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

The Role of Epicardial Adipose Tissue in Acute Coronary Syndromes, Post-Infarct Remodeling and Cardiac Regeneration

Epicardial adipose tissue (EAT) is a fat deposit surrounding the heart and located under the visceral layer of the pericardium. Due to its unique features, the contribution of EAT to the pathogenesis of cardiovascular and metabolic disorders is extensively studied. Especially, EAT can be associated with the onset and development of coronary artery disease, myocardial infarction and post-infarct heart failure which all are significant problems for public health. In this article, we focus on the mechanisms of how EAT impacts acute coronary syndromes. Particular emphasis was placed on the role of inflammation and adipokines secreted by EAT. Moreover, we present how EAT affects the remodeling of the heart following myocardial infarction. We further review the role of EAT as a source of stem cells for cardiac regeneration. In addition, we describe the imaging assessment of EAT, its prognostic value, and its correlation with the clinical characteristics of patients.

Chronic Effect of HotBalloon-Based Wide Planar Ablation on Epicardial Adipose Tissue in Persistent Atrial Fibrillation

Background: Adverse atrial remodeling, including epicardial adipose tissue (EAT) deposition in the left atrium (LA), is implicated in atrial fibrillation (AF). Radiofrequency hotballoon (RHB) ablation can produce wide planar lesions because the balloon is highly compliant; however, chronic effects of RHB ablation on structural remodeling remain unknown. This clinical-experimental investigation characterized chronic effects of RHB ablation on EAT in persistent AF (PsAF). Methods and Results: The clinical study involved 91 patients (obese, n=30; non-obese, n=61) undergoing RHB ablation for PsAF. LA-EAT was assessed from computed tomography images obtained before ablation and 6 months later. Tissue effects of RHB ablation were explored in a chronic swine model. RHB ablation significantly reduced LA volume (mean [±SD] 177.7±29.7 vs. 138.4±29.6 mL; P<0.001) and LA-EAT volume (median [interquartile range] 22.0 [12.4-33.3] vs. 16.5 [7.9-25.8] mL; P<0.001). The reduction in EAT was significantly greater in the pulmonary vein (PV) antrum than in other LA regions (37.9% vs. 15.8%; P<0.001). The percentage reduction in PV antrum EAT was equivalent between obese and non-obese patients, as was the postablation success rate (73% vs. 70%; P=0.77). RHB ablation produced transmural lesions reaching the pigs' epicardial fat region. Conclusions: RHB-based planar-transmural lesions altered the structurally remodeled LA, including EAT. Further studies are needed to determine whether factors other than PV isolation contribute to the clinical success of RHB ablation.

Epicardial Adipose Tissue in Myocardial Disease: From Physiology to Heart Failure Phenotypes

Epicardial adipose tissue (EAT) is increasingly being recognized as a determinant of myocardial biology. The EAT-heart crosstalk suggests causal links between dysfunctional EAT and cardiomyocyte impairment. Obesity promotes EAT dysfunction and shifts in secreted adipokines which adversely affect cardiac metabolism, induce cardiomyocyte inflammation, redox imbalance and myocardial fibrosis. Thus, EAT determines cardiac phenotype via effects on cardiac energetics, contractility, diastolic function, and atrial conduction. Vice-versa the EAT is altered in heart failure (HF), and such phenotypic changes can be detected by noninvasive imaging or incorporated in Artificial Intelligence-enhanced tools to aid the diagnosis, subtyping or risk prognostication of HF. In the present article, we summarize the links between EAT and the heart, explaining how the study of epicardial adiposity can improve the understanding of cardiac disease, serve as a source of diagnostic and prognostic biomarkers, and as a potential therapeutic target in HF to improve clinical outcomes.

Characterizing regional and global effects of epicardial adipose tissue on cardiac systolic and diastolic function

OBJECTIVE

The aim of this retrospective study was to determine whether regional epicardial adipose tissue (EAT) exerts localized effects on adjacent myocardial left ventricular (LV) function.

METHODS

Cardiac magnetic resonance imaging (MRI), echocardiography, dual-energy x-ray absorptiometry, and exercise testing were performed in 71 patients with obesity with elevated cardiac biomarkers and visceral fat. Total and regional (anterior, inferior, lateral, right ventricular) EAT was quantified by MRI. Diastolic function was quantified by echocardiography. MRI was used to quantify regional longitudinal LV strain.

