Epicardial adipose tissue is an independent predictor of coronary atherosclerotic burden

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.

Epicardial Adipose Tissue and Cardiovascular Disease

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Epicardial Adipose Tissue Role as a Marker of Higher Vulnerability in Patients with Coronary Artery Disease

Background: Epicardial adipose tissue (EAT) has been recently identified as a major player in the development of the atherosclerotic process. This study aimed to investigate the role of EAT as a marker associated with a higher vulnerability of atheromatous coronary plaques in patients with acute myocardial infarction (AMI) as compared to patients with stable angina.

Material and methods: This analysis enrolled a total of 89 patients, 47 with stable angina (SA) and 42 with AMI, who underwent echocardiographic investigations and epicardial fat measurement in 2D-parasternal long axis view. The study lot was divided as follows: Group 1 included patients with prior AMI, and Group 2 included patients with SA.

Results: There were no significant differences between the two groups regarding cardiovascular risk factors, excepting smoking status, which was recorded more frequently in Group 1 as compared to Group 2 (36.17% vs. 11.63%, p = 0.02). The mean epicardial fat diameter was 9.12 ± 2.28 mm (95% CI: 8.45–9.79 mm) in Group 1 and 6.30 ± 2.03 mm (95% CI: 5.675–6.93 mm) in Group 2, the difference being highly significant statistically (p <0.0001). The mean value of left ventricular ejection fraction was significantly lower in patients with AMI (Group 1 – 47.60% ± 7.96 vs. Group 2 – 51.23% ± 9.05, p = 0.04). EAT thickness values showed a weak but significant positive correlation with the level of total cholesterol (r = −0.22, p = 0.03) and with the value of end-systolic left ventricle diameter (r = 0.33, = 0.001).

Conclusions: The increased thickness of EAT was associated with other serum- or image-based biomarkers of disease severity, such as the left ventricular ejection fraction, end-systolic diameter of the left ventricle, and total cholesterol. Our results indicate that EAT is significantly higher in patients with acute coronary syndrome, proving that EAT could serve as a marker of vulnerability in cardiovascular diseases.

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

Background

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

Methods

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

Results

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

Conclusion

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

Associations between epicardial adipose tissue, subclinical atherosclerosis and high-density lipoprotein composition in type 1 diabetes

Background

The pathophysiology of cardiovascular complications in people with type 1 diabetes (T1DM) remains unclear. An increase in epicardial adipose tissue (EAT) and alterations in the composition of high-density lipoprotein (HDL) are associated with coronary artery disease, but information on its relationship in T1DM is very limited. Our aim was to determine the association between EAT volume, subclinical atherosclerosis, and HDL composition in type 1 diabetes.

Methods

Seventy-two long-term patients with T1DM without clinical atherosclerosis were analyzed. EAT volume and subclinical atherosclerosis were measured using cardiac computed tomography angiography. EAT was adjusted according to body surface to obtain an EAT index (iEAT). HDL composition was determined.

Results

The mean iEAT was 40.47 ± 22.18 cc/m². The bivariate analysis showed positive associations of the iEAT with gender, age, hypertension, dyslipidemia, smoking, body mass index, waist circumference, insulin dose, and triglyceride (P < 0.05). The iEAT correlated positively with small HDL, increased content of apolipoprotein (apo)A-II and apoC-III, and decreased content of apoE and free cholesterol. Multiple linear regression showed that age, apoA-II content in HDL, and waist circumference were independently associated with the iEAT. Fifty percent of the patients presented subclinical atherosclerotic lesions. These patients had a higher iEAT, and their HDL contained less cholesterol and more apoA-II and lipoprotein-associated phospholipase A2 than patients without subclinical atherosclerosis.

Conclusion

Alterations in the composition of HDL in TIDM are associated with increased iEAT and the presence of subclinical atherosclerosis. We propose that these abnormalities of HDL composition could be useful to identify T1DM patients at highest cardiovascular risk.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0794-9) contains supplementary material, which is available to authorized users.

Association of Epicardial Adipose Tissue Volume and Total Coronary Plaque Burden in Patients with Coronary Artery Disease

The relationship between epicardial adipose tissue volume (EATV) and plaque vulnerability in non-culprit coronary lesions is not clearly understood.Fifty-four consecutive patients/158 lesions with suspected coronary artery disease underwent computed tomography (CT) and 40 MHz intravascular ultrasound imaging (iMap-IVUS) in cardiac catheterization. Cross-sectional CT slices were semiautomatically traced from base to apex of the heart. Using a 3D workstation, EATV was measured as the sum of fat areas (-190 to -30 Hounsfield units [HU]). All coronary vessels were imaged using iMap-IVUS before stenting to analyze coronary plaques as fibrotic, lipidic, necrotic, or calcified tissue.Mean EATV was 73.7 ± 24.6 (range: 30.2 to 131.8) mL. Patients were divided into two groups by mean EATV (group H: n = 27, EATV ≥ 73.7 mL; group L: n = 27, EATV < 73.7 mL). Total luminal volume, total vessel volume, and total plaque volume were significantly larger in group H. Fibrotic plaque and lipidic plaque volumes were also significantly larger in group H. There was a significant negative correlation between EATV and fibrous tissue (r = -0.31, P = 0.02) and a significant positive correlation between EATV and necrotic tissue (r = 0.37, P = 0.007). EATV was related to plaque with vulnerability in the right coronary artery (RCA) (r = 0.57, P = 0.04) and the left anterior descending artery (LAD) (r = 0.53, P = 0.02). In conclusion, increased EATV was associated with the total coronary plaque burden and composition, particularly in the RCA and LAD.

