Epicardial adipose tissue is an independent predictor of coronary atherosclerotic burden

Cardiac adipose tissue and its relationship to diabetes mellitus and cardiovascular disease

Type-2 diabetes mellitus (T2DM) plays a central role in the development of cardiovascular disease (CVD). However, its relationship to epicardial adipose tissue (EAT) and pericardial adipose tissue (PAT) in particular is important in the pathophysiology of coronary artery disease. Owing to its close proximity to the heart and coronary vasculature, EAT exerts a direct metabolic impact by secreting proinflammatory adipokines and free fatty acids, which promote CVD locally. In this review, we have discussed the relationship between T2DM and cardiac fat deposits, particularly EAT and PAT, which together exert a big impact on the cardiovascular health.

Influence of epicardial and visceral fat on left ventricular diastolic and systolic functions in patients after myocardial infarction

Obesity has been associated with subclinical left ventricular (LV) diastolic dysfunction and increased risk of heart failure. Few data are available on the relative contribution of adiposity distribution and changes in myocardial structure and function. We evaluated the influence of visceral versus subcutaneous abdominal adipose tissue and epicardial fat on LV diastolic function after acute myocardial infarction. One month after acute myocardial infarction, 225 consecutive patients were prospectively enrolled and underwent anthropometric evaluation, bioimpedance analysis, detailed echocardiography, and multidetector 64-slice computed tomography scan for quantification of epicardial fat volume (EFV) and of total, subcutaneous and visceral abdominal fat areas. We found a significant association between LV diastolic dysfunction parameters and body mass index, fat-mass percentage, and waist-to-height ratio. E' velocity and E/E' ratio were correlated with total and visceral abdominal fat (r = -0.27, p <0.001 and r = 0.21, p <0.01, respectively), but not with subcutaneous fat. After multivariate analysis, increasing EFV was associated with decreased E' velocity (adjusted β -0.11, 95% confidence interval -0.19 to -0.03; p <0.01) and increased E/E' ratio (adjusted β 0.19, 95% confidence interval 0.07 to 0.31, p <0.01). Patients with diastolic dysfunction showed higher EFV (116.7 ± 67.9 ml vs 93.0 ± 52.3 ml, p = 0.01), and there was a progressive increase in EFV according to diastolic dysfunction grades (p = 0.001). None of the adiposity parameters correlated with ejection fraction or S' velocities. In conclusion, in patients after myocardial infarction, impaired LV diastolic function was associated with increased adiposity, especially with visceral and central fat parameters. Increasing EFV was independently associated with worse LV diastolic function.

The relationship between epicardial fat thickness and gestational diabetes mellitus

AIM

Gestational diabetes mellitus (GDM) is associated with cardiovascular diseases; however, the relationship between epicardial fat thickness (EFT) and GDM remains unclear. The present study evaluates and compares EFT using transthoracic echocardiography in pregnant women with GDM.

MATERIALS AND METHODS

This cross-sectional study included 129 pregnant women in the third trimester: 65 with GDM (GDM group) and 64 with uncomplicated pregnancies (control group). As defined by the World Health Organization, the diagnosis of GDM was based on an abnormal 2-h oral glucose tolerance test (OGTT) results. We used echocardiography to measure EFT in blood samples for all the participants.

RESULTS

The postprandial blood glucose level was significantly higher in the GDM group than in the control group (P < 0.001). There were no significant differences in BMI, heart rate, systolic and diastolic blood pressure or lipid parameters between the groups. In the GDM group, isovolumic relaxation time (IVRT) parameters were significantly higher than in the control group. EFT was significantly higher in the GDM group (P < 0.001) and was correlated with postprandial glucose, BMI, age, and heart rate in both the groups. Only postprandial glucose and BMI remained significantly associated with EFT after multiple stepwise regression analysis.

CONCLUSION

Echocardiographically measured EFT was significantly higher in the patients with GDM. The findings show that EFT was strongly correlated with postprandial glucose.

METformin in DIastolic Dysfunction of MEtabolic syndrome (MET-DIME) trial: rationale and study design : MET-DIME trial

PURPOSE

Insulin resistance plays a central role in the pathophysiology of metabolic syndrome (MS). Its cardiac deleterious effects are characterized by an increase in fibrous tissue that increases myocardial stiffness and contributes to subclinical left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction in patients with MS. In addition to lifestyle counseling (LC), metformin treatment may attenuate or even reverse diastolic dysfunction in these patients. This trial aims to evaluate if treating non-diabetic patients with MS and LVDD with metformin in addition to LC improves diastolic function and assess its impact in functional capacity and health-related quality of life (HRQoL).

DESIGN

MET-DIME is a phase II prospective, randomized, open-label, blinded-endpoint trial with a scheduled follow-up of 24 months. Fifty-four patients (adults 40-65 years old with AHA/NHLBI criteria of MS and rest LVDD) will be randomized by minimization to LC only or LC plus metformin (target dose of 1,000 mg twice daily). The primary endpoint will be change in mean of early diastolic mitral annular velocity, an echocardiographic parameter highly correlated with myocardial fibrosis (serial measurements will be performed at 6, 12 and 24 months). The secondary endpoints will include change in diastolic parameters at rest; metabolic, inflammatory and remodeling biomarkers; functional capacity; adipose tissue volumes and HRQoL.

