volume of epicardial (Confidence = 0.8, Lift = 2.2326) and mediastinal (Confidence = 0.75, Lift = 2.093) fat are related to individuals of CAD. As a result, cardiac fats can be used as a reliable biomarker tool in predicting the extent of CAD stenosis.

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

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

Deep Learning-Based Quantification of Epicardial Adipose Tissue Volume and Attenuation Predicts Major Adverse Cardiovascular Events in Asymptomatic Subjects

BACKGROUND

Epicardial adipose tissue (EAT) volume (cm³) and attenuation (Hounsfield units) may predict major adverse cardiovascular events (MACE). We aimed to evaluate the prognostic value of fully automated deep learning-based EAT volume and attenuation measurements quantified from noncontrast cardiac computed tomography.

METHODS

Our study included 2068 asymptomatic subjects (56±9 years, 59% male) from the EISNER trial (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) with long-term follow-up after coronary artery calcium measurement. EAT volume and mean attenuation were quantified using automated deep learning software from noncontrast cardiac computed tomography. MACE was defined as myocardial infarction, late (>180 days) revascularization, and cardiac death. EAT measures were compared to coronary artery calcium score and atherosclerotic cardiovascular disease risk score for MACE prediction.

RESULTS

At 14±3 years, 223 subjects suffered MACE. Increased EAT volume and decreased EAT attenuation were both independently associated with MACE. Atherosclerotic cardiovascular disease risk score, coronary artery calcium, and EAT volume were associated with increased risk of MACE (hazard ratio [95%CI]: 1.03 [1.01-1.04]; 1.25 [1.19-1.30]; and 1.35 [1.07-1.68], P<0.01 for all) and EAT attenuation was inversely associated with MACE (hazard ratio, 0.83 [95% CI, 0.72-0.96]; P=0.01), with corresponding Harrell C statistic of 0.76. MACE risk progressively increased with EAT volume ≥113 cm³ and coronary artery calcium ≥100 AU and was highest in subjects with both (P<0.02 for all). In 1317 subjects, EAT volume was correlated with inflammatory biomarkers C-reactive protein, myeloperoxidase, and adiponectin reduction; EAT attenuation was inversely related to these biomarkers.

CONCLUSIONS

Fully automated EAT volume and attenuation quantification by deep learning from noncontrast cardiac computed tomography can provide prognostic value for the asymptomatic patient, without additional imaging or physician interaction.

Relationships between visceral/subcutaneous adipose tissue FABP4 expression and coronary atherosclerosis in patients with metabolic syndrome

BACKGROUND

Cytoplasmic fatty acid-binding proteins facilitate the transport of lipids to specific compartments in cells. Fatty acid-binding protein 4 (FABP4), also known as aP2 or A-FABP, plays a key role in the development of atherosclerosis, insulin resistance, obesity, and metabolic syndrome (MS). The FABP4 polymorphisms are associated with protein expression changes in vitro and metabolic and vascular alterations in vivo. The aim of this study was to investigate the association between FABP4 messenger ribonucleic acid (mRNA) expression levels in epicardial (EAT), pericardial (PAT), and subcutaneous adipose tissues (SAT), and the extent of coronary atherosclerosis in coronary artery disease (CAD) patients with MS. Furthermore, the relationship between the extent of coronary atherosclerosis and epicardial adipose tissue volume (EATV) and FABP4 gene variations was evaluated.

PATIENTS AND METHODS

A total of 37 patients undergoing coronary artery bypass grafting because of CAD (MS CAD group) and 23 non-MS patients undergoing heart valve surgery (control group) were included. Coronary angiography was performed for all patients and the extent of coronary atherosclerosis was assessed using the Sullivan's scoring system. The mRNA expression levels of FABP4 gene in EAT, PAT, and SAT, and FABP4 polymorphisms were analyzed using the quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

An increased FABP4 expression was observed in EAT and PAT of MS CAD group compared to controls. In the MS CAD group, FABP4 mRNA expression levels in EAT was 2.8-fold higher compared to PAT. The expression of FABP4 in EAT was positively correlated with the extent of atherosclerosis and EATV in MS CAD group (r = 0.588, P= 0.001, r = 0.174, P = 0.001, respectively). There were no correlations between PAT and SAT versus the extent of atherosclerosis and EATV. The FABP4 EAT mRNA expression levels were found to significantly increase in mutant allele carriers of rs1054135, whereas they significantly decreased in mutant allele carriers of rs77878271 (T-87C) in MS CAD group (P < 0.05). The extent of atherosclerosis was also found to be significantly associated with rs1054135 (P < 0.05). A cut-off point of 57.5 cm³ EATV was used indicating the presence of CAD with a significant area under the curve of 0.783%, 98% sensitivity, and 100% specificity (95% CI 0.620-0.880; P < 0.05).

CONCLUSIONS

Our study results suggest that FABP4 expression in EAT is strongly associated with the extent of atherosclerosis and EATV in MS CAD patients.

