Secretory products from epicardial adipose tissue of patients with type 2 diabetes mellitus induce cardiomyocyte dysfunction

Effect of SGLT2-Inhibitors on Epicardial Adipose Tissue: A Meta-Analysis

(1) Sodium-glucose cotransporter-2 inhibitors (SGLT2-i) reduce adipose tissue and cardiovascular events in patients with type 2 diabetes (T2D). Accumulation of epicardial adipose tissue (EAT) is associated with increased cardio-metabolic risks and obstructive coronary disease events in patients with T2D. (2) We performed a systematic review and meta-analysis of SGLT2-i therapy on T2D patients, reporting data on changes in EAT after searching the PubMed/MEDLINE, Embase, Science Direct, Scopus, Google Scholar, and Cochrane databases. A random effects or fixed effects model meta-analysis was then applied. (3) Results: A total of three studies (n = 64 patients with SGLT2-i, n = 62 with standard therapy) were included in the final analysis. SGLT2 inhibitors reduced EAT (SMD: -0.82 (-1.49; -0.15); p < 0.0001). An exploratory analysis showed that HbA1c was significantly reduced with SGLT2-i use, while body mass index was not significantly reduced with this drug. (4) Conclusions: This meta-analysis suggests that the amount of EAT is significantly reduced in T2D patients with SGLT2-i treatment.

COVID-19 and Obesity: Role of Ectopic Visceral and Epicardial Adipose Tissues in Myocardial Injury

In March 2020, the WHO declared coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a global pandemic. Obesity was soon identified as a risk factor for poor prognosis, with an increased risk of intensive care admissions and mechanical ventilation, but also of adverse cardiovascular events. Obesity is associated with adipose tissue, chronic low-grade inflammation, and immune dysregulation with hypertrophy and hyperplasia of adipocytes and overexpression of pro-inflammatory cytokines. However, to implement appropriate therapeutic strategies, exact mechanisms must be clarified. The role of white visceral adipose tissue, increased in individuals with obesity, seems important, as a viral reservoir for SARS-CoV-2 via angiotensin-converting enzyme 2 (ACE2) receptors. After infection of host cells, the activation of pro-inflammatory cytokines creates a setting conducive to the "cytokine storm" and macrophage activation syndrome associated with progression to acute respiratory distress syndrome. In obesity, systemic viral spread, entry, and prolonged viral shedding in already inflamed adipose tissue may spur immune responses and subsequent amplification of a cytokine cascade, causing worse outcomes. More precisely, visceral adipose tissue, more than subcutaneous fat, could predict intensive care admission; and lower density of epicardial adipose tissue (EAT) could be associated with worse outcome. EAT, an ectopic adipose tissue that surrounds the myocardium, could fuel COVID-19-induced cardiac injury and myocarditis, and extensive pneumopathy, by strong expression of inflammatory mediators that could diffuse paracrinally through the vascular wall. The purpose of this review is to ascertain what mechanisms may be involved in unfavorable prognosis among COVID-19 patients with obesity, especially cardiovascular events, emphasizing the harmful role of excess ectopic adipose tissue, particularly EAT.

Mechanistic Insights of Empagliflozin in Nondiabetic Patients With HFrEF: From the EMPA-TROPISM Study

OBJECTIVES

The goal of this study was to evaluate the effect of empagliflozin, in addition to optimal medical treatment, on epicardial adipose tissue (EAT), interstitial myocardial fibrosis, and aortic stiffness in nondiabetic patients with heart failure with reduced ejection fraction (HFrEF).

BACKGROUND

Several randomized clinical trials have established the benefits of the inhibitors of the sodium-glucose cotransporter-2 receptor (SGLT2-i) in HFrEF, independent of their hypoglycemic effects. The mechanisms of the benefits of SGLT2-i in HFrEF have not been well defined.