CONCLUSION

MET-DIME is a pragmatic trial designed to evaluate if adding metformin to the standard treatment of patients with MS improves diastolic dysfunction, assessing its impact in metabolic homeostasis, proinflammatory state, functional capacity and HRQoL.

Epicardial adipose tissue thickness correlates with the presence and severity of angiographic coronary artery disease in stable patients with chest pain

Objective

Epicardial adipose tissue (EAT) is suggested to correlate with metabolic risk factors and to promote plaque development in the coronary arteries. We sought to determine whether EAT thickness was associated or not with the presence and extent of angiographic coronary artery disease (CAD).

Methods

We measured epicardial fat thickness by computed tomography and assessed the presence and extent of CAD by coronary angiography in participants from the prospective EVASCAN study. The association of EAT thickness with cardiovascular risk factors, coronary artery calcification scoring and angiographic CAD was assessed using multivariate regression analysis.

Results

Of 970 patients (age 60.9 years, 71% male), 75% (n = 731) had CAD. Patients with angiographic CAD had thicker EAT on the left ventricle lateral wall when compared with patients without CAD (2.74±2.4 mm vs. 2.08±2.1 mm; p = 0.0001). The adjusted odds ratio (OR) for a patient with a LVLW EAT value ≥2.8 mm to have CAD was OR = 1.46 [1.03–2.08], p = 0.0326 after adjusting for risk factors. EAT also correlated with the number of diseased vessels (p = 0.0001 for trend). By receiver operating characteristic curve analysis, an EAT value ≥2.8 mm best predicted the presence of>50% diameter coronary artery stenosis, with a sensitivity and specificity of 46.1% and 66.5% respectively (AUC:0.58). Coronary artery calcium scoring had an AUC of 0.76.

Conclusion

Although left ventricle lateral wall EAT thickness correlated with the presence and extent of angiographic CAD, it has a low performance for the diagnosis of CAD.

Persistent epicardial adipose tissue accumulation is associated with coronary plaque vulnerability and future acute coronary syndrome in non-obese subjects with coronary artery disease

Objective. Epicardial adipose tissue (EAT) is recognized as a novel risk factor for coronary artery disease (CAD), and its contribution is thought to be stronger in non-obese patients than in obese patients. However, the prognostic impact of the progression of EAT accumulation after comprehensive management for atherosclerotic risk factors remains unclear. This study aimed to investigate whether an increase of the EAT volume during follow-up predicts future acute coronary syndrome (ACS) events in non-obese CAD patients. Methods. This study consisted of 517 non-obese CAD patients (368 men; age, 66 ± 10 years) who underwent serial multidetector computed tomography (MDCT) examinations to evaluate coronary atherosclerosis progression. The MDCT examination was used to assess the severity of stenosis, plaque characteristics, and EAT volume. All patients received comprehensive management to reduce CAD risk factors after the first MDCT examination. The MDCT examination was repeated at 6-24 months, and patients were followed-up for more than 1 year or until the occurrence of ACS events. Results. Of 517 patients, 159 (31%) patients were classified into increase of EAT volume during follow-up, 91 (18%) into decrease of EAT volume during follow-up, and 267 (51%) patients into constant of EAT volume during follow-up. The prevalence of obstructive plaques and MDCT-derived vulnerable features of coronary plaques were significantly elevated in patients with increase of EAT volume during follow-up. In contrast, no significant changes were observed in the other 2 groups. During the follow-up period of 4.1 ± 1.8 years (median 4.4 years) after the second MDCT examination, ACS occurred in 43 (8.3%) patients. Multivariate Cox regression analysis showed that the presence of low-attenuation plaque (hazard ratio [HR]; 1.78, p = 0.04) and napkin-ring sign (HR; 3.74, p < 0.001) at second MDCT examination, and changes of EAT volume per 10 ml (HR; 1.34, p = 0.004) were associated with future ACS events. Conclusion. Patients with increase of EAT volume during follow-up despite comprehensive management for CAD risks had an increased prevalence of obstructive plaques and plaques with high-risk features, which could be associated with unfavorable ACS outcomes in non-obese CAD patients.

[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.