Fatty Acid Composition in Various Types of Cardiac Adipose Tissues and Its Relation to the Fatty Acid Content of Atrial Tissue

Diet, with its content of various types of fatty acids (FAs), is of great importance for cellular function. Adipose tissue (AT) serves as a storage for dietary FAs, but after appropriate activation it may also offer important biological properties, e.g., by releasing adipokines and cytokines to the surrounding milieu. Such effects may depend on the diet and type of FA involved. Similarly, the composition of FAs in the heart is also likely to be important for cardiac function. We investigated samples of epicardial adipose tissue (EAT), pericardial adipose tissue (PAT), subcutaneous adipose tissue (SCAT), and tissue from the right atrial appendage to compare the FA compositions in patients undergoing elective cardiac surgery. Minor differences among AT compartments were found, while the comparison of atrial tissue and EAT showed major differences in saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and n-3 and n-6 polyunsaturated fatty acids (PUFAs). These findings may be of importance for understanding biological availability, dietary effects, and the effects of FAs on the heart.

The Association of Epicardial Adipose Tissue and the Metabolic Syndrome in Community Participants in South Africa

Background:

We sought to determine the association of echocardiographically derived epicardial adipose tissue (EAT) thickness, which is a component of visceral adipose tissue, with the metabolic syndrome (MetS) in a cohort of randomly selected community participants.

Methods:

South African-Asian Indians aged 15–64 years were recruited over a 2-year period after informed consent was obtained. All participants who had complete measurements done for biochemistry and echocardiography (using established criteria), were dichotomized into the MetS or non-MetS groups defined according to the harmonized criteria.

Results:

Of the 953 (232 men and 721 women) participants recruited, 47.1% (448) were classified with the MetS. These participants had larger waist circumference and body mass index (P < 0.001), with larger LA volumes and diameter, thicker ventricular walls, higher left ventricular mass, relative wall thickness, and EAT (P < 0.001). There was a corresponding increase in EAT thickness with increasing number of MetS risk factors at the transition from 0 MetS factors to 1 (95% confidence interval [CI] −0.8; −0.2) and from 2 to 3 MetS factors (95% CI −0.9; −0.4). The AUC of the receiver operator curve was highest for triglycerides (0.845), followed by fasting plasma glucose (0.795) and then EAT (0.789). An EAT value of <3.6 mm predicted the presence of the MetS with a 78% sensitivity and 70% specificity. Using backward stepwise logistic regression, the most significant independent determinants of the MetS after adjusting for age, gender, and type 2 diabetes mellitus, was fasting plasma glucose (odds ratio [OR] = 1.2), triglycerides (OR = 7.1), and EAT (OR = 2.3).

Conclusion:

Although EAT is associated with the MetS, and can identify individuals at increased cardiometabolic risk, it has a limited additional role compared to current risk markers.

Change in Pericardial Fat Volume and Cardiovascular Risk Factors in a General Population of Japanese Men

BACKGROUND

Pericardial fat volume (PFV), defined as the volume of ectopic fat in and around the heart, is associated with the atherosclerotic process in coronary arteries. The magnitude of change in PFV over time and the factors affecting this change in a general population, however, have not been investigated.

METHODS AND RESULTS

Cardiac computed tomography (CT) was carried out at baseline and at follow-up in 623 Japanese men aged 40-79 years without a history of cardiovascular disease who were selected randomly in Kusatsu (Shiga, Japan). PFV was measured on cardiac CT in a qualified laboratory. Age, heart rate, triglycerides, and obesity measurements (weight, body mass index, and waist circumference) were significantly and positively associated with PFV at baseline. Over an average interval of 4.7 years, median PFV increased significantly from 64.1 cm3 (IQR, 47.2-90.0 cm3) to 73.6 cm3 (IQR, 53.3-98.1 cm3; P<0.001). Current smoking and heart rate were significantly and independently associated with changes in PFV (B=3.336, P<0.001 and B=6.409, P=0.003, respectively).

CONCLUSIONS

PFV increased significantly over time in a population-based observational study of Japanese men. PFV change was significantly and independently associated with smoking status and heart rate, suggesting that quitting smoking might help reduce PFV, which could be expected to decrease the risk of coronary artery disease.

Associations of cardiovascular fat radiodensity and vascular calcification in midlife women: The SWAN cardiovascular fat ancillary study

BACKGROUND AND AIMS

Fat radiodensity, measured via CT Hounsfield units (HU), is a potential marker of fat quality. We sought to determine the cross-sectional associations of total heart fat (TAT) and aortic perivascular fat (PVAT) radiodensity with cardiovascular risk factors, coronary artery calcification (CAC), and aortic calcification (AC) in midlife women.

METHODS

Fat radiodensity, CAC, and AC were quantified using CT scans. A total of 528 women (mean age: 50.9 ± 2.9 years; 37% Black) were included in analyses.

RESULTS

Women in the lowest TAT radiodensity tertile were more likely to have adverse cardiovascular risk factors. Independent of cardiovascular risk factors, women in the middle and high TAT radiodensity tertiles were less likely to have CAC (OR (95% CI): 0.32 (0.18, 0.59); 0.43 (0.24, 0.78), respectively) compared with women in the lowest TAT radiodensity tertile. Although adjusting for BMI attenuated the overall association, women in the middle TAT radiodensity tertile remained at significantly lower odds of CAC when compared to the low radiodensity tertile, 0.47 (0.24, 0.93), p=0.03. No significant associations were found for PVAT radiodensity and calcification measures in multivariable analysis.

CONCLUSIONS

Lower TAT radiodensity was associated with a less favorable cardiometabolic profile. Women with mid-range TAT radiodensity values had a lower odds of CAC presence, independent of CVD risk factors and BMI. More research is necessary to understand radiodensity as a surrogate marker of fat quality in midlife women.

Cardiovascular fat in women at midlife: effects of race, overall adiposity, and central adiposity. The SWAN Cardiovascular Fat Study

OBJECTIVES

Cardiovascular fat (CF) is associated with greater coronary heart disease (CHD) risk. Postmenopausal women have greater CF volumes than premenopausal women, and the association between specific CF depot volumes and CHD risk is more pronounced after menopause. Race, central adiposity, and visceral adiposity are important factors that could impact CF volumes. Whether racial differences in CF volumes and in their associations with central (visceral fat [VAT]) and general adiposity (body mass index [BMI]) exist in midlife women have not been addressed before.