METHODS

This study was a secondary analysis of patients enrolled in the EMPA-TROPISM [ATRU-4] (Are the cardiac benefits of Empagliflozin independent of its hypoglycemic activity?) clinical trial. It was a double-blind, placebo-controlled randomized clinical trial investigating the effect of empagliflozin in nondiabetic patients with HFrEF. Patients underwent cardiac magnetic resonance at baseline and after 6 months. Interstitial myocardial fibrosis was calculated by using T₁ mapping (extracellular volume). Aortic stiffness was calculated by using pulsed wave velocity, and EAT was measured from the cine sequences.

RESULTS

Empagliflozin is associated with significant reductions in EAT volume (-5.14 mL; 95% CI: -8.36 to -1.92) compared with placebo (-0.75 mL; 95% CI: -3.57 to 2.06; P < 0.05); this finding was paralleled by reductions in subcutaneous adipose tissue area (-5.33 cm² [95% CI: -12.61 to 1.95] vs 9.13 cm² [95% CI: -2.72 to 20.99]; P < 0.05). Empagliflozin-treated patients reported a reduction in extracellular volume (-1.25% [±0.56 95% CI] vs 0.24% [±0.57 95% CI]; (P < 0.01)]; specifically, empagliflozin reduced both matrix volume (-7.24 mL [95% CI: -11.59 to -2.91] vs 0.70 mL [95% CI: -0.89 to 2.29]; P < 0.001) and cardiomyocyte volume (-11.08 mL [95% CI: -19.62 to -2.55] vs 0.80 mL [95% CI: -1.96 to 3.55]; P < 0.05). Pulsed wave velocity was also significantly reduced in the empagliflozin group (-0.58 cm/s [95% CI: -0.92 to -0.25] vs 0.60 cm/s [95% CI: 0.14 to 1.06]; P < 0.01). Using proteomics, empagliflozin was associated with a significant reduction in inflammatory biomarkers.

CONCLUSIONS

Empagliflozin significantly improved adiposity, interstitial myocardial fibrosis, aortic stiffness, and inflammatory markers in nondiabetic patients with HFrEF. These results shed new light on the mechanisms of action of the benefits of SGLT2-i. (Are the "Cardiac Benefits" of Empagliflozin Independent of Its Hypoglycemic Activity [ATRU-4] [EMPA-TROPISM]; NCT03485222).

Epicardial fat thickness in infants of diabetic mothers

BACKGROUND

Epicardial fat thickness (EFT) in adults and children has been related to the metabolic syndrome and other cardiovascular risk factors; however, scarce studies have evaluated it in infants of diabetic mothers (IDM) in whom, alterations in the thickness of the interventricular septum have been reported. This study compares the EFT in IDM versus infants of non-diabetic mothers (INDM) and its association with others echocardiographic parameters.

METHODS

We performed a cross sectional study in 93 infants (64 IDM and 29 INDM). To evaluate EFT dimensions, an echocardiogram was performed within the first 24h of extrauterine life in both groups. In diabetic mothers, HbA1c was also determined.

RESULTS

There was no significant difference in birth weight between the groups although gestational age was lower in IDM. The EFT (3.6 vs. 2.5 mm, p <  0.0001), the interventricular septum thickness (IVST) (6.2 vs. 5.2 mm, p <  0.0001) and the IVST / left ventricle posterior wall (1.3 vs. 1.1, p = 0.001) were higher in the IDM; while the left ventricular expulsion fraction [LVFE] (71.1 vs. 77.8; p <  0.0001) was lower than in the INDM, respectively. We found a positive correlation between EFT with IVST (r = 0.577; p = 0.0001), LVPW (r = 0.262; p = 0.011), IVST/LVPW index (r = 0.353; p = 0.001), and mitral integral early velocity (r = 0.313; p = 0.002), while a negative correlation with LVFE was observed (r = -0.376; p = 0.0001).

CONCLUSIONS

The EFT is higher in IDM than in INDM. It was positively related with echocardiographic parameters of left ventricular thickness and negatively with left ventricular ejection function.