RESULTS

EAT was associated with visceral adiposity (r = 0.47, p < 0.0001) but not total fat mass. Total EAT was associated with markers of diastolic function (early tissue Doppler relaxation velocity [e'], mitral inflow velocity ratio [E/A], early mitral inflow/e' ratio [E/e']), but only E/A remained significant after adjustment for visceral adiposity (r = -0.30, p = 0.015). Right ventricular and LV EAT had similar associations with diastolic function. There was no evidence for localized effects of regional EAT deposition on adjacent regional longitudinal strain.

CONCLUSIONS

There was no association between regional EAT deposition and corresponding regional LV segment function. Furthermore, the association between total EAT and diastolic function was attenuated after adjustment for visceral fat, indicating that systemic metabolic impairments contribute to diastolic dysfunction in high-risk middle-aged adults.

Riboflavin ameliorates pathological cardiac hypertrophy and fibrosis through the activation of short-chain acyl-CoA dehydrogenase

Short-chain acyl-CoA dehydrogenase (SCAD), the rate-limiting enzyme for fatty acid β-oxidation, has a negative regulatory effect on pathological cardiac hypertrophy and fibrosis. FAD, a coenzyme of SCAD, participates in the electron transfer of SCAD-catalyzed fatty acid β-oxidation, which plays a crucial role in maintaining the balance of myocardial energy metabolism. Insufficient riboflavin intake can lead to symptoms similar to short-chain acyl-CoA dehydrogenase (SCAD) deficiency or flavin adenine dinucleotide (FAD) gene abnormality, which can be alleviated by riboflavin supplementation. However, whether riboflavin can inhibit pathological cardiac hypertrophy and fibrosis remains unclear. Therefore, we observed the effect of riboflavin on pathological cardiac hypertrophy and fibrosis. In vitro experiments, riboflavin increased SCAD expression and the content of ATP, decreased the free fatty acids content and improved PE-induced cardiomyocytes hypertrophy and AngⅡ-induced cardiac fibroblasts proliferation by increasing the content of FAD, which were attenuated by knocking down the expression of SCAD using small interfering RNA. In vivo experiments, riboflavin significantly increased the expression of SCAD and the energy metabolism of the heart to improve TAC induced pathological myocardial hypertrophy and fibrosis in mice. The results demonstrate that riboflavin improves pathological cardiac hypertrophy and fibrosis by increasing the content of FAD to activate SCAD, which may be a new strategy for treating pathological cardiac hypertrophy and fibrosis.

The Different Pathways of Epicardial Adipose Tissue across the Heart Failure Phenotypes: From Pathophysiology to Therapeutic Target

Epicardial adipose tissue (EAT) is an endocrine and paracrine organ constituted by a layer of adipose tissue directly located between the myocardium and visceral pericardium. Under physiological conditions, EAT exerts protective effects of brown-like fat characteristics, metabolizing excess fatty acids, and secreting anti-inflammatory and anti-fibrotic cytokines. In certain pathological conditions, EAT acquires a proatherogenic transcriptional profile resulting in increased synthesis of biologically active adipocytokines with proinflammatory properties, promoting oxidative stress, and finally causing endothelial damage. The role of EAT in heart failure (HF) has been mainly limited to HF with preserved ejection fraction (HFpEF) and related to the HFpEF obese phenotype. In HFpEF, EAT seems to acquire a proinflammatory profile and higher EAT values have been related to worse outcomes. Less data are available about the role of EAT in HF with reduced ejection fraction (HFrEF). Conversely, in HFrEF, EAT seems to play a nutritive role and lower values may correspond to the expression of a catabolic, adverse phenotype. As of now, there is evidence that the beneficial systemic cardiovascular effects of sodium-glucose cotransporter-2 receptors-inhibitors (SGLT2-i) might be partially mediated by inducing favorable modifications on EAT. As such, EAT may represent a promising target organ for the development of new drugs to improve cardiovascular prognosis. Thus, an approach based on detailed phenotyping of cardiac structural alterations and distinctive biomolecular pathways may change the current scenario, leading towards a precision medicine model with specific therapeutic targets considering different individual profiles. The aim of this review is to summarize the current knowledge about the biomolecular pathway of EAT in HF across the whole spectrum of ejection fraction, and to describe the potential of EAT as a therapeutic target in HF.