METHODS

In all, 524 participants from the Study of Women's Health Across the Nation (mean age: 50.9 ± 2.9 years; 62% White and 38% Black) who had data on CF volumes (epicardial fat [EAT], paracardial fat [PAT], total heart fat, and aortic perivascular fat), VAT, and BMI were studied.

RESULTS

In models adjusted for age, study site, menopausal status, comorbid conditions, alcohol consumption, and physical activity, Black women had 19.8% less EAT, 24.5% less PAT, 20.4% less total heart fat, and 13.2% less perivascular fat than White women (all P < 0.001). These racial differences remained significant after additional adjustment for BMI or VAT. Race significantly modified associations between adiposity measures and CF volumes. Every 1-SD higher BMI was associated with 66.7% greater PAT volume in White compared with 42.4% greater PAT volume in Black women (P = 0.004), whereas every 1-SD higher VAT was associated with 32.3% greater EAT volume in Black compared with 25.3% greater EAT volume in White women (P = 0.039).

CONCLUSIONS

Racial differences were found in CF volumes and in their associations with adiposity measures among midlife women. Future research should determine how race-specific changes in CF volumes impact CHD risk in women.

Perivascular adipose tissue and coronary atherosclerosis

Adipose tissue (AT) is no longer viewed as a passive, energy-storing depot, and a growing body of evidence supports the concept that both quantitative and qualitative aspects of AT are critical in determining an individual's cardiometabolic risk profile. Among all AT sites, perivascular AT (PVAT) has emerged as a depot with a distinctive biological significance in cardiovascular disease given its close anatomical proximity to the vasculature. Recent studies have suggested the presence of complex, bidirectional paracrine and vasocrine signalling pathways between the vascular wall and its PVAT, with far-reaching implications in cardiovascular diagnostics and therapeutics. In this review, we first discuss the biological role of PVAT in both cardiovascular health and disease, highlighting its dual pro-atherogenic and anti-atherogenic roles, as well as potential therapeutic targets in cardiovascular disease. We then review current evidence and promising new modalities on the non-invasive imaging of epicardial AT and PVAT. Specifically, we present how our expanding knowledge on the bidirectional interplay between the vascular wall and its PVAT can be translated into novel clinical diagnostics tools to assess coronary inflammation. To this end, we present the example of a new CT-based method that tracks spatial changes in PVAT phenotype to extract information about the inflammatory status of the adjacent vasculature, highlighting the numerous diagnostic and therapeutic opportunities that arise from our increased understanding of PVAT biology.

Non-invasive markers of cardiovascular risk in patients with subclinical hypothyroidism: A systematic review and meta-analysis of 27 case control studies

It has been reported that subclinical hypothyroidism (SCH) is closely related to subclinical atherosclerosis. According to the impact of SCH on noninvasive markers of cardiovascular risk, we fulfilled a meta-analysis of included studies to provide an integrated overview. We searched electronic databases and included all relevant studies involving SCH and epicardial adipose tissue (EAT), carotid intima-media thickness (CIMT), pulse wave velocity (PWV), flow-mediated dilation (FMD) and glyceryl trinitrate-induced dilation (GNT- induced dilation). The result was calculated in a meta-analysis to assess the impact of SCH on these markers. A total of 27 studies were entered in the final analysis. Compared with euthyroid subjects, SCH patients exhibited a significantly increased CIMT (SMD: 0.369 mm; 95%CI: 0.038, 0.700; P = 0.029) and EAT (SMD: 1.167 mm; 95%CI: 0.869, 1.466; P = 0.000) and increased PWV (SMD: 3.574 m/s; 95%CI: 0.935, 6.213, P = 0.008). We also found significantly lower FMD (SMD: −1.525%, 95%CI: −2.156, −0.894, P = 0.000) and lower GNT-induced dilation (SMD: −0.384%, 95%CI: −0.625, −0.142, P = 0.002). Sensitivity analysis and subgroup analysis confirmed the above results. Our meta-analysis confirmed a significant association of SCH and cardiovascular risk with arterial wall thickening and stiffening and endothelial dysfunction. These findings will help to establish detailed cardiovascular prevention strategies for SCH patients.

Effects of dapagliflozin on human epicardial adipose tissue: modulation of insulin resistance, inflammatory chemokine production, and differentiation ability

AIMS

In patients with cardiovascular disease, epicardial adipose tissue (EAT) is characterized by insulin resistance, high pro-inflammatory chemokines, and low differentiation ability. As dapagliflozin reduces body fat and cardiovascular events in diabetic patients, we would like to know its effect on EAT and subcutaneous adipose tissue (SAT).

METHODS AND RESULTS

Adipose samples were obtained from 52 patients undergoing heart surgery. Sodium-glucose cotransporter 2 (SGLT2) expression was determined by real-time polymerase chain reaction (n = 20), western blot, and immunohistochemistry. Fat explants (n = 21) were treated with dapagliflozin and/or insulin and glucose transporters expression measured. Glucose, free fatty acid, and adipokine levels (by array) were measured in the EAT secretomes, which were then tested on human coronary endothelial cells using wound healing assays. Glucose uptake was also measured using the fluorescent glucose analogue (6NBDG) in differentiated stromal vascular cells (SVCs) from the fat pads (n = 11). Finally, dapagliflozin-induced adipocyte differentiation was assessed from the levels of fat droplets (AdipoRed staining) and of perilipin. SGLT2 was expressed in EAT. Dapagliflozin increased glucose uptake (20.95 ± 4.4 mg/dL vs. 12.97 ± 4.1 mg/dL; P < 0.001) and glucose transporter type 4 (2.09 ± 0.3 fold change; P < 0.01) in EAT. Moreover, dapagliflozin reduced the secretion levels of chemokines and benefited wound healing in endothelial cells (0.21 ± 0.05 vs. 0.38 ± 0.08 open wound; P < 0.05). Finally, chronic treatment with dapagliflozin improved the differentiation of SVC, confirmed by AdipoRed staining [539 ± 142 arbitrary units (a.u.) vs. 473 ± 136 a.u.; P < 0.01] and perilipin expression levels (121 ± 10 vs. 84 ± 11 a.u.).