Heart failure with preserved ejection fraction based on aging and comorbidities

Heart failure (HF) with preserved ejection fraction (HFpEF) is a leading cause of hospitalizations and mortality when diagnosed at the age of ≥ 65 years. HFpEF represents multifactorial and multisystemic syndrome and has different pathophysiology and phenotypes. Its diagnosis is difficult to be established based on left ventricular ejection fraction and may benefit from individually tailored approaches, underlying age-related changes and frequent comorbidities. Compared with the rapid development in the treatment of heart failure with reduced ejection fraction, HFpEF presents a great challenge and needs to be addressed considering the failure of HF drugs to improve its outcomes. Further extensive studies on the relationships between HFpEF, aging, and comorbidities in carefully phenotyped HFpEF subgroups may help understand the biology, diagnosis, and treatment of HFpEF. The current review summarized the diagnostic and therapeutic development of HFpEF based on the complex relationships between aging, comorbidities, and HFpEF.

Role of novel biomarkers in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is commonly defined as cardiomyopathy in patients with diabetes mellitus in the absence of coronary artery disease and hypertension. As DCM is now recognized as a cause of substantial morbidity and mortality among patients with diabetes mellitus and clinical diagnosis is still inappropriate, various expert groups struggled to identify a suitable biomarker that will help in the recognition and management of DCM, with little success so far. Hence, we thought it important to address the role of biomarkers that have shown potential in either human or animal studies and which could eventually result in mitigating the poor outcomes of DCM. Among the array of biomarkers we thoroughly analyzed, long noncoding ribonucleic acids, soluble form of suppression of tumorigenicity 2 and galectin-3 seem to be most beneficial for DCM detection, as their plasma/serum levels accurately correlate with the early stages of DCM. The combination of relatively inexpensive and accurate speckle tracking echocardiography with some of the highlighted biomarkers may be a promising screening method for newly diagnosed diabetes mellitus type 2 patients. The purpose of the screening test would be to direct affected patients to more specific confirmation tests. This perspective is in concordance with current guidelines that accentuate the importance of an interdisciplinary team-based approach.

Pericardial Fat and the Risk of Heart Failure

BACKGROUND

Obesity is a well-established risk factor for heart failure (HF). However, implications of pericardial fat on incident HF is unclear.

OBJECTIVES

This study sought to examine the association between pericardial fat volume (PFV) and newly diagnosed HF.

METHODS

This study ascertained PFV using cardiac computed tomography in 6,785 participants (3,584 women and 3,201 men) without pre-existing cardiovascular disease from the MESA (Multi-Ethnic Study of Atherosclerosis). Cox proportional hazards regression was used to evaluate PFV as continuous and dichotomous variable, maximizing the J-statistic: (Sensitivity + Specificity - 1).

RESULTS

In 90,686 person-years (median: 15.7 years; interquartile range: 11.7 to 16.5 years), 385 participants (5.7%; 164 women and 221 men) developed newly diagnosed HF. PFV was lower in women than in men (69 ± 33 cm3 vs. 92 ± 47 cm3; p < 0.001). In multivariable analyses, every 1-SD (42 cm3) increase in PFV was associated with a higher risk of HF in women (hazard ratio [HR]: 1.44; 95% confidence interval [CI]: 1.21 to 1.71; p < 0.001) than in men (HR: 1.13; 95% CI: 1.01 to 1.27; p = 0.03) (interaction p = 0.01). High PFV (≥70 cm3 in women; ≥120 cm3 in men) conferred a 2-fold greater risk of HF in women (HR: 2.06; 95% CI: 1.48 to 2.87; p < 0.001) and a 53% higher risk in men (HR: 1.53; 95% CI: 1.13 to 2.07; p = 0.006). In sex-stratified analyses, greater risk of HF remained robust with additional adjustment for anthropometric indicators of obesity (p ≤ 0.008), abdominal subcutaneous or visceral fat (p ≤ 0.03) or biomarkers of inflammation and hemodynamic stress (p < 0.001) and was similar among Whites, Blacks, Hispanics, and Chinese (interaction p = 0.24). Elevated PFV predominantly augmented the risk of HF with preserved ejection fraction (p < 0.001) rather than reduced ejection fraction (p = 0.31).