Fully Automated CT Quantification of Epicardial Adipose Tissue by Deep Learning: A Multicenter Study

Purpose

To evaluate the performance of deep learning for robust and fully automated quantification of epicardial adipose tissue (EAT) from multicenter cardiac CT data.

Materials and Methods

In this multicenter study, a convolutional neural network approach was trained to quantify EAT on non-contrast material-enhanced calcium-scoring CT scans from multiple cohorts, scanners, and protocols (n = 850). Deep learning performance was compared with the performance of three expert readers and with interobserver variability in a subset of 141 scans. The deep learning algorithm was incorporated into research software. Automated EAT progression was compared with expert measurements for 70 patients with baseline and follow-up scans.

Results

Automated quantification was performed in a mean (± standard deviation) time of 1.57 seconds ± 0.49, compared with 15 minutes for experts. Deep learning provided high agreement with expert manual quantification for all scans (R = 0.974; P < .001), with no significant bias (0.53 cm³; P = .13). Manual EAT volumes measured by two experienced readers were highly correlated (R = 0.984; P < .001) but with a bias of 4.35 cm³ (P < .001). Deep learning quantifications were highly correlated with the measurements of both experts (R = 0.973 and R = 0.979; P < .001), with significant bias for reader 1 (5.11 cm³; P < .001) but not for reader 2 (0.88 cm³; P = .26). EAT progression by deep learning correlated strongly with manual EAT progression (R = 0.905; P < .001) in 70 patients, with no significant bias (0.64 cm³; P = .43), and was related to an increased noncalcified plaque burden quantified from coronary CT angiography (5.7% vs 1.8%; P = .026).

Conclusion

Deep learning allows rapid, robust, and fully automated quantification of EAT from calcium scoring CT. It performs as well as an expert reader and can be implemented for routine cardiovascular risk assessment.© RSNA, 2019See also the commentary by Schoepf and Abadia in this issue.

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.

Quantification of epicardial fat with cardiac CT angiography and association with cardiovascular risk factors in symptomatic patients: from the ALTER-BIO (Alternative Cardiovascular Bio-Imaging markers) registry

PURPOSE

We aimed to assess the association between features of epicardial adipose tissue and demographic, morphometric and clinical data, in a large population of symptomatic patients with clinical indication to cardiac computed tomography (CT) angiography.

METHODS

Epicardial fat volume (EFV) and adipose CT density of 1379 patients undergoing cardiac CT angiography (918 men, 66.6%; age range, 18-93 years; median age, 64 years) were semi-automatically quantified. Clinical variables were compared between diabetic and nondiabetic patients to assess potential differences in EFV and adipose CT density. Multiple regression models were calculated to find the clinical variables with a significant association with EFV and adipose CT density.

RESULTS

The median EFV in diabetic patients (112.87 mL) was higher compared with nondiabetic patients (82.62 mL; P < 0.001). The explanatory model of the multivariable analysis showed the strongest associations between EFV and BMI (β=0.442) and age (β=0.365). Significant yet minor association was found with sex (β=0.203), arterial hypertension (β=0.072), active smoking (β=0.068), diabetes (β=0.068), hypercholesterolemia (β=0.046) and cardiac height (β=0.118). The mean density of epicardial adipose tissue was associated with BMI (β=0.384), age (β=0.105), smoking (β=0.088), and diabetes (β=0.085).

CONCLUSION

In a large population of symptomatic patients, EFV is higher in diabetic patients compared with nondiabetic patients. Clinical variables are associated with quantitative features of epicardial fat.

Association of epicardial adipose tissue attenuation with coronary atherosclerosis in patients with a high risk of coronary artery disease

BACKGROUND AND AIMS

Density may indicate some tissue characteristics and help reveal the role of epicardial adipose tissue (EAT) in coronary artery disease (CAD). Therefore, we assessed the association of EAT density with the coronary artery plaque burden in patients presenting with chest pain.

METHODS

This retrospective cohort study comprised 614 patients (mean age 61 ± 9 years, 61% males) with a high cardiovascular disease risk, who underwent cardiac computed tomography angiography. Density was reflected as attenuation.

RESULTS

EAT attenuation was significantly associated with EAT volume with a negative Pearson's correlation coefficient and gradually increased across coronary artery calcium (CAC) scores of 0, 1-100, 101-400 and > 400. EAT attenuation was tightly associated with CAD risk factors, including age, sex, BMI, total cholesterol, neutrophil to lymphocyte ratios and CAC score. The association between EAT attenuation and CAC score was strengthened after adjusting for multivariable indices (OR 1.21, 95% CI 1.05-1.40, p = 0.01) and further adjusting for EAT volume (OR 1.26 95% CI 1.06-1.51, p<0.01). However, EAT attenuation was associated only with CAD presence (OR 1.32, 95% CI 1.02-1.69, p<0.05), CAC presence (OR 1.28, 95% CI 1.02-1.60, p<0.05), segment involvement score (OR 1.19, 95% CI 1.01-1.40, p<0.05) and segment stenosis score (OR 1.19, 95% CI 1.01-1.40, p<0.05) in the EAT volume- and multivariable-adjusted model. Additionally, EAT attenuation was not associated with significant coronary artery lesions and triple-vessel plaques.

