Relation of epicardial fat to central aortic pressure and left ventricular diastolic function in patients with known or suspected coronary artery disease

Association of epicardial adipose tissue volume with heart weight in post-mortem cases

Epicardial adipose tissue (EAT) deposition has been long associated with heart weight. However, recent research has failed to replicate this association. We aimed to determine the association of EAT volume with heart weight in post-mortem cases and identify potential confounding variables. EAT volume derived from post-mortem computed tomography (PMCT) and heart weight were measured in post-mortem cases (N = 87, age: 56 ± 16 years, 28% female). Cases with hypertrophied heart weights (N = 44) were determined from reference tables. Univariable associations were tested using Spearman correlation and simple linear regression. Independence was determined with stepwise regression. In the total cohort, EAT volume (median 66 ± 45 cm3) was positively associated with heart weight (median 435 ± 132 g) at the univariable level (r = 0.6, P < 0.0001) and after adjustment for age, female sex, and various body size metrics (R2 adjusted = 0.41-0.57). Median EAT volume was 1.9-fold greater in cases with hypertrophic hearts (P < 0.0001) but with considerably greater variability, especially in cases with extreme EAT volume or heart weight. As such, EAT volume was not associated with heart weight in hypertrophic cases, while a robust independent association was found in non-hypertrophic cases (R2 adjusted = 0.62-0.86). EAT mass estimated from EAT volume found that EAT comprised approximately 13% of overall heart mass in the total cases. This was significantly greater in cases with hypertrophy (median 15.5%; range, 3.6-36.6%) relative to non-hypertrophied cases (12.5%, 3.3-24.3%) (P = 0.04). EAT volume is independently and positively associated with heart weight in post-mortem cases. Excessive heart weight significantly confounded this association.

Association of epicardial and intramyocardial fat with ventricular arrhythmias

BACKGROUND

Among patients with ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM), myocardial fibrosis is associated with an increased risk for ventricular arrhythmia (VA). Growing evidence suggests that myocardial fat contributes to ventricular arrhythmogenesis. However, little is known about the volume and distribution of epicardial adipose tissue and intramyocardial fat and their relationship with VAs.

OBJECTIVE

The purpose of this study was to assess the association of contrast-enhanced computed tomography (CE-CT)-derived left ventricular (LV) tissue heterogeneity, epicardial adipose tissue volume, and intramyocardial fat volume with the risk of VA in ICM and NICM patients.

METHODS

Patients enrolled in the PROSE-ICD registry who underwent CE-CT were included. Intramyocardial fat volume (voxels between -180 and -5 Hounsfield units [HU]), epicardial adipose tissue volume (between -200 and -50 HU), and LV tissue heterogeneity were calculated. The primary endpoint was appropriate ICD shocks or sudden arrhythmic death.

RESULTS

Among 98 patients (47 ICM, 51 NICM), LV tissue heterogeneity was associated with VA (odds ratio [OR] 1.10; P = .01), particularly in the ICM cohort. In the NICM subgroup, epicardial adipose tissue and intramyocardial fat volume were associated with VA (OR 1.11, P = .01; and OR = 1.21, P = .01, respectively) but not in the ICM patients (OR 0.92, P =.22; and OR = 0.96, P =.19, respectively).

CONCLUSION

In ICM patients, increased fat distribution heterogeneity is associated with VA. In NICM patients, an increased volume of intramyocardial fat and epicardial adipose tissue is associated with a higher risk for VA. Our findings suggest that fat's contribution to VAs depends on the underlying substrate.

Impact of Sex and Menopausal Status on the Association Between Epicardial Adipose Tissue and Diastolic Function in Patients with Type 2 Diabetes Mellitus

OBJECTIVE

To evaluate the impact of sex and menopausal status on the association between the epicardial adipose tissue (EAT) volume and diastolic function in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

A total of 542 consecutive patients with T2DM were retrospectively included in this study. All patients underwent cardiac computed tomographic as well as echocardiography. To assess the independent association of EAT and diastolic function parameters, we performed a multivariate linear regression analysis.

RESULTS

The median EAT volume was 113.11 cm³ (interquartile range (IQR): 88.38, 148.03), and EAT volume was higher in men than in women (p < 0.05). We also discovered that EAT volume was significantly associated with diastolic function in both sexes after adjusting for risk factors (p < 0.05). Concerning menopausal status, EAT volume was higher in postmenopausal women than premenopausal women and was independently associated with the diastolic function only in postmenopausal women.

CONCLUSION

In patients with T2DM, EAT is independently associated with diastolic function in the male population and a portion of the female population. In contrast to premenopausal women, EAT volume is only significantly correlated with diastolic function in postmenopausal women.