CONCLUSIONS

Dapagliflozin increased glucose uptake, reduced the secretion of pro-inflammatory chemokines (with a beneficial effect on the healing of human coronary artery endothelial cells), and improved the differentiation of EAT cells. These results suggest a new protective pathway for this drug on EAT from patients with cardiovascular disease.

Leveraging the coronary calcium scan beyond the coronary calcium score

Non-contrast cardiac computed tomography in order to obtain the coronary artery calcium score has become an established diagnostic procedure in the clinical setting, and is commonly employed in clinical and population-based research. This state-of-the-art review paper highlights the potential gain in information that can be obtained from the non-contrast coronary calcium scans without any necessary modifications to the scan protocol. This includes markers of cardio-metabolic health, such as the amount of epicardial fat and liver fat, but also markers of general health including bone density and lung density. Finally, this paper addresses the importance of incidental findings and of radiation exposure accompanying imaging with non-contrast cardiac computed tomography. Despite the fact that coronary calcium scan protocols have been optimized for the visualization of coronary calcification in terms image quality and radiation exposure, it is important for radiologists, cardiologists and medical specialists in the field of preventive medicine to acknowledge that numerous additional markers of cardio-metabolic health and general health can be readily identified on a coronary calcium scan.

KEY POINTS

• The coronary artery calcium score substantially increased the use of cardiac CT. • Cardio-metabolic and general health markers may be derived without changes to the scan protocol. • Those include epicardial fat, aortic valve calcifications, liver fat, bone density, and lung density. • Clinicians must be aware of this potential additional yield from non-contrast cardiac CT.

Gene expression profiling reveals heterogeneity of perivascular adipose tissues surrounding coronary and internal thoracic arteries

The internal thoracic artery (ITA) that differs from coronary artery (CA), rarely develops atherosclerosis. Understanding the mechanism underlying such a difference will help to pave a new way to the prevention and treatment of the disease. We hypothesize herein that the difference in susceptibility to atherosclerosis between CA and ITA is attributable to the heterogeneity of perivascular adipose tissues (PVATs) surrounding these two kinds of arteries, i.e. PVAT-CA and PVAT-ITA. We isolated PVAT from eight patients of coronary heart disease (CHD) and four non-CHD patients. Gene expression patterns were analyzed by using Agilent whole gene expression profile chips. By comparison between PVAT-CA and PVAT-ITA, we identified 2053 differentially expressed genes, of which 1042 were up-regulated and 1011 were down-regulated, respectively, in CHD group. KEGG pathway and gene ontology (GO) analysis revealed that those differentially expressed genes related to inflammation, lipid metabolism and myocardial processes were particularly noted in the CHD group, but not in non-CHD. Several selected genes, including interleukin-1β (IL-1β), interleukin-6 (IL-6), Toll-like receptor 2 (TLR2), Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP), serum amyloid A2 (SAA2), and Leptin were validated by real-time PCR analysis. The results showed that the expression levels of IL-1β, IL-6, and Leptin were significantly higher in PVAT-CA than in PVAT-ITA (P = 0.016, 0.021, and 0.018) in CHD patients. Levels of TLR2, TIRAP, and SAA2 expression were also higher in PVAT-CA, however no significant difference was observed (P = 0.054, 0.092, and 0.058). In conclusion, our findings demonstrate differential gene expression patterns between PVAT-CA and PVAT-ITA, revealing a high heterogeneity in PVAT. Particularly, those genes related to inflammation, lipid metabolism and myocardial processes are differentially expressed in PVAT-CA and PVAT-ITA in CHD patients, suggesting an important role of PVAT in the development of coronary atherosclerosis.

Functional characterization of the Ucp1-associated oxidative phenotype of human epicardial adipose tissue

Brown fat presence and metabolic activity has been associated with lower body mass index, higher insulin sensitivity and better cardiometabolic profile in humans. We, and others, have previously reported the presence of Ucp1, a marker of brown adipocytes, in human epicardial adipose tissue (eAT). Characterization of the metabolic activity and associated physiological relevance of Ucp1 within eAT, however, is still awaited. Here, we validate the presence of Ucp1 within human eAT and its ‘beige’ nature. Using in-vitro analytical approaches, we further characterize its thermogenic potential and demonstrate that human eAT is capable of undergoing enhanced uncoupling respiration upon stimulation. Direct biopsy gene expression analysis reveals a negative association between thermogenic markers and oxidative stress-related genes in this depot. Consistently, isoproterenol (Iso) stimulation of eAT leads to a downregulation of secreted proteins included in the GO terms ‘cell redox homeostasis’ and ‘protein folding’. In addition, cardiac endothelial cells exhibit a downregulation in the expression of adhesion markers upon treatment with Iso-stimulated eAT derived conditioned media. Overall, these observations suggest that Ucp1- associated metabolic activity plays a significant role in local tissue homeostasis within eAT and can plausibly alter its communication with neighboring cells of the cardiovascular system.

Morphometric measurements of systemic atherosclerosis and visceral fat: Evidence from an autopsy study

Background

Morphometric measurements of systemic atherosclerosis and direct quantification of visceral fat are only possible using materials from autopsy studies. However, the few autopsy studies that have investigated the association of visceral fat with atherosclerosis had small sample sizes and focused on coronary arteries of young or middle-aged White subjects. We aimed to investigate the association of pericardial fat (PF) and abdominal visceral fat (AVF) with atherosclerosis in the aorta, coronary, carotid, and cerebral arteries in a large autopsy study.