CONCLUSIONS

Higher EAT attenuation is associated with a higher risk of CAD.

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

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

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

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

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

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.

The association of epicardial fat volume with coronary characteristics and clinical outcome

Recent studies have demonstrated the relationship between epicardial fat volume (EFV) and coronary atherosclerosis, but their association is modest at best. Our purpose is to elucidate the association of epicardial fat with coronary characteristics and clinical outcome. We performed coronary computed tomographic angiography in 651 patients and divided them into three groups according to tertiles of EFV; low-tertile (n = 215), 36-123 ml; middle-tertile (n = 218), 124-165 ml; high-tertile (n = 218), 166-489 ml. The prevalence of coronary calcium score (CCS) >0 (71.6, 73.4, and 83.9% in low-, middle-, and high-tertile group, respectively) and CCS >100 (39.1, 39.9, and 59.2% in each group) was significantly higher in patients with high-tertile EFV compared to the other two groups (p = 0.0047 and p < 0.0001, respectively). The prevalence of CCS >400 was 17.2, 25.7, and 33.1% in each group, which increased stepwise as EFV increased. The significant stenosis (36.2 vs. 27.0%, p = 0.0383), total coronary occlusion (5.5 vs. 0.9%, p = 0.0156), and high-risk plaque (11.0 vs. 5.6%, p = 0.0368) were more prevalent in patients with high-tertile EFV compared to those with low-tertile EFV. The combined rate of cardiac death and myocardial infarction was 0.9, 2.3, and 6.4% in each patient group, respectively, which was significantly higher in patients with high-tertile EFV compared to those with low-tertile EFV (p = 0.0004). The prevalence of coronary artery calcium, significant stenosis, and high-risk plaque increased sharply in patients with high EFV, which was associated with higher rate of cardiac death and myocardial infarction. Thus, high EFV was associated with advanced coronary atherosclerosis and poor prognosis.

Quantitative analysis of epicardial fat volume: effects of scanning protocol and reproducibility of measurements in non-contrast cardiac CT vs. coronary CT angiography

BACKGROUND

Several studies have focused on the role of epicardial fat in the pathogenesis of cardiovascular disease (CVD). The main purpose of the study was to evaluate a computerized method for the quantitative analysis of epicardial fat volume (EFV) by non-contrast cardiac CT (NCT) for coronary calcium scan and coronary CT angiography (coronary CTA).

METHODS

Thirty patients (61±12.5 years, 73% male, body mass index (BMI) =25.9±6.3 kg/m²) referred to our Institution for suspected coronary artery disease (CAD) underwent NCT and coronary CTA. Epicardial boundaries were traced by 2 experienced operators (operator 1, operators 2) on 3 and 6 short-axis (SA) slices. EFV was computed with a semi-automatic method using an in-house developed software based on spherical harmonic representation of the epicardial surface. In order to analyze the inter-observer variability both the Coefficient of Repeatability (CR) and Intra Class Correlation (ICC) were computed.

RESULTS

The total EFV was 103.62±50.97 and 94.96±67.91 cc in NCT and coronary CTA with non-significant difference (P=0.292). CR error was 10.22 cc for operator 1 and 11.31 cc for operator 2 in NCT and 7.99 cc for operator 1 and 7.75 cc for operator 2 in coronary CTA. To analyze the inter-observer variability CR and ICC were computed. CR was 8.17 and 8.39 cc with NCT and 7.07 and 7.21 cc with CTA for 6 and 3 SA slices respectively. ICC values >0.99 were obtained in all cases. The right ventricular EFV was 67.23±31.4 and 57.41±34.3 cc for NCT and coronary CTA respectively; the corresponding values for left ventricular EFV were 38.01±19.1 and 35.27±25.9 cc.

CONCLUSIONS

Both NCT and coronary CTA can be used with low intra- and inter-observer variability for computer-assisted measurements of EFV. Cardiac CT may allow a fast and reliable computation of EFV in clinical setting.

Pericoronary adipose tissue ratio is a stronger associated factor of plaque vulnerability than epicardial adipose tissue on coronary computed tomography angiography

This study was designed to clarify the influence of pericoronary adipose tissue (PAT) on plaque vulnerability using coronary computed tomography angiography (CCTA). A total of 103 consecutive patients who underwent CCTA and subsequent percutaneous coronary intervention (PCI) using intravascular ultrasound (IVUS) for coronary artery disease were enrolled. The PAT ratio was calculated as the sum of the perpendicular thickness of the visceral layer between the coronary artery and the pericardium, or the coronary artery and the surface of the heart at the PCI site, divided by the PAT thickness without a plaque in the same vessel. PAT ratios were divided into low, mid and high tertile groups. Epicardial adipose tissue (EAT) thickness was measured at the eight points surrounding the heart. Multivariate logistic analysis was performed to determine whether the PAT ratio is predictive of vulnerable plaques (positive remodeling, low attenuation and/or spotty calcification) on CCTA or echo-attenuated plaque on IVUS. The Hounsfield unit of obstructive plaques >50% was lower in the high PAT group than in the mid and low PAT groups (47.5 ± 28.8 vs. 53.1 ± 29.7 vs. 64.7 ± 27.0, p = 0.04). In multivariate logistic analysis, a high PAT ratio was an independent, associated factor of vulnerable plaques on CCTA (OR: 3.55, 95% CI: 1.20-10.49), whereas mean EAT thickness was not (OR: 1.22, 95% CI: 0.82-1.83). We observed a similar result in predicting echo-attenuated plaque on IVUS. PAT ratio on CCTA was an associated factor of vulnerable plaques, while EAT was not. These results support the important concept of local effects of cardiac adipose tissue on plaque vulnerability.