Magnetic Resonance Imaging Quantification of Accumulation of Epicardial Adipose Tissue Adds Independent Risks for Diastolic Dysfunction among Dialysis Patients

BACKGROUND

Diastolic dysfunction (DD) frequently occurs in dialysis patients; however, the risk factors of DD remain to be further explored in such a population. Epicardial adipose tissue (EAT) volume has proven to be an independent clinical risk factor for multiple cardiac disorders.

PURPOSE

To assess whether EAT volume is an independent risk factor for DD in dialysis patients.

STUDY TYPE

Case-control study.

POPULATION

A total of 113 patients (mean age: 54.5 ± 14.4 years; 41 women) who had underwent dialysis for at least 3 months due to uremia.

FIELD STRENGTH

A 3 T, steady-state free precession (SSFP) sequence for cine imaging, modified Look-Locker imaging (MOLLI) for T1 mapping and gradient-recalled-echo for T2*.

ASSESSMENT

All participants were performed cardiac magnetic resonance imaging (MRI) and echocardiogram. For MRI images analysis, borders of the EAT were manually delineated, as well as, pericardial adipose tissue (PeAT) and paracardial adipose tissue (PaAT), T1 mapping, T2* mapping, global longitudinal strain (GLS), and left atrial strain. For echocardiogram assessments, the thickness of PaAT, e' velocity, E velocity, E/e ratio, A velocity, and deceleration time were measured.

STATISTICAL TESTS

Univariate and multivariate logistic regressions were performed to explore the independent risk factors for DD. P value less than 0.05 was considered as significant.

RESULTS

Compared with the DD(-) group, the DD(+) group had significantly more epicardial tissue fat (18.5 ± 1.3 vs. 30.9 ± 2.3) In addition, EAT volumes increased significantly with the grades of DD (grade 1 vs. grade 2 and 3: 27.9 ± 15.9 vs. 35.4 ± 13.1). Moreover, EAT had significant correlations with T1 mapping, T2* mapping, GLS, left atrial strain, e' velocity, and E/e ratio. EAT accumulation added an independent risk for DD (Odds Ratio = 1.03) over conventional clinical risk factors including age, diabetes mellitus, and hemodialysis.

DATA CONCLUSION

EAT was associated with diastolic function, and its accumulation may be an independent risk factor for DD among dialysis patients.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Association of epicardial fat thickness with left ventricular diastolic function parameters in a community population

Background

We examined the relationship between epicardial fat thickness (EFT) measured by echocardiography and left ventricular diastolic function parameters in a Beijing community population.

Methods

We included 1004 participants in this study. Echocardiographic parameters including E and A peak velocity, the early diastolic velocities (e′) of the septal and lateral mitral annulus using tissue doppler imaging, E/e′, and EFT were measured. EFT1 was measured perpendicularly on the right ventricular free wall at end diastole in the extension line of the aortic root. EFT2 was the maximum thickness measured perpendicularly on the right ventricular free wall at end diastole. Multivariable linear regression was used to analyze the relationship between EFT and the mean e′ and E/e′.

Results

The mean age of the participants was 63.91 ± 9.02 years, and 51.4% were men. EFT1 and EFT2 were negatively correlated with lateral e′, septal e′, and mean e′ (p < 0.05), and the correlation coefficient for EFT1 and EFT2 and mean e′ was − 0.138 and − 0.180, respectively. EFT1 and EFT2 were positively correlated with lateral E/e′, septal E/e′, and mean E/e′ (p < 0.05), and the correlation coefficient for EFT1 and EFT2 and mean e′ was 0.100 and 0.090, respectively. Multivariable egression analysis showed that EFT2 was independently and negatively associated with e′ mean (β = − 0.078 [95% confidence interval = − 0.143, − 0.012, p = 0.020]). There were no interactions between EFT2 and any covariates, including age or heart groups, sex, BMI, or presence of hypertension, diabetes, or coronary heart disease, in relation to left ventricular diastolic dysfunction.

Conclusions

EFT2 was negatively and independently associated with e′ mean, which suggests that more attention to this type of adipose fat is required for cardiovascular disease therapy.