CONCLUSIONS

In this large, community-based, ethnically diverse, prospective cohort study, pericardial fat was associated with an increased risk of HF, particularly HF with preserved ejection fraction, in women and men.

Can We Decrease Epicardial and Pericardial Fat in Patients With Diabetes?

Diabetes mellitus (DM) is a chronic and complex metabolic disorder and also an important cause of cardiovascular (CV) disease (CVD). Patients with type 2 DM (T2DM) and obesity show a greater propensity for visceral fat deposition (and excessive fat deposits elsewhere) and the link between adiposity and CVD risk is greater for visceral than for subcutaneous (SC) adipose tissue (AT). There is growing evidence that epicardial AT (EAT) and pericardial AT (PAT) play a role in the development of DM-related atherosclerosis, atrial fibrillation (AF), myocardial dysfunction, and heart failure (HF). In this review, we will highlight the importance of PAT and EAT in patients with DM. We also consider therapeutic interventions that could have a beneficial effect in terms of reducing the amount of AT and thus CV risk. EAT is biologically active and a likely determinant of CV morbidity and mortality in patients with DM, given its anatomical characteristics and proinflammatory secretory pattern. Consequently, modification of EAT/PAT may become a therapeutic target to reduce the CV burden. In patients with DM, a low calorie diet, exercise, antidiabetics and statins may change the quantity of EAT, PAT or both, alter the secretory pattern of EAT, improve the metabolic profile, and reduce inflammation. However, well-designed studies are needed to clearly define CV benefits and a therapeutic approach to EAT/PAT in patients with DM.

Implications of Inflammation and Fibrosis in Atrial Fibrillation Pathophysiology

Inflammation and fibrosis have been implicated in the pathophysiology of atrial fibrillation. Atrial fibrosis causes conduction disturbances and is a central component of atrial remodeling in atrial fibrillation. Cardiac fibroblasts, the cells responsible for fibrosis formation, are activated by inflammatory mediators and growth factors associated with systemic inflammatory conditions. Thus, inflammation contributes to atrial fibrosis; the complex interplay of these maladaptive components creates a vicious cycle of atrial remodeling progression, maintaining atrial fibrillation and increasing thrombogenicity. This review provides up-to-date knowledge regarding inflammation and fibrosis in atrial fibrillation pathophysiology and their potential as therapeutic targets.

Metformin Is Associated With a Lower Risk of Atrial Fibrillation and Ventricular Arrhythmias Compared With Sulfonylureas: An Observational Study

[Figure: see text].

Increased epicardial adipose tissue thickness associated with increased metabolic risk and the presence of heart failure in patients with Chronic Chagas disease

BACKGROUND

It has been described that Trypanosoma cruzi is capable of promoting metabolic disturbances currently considered as cardiovascular risk factors. Moreover, it has been observed that the protozoa can remain in adipose tissue and alter its immune endocrine functions. The aim of this study was to characterize the thickness of epicardial adipose tissue (EAT) in patients with chronic Chagas disease (CCD) concerning their cardiovascular metabolic risk profile compared with those without CCD.

METHODS

A cross-sectional study was performed including T. cruzi seropositive individuals categorized according to a standard CCD classification and a matched seronegative control group. Complete clinical examination, metabolic laboratory tests and transthoracic echocardiography to assess cardiac function and to quantify EAT were performed.

RESULTS

Fifty-five individuals aged 46.7±11.9 y, 34 with CCD and 21 in the control group, were included. The CCD group presented higher EAT thickness in relation to controls (4.54±1.28 vs 3.22±0.99 mm; p=0.001), which was significantly associated with the presence of insulin resistance (OR=3, 95% CI 1.58 to 5.73; p<0.001). This group presented lower levels of plasmatic adiponectin than controls, especially in those patients with EAT ≥4.5 mm (p=0.005) who also presented with heart failure more frequently (p=0.01).