Materials and methods

We evaluated deceased subjects aged 30 years or above. We dissected and weighted the PF and the AVF and evaluated the atherosclerotic burden in the aorta, as well as the carotid, coronary, and cerebral arteries using morphometric measurements. We also investigated the interaction of PF and AVF with age regarding the atherosclerotic burden.

Results

The mean age of the 240 included subjects was 64.8±15.3 years, and 63% was male. Greater PF was associated with a higher degree of aortic atherosclerosis after adjusting for confounding variables (coefficient = 4.39, 95% CI = 0.83; 7.94, p = 0.02). Greater AVF was associated with a higher coronary stenosis index (coefficient = 1.49, 95% CI = 0.15; 2.83, p = 0.03) and a greater number of coronary plaques (coefficient = 0.71, 95% CI = 0.24; 1.19, p = 0.003). We did not find an association of PF or AVF with carotid or cerebral atherosclerotic burden. We found a significant interaction of AVF (coefficient = -0.08; 95% CI = -0.14; -0.02, p = 0.009) and PF (coefficient = -0.87, 95% CI = -1.70; -0.04, p = 0.04) with age regarding carotid artery atherosclerotic burden.

Conclusions

Greater AVF was associated with greater atherosclerotic burden and extent in coronary arteries, while greater PF correlated with a higher degree of atherosclerosis in the aorta.

Gender differences in the association of epicardial adipose tissue and coronary artery calcification: EPICHEART study: EAT and coronary calcification by gender

BACKGROUND

The association of epicardial adipose tissue (EAT) and coronary artery calcification (CAC) seems to differ by gender. However, few studies have controlled for body size, and the ideal method for body size indexing has not been explored.

OBJECTIVES

To analyse the effect of gender related-body size and-body fat differences on the association of EAT with CAC.

METHODS

This was a prospective cohort of 371 severe aortic stenosis patients (77±8.5year-old, 51% females) referred to cardiac surgery. Agatston calcium score, EAT volume and visceral abdominal fat (VAF) were obtained by computed tomography. Body composition was determined using bioelectrical impedance analysis. Body weight and height were measured to derive body mass index (BMI), body surface area (BSA), and body surface index (BSI). EAT volume was normalized for BSA, weight and height.

RESULTS

Median CAC score was higher in men (887; IQR: 2010) than in women (279: IQR: 145) (p<0.01). Similarly, men had higher volume of EAT than women (137±65.6 vs. 106±65.6mL, p<0.01), even when BSA- or height-indexed, but not if weight-indexed. EAT volume was associated with CAC adjusting for adiposity (BMI or BSI and VAF, or fat mass), but not with further adjustment for gender. In a stratified analysis, absolute- and indexed-volumes of EAT were independently associated with CAC in men while no association was found in women (gender-interaction p<0.05).

CONCLUSIONS

In these high-risk patients, we demonstrated that EAT was associated with CAC score irrespective of body size, body fat and cardiovascular risk factors in men but not in women.

Association between echocardiographic epicardial fat thickness and circulating endothelial progenitor cell level in patients with stable angina pectoris

BACKGROUND

Epicardial adipose tissue is associated with coronary artery disease (CAD). Circulating endothelial progenitor cell (EPC) level represents a marker of endothelial dysfunction and vascular health. However, the relationship between epicardial fat and circulating EPC remains unknown. This study aimed to investigate association between echocardiographic epicardial fat thickness (EFT) and circulating EPC level.

HYPOTHESIS

Epicardial fat causes inflammation and contributes to progression of CAD.

METHODS

We enrolled 213 consecutive patients with stable angina, and EFT was determined by echocardiography. Quantification of EPC markers (defined as CD34 + , CD34 + KDR + , CD34 + KDR + CD133 + cells) in peripheral blood samples was used to measure circulating EPCs. All patients were divided into 3 tertiles according to EFT levels: group 1, low tertile of EFT; group 2, middle tertile of EFT; and group 3, high tertile of EFT.

RESULTS

Among the 3 groups, CAD disease severity determined by SXscore was negatively correlated with EFT, but the difference did not reach statistical significance (P = 0.066). Additionally, patients in the high and middle tertiles of EFT had higher circulating EPC levels than did those in the low tertile of EFT (P = 0.001 and P < 0.001, respectively). In multivariate analysis, EPC level was significantly associated with echocardiographic EFT (standardized β = -0.233, P = 0.001), independent of multiple covariates.

CONCLUSIONS

Epicardial adipose tissue is associated with circulating EPC levels. There was a trend between epicardial fat and severity of CAD, though analysis did not reach statistical significance, and this may be attributed to the interaction between several risk factors of CAD.

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.

Association of ectopic fat with abdominal aorto-illiac and coronary artery calcification in african ancestry men

BACKGROUND AND AIMS

There is strong evidence that fat accumulating in non-adipose sites, "ectopic fat", is associated with cardiovascular disease (CVD), including vascular calcification. Most previous studies of this association have assessed only a single ectopic fat depot. Therefore, our aim was to assess the association of total, regional, and ectopic fat with abdominal aorto-illiac calcification (AAC) and coronary artery calcification (CAC) in 798 African ancestry men.

METHODS

Participants (mean age 62) were from the Tobago Bone Health Study cohort. Adiposity was assessed via clinical examination, dual x-ray absorptiometry, and computed tomography (CT). Ectopic fat depots included: abdominal visceral adipose tissue (VAT), liver attenuation, and calf intermuscular adipose tissue (IMAT). Vascular calcification was assessed by CT and quantified as present versus absent. Associations were tested using multiple logistic regression adjusted for traditional cardiovascular risk factors. Models of ectopic fat were additionally adjusted for total body fat and standing height.

RESULTS

All adiposity measures, except VAT, were associated with AAC. Lower liver attenuation or greater calf IMAT was associated with 1.2-1.3-fold increased odds of AAC (p < 0.03 for both), though calf IMAT was a stronger predictor than liver attenuation (p < 0.001) when entered in a single model. No ectopic fat measure was associated with CAC.