Cardiac CT scanning in coronary artery disease: Epicardial fat volume and its correlation with coronary artery lesions and left ventricular function

Coronary artery disease (CAD) is a major and common disease that poses a threat to human health. Recent studies suggested that epicardial fat may have an important role in the pathogenesis of CAD. Therefore, the association between epicardial fat volume (EFV) and left ventricular function with CAD was investigated in the present study. A total of 61 patients with suspected CAD who underwent CT scanning were enrolled. Baseline data, parameters of left heart function and EFV of the subjects were collected and analyzed. The degree of coronary artery lesions was assessed using the Gensini score. Pearson's correlation analysis and a logistic regression model were applied to assess the association between EFV and risk factors for CAD, the Gensini score and left ventricular function index. A total of 29 female and 32 male subjects with a median age of 63 years were enrolled. The median body mass index (BMI) of the subjects was 23.37 kg/m² and the median EFV was 86.41 cm³. It was revealed that risk factors of CAD, specially hypertension, diabetes mellitus, dyslipidemia, history of myocardial infarction and smoking, had no significant association with the EFV (P>0.05); however, the EFV was significantly positively correlated with the BMI (r=0.479, P<0.0001), interventricular septal thickness (r=0.436, P=0.004), left ventricular posterior wall thickness (r=0.350, P=0.0058), left ventricular end diastolic diameter (r=0.265, P=0.0388), left ventricular mass (r=0.445, P=0.0003) and left ventricular mass index (r=0.371, P=0.0035). However, no correlation was identified between the EFV and the Gensini score (r=0.131, P=0.3137). In conclusion, the EFV measured by cardiac CT scanning was positively correlated with the BMI and left ventricular function, but was not associated with the presence of CAD according to the Gensini scores.

Effects of epicardial adipose tissue volume and density on cardiac structure and function in patients free of coronary artery disease

PURPOSE

To determine the association of epicardial adipose tissue (EAT) volume and density with cardiac geometry and function.

METHODS

We included 178 consecutive patients who performed coronary computed tomography angiography but were not diagnosed with coronary artery disease (CAD). The EAT volume, density, and following cardiac structure and function parameters were measured: left ventricular ejection fraction, left ventricular mass (LVM), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular stroke volume (LVSV), left ventricular end-diastolic diameter (LVEDD), interventricular septal thickness (IVST) and posterior wall thickness (PWT). All the parameters were standardized using the height^2.7.

RESULTS

A significant correlation was found between larger EAT volume and increased LVM, LVEDV, LVESV, LVSV, LVEDD, IVST and corresponding standardized indexes (P < 0.05 for all). Higher EAT density significantly correlated with increased LVM, LVEDV, LVESV, LVSV, LVEDD, IVST, PWT and corresponding standardized indexes (P < 0.05 for all). The largest cardiac structure and function parameters were observed in the population with above-median EAT volume and density.

CONCLUSION

Both large EAT volume and high EAT density were associated with cardiac structure and function in patients with no CAD. The EAT density may render complementary information to EAT volume regarding cardiac geometry changes.

The predictive value of the epicardial adipose thickness in the rate of expansion of the aortic root

BACKGROUND

Epicardial adipose tissue (ECAT) is metabolically active and is involved in the development of atherosclerosis. The thickness of ECAT has been positively correlated with the dimensions of the ascending aorta. We aimed to examine whether ECAT thickness predicted the expansion of the aortic dimensions.

METHODS

The imaging results of patients who had undergone transthoracic echocardiographic (TTE) examinations more than twice during the period 2005-2015 were surveyed. We included adult patients who had undergone TTE examinations at least 1 year apart. The ECAT was measured in the parasternal long-axis view from the index TTE study. End-diastolic dimensions in three consecutive beats were averaged for all measurements. The annulus, root, and sinotubular junction (STJ) were also measured. The amount of increase (if any) in aortic dimensions per year was calculated and the correlation of this increase with the initial thickness of the ECAT was analyzed.

RESULTS

In total, 429 examinations were performed with 197 patients (17 females), from which 394 examinations were analyzed. The ECAT thickness was 8.6 ± 3.6 mm. In the initial examinations, the annulus, STJ, and root measured 23 ± 4, 28 ± 4, and 34 ± 4 mm, respectively. In univariate analysis, for every 1 mm of ECAT thickness, the STJ expanded 0.056 (95% CI: 0.001-0.112 mm/year; p = 0.030) and the aortic root expanded 0.088 mm/year (p < 0.001). In multivariate analysis, ECAT thickness remained an independent predictor of the aortic root expansion. For every 1‑mm increase in ECAT thickness, the aortic root expanded by 0.036 mm (95% CI: 0.010-0.062) per year (p = 0.007).

CONCLUSION

The thickness of the ECAT is a predictor of more rapid increases in the dimensions of the aortic root. Further studies of patients with established aortic aneurysm are warranted.