Relationship between indexed epicardial fat volume and coronary plaque volume assessed by cardiac multidetector CT

We explored whether baseline indexed epicardial fat volume (EFVi) and serial changes in EFVi were associated with increase in coronary plaque volume as assessed by multidetector computed tomography.We retrospectively reviewed 87 patients with coronary artery plaque, identified during either baseline or follow-up cardiac computed tomography (CT) examinations. Each plaque volume was measured in volumetric units using a semiautomatic software tool. EFVi was quantified by calculating the total volume of epicardial tissue of CT density -190 to -30 HU, indexed to the body surface area. Clinical cardiovascular risk factors were extracted by medical record review at the time of the cardiac CT examinations. The relationship between EFVi and coronary plaque volume was explored by regression analysis.Although the EFVi did not change significantly from baseline to the time of the follow-up CT (65.7 ± 21.8 vs 66.0 ± 21.8 cm/m, P = 0.620), the plaque volumes were increased significantly on the follow-up CT scans. The annual change in EFVi was not accompanied by a parallel change in coronary plaque volume (P = 0.096-0.500). On univariate analysis, smoking, hypercholesterolemia, 10-year coronary heart disease risk, obesity, and baseline EFVi predicted rapid increases in lipid-rich and fibrous plaque volumes. On multivariate analysis, baseline EFVi (odds ratio = 1.029, P = 0.016) was an independent predictor of a rapid increase in lipid-rich plaque volume.EFVi was shown to be an independent predictor of a rapid increase in lipid-rich plaque volume. However, changes in EFVi were not associated with parallel changes in coronary plaque volume.

Automated pericardium delineation and epicardial fat volume quantification from noncontrast CT

PURPOSE

The authors aimed to develop and validate an automated algorithm for epicardial fat volume (EFV) quantification from noncontrast CT.

METHODS

The authors developed a hybrid algorithm based on initial segmentation with a multiple-patient CT atlas, followed by automated pericardium delineation using geodesic active contours. A coregistered segmented CT atlas was created from manually segmented CT data and stored offline. The heart and pericardium in test CT data are first initialized by image registration to the CT atlas. The pericardium is then detected by a knowledge-based algorithm, which extracts only the membrane representing the pericardium. From its initial atlas position, the pericardium is modeled by geodesic active contours, which iteratively deform and lock onto the detected pericardium. EFV is automatically computed using standard fat attenuation range.

RESULTS

The authors applied their algorithm on 50 patients undergoing routine coronary calcium assessment by CT. Measurement time was 60 s per-patient. EFV quantified by the algorithm (83.60 ± 32.89 cm(3)) and expert readers (81.85 ± 34.28 cm(3)) showed excellent correlation (r = 0.97, p < 0.0001), with no significant differences by comparison of individual data points (p = 0.15). Voxel overlap by Dice coefficient between the algorithm and expert readers was 0.92 (range 0.88-0.95). The mean surface distance and Hausdorff distance in millimeter between manually drawn contours and the automatically obtained contours were 0.6 ± 0.9 mm and 3.9 ± 1.7 mm, respectively. Mean difference between the algorithm and experts was 9.7% ± 7.4%, similar to interobserver variability between 2 readers (8.0% ± 5.3%, p = 0.3).

CONCLUSIONS

The authors' novel automated method based on atlas-initialized active contours accurately and rapidly quantifies EFV from noncontrast CT.

Epicardial and paracardial adipose tissue volume and attenuation - Association with high-risk coronary plaque on computed tomographic angiography in the ROMICAT II trial

BACKGROUND AND AIMS

To determine whether epicardial (EAT) and paracardial adipose tissue (PAT) volume and attenuation are associated with high-risk coronary plaque features.

METHODS

In subjects with suspected acute coronary syndrome (ACS) enrolled in the ROMICAT II trial, EAT and PAT volumes indexed to body surface area (BSA) and attenuation were measured on non-contrast coronary artery calcium score (CACS) CT. High-risk plaque features (napkin-ring sign, positive remodeling, low density plaque, spotty calcium) and stenosis were assessed on coronary CT angiography (CTA). The association of EAT and PAT volume and attenuation with high-risk plaque and whether this was independent of clinical risk assessment, CACS and significant coronary artery disease (CAD) was determined.