CONCLUSION

In patients with CCD, a higher EAT thickness is observed and is associated with an increased metabolic risk profile indicated mainly by insulin resistance.

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.

Diabesity: the combined burden of obesity and diabetes on heart disease and the role of imaging

Diabesity is a term used to describe the combined adverse health effects of obesity and diabetes mellitus. The worldwide dual epidemic of obesity and type 2 diabetes is an important public health issue. Projections estimate a sixfold increase in the number of adults with obesity in 40 years and an increase in the number of individuals with diabetes to 642 million by 2040. Increased adiposity is the strongest risk factor for developing diabetes. Early detection of the effects of diabesity on the cardiovascular system would enable the optimal implementation of effective therapies that prevent atherosclerosis progression, cardiac remodelling, and the resulting ischaemic heart disease and heart failure. Beyond conventional imaging techniques, such as echocardiography, CT and cardiac magnetic resonance, novel post-processing tools and techniques provide information on the biological processes that underlie metabolic heart disease. In this Review, we summarize the effects of obesity and diabetes on myocardial structure and function and illustrate the use of state-of-the-art multimodality cardiac imaging to elucidate the pathophysiology of myocardial dysfunction, prognosticate long-term clinical outcomes and potentially guide treatment strategies.

Inflammation and adiposity: new frontiers in atrial fibrillation

The aetiology of atrial fibrillation (AF) remains poorly understood, despite its growing prevalence and associated morbidity, mortality, and healthcare costs. Obesity is implicated in myriad different disease processes and is now recognized a major risk factor in the pathogenesis of AF. Moreover, the role of distinct adipose tissue depots is a matter of intense scientific interest with the depot directly surrounding the heart—epicardial adipose tissue (EAT) appearing to have the greatest correlation with AF presence and severity. Similarly, inflammation is implicated in the pathophysiology of AF with EAT thought to act as a local depot of inflammatory mediators. These can easily diffuse into atrial tissue with the potential to alter its structural and electrical properties. Various meta-analyses have indicated that EAT size is an independent risk factor for AF with adipose tissue expansion being inevitably associated with a local inflammatory process. Here, we first briefly review adipose tissue anatomy and physiology then move on to the epidemiological data correlating EAT, inflammation, and AF. We focus particularly on discussing the mechanistic basis of how EAT inflammation may precipitate and maintain AF. Finally, we review how EAT can be utilized to help in the clinical management of AF patients and discuss future avenues for research.

Inotropic and lusitropic, but not arrhythmogenic, effects of adipocytokine resistin on human atrial myocardium

The adipocytokine resistin is released from epicardial adipose tissue (EAT). Plasma resistin and EAT deposition are independently associated with atrial fibrillation. The EAT secretome enhances arrhythmia susceptibility and inotropy of human myocardium. Therefore, we aimed to determine the effect of resistin on the function of human myocardium and how resistin contributes to the proarrhythmic effect of EAT. EAT biopsies were obtained from 25 cardiac surgery patients. Resistin levels were measured by ELISA in 24-h EAT culture media (n = 8). The secretome resistin concentrations increased over the culture period to a maximal level of 5.9 ± 1.2 ng/mL. Coculture with β-adrenergic agonists isoproterenol (n = 4) and BRL37344 (n = 13) had no effect on EAT resistin release. Addition of resistin (7, 12, 20 ng/mL) did not significantly increase the spontaneous contraction propensity of human atrial trabeculae (n = 10) when given alone or in combination with isoproterenol. Resistin dose-dependently increased trabecula-developed force (maximal 2.9-fold increase, P < 0.0001), as well as the maximal rates of contraction (2.6-fold increase, P = 0.002) and relaxation (1.8-fold increase, P = 0.007). Additionally, the postrest potentiation capacity of human trabeculae was reduced at all resistin doses, suggesting that the inotropic effect induced by resistin might be due to altered sarcoplasmic reticulum Ca²⁺ handling. EAT resistin release is not modulated by common arrhythmia triggers. Furthermore, exogenous resistin does not promote arrhythmic behavior in human atrial trabeculae. Resistin does, however, induce an acute dose-dependent positive inotropic and lusitropic effect.