Epicardial adipose tissue volume is not an independent predictor of atrial fibrillation recurrence after catheter ablation

INTRODUCTION AND OBJECTIVES

Previous studies have suggested that epicardial adipose tissue (EAT) could exert a paracrine effect in the myocardium. However, few studies have assessed its role in the risk of atrial fibrillation (AF) recurrence. This study aimed to evaluate the association between EAT volume, and its attenuation, with the risk of AF recurrence after AF ablation.

METHODS

A total of 350 consecutive patients who underwent AF ablation were included. The median age was 57 [IQR 48-65] years and 21% had persistent AF. Epicardial fat was quantified by multidetector computed tomography using Syngo.via Frontier-Cardiac Risk Assessment software, measuring pericardial fat volume (PATV), EAT volume, and attenuation of EAT posterior to the left atrium. AF recurrence was defined as any documented episode of AF, atrial flutter, or atrial tachycardia more than 3 months after the procedure.

RESULTS

After a median follow-up of 34 [range, 12-57] months, 114 patients (33%) had AF recurrence. Univariable Cox regression showed that patients with an EAT volume ≥ 80mL had an increased risk of AF recurrence (HR, 1.65; 95%CI, 1.14-2.39; P=.007). However, after multivariable adjustment, EAT volume did not remain an independent predictor of AF recurrence (HR, 1.24; 95%CI, 0.83-1.87; P=.3). Similar results were observed with PATV. Patients with lower attenuation of EAT did not have a higher risk of AF recurrence (log-rank test, P=.75).

CONCLUSIONS

EAT parameters including the evaluation of EAT volume, PATV and EAT attenuation were not independent predictors of AF recurrence after catheter ablation.

Adverse association of epicardial adipose tissue accumulation with cardiac function and atrioventricular coupling in postmenopausal women assessed by cardiac magnetic resonance imaging

Background

This study aims to investigate the association of epicardial adipose tissue (EAT) accumulation with cardiac function and atrioventricular coupling in a cohort of postmenopausal women assessed by cardiac magnetic resonance imaging (CMR).

Materials and methods

Overall, 283 postmenopausal women (mean age 61.5 ± 9.1 years) who underwent CMR examination were enrolled. Participants were classified into four groups by the quartile of EAT volume. EAT volume was quantified on short-axis cine stacks covering the entire epicardium. CMR-derived cardiac structure and function, including left atrial (LA)- volume, emptying fraction, deformation, and left ventricular (LV)- mass, volume, ejection fraction, and deformation, were compared among the four groups of graded EAT volume.

Results

Left ventricular mass (LVM) and LV remodeling index were both increased in the group with the highest EAT volume, compared to those in the lowest quartile (p = 0.016 and p = 0.003). The LV global longitudinal strain (LV-GLS), circumferential strain (LV-GCS), and LA- reservoir strain (LA-RS), conduit strain (LA-CS), and booster strain (LA-BS), were all progressively decreased from the lowest quartile of EAT volume to the highest (all p &lt; 0.05). Multivariable linear regression analyses showed that EAT was independently associated with LV-GLS, LA-RS, LA-CS, and LA-BS after adjusting for body mass index and other clinical factors.

Conclusion

Epicardial adipose tissue accumulation is independently associated with subclinical LV and LA function in postmenopausal women. These associations support the role of EAT in mediating deleterious effects on cardiac structure and function.

Equations for predicting DXA-measured visceral adipose tissue mass based on BMI or weight in adults

Background

Obesity, especially presenting with excessive amounts of visceral adipose tissue (VAT), is strongly associated with insulin resistance (IR), atherosclerosis, metabolic syndrome, and cardiovascular diseases (CVDs).

Aims

To construct a predication equation for estimating VAT mass using anthropometric parameters and validate the models with a validation group.