Complement C3 as a marker of cardiometabolic risk in psoriasis

Complement C3 is an emerging risk factor in metabolic and cardiovascular diseases. It is elevated in patients with cardiovascular disease, predicts future myocardial infarction, is closely related to insulin resistance and appears to be involved in atherogenesis. C3 levels have been associated with body fat. The aim of this study was to compare C3 levels in psoriasis patients and controls and to investigate within psoriasis patients the relationship between C3 levels with several measures of body fat, markers of cardiometabolic risk and subclinical atherosclerosis. Eighty adult patients with severe plaque-type psoriasis, without psoriatic arthritis or receiving systemic therapy/phototherapy in the previous 3 months, and 95 otherwise healthy patients were enrolled. Subjects with cardiovascular disease, other systemic inflammatory diseases, use of anti-inflammatory drugs or any infectious diseases in the 4 weeks prior to study enrollment were excluded. All subjects underwent clinical and laboratory evaluation and psoriasis patients underwent multidetector computed tomography scan for coronary artery calcification, abdominal fat and epicardial adipose tissue quantification. C3 levels were increased in psoriasis patients compared to controls (129.25 ± 20.92 vs 118.24 ± 17.86, P < 0.001), even after adjustment for age, sex and waist circumference (P = 0.043), indicating that this association was not solely mediated by the adipose tissue. Within psoriasis patients, C3 levels were independently associated with abdominal visceral fat, insulin resistance, metabolic syndrome and oxidized LDL-cholesterol, while C-reactive protein did not, showing that C3 may be a better marker of cardiometabolic risk than C-reactive protein. Although more studies are needed, C3 may be a useful marker of cardiometabolic risk in psoriasis.

The associations of epicardial adipose tissue with coronary artery disease and coronary atherosclerosis

Epicardial adipose tissue (EAT) is presumed to play an important role in the development of coronary artery disease (CAD). The purpose of our study was to examine the influence of EAT volume measured by cardiac CT on the severity and presence of CAD. A total of 209 subjects (114 normal subjects and 95 patients with CAD) underwent cardiac and abdominal computed tomography (CT) scan before diagnostic coronary angiography. Pixels with a threshold range of -190 to -30 Hounsfield units were identified as EAT. CAGE ≥ 20, CAGE ≥ 50, and modified Gensini index were used to define the extent and severity of CAD. While there was no significant difference in BMI and WC between the two groups, the mean EAT volume was higher in the CAD group than in the normal subjects (102.4 ± 41.87 cm(3) versus 125.36 ± 47.64 cm(3), P < 0.001). EAT was significantly associated with CAGE ≥ 20, CAGE ≥ 50, and Gensini score by linear regression analyses after adjusting for age, gender, smoking, and alcohol use. The severity of CAD increased linearly with each tertile increase in EAT volume (P for trend < 0.05). Similarly, the coronary artery calcium (CAC) score was also increased with each increase in EAT tertile (P = 0.002). In multivariate logistic regression models, EAT and VAT were significantly associated with the presence of CAD and CAC in age, gender, smoking, alcohol use, and BMI adjusted models. In conclusion, EAT volume measured by CT is associated with the presence and severity of CAD. EAT may give important information for risk evaluation in CAD.

The relation of location-specific epicardial adipose tissue thickness and obstructive coronary artery disease: systemic review and meta-analysis of observational studies

BACKGROUND

There is growing evidence about the importance of epicardial adiposity on cardiometabolic risk. However, the relation of location-specific epicardial adipose tissue (EAT) thickness to coronary atherosclerotic burden is still unclear.

METHODS

This meta-analysis was used to study the relations between location-specific EAT thickness and obstructive coronary artery disease (CAD). A systemic literature search to identify eligible studies that met the inclusion criteria from the beginning until January 2014 was made. We conducted the meta-analysis of all included 10 published studies. Pre-specified subgroup analyses were performed according to ethnicity, body mass index, diagnostic tools for CAD, and measurement tool if presence of high heterogeneity between studies. Potential publication bias was also assessed.

RESULTS

We identified ten observed studies with a total of 1625 subjects for planned comparison. With regard to the association between obstructive CAD and location-specific EAT thickness at the right ventricular free wall, caution is warranted. The pooled estimate showed that location-specific EAT thickness at the right ventricular free wall was significantly higher in the CAD group than non-CAD group (standardized mean difference (SMD): 0.70 mm, 95% CI: 0.26-1.13, P = 0.002), although heterogeneity was high (I2 = 93%). It should be clear that only the result of echocardiography-based studies showed a significant association (SMD: 0.98 mm, 95% CI: 0.43-1.53, P = 0.0005), and the result of all included CT-based studies showed a non-significant association (SMD: 0.06 mm, 95% CI: -0.12-0.25, P = 0.50). In the subgroup analysis, the "diagnostic tools for CAD" or "measurement tool of EAT thickness" are potential major sources of heterogeneity between studies. With regard to location-specific EAT thickness at the left atrioventricular (AV) groove, it was significantly higher in the CAD group than non-CAD group (SMD: 0.74 mm, 95% CI: 0.55-0.92, P <0.00001; I2 = 0%).

CONCLUSION

Our meta-analysis suggests that significantly elevated location-specific EAT thickness at the left AV groove is associated with obstructive CAD. Based on the current evidence, the location-specific EAT thickness at the left AV groove appears to be a good predictor in obstructive CAD, especially in Asian populations. Furthermore well-designed studies are warranted because of the current limited number of studies.

Epicardial adipose tissue and coronary artery calcification in psoriasis patients

BACKGROUND

Psoriasis is a chronic, immune-mediated disease associated with several cardio-metabolic comorbidities, accelerated atherosclerosis and cardiovascular disease (CVD). Other causes beyond systemic inflammation and traditional cardiovascular risk factors (CVRF) may be implicated in the increased risk of CVD observed in these patients. Epicardial adipose tissue (EAT), a type of visceral adipose tissue surrounding the heart and coronary vessels has been implicated in the development of coronary artery disease, by endocrine mechanisms, but particularly by local inflammation.