RESULTS

Of 467 (mean 54 ± 8 yrs, 53% male) with CACS and CTA, 167 (36%) had high-risk plaque features. Those with high-risk plaque had significantly higher indexed EAT (median 59 (Q1-Q3:45-75) cc/m(2) vs. 49 (35-65) cc/m(2), p < 0.001) and PAT volume (median:51 (36-73) cc/m(2) vs. 33 (22-52) cc/m(2), p < 0.001). Higher indexed EAT volume was associated with high-risk plaque [univariate OR 1.02 (95%-CI:1.01-1.03) per cc/m(2) of EAT, p < 0.001], which remained significant [univariate OR 1.04 (95%-CI:1.00-1.08) per cc/m(2) of EAT, p = 0.040] after adjustment for risk factors, CACS, and stenosis ≥50%. Higher indexed PAT volume was associated with high-risk plaque in univariate analysis [OR 1.02 (1.01-1.03) per cc/m(2) of PAT, p < 0.001], though this was not significant in multivariate analysis. At a threshold of >62.3 cc/m(2), EAT volume was associated with high-risk plaque [univariate OR 2.50 (95%-CI:1.69-3.72), p < 0.001)], which remained significant [OR 1.83 (95%-CI:1.10-3.05), p = 0.020] after adjustment. Subjects with high-risk plaque had lower mean attenuation EAT (-88.1 vs. -86.9 HU, p = 0.008) and PAT (-106 vs. -103 HU, p < 0.001), though this was not significant in multivariable analysis.

CONCLUSIONS

Greater volumes of EAT are associated with high-risk plaque independent of risk factors, CACS and obstructive CAD. This observation supports possible local influence of EAT on development of high-risk coronary plaque.

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.

Efficacy study of olmesartan medoxomil on coronary atherosclerosis progression and epicardial adipose tissue volume reduction in patients with coronary atherosclerosis detected by coronary computed tomography angiography: study protocol for a randomized controlled trial

Background

Epicardial adipose tissue (EAT) is a newly discovered independent risk factor for coronary atherosclerosis. There is a scarcity of information on the reduction of EAT volume to reduce atherosclerosis risk. Coronary computed tomography angiography (CCTA) has emerged as a noninvasive imaging method for the analysis of coronary atherosclerosis and EAT volume. The purpose of this trial is to determine whether olmesartan medoxomil is effective at both treatment of coronary atherosclerosis progression and EAT volume reduction in patients with coronary atherosclerosis detected by CCTA.

Methods/design

This study is a prospective, single-center, open-label, randomized controlled clinical trial aimed at exploring the efficacy of olmesartan medoxomil on coronary atherosclerosis and EAT. A total of 194 patients with coronary stenosis greater than 30 % and less than 70 % detected by CCTA will be randomly divided into olmesartan medoxomil or conventional antihypertensive medication groups (1:1 ratio). The primary outcome measures include coronary atherosclerosis progression and EAT volume reduction, as detected by CCTA at 12 months. The secondary outcome measures include the levels of blood lipids, glucose, high-sensitivity C-reactive protein, IL-6, monocyte chemotactic protein 1, TNF-α, matrix metalloproteinase 9, NO, endothelin 1, adiponectin, and leptin at baseline and after 6 and 12 months.

Discussion

Treatments aimed at reducing EAT volume can eventually achieve an antiatherosclerotic effect. This is the first trial designed to explore the effect of olmesartan medoxomil on both coronary atherosclerosis progression and EAT volume reduction in patients with coronary atherosclerosis detected by CCTA.

Trial registration

ClinicalTrials.gov: NCT02360956.

Plaque disruption by coronary computed tomographic angiography in stable patients vs. acute coronary syndrome: a feasibility study

AIMS

This study was designed to determine whether coronary CT angiography (CTA) can detect features of plaque disruption in clinically stable patients and to compare lesion prevalence and features between stable patients and those with acute coronary syndrome (ACS).

METHODS

We retrospectively identified patients undergoing CTA, followed by invasive coronary angiography (ICA) within 60 days. Quantitative 3-vessel CTA lesion analysis was performed on all plaques ≥25% stenosis to assess total plaque volume, low attenuation plaque (LAP, <50 HU) volume, and remodelling index. Plaques were qualitatively assessed for CTA features of disruption, including ulceration and intra-plaque dye penetration (IDP). ICA was employed as a reference standard for disruption. A total of 145 (94 ACS and 51 stable) patients were identified. By CTA, plaque disruption was evident in 77.7% of ACS cases. Although more common among those with ACS, CTA also detected plaque disruption in 37.3% of clinically stable patients (P < 0.0001).

CONCLUSIONS

Clinically stable patients commonly manifest plaques with features of disruption as determined by CTA. Though the prevalence of plaque disruption is less than patients with ACS, these findings support the concept that some clinically stable patients may harbour 'silent' disrupted plaques. These findings may have implications for detection of 'at risk' plaques and patients.