Epicardial adipose tissue affects the efficacy of left atrial posterior wall isolation for persistent atrial fibrillation

BACKGROUND

Epicardial adipose tissue (EAT) contributes to atrial fibrillation (AF). However, its impact on the efficacy of left atrial posterior wall isolation (LAPWI) is unclear.

METHODS

Forty-four nonparoxysmal AF patients underwent LAPWI after pulmonary vein isolation. EAT overlap on LAPWI was assessed by fusing computed tomography images with electro-anatomical mapping.

RESULTS

During the 21 ± 7 months of follow-up, AF recurred in 10 patients (23%). The total and left atrial EAT volumes were 113 ± 36 and 33 ± 12 cm3, respectively. No differences were found between the AF-free and AF-recurrent groups regarding EAT volume. The EAT overlaps on LAPWI lines and LAPWI area were 1.2 ± 1.0 and 0.5 ± 0.9 cm2 respectively. Although no difference was found between groups regarding the EAT overlap on LAPWI area, the AF-free group had a significantly larger EAT overlap on LAPWI lines (1.4 ± 1.0 vs 0.6 ± 0.6 cm2, P = .014). Multivariate analysis identified EAT overlap on LAPWI lines as an independent predictor of AF recurrence (hazard ratio: 0.399, 95% confidence interval: 0.178-0.891, P = .025). Kaplan-Meier analysis revealed that, during follow-up, 92% of the large EAT overlap group (≥1.0 cm2) and 58% of the small EAT overlap group (<1.0 cm2) remained AF-free (P = .008).

CONCLUSIONS

EAT overlap on LAPWI lines is related to a high AF freedom rate. Direct radiofrequency application to EAT overlap may be necessary to suppress AF.

SGLT2 inhibitors: mechanisms of cardiovascular benefit beyond glycaemic control

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are effective antidiabetic therapies in patients with type 2 diabetes mellitus and are associated with improved glycaemic control as well as with reductions in body mass and blood pressure. In large cardiovascular outcome trials in patients with diabetes, SGLT2 inhibitors improve cardiovascular and renal outcomes, including hospitalization for heart failure, with this benefit extending to patients without diabetes who have heart failure with reduced ejection fraction. The possible mechanisms of benefit are being extensively investigated because they are unlikely to be related to improved glycaemic control. Early natriuresis with a reduction in plasma volume, a consequent rise in haematocrit, improved vascular function, a reduction in blood pressure and changes in tissue sodium handling are all likely to have a role. Additional mechanisms of SGLT2 inhibitors that might be beneficial include a reduction in adipose tissue-mediated inflammation and pro-inflammatory cytokine production, a shift towards ketone bodies as the metabolic substrate for the heart and kidneys, reduced oxidative stress, lowered serum uric acid level, reduced glomerular hyperfiltration and albuminuria, and suppression of advanced glycation end-product signalling. Further outcome trials and mechanistic studies, including in patients with heart failure with preserved ejection fraction or non-diabetic kidney disease, might identify other possible mechanisms of benefit of SGLT2-inhibitor therapy.

Hemodynamic and Functional Impact of Epicardial Adipose Tissue in Heart Failure With Preserved Ejection Fraction

OBJECTIVES

This study determined the impact of excess epicardial adipose tissue (EAT) in patients with the obese phenotype of heart failure with preserved ejection fraction (HFpEF).

BACKGROUND

Patients with HFpEF and an elevated body mass index differ from nonobese patients, but beyond generalized obesity, fat distribution may be more important. Increases in EAT are associated with excess visceral adiposity, inflammation, and cardiac fibrosis, and EAT has been speculated to play an important role in the pathophysiology of HFpEF, but no study has directly evaluated this question.