OBJECTIVE

To compare EAT volumes in psoriasis patients and controls using multidetector computed tomography (MDCT) and to analyse if eventual differences were independent from abdominal visceral adiposity; to determine, within psoriasis patients, its relation with subclinical atherosclerosis and other markers of cardiometabolic risk.

METHODS

One hundred patients with severe psoriasis, without CVD underwent MDCT, with EAT and abdominal visceral fat (AVF) assessment and coronary artery calcification (CAC) quantification and were compared with 202 control patients.

RESULTS

EAT volume was increased in psoriasis patients compared to control subjects, independently from age, sex and AVF, being, on average, 15.2 ± 4.41 mL higher (95% CI: 6.5-26.0, P = 0.001) than in controls. Moreover, psoriasis patients had a statistically significant higher risk of having subclinical atherosclerosis (OR 2.52, 95% CI: 1.23-5.16) than controls, after adjusting for traditional CVRF. Within psoriasis patients EAT volume was associated with subclinical atherosclerosis, independently of age, sex, psoriasis duration, classical CVRF and AVF.

CONCLUSION

This study showed that psoriasis was associated with increased EAT volume independently of visceral abdominal fat and with subclinical atherosclerosis. Within psoriasis patients EAT volume was independently associated with CAC. EAT may be another important contributor to the higher cardiovascular risk observed in psoriasis.

Does epicardial adipose tissue volume provide information about the presence and localization of coronary artery disease?

Objective

This study is important for the determination of branches and segments of the first atherosclerotic coronary artery. The objective was to examine the role of epicardial adipose tissue (EAT) volume in estimating the presence and localization of plaque of coronary arteries.

Methods

Our study is a retrospective study, consisting of 50 male (mean age: 45.5±12 yrs) and 58 female (mean age: 52.5±11.6 yrs). A total of 108 consecutive patients underwent coronary computerized tomography (CT) angiography. Each coronary artery segment was assessed for the presence of atherosclerotic plaque. According to the plaque-involved vessel, patients were grouped as without plaque; plaque-involved left anterior descending artery (LAD), right coronary artery (RCA), or circumflex artery (Cx); and mixed (two or more vessels).

Results

The differences in mean values between the two groups were compared using the independent samples t test. Mann-Whitney U test was used for the comparison of continuous variables among groups. While EAT volume was found to be higher in the group with plaque, the difference between the two groups was statistically significant (88.6±9.2 cm³, 67.4±7.2 cm³, respectively, p=0.001). EAT volume was 67.3±7.1 cm³ in the without plaque group, 97.7±22.8 cm³ in LAD, 79.7±10.1 cm³ in RCA, 70.7±8.9 cm³ in Cx, and 101.9±18.6 cm³ in mixed vessels. In the intragroup comparison, the EAT volume of plaque-involved LAD and mixed vessels was significantly higher than in the other groups. The EAT volume of plaque-involved RCA was significantly higher (p=0.015) than in plaque-involved Cx.

Conclusion

Increased EAT volume is directly proportional to the presence of coronary artery plaques, especially in LAD and with more than one artery.

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

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

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

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

Relationship between epicardial adipose tissue and subclinical coronary artery disease in patients with extra-cardiac arterial disease

OBJECTIVE

Epicardial adipose tissue (EAT) and mediastinal adipose tissue (MAT) are linked to coronary artery disease (CAD). The association between EAT, MAT, and severity of CAD in known extra-cardiac arterial disease was investigated.

DESIGN AND METHODS

Sixty-five cardiac asymptomatic patients (mean age 65 ± 8 years, 69% male) with peripheral arterial disease, carotid stenosis, or aortic aneurysm underwent coronary computed tomography angiography. Patients were divided into non-significant (<50% stenosis, N = 35), single vessel (N = 15) and multi-vessel CAD (N = 15). EAT and MAT were quantified on computed tomography images using volumetric software.

RESULTS

Subgroups did not significantly differ by age, gender, or cardiovascular risk factors. Median EAT was 99.5, 98.0, and 112.0 cm(3) (P = 0.38) and median MAT was 66.0, 90.0, and 81.0 cm(3) (P = 0.53) for non-significant, single vessel, and multi-vessel CAD, respectively. In age- and gender-adjusted analysis, only EAT was significantly associated with CAD (odds ratio [OR] 1.12 [95% confidence interval, 1.01-1.25] per 10 cm(3) increase in EAT; P = 0.04). This remained in multivariate-adjusted analysis (OR 1.21 [1.04-1.39]; P = 0.01).

CONCLUSIONS

In patients with known extra-cardiac arterial disease, CAD is correlated with EAT, but not with MAT. These results suggest that EAT has a local effect on coronary atherosclerosis, apart from the endocrine effect of visceral fat.