A carotid extra-media thickness, PATIMA combined index and coronary artery disease: Comparison with well-established indexes of carotid artery and fat depots

BACKGROUND

The clinical utility of traditional cardiovascular (CV) risk factors to predict coronary artery disease (CAD) is insufficient and limited. Our aim was to evaluate the association between a novel ultrasound index of periarterial fat and adventitia (carotid extra-media thickness; EMT) and the severity of CAD and to compare this with well-known vascular indexes in patients with high and very high CV risk.

METHODS AND RESULTS

Four hundred twenty two patients scheduled for elective coronary angiography were included in the study (age: 61.3 ± 7.4 years; males 65%). Several clinical parameters of obesity were obtained as well as the following ultrasound indexes: carotid EMT and intima-media thickness (IMT), epicardial and pericardial fat thickness (EFT and PFT), and intra-abdominal fat thickness (IAT). These were then related to CAD severity in all individuals. Our study patients had a very high estimated CV risk (82%), and most (60%) fulfilled the MS criteria. Most individuals (71%) had CAD (≥50% stenosis) with equal rates of one, two, or three-vessel disease, and critical (≥70%) coronary stenosis was found in 40% of patients. Carotid EMT was significantly increased in patients with CAD (812 ± 116 vs 746 ± 131 μm) and patients with critical coronary stenosis (829 ± 119 vs 769 ± 122 μm) compared to the appropriate control groups. Moreover, carotid EMT was significantly associated with the severity of CAD. Carotid IMT and EFT (but not PFT and IAT) also revealed significant relations to the number of diseased vessels. Carotid EMT and the new proposed combined index (PATIMA = EMT/BMIx35 + IMT + EFTx60) were predictive for CAD (AUC: 686 ± 304 and 755 ± 260, sensitivity: 60 and 62%, specificity: 76 and 81% for 772 μm and 2015u).

CONCLUSIONS

We present the first study showing that the new vascular index (carotid EMT) and the proposed combined index PATIMA are associated with the presence and the severity of CAD.

The relationship between inflammation and neoangiogenesis of epicardial adipose tissue and coronary atherosclerosis based on computed tomography analysis

OBJECTIVE

Previous studies indicate that epicardial adipose tissue (EAT) biologically contributes to the progression of coronary atherosclerosis. We evaluated the relationship between EAT pathology, represented by inflammation and neoangiogenesis, and coronary atherosclerosis on computed tomography (CT) images.

METHODS

We performed CT examination in 45 patients scheduled for cardiac surgery (coronary artery bypass graft [CABG], n = 21; non-CABG, n = 24) to assess visceral adipose tissue (VAT) area, EAT volume, coronary calcium score (CCS), and presence of non-calcified coronary plaque (NCP) on CT angiography. Each patient was assessed with the numbers of CD68(+) individual macrophages and CD31(+) neovessels in six random high-power fields (400×) of EAT samples subsequently obtained during cardiac surgery.

RESULTS

In three groups based on CCS (mild, 0-100; moderate, 101-400; severe, >400), the moderate group had the most extensive macrophage infiltration (p = 0.0025) and neoangiogenesis (p = 0.0036) in EAT. The patients with NCP had more extensive macrophage infiltration (p = 0.010) and neoangiogenesis (p = 0.0043) in EAT than those without. On multivariate analysis adjusted for age, sex, CABG versus. non-CABG, VAT area, and EAT volume, moderate CCS and the presence of NCP showed significant correlations with increased macrophage infiltration (β = 0.65; p < 0.0001, and β = 0.49; p = 0.0089, respectively) and neoangiogenesis (β = 0.55; p = 0.0011, and β = 0.53; p = 0.012, respectively) in EAT.

CONCLUSION

Inflammation and neoangiogenesis in EAT independently correlate with moderate coronary calcification and presence of NCP, suggesting that these two factors may have a role in promoting coronary atherosclerosis.

Relationship between epicardial fat and quantitative coronary artery plaque progression: insights from computer tomography coronary angiography

Epicardial fat volume (EFV) has been suggested to promote atherosclerotic plaque development in coronary arteries, and has been correlated with both coronary stenosis and acute coronary events. Although associated with progression of coronary calcification burden, a relationship with progression of coronary atheroma volume has not been previously tested. We studied patients who had clinically indicated serial 320-row multi-detector computer tomography coronary angiography with a median 25-month interval. EFV was measured at baseline and follow-up. In vessels with coronary stenosis, quantitative analysis was performed to measure atherosclerotic plaque burden, volume and aggregate plaque volume at baseline and follow-up. The study comprised 64 patients (58.4 ± 12.2 years, 27 males, 192 vessels, 193 coronary segments). 79 (41 %) coronary segments had stenosis at baseline. Stenotic segments were associated with greater baseline EFV than those without coronary stenosis (117.4 ± 45.1 vs. 102.3 ± 51.6 cm(3), P = 0.046). 46 (24 %) coronary segments displayed either new plaque formation or progression of adjusted plaque burden at follow-up. These were associated with higher baseline EFV than segments without stenosis or those segments that had stenoses that did not progress (128.7 vs. 101.0 vs. 106.7 cm(3) respectively, P = 0.006). On multivariate analysis, baseline EFV was the only independent predictor of coronary atherosclerotic plaque progression or new development (P = 0.014). High baseline EFV is associated with the presence of coronary artery stenosis and plaque volume progression. Accumulation of EFV may be implicated in the evolution and progression of coronary atheroma.