Association of Volumetric Epicardial Adipose Tissue Quantification and Cardiac Structure and Function

Background Epicardial adipose tissue ( EAT ) is in immediate apposition to the underlying myocardium and, therefore, has the potential to influence myocardial systolic and diastolic function or myocardial geometry, through paracrine or compressive mechanical effects. We aimed to review the association between volumetric EAT and markers of myocardial function and geometry. Methods and Results PubMed, Medline, and Embase were searched from inception to May 2018. Studies were included only if complete EAT volume or mass was reported and related to a measure of myocardial function and/or geometry. Meta-analysis and meta-regression were used to evaluate the weighted mean difference of EAT in patients with and without diastolic dysfunction. Heterogeneity of data reporting precluded meta-analysis for systolic and geometric associations. In the 22 studies included in the analysis, there was a significant correlation with increasing EAT and presence of diastolic dysfunction and mean e' (average mitral annular tissue Doppler velocity) and E/e' (early inflow / annular velocity ratio) but not E/A (ratio of peak early (E) and late (A) transmitral inflow velocities), independent of adiposity measures. There was a greater EAT in patients with diastolic dysfunction (weighted mean difference, 24.43 mL; 95% confidence interval, 18.5-30.4 mL; P<0.001), and meta-regression confirmed the association of increasing EAT with diastolic dysfunction ( P=0.001). Reported associations of increasing EAT with increasing left ventricular mass and the inverse correlation of EAT with left ventricular ejection fraction were inconsistent, and not independent from other adiposity measures. Conclusions EAT is associated with diastolic function, independent of other influential variables. EAT is an effect modifier for chamber size but not systolic function.

Hypoxia-inducible factor 1-alpha (HIF-1α) as a factor mediating the relationship between obesity and heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF), a common condition with an increased mortality, is strongly associated with obesity and the metabolic syndrome. The latter two conditions are associated with increased epicardial fat that can extend into the heart. This review advances the proposition that hypoxia-inhibitory factor-1α (HIF-1α) maybe a key factor producing HFpEF. HIF-1α, a highly conserved transcription factor that plays a key role in tissue response to hypoxia, is increased in adipose tissue in obesity. Increased HIF-1α expression leads to expression of a potent profibrotic transcriptional programme involving collagen I, III, IV, TIMP, and lysyl oxidase. The net effect is the formation of collagen fibres leading to fibrosis. HIF-1α is also responsible for recruiting M1 macrophages that mediate obesity-associated inflammation, releasing IL-6, MCP-1, TNF-α, and IL-1β with increased expression of thrombospondin, pro α2 (I) collagen, transforming growth factor β, NADPH oxidase, and connective tissue growth factor. These factors can accelerate cardiac fibrosis and impair cardiac diastolic function. Inhibition of HIF-1α expression in adipose tissue of mice fed a high-fat diet suppressed fibrosis and reduces inflammation in adipose tissue. Delineation of the role played by HIF-1α in obesity-associated HFpEF may lead to new potential therapies.

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.

Meta-Analysis of Relation of Epicardial Adipose Tissue Volume to Left Atrial Dilation and to Left Ventricular Hypertrophy and Functions

Many studies have explored the hypothesis that epicardial adipose tissue (EAT) accumulation adversely affects cardiac remodeling. We assessed, through a systematic review and meta-analysis, whether EAT is linked to left atrial (LA) and left ventricular (LV) structure and function, irrespective of global or abdominal visceral adiposity. We searched MEDLINE, Scopus, and Web of Science for studies evaluating the association of EAT volume quantified by computed tomography with cardiac morphology and function. We used DerSimonian and Laird random-effects models to summarize the adjusted-effect of 10 ml variation of EAT on LA size, LV mass, LV diastolic and systolic functions parameters, and presence of diastolic dysfunction. We quantified heterogeneity using I² statistic. We included 19 studies. Quantitative analysis by cardiac parameters, including LA dimension (n = 2,719), LV mass (n = 2,519), diastolic function (n = 3,741), and systolic function (n = 2,037) showed that EAT was associated with LA dilation (pooled B-coefficient: 0.12 mm; 95% confidence interval [CI] 0.08 to 0.17; I²: 97%), LV hypertrophy (pooled B-coefficient: 1.21 g; 95% CI 0.63 to 1.79; I²: 77%), diastolic dysfunction (odds ratio: 1.35; 95% CI 1.16 to 1.57; I²: 0%), higher E/E' ratio (pooled B-coefficient: 0.28 cm/s; 95% CI 0.08 to 0.49; I²: 67%), lower E' velocity (pooled B-coefficient: -0.16 cm/s; 95% CI -0.22 to -0.09; I²: 43%), and E/A ratio (pooled B-coefficient: -0.01; 95% CI -0.02 to -0.001; I²: 70%), independently of body mass index. There was no association between EAT and LV systolic function. In conclusion, EAT volume measured by computed tomography was independently associated with LA dilation, LV hypertrophy, and diastolic dysfunction.

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.