METHODS

Patients with HFpEF and obesity (n = 169) underwent invasive hemodynamic exercise testing with expired gas analysis and echocardiography. Increased EAT was defined by echocardiography (EAT thickness ≥9 mm).

RESULTS

Compared with obese patients without increased EAT (HFpEF_EAT-, n = 92), obese patients with HFpEF with increased EAT (HFpEF_EAT+; n = 77) displayed a higher left ventricular eccentricity index, indicating increased pericardial restraint, but similar resting biventricular structure and function. In contrast, hemodynamics were more abnormal in patients with HFpEF_EAT+, with higher right atrial, pulmonary artery, and pulmonary capillary wedge pressures at rest and during exercise compared with those of patients with HFpEF_EAT-. Peak oxygen consumption (VO₂) was reduced in both groups but was 20% lower in patients with HFpEF_EAT+ (p < 0.01).

CONCLUSIONS

Among patients with the obese phenotype of HFpEF, the presence of increased EAT is associated with more profound hemodynamic derangements at rest and exercise, including greater elevation in cardiac filling pressures, more severe pulmonary hypertension, and greater pericardial restraint, culminating in poorer exercise capacity. Further study is needed to understand the biology and treatment of excessive EAT in patients with HFpEF.

Assessing Atrial Fibrillation Substrates by P Wave Analysis: A Comprehensive Review

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while leaving largely unaffected the risk of stroke. Moreover, up to 20% of AF patients are asymptomatic during paroxysmal relapses of arrhythmia, thus underlying the need for early markers to identify at-risk patients and prevent cerebrovascular accidents. Indeed, non-invasive assessment of pre-clinical substrate changes that predispose to AF could provide early identification of at-risk patients and allow for tailored care paths. ECG-derived P wave analysis is a simple-to-use and inexpensive tool that has been successfully employed to detect AF-associated structural and functional atrial changes. Beyond standard electrocardiographic techniques, high resolution signal averaged electrocardiography (SAECG), by recording microvolt amplitude atrial signals, allows more accurate analysis of the P wave and possibly AF risk stratification. This review focuses on the evidence that support P wave analysis to assess AF substrates, predict arrhythmia relapses and guide rhythm-control interventions.

Link Between Synovial and Myocardial Inflammation: Conceptual Framework to Explain the Pathogenesis of Heart Failure with Preserved Ejection Fraction in Patients with Systemic Rheumatic Diseases

Patients with a broad range of systemic rheumatic diseases are at increased risk of heart failure (HF), an event that is not related to traditional cardiovascular risk factors or underlying ischaemic heart disease. The magnitude of risk is linked to the severity of arthritic activity, and HF is typically accompanied by a preserved ejection fraction. Subclinical evidence for myocardial fibrosis, microcirculatory dysfunction and elevated cardiac filling pressures is present in a large proportion of patients with rheumatic diseases, particularly those with meaningful systemic inflammation. Drugs that act to attenuate pro-inflammatory pathways (methotrexate and antagonists of tumour necrosis factor and interleukin-1) may ameliorate myocardial inflammation and cardiac structural abnormalities and reduce the risk of HF events.

Elevated Cholesteryl Ester Transfer Protein Activity Early in Pregnancy Predicts Prediabetes 5 Years Later

CONTEXT

Cholesteryl ester transfer protein (CETP) regulates high-density lipoprotein (HDL) cholesterol levels and interaction between glucose, and HDL metabolism is central in the development of diabetes.

OBJECTIVE

We hypothesized that CETP levels would be regulated in diabetic pregnancies. We tested the hypothesis by evaluating CETP activity measured multiple times during pregnancy and at 5 years' follow-up in a prospective cohort (STORK) and investigated its association with gestational diabetes mellitus (GDM) during pregnancy or development of prediabetes 5 years after pregnancy. We also evaluated the strongest correlation of CETP activity among measures of adipocity and glucose metabolism, lipoproteins, adipokines, and monocyte/macrophage activation markers.