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 adipose tissue: far more than a fat depot

Epicardial adipose tissue (EAT) refers to the fat depot that exists on the surface of the myocardium and is contained entirely beneath the pericardium, thus surrounding and in direct contact with the major coronary arteries and their branches. EAT is a biologically active organ that may play a role in the association between obesity and coronary artery disease (CAD). Given recent advances in non-invasive imaging modalities such a multidetector computed tomography (MDCT), EAT can be accurately measured and quantified. In this review, we focus on the evidence suggesting a role for EAT as a quantifiable risk marker in CAD, as well as describe the role EAT may play in the development and vulnerability of coronary artery plaque.

Epicardial and pericardial fat volume correlate with the severity of coronary artery stenosis

Introduction: Epicardial fat volume (EFV) has been reported to correlate with the severity of coronary artery disease (CAD). Pericardial fat volume (PFV) has recently been reported to be strongly associated with CAD severity and presence. We aimed to investigate the relationship between EFV and PFV with severity of coronary artery stenosis in patients undergoing 64-slice multi-slice computed tomography (MSCT).

Methods: One hundred and fifty one patients undergoing MSCT for suspected CAD were enrolled. Non-enhanced images were acquired to assess calcium score. Contrast enhanced images were used to quantify EFV, PFV and severity of luminal stenosis.

Results: Coronary artery stenosis was mild in 25 cases (16.6%), moderate in 58 cases (38.4%) and severe in 68 cases (45%). With increase in severity of coronary artery stenosis, there was significant increase in PFV, EFV as well as epicardial fat thickness in right ventricle free wall in basal view and epicardial fat thickness in left ventricle posterior wall in mid and apical view. There was significant linear correlation between PFV with coronary calcification score (r=0.18, P=0.02), between coronary artery stenosis severity and PFV (r=0.75, P<0.001), EFV (r=0.79, P<0.001), apical epicardial fat thickness in right ventricle free wall (r=0.29, P<0.001), Mid (r=0.28, P<0.001) and basal (r=0.23, P=0.004) epicardial fat thickness in left ventricle posterior wall.

Conclusion: PFV, EFV and regional epicardial thickness are correlated with severity of CAD and could be used as a reliable marker in predicting CAD severity.

Pericardial fat is associated with coronary artery calcification in non-dialysis dependent chronic kidney disease patients

Pericardial fat (PF) a component of visceral adipose tissue has been consistently related to coronary atherosclerosis in the general population. This study evaluated the association between PF and coronary artery calcification (CAC) in non-dialysis dependent chronic kidney disease (CKD) patients. This is a post-hoc cross sectional analysis of the baseline of a prospective cohort of 117 outward CKD patients without manifest coronary artery disease (age, 56.9±11.0 years, 64.1% males, 95.1% hypertensives, 25.2% diabetics, 15.5% ever smokers, CKD stage 2 to 5 with estimated glomerular filtration rate 36.8±18.1 ml/min). CAC scores, PF volume and abdominal visceral fat (AVF) areas were measured by computed tomography. The association of PF as a continuous variable with the presence of CAC was analyzed by multivariate logistic regression. CAC (calcium score >0) was present in 59.2% patients. Those presenting CAC were on average 10 years older, had a higher proportion of male gender (78.7% vs. 42.9%, p<0.001), and had higher values of waist circumference (95.9±10.7 vs. 90.2±13.2 cm, p = 0.02), PF volumes (224.8±107.6 vs. 139.1±85.0 cm³, p<0.01) and AVF areas (109.2±81.5 vs. 70.2±62.9 cm², p = 0.01). In the multivariate analysis, adjusting for age, gender, diabetes, smoking and, left ventricular concentric hypertrophy, PF was significantly associated with the presence of CAC (OR: 1.88 95% CI: 1.03–3.43 per standard deviation). PF remained associated with CAC even with additional adjustments for estimated glomerular filtration rate or serum phosphorus (OR: 1.85 95% CI: 1.00–3.42, p = 0.05). PF is independently associated with CAC in non-dialysis dependent CKD patients.

Impaired aortic elasticity and diastolic functions are associated with findings of coronary computed tomographic angiography

BACKGROUND

Coronary artery disease (CAD) is the leading cause of mortality and morbidity worldwide. Aortic elasticity and diastolic functions are helpful parameters in assessment of CAD. In this study we aimed to learn whether diastolic function and aortic elastic properties measured by echocardiography are associated with coronary calcium score (CACS), epicardial fat volume (EFV), and plaque area measured by coronary tomographic angiography.

MATERIAL AND METHODS

We enrolled 106 consecutive patients suspected of CAD undergoing coronary CTA and transthoracic echocardiography in this prospective study. Total CACS, plaque area, and EFV were calculated via CTA. Aortic stiffness index (ASI) and aortic distensibility (AD) were measured via echocardiography.