Methods

Five hundred fifteen subjects (366 for the derivation group and 149 for the validation group) were enrolled in the study. The anthropometric parameters, blood lipid profile, and VAT mass were accessed from medical records. Stepwise regression was applied to develop prediction models based on the dual X–ray absorptiometry (DXA)-measured VAT mass in the derivation group. Bland–Altman plots and correlation analysis were performed to validate the agreements in the validation group. The performance of the prediction equations was evaluated with the Hosmer–Lemeshow test and area under the curve (AUC).

Results

Model 1, which included age, sex, body mass index (BMI), triglyceride (TG), high-density lipoprotein (HDL), and the grade of hepatic steatosis, had a variance of 70%, and model 2, which included age, sex, weight, height, TG, HDL, and the grade of hepatic steatosis, had a variance of 74%. The VAT mass measured by DXA was correlated with age, sex, height, weight, BMI, TG, HDL, and grade of hepatic steatosis. In the validation group, the VAT mass calculated by the prediction equations was strongly correlated with the DXA–VAT mass (r = 0.870, r = 0.875, respectively). The AUC, sensitivity, and specificity of the two prediction equations were not significantly different (both P = 0.933).

Conclusion

The study suggests that prediction equations including age, sex, height, BMI, weight, TG, HDL, and the grade of hepatic steatosis could be useful tools for predicting VAT mass when DXA is not available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01652-8.

Epicardial Adipose Tissue and Outcome in Heart Failure With Mid-Range and Preserved Ejection Fraction

Supplemental Digital Content is available in the text.

Epicardial adipose tissue (EAT) accumulation is thought to play a role in the pathophysiology of heart failure (HF) with mid-range and preserved ejection fraction, but its effect on outcome is unknown. We evaluated the prognostic value of EAT volume measured with cardiac magnetic resonance in patients with HF with mid-range ejection fraction and HF with preserved ejection fraction.

Association between epicardial adipose tissue and blood pressure: A systematic review and meta-analysis

AIMS

Epicardial adipose tissue has been reported to be associated with the development of cardiometabolic disease. Whether this is true for hypertension and non-dipper blood pressure remains controversial. Here, we conducted a systemic review and meta-analysis to evaluate the association between EAT and blood pressure.

DATA SYNTHESIS

Pubmed, Embase, and Web of Science were searched for relevant papers. Studies reported on the difference of EAT thickness between hypertensive and normotensive patients, or those recorded odds ratio (OR) between EAT and hypertension were included. The standard mean difference (SMD) and ORs were extracted and pooled using a random-effects model respectively. We further assessed the effect of EAT on circadian rhythm of blood pressure by combining multiple-adjusted ORs for non-dipper blood pressure. Seven studies with an overall sample of 1089 patients reported the mean difference of EAT thickness between hypertensive and normotensive patients, and the hypertensive patients had higher EAT (SMD = 1.07; 95% CI: 0.66-1.48; I2 = 89.2%) compared with controls. However, the pooled association between EAT and hypertension from two studies was not significant (OR = 1.65, 95%CI 0.62-4.68; I2 = 87.5%). The summary risk effect of EAT on non-dipper blood pressure from six studies comprising1208 patients showed that each 1 mm increment of EAT was associated with a 2.55-fold risk of non-dipper blood pressure.

CONCLUSION

Hypertensive patients tend to present higher EAT thickness near the right ventricular wall and increased EAT thickness might be associated with high risk of non-dipper blood pressure. Future researches are warranted to determine the causal link between EAT and hypertension and the underlying mechanism.

Structural Cardiac Remodeling in Atrial Fibrillation

OBJECTIVES

This study sought to evaluate preablation computed tomography angiography (CTA) for atrial and epicardial features to predict atrial fibrillation (AF) recurrence after ablation.

BACKGROUND

Structural atrial remodeling is a process associated with occurrence or persistence of AF. Different anatomical imaging features have been proposed to influence atrial remodeling both negatively and positively as substrate for AF.

METHODS

Patients with nonvalvular AF underwent cardiac CTA before pulmonary vein isolation at 2 high-volume centers. Left atrial (LA) and right atrial volumes, LA wall thickness (LAWT), and epicardial adipose tissue volume and attenuation were evaluated. Additional subanalyses of electroanatomical maps were made. Follow-up was performed for at least 12 months, including subanalysis of repeated cardiac CTA studies. Interrater variability was assessed.