Epicardial adipose tissue: relationship between measurement location and metabolic syndrome

Epicardial adipose tissue (EAT) is a contributing factor of metabolic syndrome (MS) and coronary artery disease (CAD). However, it is still unclear which measurement location of EAT area best reflects its cardiometabolic risk. The purpose of our study was to investigate the distribution of EAT and its relationship to the total EAT volume and MS. To assess volume and cross-sectional areas of EAT, coronary CT angiography were obtained in 256 asymptomatic subjects. The EAT areas within the threshold range of -190 to -30 Hounsfield units were measured at six representative slices. Correlations between single slice EAT areas and total EAT volumes were high across all measurement locations (correlation coefficient r > 0.80). The receiver-operator characteristic curves demonstrated EAT area at left main coronary artery (LMCA) was well discriminative for MS (AUC 0.82, p < 0.001) and CAD (AUC 0.76, p < 0.001). EAT areas across all measurement locations were significantly increased linearly with increasing number of MS components. EAT areas were significantly associated with MS at all measurement locations; the highest odds ratio (OR) between EAT area and MS was at the LMCA level (OR 5.86, p < 0.001). The OR between EAT area and coronary artery calcium was also significant in LMCA locations (OR 1.56, p = 0.042). We demonstrated that the single-slice EAT area measurement is a simple and reliable method compared with time-consuming volumetric measurements. The EAT area at LMCA level was the best single slice representing the risk of metabolic syndrome and coronary atherosclerosis.

The relationship between epicardial fat and indices of obesity and the metabolic syndrome: a systematic review and meta-analysis

Epicardial fat (epicardial adipose tissue, EAT) has been implicated in the pathogenesis of coronary artery disease (CAD). The objective of this study was to examine the relationship between EAT and generalized obesity, central or visceral adipose tissue (VAT), and the components of the metabolic syndrome--systolic blood pressure (SBP), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), and fasting blood glucose (FBG)--that are linked to CAD. A systematic review of the literature, following meta-analysis guidelines, was conducted until May, 2013, using the search strategy "Obesity" OR "abdominal obesity" OR "metabolic syndrome" OR "metabolic syndrome X" AND "epicardial fat". Thirty-eight studies fulfilled the criteria. There was a highly significant (P<0.00001) correlation between EAT and body mass index (BMI), waist circumference (WC), or VAT. The correlation between EAT and VAT was significantly (P<0.0001) greater than the correlation between EAT and WC, which in turn was significantly greater than the correlation between EAT and BMI. Overall, EAT was 7.5 ± 0.1 mm in thickness in the metabolic syndrome (n=427) compared to 4.0 ± 0.1 mm in controls (n=301). EAT correlated significantly (P<0.0001) with SBP, TGs, HDL, and FBG, but the strength of the association was less than one-half of the relationship of EAT to indices of obesity. The results of multivariate analysis were less consistent but show a relationship between EAT and metabolic syndrome independent of BMI. In summary, the very strong correlation between EAT and VAT suggests a relationship between these two adipose tissue depots. Measurement of EAT can be useful to indicate VAT. Whereas EAT correlates significantly with each of the components of the metabolic syndrome- SBP, TGs, HDL, or FBG-the magnitude of the relationship is considerably and significantly less than the relationship of EAT to BMI. These data show the strong relationship between EAT and BMI but especially with WC and VAT. They also demonstrate the smaller magnitude of the association of EAT with standard coronary risk factors, related to the metabolic syndrome, and suggest that the unique features of this adipose tissue warrant detailed investigation.

Association of epicardial fat with cardiovascular risk factors and incident myocardial infarction in the general population: the Heinz Nixdorf Recall Study

OBJECTIVES

This study sought to determine whether epicardial fat volume predicts coronary events in the general population.

BACKGROUND

Epicardial adipose tissue (EAT) is suggested to promote plaque development in the coronary artery tree.

METHODS

We quantified EAT volume in participants from the prospective population-based Heinz Nixdorf Recall cohort study free of cardiovascular disease. Incident coronary events were assessed during a follow-up period of 8.0 ± 1.5 years. Multivariable association of EAT with cardiovascular risk factors, coronary artery calcification (CAC), and coronary events was assessed using regression analysis.

RESULTS

From the overall 4,093 participants (age 59.4 years, 47% male), 130 subjects developed a fatal or nonfatal coronary event. Incidence of coronary events increased by quartile of EAT (0.9% vs. 4.7% for 1(st) and 4th quartile, respectively, p < 0.001). Doubling of EAT was associated with a 1.5-fold risk of coronary events when adjusting for cardiovascular risk factors (hazard ratio [HR] [95% confidence interval (CI)]: 1.54 [1.09 to 2.19]), which remained unaltered after further adjustment for CAC score (HR [95% CI]: 1.50 [1.07 to 2.11]). For discrimination of subjects with events from those without, we observed a trend for improvement of Harrell's C and explained variance by EAT over traditional cardiovascular risk factors, which, however, did not reach statistical significance (0.720 to 0.730 for risk factors alone and with EAT added, respectively, p = 0.10, R(2) = 2.73% to R(2) = 2.92%, time-dependent integrated discrimination improvement = 0.196%).

CONCLUSIONS

Epicardial fat is associated with fatal and nonfatal coronary events in the general population independent of traditional cardiovascular risk factors and complements information from cardiac computed tomography above the CAC score.