CONCLUSIONS

Greater adiposity in the skeletal muscle and liver, but not in the visceral compartment, was associated with increased odds of AAC in African ancestry men. These results highlight the potential importance of both quantity and location of adiposity accumulation throughout the body.

Original research. The Assessment of Epicardial Adipose Tissue in Acute Coronary Syndrome Patients. A Systematic Review

Background: This systematic review seeks to evaluate the role of epicardial adipose tissue (EAT), quantified either by thickness, assessed by transthoracic echocardiography, or by volume, assessed by cardiac computed tomography (CT), in the follow-up of patients with acute coronary syndromes (ACS). Method: One-hundred forty-four articles were screened, from which 56 were reviewed in full-text. From those, 47 studies were excluded for the following reasons: they did not meet the inclusion criteria; they were either reviews or meta-analyses; the study cohorts included only stable coronary artery disease patients; they did not state a clear and concise study design, endpoints, or follow-up. The final draft included nine studies for systematic evaluation. Results: Of the 2,306 patients included in the review, 170 underwent cardiac CT while the remaining 2,136 underwent transthoracic echocardiography for the measurement of EAT. The analysis found that the EAT thickness was significantly associated with major adverse cardiovascular events (MACE) rates during hospitalization (OR: -1.3, 95% CI: 1.05-1.62, p = 0.020) and at three years (HR: 1.524, 95% CI: 1.0-2.2, p = 0.038). The included studies found that EAT was correlated with the following clinical and angiographic risk scores for ACS: GRACE (r = 0.438, p <0.001), TIMI risk score (r = 0.363, p = 0.001), SYNTAX score (r = 0.690, p <0.0001; r = 0.610, p <0.01), and Gensini score (r = 0.438, p = 0.001). There was an inverse correlation between ST-segment resolution of <70% after revascularization and EAT (r = −0.414, p = 0.01), and the myocardial blush grade (r = −0.549, p <0.001). The EF aggregation ranged between 2.65 mm and 4.7 mm within the included studies. Conclusions: EAT, evaluated either by echocardiography or cardiac CT, correlates with the severity of coronary lesions, with the clinical and angiographic risk scores for acute coronary syndromes, with indicators for coronary reperfusion, and with short- and long-term MACE rates. Further studies are required to fully elucidate the role of this extensively studied but still novel cardiovascular biomarker as part of a risk prediction tool.

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.

Frailty Syndrome: Visceral Adipose Tissue and Frailty in Patients with Symptomatic Severe Aortic Stenosis

BACKGROUND/OBJECTIVES

In patients with severe aortic stenosis (AS), frailty is a clinically relevant measure of increased vulnerability that should be included in the preoperative risk assessment. Bioelectrical impedance analysis (BIA) derived phase angle (PA) reflects cell membrane integrity and function. Few studies are available on the relative contribution of adiposity distribution on frailty, and about the influences of frailty and visceral obesity in PA value. Therefore, we aimed to evaluate associations among frailty, visceral fat depots and PA in patients with symptomatic severe AS.

METHODS

In a cohort of patients with symptomatic severe AS and preserved ejection fraction, we examined the associations between frailty, visceral fat depots and bioelectrical impedance analysis (BIA) derived phase angle (PA); and between visceral fat and PA. Frailty was defined according the Fried et al. scale criteria and the body fat distribution was determined by multidetector computed tomography and by BIA.

RESULTS

Of the fifty-five included patients, 26 were frail (47%). Adjusting for age and gender, frailty was associated with indexed epicardial adipose tissue volume (EATVi) (the odds of frailty increased 4.1-fold per additional 100 cm3/m2 of EAT [95% confidence interval (CI) of 1.03 to 16.40, p=0.04] and with PA (OR of 0.50, 95% CI, 0.26 to 0.97, p=0.04), but not with body mass index (BMI), waist circumference (WC), indexed total, visceral and subcutaneous abdominal fat areas (TAFAi, VAFAi and SAFAi) nor with indexed mediastinal adipose tissue volume (MATVi). In an age and gender adjusted linear model, PA was inversely correlated with EATVi (β=-0.008, 95% CI, -0.016 to -0.001, p=0.03), but not with BMI, WC, nor with MATVi, VAFAi, SAFAi and TAFAi.

CONCLUSIONS

In patients with symptomatic severe AS, EATVi is associated with frailty, independently of age and gender, but not with MAFVi or VAFAi. Moreover, frailty and EATVi are associated with impaired cell membrane integrity and function assessed by PA.

The Ratio Between Visceral and Subcutaneous Abdominal Fat Assessed by Computed Tomography Is an Independent Predictor of Mortality and Cardiac Events

INTRODUCTION AND OBJECTIVES

Obesity is an important cardiovascular risk factor and the location of fat deposits seems to be an important determinant of its metabolic impact. Visceral adipose tissue (VAT) exerts a harmful effect on metabolic homeostasis, but few longitudinal studies have evaluated the prognostic impact of the ratio of VAT to subcutaneous adipose tissue (SAT). This study aimed to evaluate whether the VAT/SAT ratio was associated with all-cause mortality and cardiac events.

METHODS

Registry-based retrospective cohort study. Eligible patients consisted of those without known heart disease referred to cardiac computed tomography (CT) angiography to evaluate suspected coronary artery disease (CAD). We included all patients with available information on VAT and SAT areas and coronary artery calcium (CAC) score. We assessed the combined endpoint of all-cause mortality, myocardial infarction or revascularization procedure at least 1 month after cardiac CT.

RESULTS

The final population consisted of 713 participants (61% male; mean age, 57.7±10.2 years) followed up for a median of 1.3 years. The combined endpoint occurred in 66 patients; these patients showed a higher VAT/SAT ratio (1.06±0.74 vs 0.80±0.52, P=.0001). The VAT/SAT ratio was an independent predictor of death and cardiac events (HR = 1.43; 95%CI, 1.03-1.99), irrespective of cardiovascular risk factors, CAC, and the presence of CAD.