RESULTS

Of 732 patients, 270 (36.9%) had AF recurrence after a mean of 7 months. CT analysis revealed larger indexed LA volume (47.3 mL/m² vs 43.6 mL/m²; P = 0.0001) and higher mean anterior (1.91 mm vs 1.65 mm; P < 0.0001) and posterior (1.61 mm vs 1.39 mm; P = 0.001) LAWT in patients with AF recurrence. Epicardial adipose tissue volume in patients with AF recurrence was higher (144.5 mm³ vs 128.5 mm³; P < 0.0001) and further progressed significantly in a subset of 85 patients after 2 years (+11.8 mm² vs -3.5 mm²; P = 0.041). Attenuation levels were lower, indicating a higher lipid component associated with AF recurrence (-69.1 HU vs -67.5 HU; P = 0.001). A total of 103 atrial voltage maps were highly predictive of AF recurrence and showed good discriminatory power for patients with low voltage >50% and LAWT (1.55 ± 0.5 mm vs 1.81 ± 0.6 mm; P = 0.032). Net reclassification improvement (NRI) showed a significant incremental benefit (NRI = 0.279; P < 0.0001) when adding LAWT to established risk models.

CONCLUSIONS

Atrial wall thickness, epicardial fat volume, and attenuation are associated with AF recurrence in patients undergoing ablation therapy.

Association of pericardial adipose tissue with left ventricular structure and function: a region-specific effect?

BACKGROUND

The independent role of pericardial adipose tissue (PAT) as an ectopic fat associated with cardiovascular disease (CVD) remains controversial. This study aimed to determine whether PAT is associated with left ventricular (LV) structure and function independent of other markers of general obesity.

METHODS

We studied 2471 participants (50.9 % women) without known CVD from the Korean Genome Epidemiology Study, who underwent 2D-echocardiography with tissue Doppler imaging (TDI) and computed tomography measurement for PAT.

RESULTS

Study participants with more PAT were more likely to be men and had higher cardiometabolic indices, including blood pressure, glucose, and cholesterol levels (all P < 0.001). Greater pericardial fat levels across quartiles of PAT were associated with increased LV mass index and left atrial volume index (all P < 0.001) and decreased systolic (P = 0.015) and early diastolic (P < 0.001) TDI velocities, except for LV ejection fraction. These associations remained after a multivariable-adjusted model for traditional CV risk factors and persisted even after additional adjustment for general adiposity measures, such as waist circumference and body mass index. PAT was also the only obesity index independently associated with systolic TDI velocity (P < 0.001).

CONCLUSIONS

PAT was associated with subclinical LV structural and functional deterioration, and these associations were independent of and stronger than with general and abdominal obesity measures.

Associations of region-specific visceral adiposity with subclinical atrial dysfunction and outcomes of heart failure

AIMS

Excessive visceral adiposity (VAT) plays an essential role in metabolic derangements with those close to heart further mediates myocardial homeostasis. The disparate biological links between region-specific VAT and cardiometabolic profiles as mediators influencing atrial kinetics remain unexplored.

METHODS AND RESULTS

Among 1326 asymptomatic individuals, region-specific VAT including peri-aortic root fat (PARF) and total pericardial fat (PCF) of cardiac region, together with thoracic peri-aortic adipose tissue (TAT), was assessed using multiple-detector computed tomography. VAT measures were related to functional left atrial (LA) metrics assessed by speckle-tracking algorithm and clinical outcomes of atrial fibrillation (AF) and heart failure (HF). Multivariate linear regression models incorporating body fat, metabolic syndrome, and E/TDI-e' consistently demonstrated independent associations of larger PARF/PCF with peak atrial longitudinal systolic strain (PALS) reduction, higher LA stiffness, and worsened strain rate components; instead, TAT was independently associated with cardiometabolic profiles. PARF rather than PCF or TAT conferred independent prognostic values for incident AF/HF by multivariate Cox regression (adjusted hazard ratio: 1.56, 95% confidence interval: 1.17-2.08, P = 0.002) during a median of 1790 days (interquartile range: 25th to 75th: 1440-1927 days) of follow-up, with subjects categorized into worst PALS and largest VAT tertiles demonstrating highest events (all log-rank P < 0.001). Mediation analysis showed that higher triglyceride and lower high-density lipoproteins may serve as intermediary factors for effects between VAT and LA functional metrics, with lesser role by glucose level.