Epicardial adipose tissue increased in patients with newly diagnosed subclinical hypothyroidism

OBJECTIVE

To investigate whether or not patients with subclinical hypothyroidism (SH) have increased epicardial adipose tissue (EAT).

SUBJECTS AND METHODS

Sixty-one patients with newly diagnosed SH and without any known cardiovascular disease were enrolled. Twenty-four subjects matched for age, gender and body mass index without any thyroid dysfunctions were included as a control group. The EAT was measured by echocardiography and thyroid functions were assessed by routine blood examination.

RESULTS

Patients with SH had higher EAT values than control subjects (3.6 ± 0.9 vs. 2.8 ± 1.4, p = 0.005). Also, SH patients with thyroid-stimulating hormone (TSH) ≥10 mU/l had higher EAT than those with SH with TSH <10 mU/l and control subjects (p = 0.013). In addition, while there was significant correlation between EAT and TSH (r = 0.31, p = 0.014) in patients with SH, there was no significant relation between EAT and TSH in normal subjects (r = 0.09, p = 0.64).

CONCLUSIONS

There was a higher level of EAT in patients with SH compared with normal subjects and a significant correlation between EAT and TSH was found.

The relationship between the severity of coronary artery disease and epicardial adipose tissue depends on the left ventricular function

Background

Epicardial adipose tissue (EAT) is an active metabolic and endocrine organ. Previous studies focusing mainly on patients with preserved left ventricular function (LVF) could show a correlation between increased amounts of EAT and the extent and activity of coronary artery disease (CAD). However, to date, there are no data available about the relationship between EAT and the severity of CAD with respect to the whole spectrum of LVF impairment. Therefore, we evaluated this relationship in patients with CAD.

Methods

250 patients with CAD and 50 healthy controls underwent CMR examination to assess EAT. The severity of CAD was defined using the angiographic Gensini score (GSS).

Results

The GSS ranged from 2–364. Linear regression analysis revealed a significant correlation between EAT and GSS (r = 0.177, p = 0.01). Patients with mild (GSS≤10) and moderate CAD (GSS>10−≤40) showed comparable EAT to healthy controls. However, in patients with severe CAD (GSS>40) EAT was significantly reduced (p<0.0001) compared to healthy controls. Interestingly, patients with the same GSS revealed different EAT depending on the left ventricular function (LVF). Patients with preserved LVF (LVF≥50%) showed more EAT mass compared to those with reduced LVF (LVF<50%) regardless of the GSS. In patients with preserved LVF and mild CAD, EAT was comparable to healthy controls (61.8±19.4 g vs. 62.9±14.4 g, p = 0.8). In patients with moderate CAD, EAT rose significantly to 83.1±24.9 g (p = 0.01) and started to decline to 66.4±23.6 g in patients with severe CAD (p = 0.03). Contrary, in CAD patients with reduced LVF, EAT was already significantly reduced in patients with mild CAD as compared to healthy controls (p = 0.001) and showed a stepwise decline with increasing CAD severity.

Conclusion

The relationship between EAT and the severity of CAD depends on LVF. These findings emphasize the multifactorial interaction between EAT and the severity of CAD.

Impact of epicardial fat volume on coronary artery disease in symptomatic patients with a zero calcium score

BACKGROUND

This study sought to evaluate the prevalence of coronary artery disease (CAD) and the impact of epicardial fat volume (EFV) on CAD in symptomatic patients with a zero calcium score (CS) using multislice computed tomography (MSCT).

METHODS

In this study, 1308 consecutive symptomatic patients who underwent 64-slice MSCT with a zero CS were evaluated. EFV was quantified with CS data sets. Presence of an obstructive plaque (diameter stenosis >50%) and a CT-derived vulnerable plaque, which was defined as a plaque with remodeling index >1.10 and mean CT density value <3 0HU, was assessed with a CT coronary angiography.

RESULTS

Obstructive plaques were detected in 86 patients (7%) and CT-derived vulnerable plaques in 63 (5%). EFV was larger in patients with obstructive plaques than no plaque (124.3 ± 43.2 cm(3) vs. 95.1 ± 40.3 cm(3); p<0.01). Patients with CT-derived vulnerable plaques had a greater amount of EFV than no plaque (133.0 ± 40.2 cm(3) vs. 95.1 ± 40.3 cm(3); p<0.01). Multivariate analysis revealed EFV as a predictor of the presence of an obstructive and a CT-derived vulnerable plaque (per 10 cm(3); Odds ratio (OR) 1.10; 95% confidence interval (CI), 1.04-1.16; p<0.01 and OR 1.19; 95% CI, 1.12-1.27; p<0.01). The combination of EFV and Framingham risk score (FRS) resulted in an area under the receiver-operating characteristic curve for prediction of obstructive and CT-derived vulnerable plaque of 0.75 and 0.75, which was significantly higher than 0.68 and 0.64 for FRS alone (p=0.02 and p<0.01).

CONCLUSIONS

A zero CS doesn't exclude CAD and EFV can be a useful marker of CAD in symptomatic zero CS patients.