RESULTS

The patients with diastolic dysfunctions of any degree had significantly higher ASI, higher CACS, higher plaque area, and EFV. We found that as the ASI increases, the CACS and total coronary plaque area both increase, showing that there is a strong positive correlation between ASI, CACS, and total coronary plaque area. There was a significant correlation between ASI and EFV, but with a lower statistical value.

CONCLUSIONS

Aortic elasticity was correlated with CACS and plaque area. Diastolic dysfunction was observed more commonly among patients with higher CACS and EFV. Epicardial fat volume was not as strong as CACS in reflecting aortic elasticity.

Correlation between pericardial, mediastinal, and intrathoracic fat volumes with the presence and severity of coronary artery disease, metabolic syndrome, and cardiac risk factors

AIMS

To investigate the association of pericardial, mediastinal, and intrathoracic fat volumes with the presence and severity of coronary artery disease (CAD), metabolic syndrome (MS), and cardiac risk factors (CRFs).

METHODS AND RESULTS

Two hundred and sixteen consecutive patients who underwent cardiac magnetic resonance (CMR) imaging and had a coronary angiogram within 12 months of the CMR were studied. Fat volume was measured by drawing region of interest curves, from short-axis cine views from base to apex and from a four-chamber cine view. Pericardial fat, mediastinal fat, intrathoracic fat (addition of pericardial and mediastinal fat volumes), and fat ratio (pericardial fat/mediastinal fat) were analysed for their association with the presence and severity of CAD (determined based on the Duke CAD Jeopardy Score), MS, CRFs, and death or myocardial infarction on follow-up. Pericardial fat volume was significantly greater in patients with CAD when compared with those without CAD [38.3 ± 25.1 vs. 31.9 ± 21.4 cm(3) (P = 0.04)]. A correlation between the severity of CAD and fat volume was found for pericardial fat (β = 1, P < 0.01), mediastinal fat (β = 1, P = 0.03), intrathoracic fat (β = 2, P = 0.01), and fat ratio (β = 0.005, P = 0.01). These correlations persisted for all four thoracic fat measurements even after performing a stepwise linear regression analysis for relevant risk factors. Patients with MS had significantly greater mediastinal and intrathoracic fat volumes when compared with those without MS [126 ± 33.5 vs. 106 ± 30.1 cm(3) (P < 0.01) and 165 ± 54.9 vs. 140 ± 52 cm(3) (P < 0.01), respectively]. However, there was no significant difference in pericardial fat, mediastinal fat, intrathoracic fat, or fat ratio between patients with or without myocardial infarction during the follow-up [33.6 ± 22.1 vs. 35.7 ± 23.8 cm(3) (P = 0.67); 115 ± 26.2 vs. 114 ± 33.8 cm(3) (P = 0.84); 149 ± 44.7 vs. 150 ± 55.7 cm(3) (P = 0.95); and 0.27 ± 0.15 vs. 0.28 ± 0.14 (P = 0.70), respectively]. There was no significant difference in pericardial fat, mediastinal fat, intrathoracic fat, or fat ratio between patients who were alive compared with those who died during follow-up [36.6 ± 26.6 vs. 35.3 ± 23.2 cm(3) (P = 0.76); 114 ± 40.2 vs. 114 ± 31.4 cm(3) (P = 0.95); 150 ± 64.7 vs. 149 ± 52.5 cm(3) (P = 0.92); and 0.29 ± 0.15 vs. 0.28 ± 0.14 (P = 0.85), respectively].

CONCLUSION

Our study confirms an association between pericardial fat volume with the presence and severity of CAD. Furthermore, an association between mediastinal and intrathoracic fat volumes with MS was found.

[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.

Association of pericardial fat volume with coronary atherosclerotic disease assessed by CT angiography

OBJECTIVE

To investigate the association of pericardial fat volume (PFV) with coronary artery disease (CAD) in patients with intermediate pre-test probability of ischaemic heart disease assessed by coronary CT angiography.

METHODS

From a total of 115 consecutive Iraqi patients who underwent 64-multislice multidetector CT angiography examinations, only 74 patients (females, 38% and males, 68%) with a mean age of 54 ± 8 years were found to be eligible for statistical analysis. The patients were divided into two groups according to the median value of PFV (above and below 100 ml).

RESULTS

The median value of PFV in our study was 100 ml (range, 17-319 ml). A significant association was observed between high PFV and significant coronary artery stenosis (p = 0.005), between high PFV and significant left circumflex stenosis (p = 0.021) and between high PFV and the presence of coronary plaque (p = 0.005). Whereas there was no significant correlation between high PFV and coronary calcium score (p = 0.188), between high PFV and number of diseased coronary vessels (p > 0.3), and between high PFV and body weight and body mass index.

CONCLUSION

Increased PFV is strongly associated with the presence and severity of CAD.

ADVANCES IN KNOWLEDGE

Our study highlights the role of pericardial fat as an emerging biomarker in cardiovascular risk assessment and supports its association with the magnitude of CAD.

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.