CONCLUSIONS

Visceral adiposity surrounding atrial region was tightly associated with subclinical atrial dysfunction and incident AF or HF beyond metabolic factors. Instead, peri-aortic adiposity may mediate their toxic effects mainly through circulating cardiometabolic profiles.

Adverse remodeling in atrial fibrillation following isolated aortic valve replacement surgery

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia with adverse clinical outcomes. Aortic valve replacement (AVR) is one of the most frequently performed cardiac surgeries, although there is scarce evidence on arrhythmic outcomes. We aimed to evaluate AF during the first year post- isolated aortic valve replacement surgery and its clinical, analytical, and echocardiographic predictors.

METHODS

Severe aortic stenosis patients with no prior atrial fibrillation submitted to isolated aortic valve replacement surgery were included in our study, of which 316 remained in sinus rhythm and 24 developed AF. We performed logistic regression searching for AF predictors and a longitudinal comparison between pre and post-operative echocardiographic data.

RESULTS

Postoperative AF (POAF), diabetes, and follow-up indexed Left Atrium Diameter (iLAD) were significantly higher in the group of patients developing AF. POAF and iLAD were independent AF predictors at follow-up. No differences between groups were found regarding baseline and follow-up echocardiographic data except for indexed Left Ventricle End-diastolic Diameter (LVED), which failed to decrease after surgery in the AF group.

CONCLUSIONS

POAF and iLAD independently predicted AF at 1 year following isolated AVR surgery in aortic stenosis patients with no AF history. iLVED did not decrease significantly at follow-up in AF patients, possibly reflecting adverse ventricular remodeling.

Quantification of epicardial fat using 3D cine Dixon MRI

Background

There is an increased interest in quantifying and characterizing epicardial fat which has been linked to various cardiovascular diseases such as coronary artery disease and atrial fibrillation. Recently, three-dimensional single-phase Dixon techniques have been used to depict the heart and to quantify the surrounding fat. The purpose of this study was to investigate the merits of a new high-resolution cine 3D Dixon technique for quantification of epicardial adipose tissue and compare it to single-phase 3D Dixon in patients with cardiovascular disease.

Methods

Fifteen patients referred for clinical CMR examination of known or suspected heart disease were scanned on a 1.5 T scanner using single-phase Dixon and cine Dixon. Epicardial fat was segmented by three readers and intra- and inter-observer variability was calculated per slice. Cine Dixon segmentation was performed in the same cardiac phase as single-phase Dixon. Subjective image quality assessment of water and fat images were performed by three readers using a 4-point Likert scale (1 = severe; 2 = significant; 3 = mild; 4 = no blurring of cardiac structures).

Results

Intra-observer variability was excellent for cine Dixon images (ICC = 0.96), and higher than single-phase Dixon (ICC = 0.92). Inter-observer variability was good for cine Dixon (ICC = 0.76) and moderate for single-phase Dixon (ICC = 0.63). The intra-observer measurement error (mean ± standard deviation) per slice for cine was − 0.02 ± 0.51 ml (− 0.08 ± 0.4%), and for single-phase 0.39 ± 0.72 ml (0.18 ± 0.41%). Inter-observer measurement error for cine was 0.46 ± 0.98 ml (0.11 ± 0.46%) and for single-phase 0.42 ± 1.53 ml (0.17 ± 0.47%). Visual scoring of the water image yielded median of 2 (interquartile range = [Q3-Q1] 2–2) for cine and median of 3 (interquartile range = 3–2) for single-phase (P < 0.05) while no significant difference was found for the fat images, both techniques yielding a median of 3 and interquartile range of 3–2.

Conclusion

Cine Dixon can be used to quantify epicardial fat with lower intra- and inter-observer variability compared to standard single-phase Dixon. The time-resolved information provided by the cine acquisition appears to support the delineation of the epicardial adipose tissue depot.