Correlation between epicardial fat thickness by echocardiography and other parameters in obese adolescents

BACKGROUND AND OBJECTIVES

Obesity has reached epidemic proportions globally and affects people of all ages. Recent studies have shown that visceral adipose tissue measured by magnetic resonance imaging and/or computed tomography correlates positively with epicardial adipose tissue. Epicardial fat, which is correlated to several metabolic parameters, can be assessed by echocardiography. The aim of this study was to evaluate epicardial fat thickness and other metabolic parameters in obese adolescents and investigate the correlation between epicardial fat thickness and other metabolic parameters in obese adolescents.

SUBJECTS AND METHODS

We selected 99 subjects, between ages 15-17 years of age, to be enrolled in this study. Sixty five obese adolescents with a body mass index (BMI) >95 percentile and 34 control subjects were included in this study. Echocardiographic measurements including epicardial fat thickness as well as anthropometric and blood pressure (BP) measurements were performed. The following parameters were estimated: blood glucose, total cholesterol, triglyceride, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol, aspartate aminotransferase, alanine aminotransferase, free fatty acid, interleukin-6, tumor necrosis factor-α, leptin, adiponectin and high sensitive C reactive protein.

RESULTS

The obese group showed a statistically significant correlation with echocardiographic epicardial fat thickness and, BMI, waist circumference, obesity index, fat percentage, systolic BP, insulin level, leptin and adiponectin. Multivariate linear regression analysis showed epicardial fat thickness as the most significant independent parameter to correlate with obese adolescents.

CONCLUSION

These data suggest that epicardial fat thickness measured by echocardiography is a practical and accurate parameter for predicting visceral obesity.

Epicardial adipose tissue thickness is an indicator for coronary artery stenosis in asymptomatic type 2 diabetic patients: its assessment by cardiac magnetic resonance

BACKGROUND

We used cardiovascular magnetic resonance (CMR) to investigate the association between epicardial adipose tissue (EAT) thickness and silent myocardial ischemia, as well as coronary artery stenosis, in asymptomatic type 2 diabetic patients.

METHODS

The study included 100 type 2 diabetic subjects (51 male and 49 female; mean age: 56 ± 7 years). Silent myocardial ischemia, as determined by CMR, was defined as evidence of inducible ischemia or myocardial infarction. Signal reduction or stenosis of ≥ 50% in the vessel diameter was used as the criteria for significant coronary artery stenosis on coronary magnetic resonance (MR) angiography.

RESULTS

EAT thickness was positively correlated with body mass index (BMI), waist-to-hip ratio, systolic blood pressure, postprandial glucose, fasting/postprandial triglyceride (TG), serum glycated hemoglobin (HbA1c) level, and homeostasis model assessment of insulin resistance (HOMA-IR) score. Significant coronary artery stenosis was found in 24 patients, while 14 patients had silent myocardial ischemia in CMR (1 with silent myocardial infarction, 11 with inducible ischemia, and 2 with both). EAT thickness was greater in patients who had coronary artery stenosis (13.0 ± 2.6 mm vs. 11.5 ± 2.1 mm, p = 0.01), but did not differ between the subjects with or without silent myocardial ischemia on CMR images (12.8 ± 2.1 vs. 11.7 ± 2.3 mm, p = 0.11). Multivariate logistic regression analysis indicated that EAT thickness was an independent indicator for significant coronary artery stenosis after adjusting for traditional risk factors (OR 1.403, p = 0.026).

CONCLUSIONS

Increased EAT thickness assessed by CMR is an independent risk factor for significant coronary artery stenosis in asymptomatic type 2 diabetes. However, EAT thickness was not associated with silent myocardial ischemia.

Brown fat like gene expression in the epicardial fat depot correlates with circulating HDL-cholesterol and triglycerides in patients with coronary artery disease

BACKGROUND

Recent evidence indicates that epicardial adipose tissue (EAT) expresses uncoupling protein-1 (UCP1), a marker of brown adipocytes. However, the putative effects of the presence of brown adipocytes in EAT remain unknown.

METHODS

The mRNA expression of genes related to brown adipocyte-mediated thermogenesis was measured in the fat samples collected from the epicardial-, mediastinal- and subcutaneous-depots of patients undergoing coronary artery bypass grafting. Both univariate and multivariate analyses were then utilized to determine any association between gene expression and the anthropometrics and fasting blood chemistries of these patients.

RESULTS

EAT exhibited significantly higher expression of UCP1 and cytochrome c oxidase subunit-IV (COX-IV) compared to mediastinal- and subcutaneous-fat depots (P ≤ 0.05). EAT expression of UCP1 (r=0.50), COX-IV (r=0.37) and lipoprotein lipase (LPL) (r=0.58) positively associated with circulating levels of HDL-cholesterol (P ≤ 0.05). In addition, EAT expression of LPL, acyl coA dehydrogenase-short, -medium and -long chain genes associated negatively with circulating TG levels (P ≤ 0.05).

CONCLUSIONS

Abundance of UCP-1 in the EAT relative to other fat depots confirms the presence of brown adipocytes in human EAT. Furthermore, the correlations among the EAT expression of thermogenesis-related genes with the circulating HDL and TG levels indicate that presence of active brown adipocytes shares a functional association with the circulating plasma lipids in humans.