CONCLUSIONS

The ratio between abdominal VAT/SAT was an independent predictor of death and coronary events, irrespective of cardiovascular risk factors, CAC, and the presence of CAD. This ratio is a CT-derived metric that may help to better identify patients with increased risk of death or cardiac events.

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.

Epicardial Adipose Tissue Volume and Left Ventricular Myocardial Function Using 3-Dimensional Speckle Tracking Echocardiography

BACKGROUND

Although epicardial adipose tissue (EAT) volume is associated with increased incidence of coronary artery disease (CAD), its role in myocardial systolic dysfunction is unclear. The present study aimed to identify independent determinants of EAT volume in patients without obstructive CAD, and to evaluate the association between EAT volume (vs other measures of obesity) and myocardial systolic strain analysis.

METHODS

We prospectively recruited 130 patients without obstructive CAD on contrast-enhanced cardiac computed tomography imaging and normal left ventricular ejection fraction on 3-dimensional (3D) echocardiography. EAT volume was quantified from cardiac computed tomography imaging, and 3D multidirectional (longitudinal, circumferential, radial, and area) strain were measured.

RESULTS

The mean EAT volume was 97.5 ± 43.7 cm³. In multivariable analysis, measures of obesity (body mass index [P = 0.007] and waist/hip ratio [P = 0.001]) were independently associated with larger EAT volume. EAT volume was correlated with 3D global longitudinal (r = 0.601; P < 0.001), circumferential (r = 0.375; P < 0.001), radial (r = -0.546; P < 0.001), and area (r = 0.558; P < 0.001) strain. In multivariable analyses, epicardial fat volume was the strongest predictor of 3D global longitudinal (standardized β = 0.512; P < 0.001), circumferential (standardized β = 0.242; P = 0.006), radial (standardized β = -0.422; P < 0.001), and area (standardized β = 0.428; P < 0.001) strain. In contrast, other measures of obesity including body mass index and waist/hip ratio were not independent determinants of 3D multidirectional global strain (all P > 0.05).

CONCLUSIONS

EAT volume is independently associated with impaired myocardial systolic function despite preserved 3D left ventricular ejection fraction and absence of obstructive CAD, and might play a significant role in the pathophysiology of diabetic, obesity, and metabolic heart disease.

Epicardial Adipose Tissue Is Associated with Plaque Burden and Composition and Provides Incremental Value for the Prediction of Cardiac Outcome. A Clinical Cardiac Computed Tomography Angiography Study

Objectives

We sought to investigate the association of epicardial adipose tissue (eCAT) volume with plaque burden, circulating biomarkers and cardiac outcomes in patients with intermediate risk for coronary artery disease (CAD).

Methods and Results

177 consecutive outpatients at intermediate risk for CAD and completed biomarker analysis including high-sensitive Troponin T (hs-TnT) and hs-CRP underwent 256-slice cardiac computed tomography angiography (CCTA) between June 2008 and October 2011. Patients with lumen narrowing ≥50% exhibited significantly higher eCAT volume than patients without any CAD or lumen narrowing <50% (median (interquartile range, IQR): 108 (73–167) cm³ vs. 119 (82–196) cm³, p = 0.04). Multivariate regression analysis demonstrated an independent association eCAT volume with plaque burden by number of lesions (R² = 0.22, r_partial = 0.29, p = 0.026) and CAD severity by lumen narrowing (R² = 0.22, r_partial = 0.23, p = 0.038) after adjustment for age, diabetes mellitus, hyperlidipemia, body-mass-index (BMI), hs-CRP and hs-TnT. Univariate Cox proportional hazards regression analysis identified a significant association for both increased eCAT volume and maximal lumen narrowing with all cardiac events. Multivariate Cox proportional hazards regression analysis revealed an independent association of increased eCAT volume with all cardiac events after adjustment for age, >3 risk factors, presence of CAD, hs-CRP and hs-TnT.

Conclusion

Epicardial adipose tissue volume is independently associated with plaque burden and maximum luminal narrowing by CCTA and may serve as an independent predictor for cardiac outcomes in patients at intermediate risk for CAD.

Glucose and Inflammatory Cells Decrease Adiponectin in Epicardial Adipose Tissue Cells: Paracrine Consequences on Vascular Endothelium

Epicardial adipose tissue (EAT) is a source of energy for heart that expresses the insulin-sensitizer, anti-inflammatory and anti-atherogenic protein, adiponectin. But, in coronary artery disease, adiponectin production declines. Our objective was to determine its regulation by glucose and inflammation in stromal cells from EAT and subcutaneous adipose tissue (SAT) and its paracrine effect on endothelial cells. Stromal cells of EAT and SAT were obtained from patients who underwent cardiac surgery. Adipogenesis was induced at 117, 200, or 295 mg/dl glucose, with or without macrophage-conditioned medium (MCM). Expression of adiponectin, GLUT-4 and the insulin receptor was analyzed by real-time PCR. The paracrine effect of stromal cells was determined in co-cultures with endothelial cells, by exposing them to high glucose and/or MCM, and, additionally, to leukocyte-conditioned medium from patients with myocardial infarction. The endothelial response was determined by analyzing vascular adhesion molecule expression. Our results showed a U-shaped dose-response curve of glucose on adiponectin in EAT, but not in SAT stromal cells. Conversely, MCM reduced the adipogenesis-induced adiponectin expression of EAT stromal cells. The presence of EAT stromal increased the inflammatory molecules of endothelial cells. This deleterious effect was emphasized in the presence of inflammatory cell-conditioned medium from patients with myocardial infarction. Thus, high glucose and inflammatory cells reduced adipogenesis-induced adiponectin expression of EAT stromal cells, which induced an inflammatory paracrine process in endothelial cells. This inflammatory effect was lower in presence of mature adipocytes, producers of adiponectin. These results contribute to understanding the role of EAT dysfunction on coronary atherosclerosis progression.