Validation of reference genes for the relative quantification of gene expression in human epicardial adipose tissue

Background

Relative quantification is a commonly used method for assessing gene expression, however its accuracy and reliability is dependent upon the choice of an optimal endogenous control gene, and such choice cannot be made a priori. There is limited information available on suitable reference genes to be used for studies involving human epicardial adipose tissue. The objective of the current study was to evaluate and identify optimal reference genes for use in the relative quantification of gene expression in human epicardial fat depots of lean, overweight and obese subjects.

Methodology/Principal Findings

Some of the commonly used reference genes including 18S, ACTB, RPL27, HPRT, CYCA, GAPDH, RPLPO, POLR2A and B2M were quantified using real-time PCR analysis. The expression stability of these genes was evaluated using Genorm, Normfinder and Bestkeeper algorithms. In addition, the effect of sample size on the validation process was studied by randomly categorizing subjects in two cohorts of n = 2 and n = 33.

Conclusions/Significance

CYCA, GAPDH and RPL27 were identified as the most stable genes common to all three algorithms and both sample sizes. Their use as reference gene pairs might contribute to the enhanced robustness of relative quantification in the studies involving the human epicardial adipose tissue.

Association of pericardial fat and coronary high-risk lesions as determined by cardiac CT

OBJECTIVE

Pericardial adipose tissue (PAT) is a pathogenic fat depot associated with coronary atherosclerosis and cardiovascular events. We hypothesized that higher PAT is associated with coronary high-risk lesions as determined by cardiac CT.

METHODS

We included 358 patients (38% female; median age 51 years) who were admitted to the ED with acute chest pain and underwent 64-slice CT angiography. The cardiac CT data sets were assessed for presence and morphology of CAD and PAT. Coronary high-risk lesions were defined as >50% luminal narrowing and at least two of the following characteristics: positive remodeling, low-density plaque, and spotty calcification. PAT was defined as any pixel with CT attenuation of -190 to -30 HU within the pericardial sac.

RESULTS

Based on cardiac CT, 50% of the patients (n=180) had no CAD, 46% (n=165) had CAD without high-risk lesions, and 13 patients had CAD with high-risk lesions. The median PAT in patients with high-risk lesions was significantly higher compared to patients without high-risk lesions and without any CAD (151.9 [109.0-179.4]cm(3) vs. 110.0 [81.5-137.4]cm(3), vs. 74.8 [58.2-111.7]cm(3), respectively p=0.04 and p<0.0001). These differences remained significant after adjusting for traditional risk factors including BMI (all p<0.05). The area under the ROC curve for the identification of high-risk lesions was 0.756 in a logistic regression model with PAT as a continuous predictor.

CONCLUSION

PAT volume is nearly twice as high in patients with high-risk coronary lesions as compared to those without CAD. PAT volume is significantly associated with high risk coronary lesion morphology independent of clinical characteristics and general obesity.

Incremental value of an integrated adenosine stress-rest MDCT perfusion protocol for detection of obstructive coronary artery disease

BACKGROUND

Preliminary studies have shown the potential of myocardial computed tomography perfusion (CTP) analysis for ischemia detection in both animals and humans.

OBJECTIVE

To provide validation data on stress-rest CTP protocols as additive tools to improve the accuracy of multidetector computed tomography (MDCT) for coronary artery disease (CAD) in symptomatic patients.

METHODS

Ninety symptomatic patients with suspected CAD (62 ± 8 years, 66% males) underwent both MDCT and invasive coronary angiography (XA). The MDCT protocol included a prospective calcium score acquisition, a helical acquisition with retrospective gating during infusion of adenosine (140 μg/kg/min) and a prospective scan for computed tomography angiography (CTA) at rest (total effective radiation dose: 5.1 ± 0.8 mSv). Significant and higher-grade CADs were defined by the presence of ≥50% or ≥70% stenosis in at least one coronary artery, as evaluated by quantitative coronary angiography (QCA) using XA images.

RESULTS

On a patient-based model, CTA sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) to detect ≥50% or ≥70% stenosis were 98%, 71%, 80%, and 97% (global accuracy 86%) and 100%, 60%, 64%, and 100% (accuracy 77%), respectively. An integrative approach of CTA and CTP results had the best performance for detection of CAD with sensitivity of 83%, specificity of 98%, PPV of 98%, and NPV of 84% (accuracy 84%) for detection of 50% stenosis and 97%, 90%, 88%, and 98% (accuracy 93%), respectively, for the 70% threshold. The integration of results had the best overall performance in all scenarios but was particularly advantageous in the prediction of higher-grade CAD, with an area under the curve of 0.93, compared with 0.80 for isolated CTA and 0.82 for CTP and in patients with severe calcifications (sensitivity 92%, specificity 87%, overall accuracy of 90%).

CONCLUSIONS

The integration of functional and morphological data using CTA and CTP improved MDCT accuracy for detection of clinically relevant CAD at both thresholds of 50% and 70% in this intermediate to high pretest probability population.