Quantification of epicardial adipose tissue in coronary calcium score and CT coronary angiography image data sets: comparison of attenuation values, thickness and volumes

OBJECTIVE

The aim of the study was to compare epicardial adipose tissue (EAT) characteristics assessed with coronary calcium score (CS) and CT coronary angiography (CTCA) image data sets.

METHODS

In 76 patients (mean age 59 ± 13 years) who underwent CS and CTCA owing to suspected coronary artery disease (CAD), EAT was quantified in terms of density (Hounsfield units), thickness and volume. The EAT volume was extracted with a semi-automatic software.

RESULTS

A moderate correlation was found between EAT density in CS and CTCA image data sets (-100 ± 19 HU vs -70 ± 24 HU; p < 0.05, r = 0.55). The distribution of EAT was not symmetrical with a maximal thickness at the right atrioventricular groove (14.2 ± 5.3 mm in CS, 15.7 ± 5 mm in CTCA; p > 0.05, r = 0.76). The EAT volume resulted as 122 ± 50 cm(3) in CS and 86 ± 40 cm(3) in CTCA (Δ = 30%, p < 0.05, r = 0.92). After adjustment for post-contrast EAT attenuation difference (Δ = 30 HU), the volume was 101 ± 47 cm(3) (Δ = 17%, p < 0.05, r = 0.92). Based on EAT volume median values, no differences were found between groups with smaller and larger volumes in terms of Agatston score and CAD severity.

CONCLUSION

CS and CTCA image data sets may be equally employed for EAT assessment; however, an underestimation of volume is found with the latter acquisition even after post-contrast attenuation adjustment.

ADVANCES IN KNOWLEDGE

EAT may be measured by processing either the CS or CTCA image data sets.

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.

Transcardial gradient of adiponectin, interleukin-6 and tumor necrosis factor-α in overweight coronary artery disease patients

BACKGROUND

Obesity is associated with coronary artery disease (CAD), where epicardial adipose tissue (EAT) express proatherogenic cytokines (i.e., interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)) and decreases production of beneficial adiponectin. Studies on endocrine role of EAT are mostly based on assessing cytokines' mRNAs, whereas cytokine blood levels might not readily correlate. In order to get better insight into the endocrine role of thickened EAT in CAD, we assessed transcardial gradient of adiponectin, IL-6 and TNF-α.

METHODS

We assessed anthropometric and ultrasound measures in cohort of fifty nondiabetic subjects (21 CAD and 29 non-CAD). Blood sampled from aortic root and coronary sinus was assayed for adiponectin, IL-6 and TNF-α, using ELISA.

RESULTS

Except thicker EAT in CAD subjects, anthropometric measures were similar (overweight), with higher adiponectin in coronary sinus than in aortic root (p<0.001) in both groups. CAD subjects had lower adiponectin in aortic root (p<0.001) and higher levels of TNF-α in coronary sinus than in aortic root (p=0.05). EAT thickness positively correlated with hip circumference (p=0.038) and negatively correlated with adiponectin levels (for both p<0.05).

CONCLUSIONS

Transcardial gradient of adiponectin in non-CAD and CAD overweight subjects was similar, while latter had lower systemic adiponectin level and thicker EAT. EAT with thickening reaches the threshold level of near-maximal down-regulation of adiponectin and its further thickening is not associated with continued decrease of adiponectin production. In CAD patients levels of TNF-α were higher, but IL-6 were not, and these cytokines might be flush out by lymphatic route.

Thermogenic potential and physiological relevance of human epicardial adipose tissue

Epicardial adipose tissue is a unique fat depot around the heart that shares a close anatomic proximity and vascular supply with the myocardium and coronary arteries. Its accumulation around the heart, measured using various imaging modalities, has been associated with the onset and progression of coronary artery disease in humans. Epicardial adipose tissue is also the only fat depot around the heart that is known to express uncoupling protein 1 at both mRNA and protein levels in the detectable range. Recent advances have further indicated that human epicardial fat exhibits beige fat-like features. Here we provide an overview of the physiological and pathophysiological relevance of human epicardial fat, and further discuss whether its thermogenic properties can serve as a target for the therapeutic management of coronary heart disease in humans.

Effects of restoration of the euthyroid state on epicardial adipose tissue and carotid intima media thickness in subclinical hypothyroid patients

Epicardial adipose tissue (EAT) thickness is a novel cardiovascular risk indicator, whereas carotid intima media thickness (CIMT) is a known marker of subclinical atherosclerosis. The aim of this study was to measure EAT thickness and CIMT in subclinical hypothyroid (SCH) patients and to determine the effect of restoration of the euthyroid state on these variables. The study included 43 patients with SCH (mean age: 35.2±10.7 years; F-M ratio: 42:1) and 30 healthy controls (mean age: 34.5±8.2 years; F-M ratio: 25:5). EAT thickness and CIMT were measured via conventional echocardiography and ultrasonography. Among the patients, 23 were followed up with L-thyroxine replacement until restoration of the euthyroid state and re-evaluated 6 months after baseline. Basal EAT thickness was higher in the SCH patients than in the controls (3.2±0.7 vs. 2.3±0.3 mm-p<0.0001), whereas CIMT was similar in both groups (0.50±0.09 vs. 0.48±0.04 mm). EAT thickness was correlated with CIMT in the patient group (r=0.39, p=0.01), but this correlation was not evident based on multivariate analysis when corrected for age and body mass index (r2=0.47 and p=0.0001 for the model). In the follow-up patient subgroup, both EAT thickness and CIMT decreased significantly following L-thyroxine treatment, when normal TSH levels were attained (3.4±0.7 vs. 2.3±0.5 mm-p=0.007 and 0.51±0.09 vs. 0.46±0.07 mm-p=0.01, respectively). EAT thickness was greater in the SCH patients than in controls, whereas CIMT was similar in both groups. Restoration of the euthyroid state with L-thyroxine treatment was associated with significant decreases in EAT thickness and CIMT in the group of patients that received L-thyroxine treatment and, as such, might reduce the cardiovascular risk associated with SCH.