DESIGN

A population-based longitudinal cohort study was conducted from 2001 to 2013.

SETTING

The study setting was Oslo University Hospital.

PATIENTS OR OTHER PARTICIPANTS

A total of 300 women during pregnancy and at 5 years postpartum participated in this study.

MAIN OUTCOME MEASURES

CETP activity was measured at 14 to 16, 22 to 24, 30 to 32, and 36 to 38 weeks' gestation, and at 5 years' follow-up.

RESULTS

We found higher CETP activity in pregnancy in women developing prediabetes but no association with GDM. CETP activity decreased throughout pregnancy and remained low at follow-up. High CETP activity was associated with sCD14 levels, in particular in women who developed prediabetes. These data show that enhanced CETP activity during pregnancy is associated with systemic indices of monocyte/macrophage activation, in particular in women who develop prediabetes later in life.

CONCLUSIONS

CETP activity during pregnancy identifies women at risk for later diabetes development.

Acute interaction between human epicardial adipose tissue and human atrial myocardium induces arrhythmic susceptibility

Epicardial adipose tissue (EAT) deposition has a strong clinical association with atrial arrhythmias; however, whether a direct functional interaction exists between EAT and the myocardium to induce atrial arrhythmias is unknown. Therefore, we aimed to determine whether human EAT can be an acute trigger for arrhythmias in human atrial myocardium. Human trabeculae were obtained from right atrial appendages of patients who have had cardiac surgery (n = 89). The propensity of spontaneous contractions (SCs) in the trabeculae (proxy for arrhythmias) was determined under physiological conditions and during known triggers of SCs (high Ca²⁺, β-adrenergic stimulation). To determine whether EAT could trigger SCs, trabeculae were exposed to superfusate of fresh human EAT, and medium of 24 h-cultured human EAT treated with β_1/2 (isoproterenol) or β₃ (BRL37344) adrenergic agonists. Without exposure to EAT, high Ca²⁺ and β_1/2-adrenergic stimulation acutely triggered SCs in, respectively, 47% and 55% of the trabeculae that previously were not spontaneously active. Acute β₃-adrenergic stimulation did not trigger SCs. Exposure of trabeculae to either superfusate of fresh human EAT or untreated medium of 24 h-cultured human EAT did not induce SCs; however, specific β₃-adrenergic stimulation of EAT did trigger SCs in the trabeculae, either when applied to fresh (31%) or cultured (50%) EAT. Additionally, fresh EAT increased trabecular contraction and relaxation, whereas media of cultured EAT only increased function when treated with the β₃-adrenergic agonist. An acute functional interaction between human EAT and human atrial myocardium exists that increases the propensity for atrial arrhythmias, which depends on β₃-adrenergic rather than β_1/2-adrenergic stimulation of EAT.

Epicardial adipose tissue: an emerging biomarker of cardiovascular complications in type 2 diabetes?

Type 2 diabetes (T2D) is associated with an increased risk of cardiovascular disease and heart failure, which highlights the need for improved understanding of factors contributing to the pathophysiology of these complications as they are the leading cause of mortality in T2D. Patients with T2D have high levels of epicardial adipose tissue (EAT). EAT is known to secrete inflammatory factors, lipid metabolites, and has been proposed to apply mechanical stress on the cardiac muscle that may accelerate atherosclerosis, cardiac remodeling, and heart failure. High levels of EAT in patients with T2D have been associated with atherosclerosis, diastolic dysfunction, and incident cardiovascular events, and this fat depot has been suggested as an important link coupling diabetes, obesity, and cardiovascular disease. Despite this, the predictive potential of EAT in general, and in patients with diabetes, is yet to be established, and, up until now, the clinical relevance of EAT is therefore limited. Should this link be established, importantly, studies show that this fat depot can be modified both by pharmacological and lifestyle interventions. In this review, we first introduce the role of adipose tissue in T2D and present mechanisms involved in the pathophysiology of EAT and pericardial adipose tissue (PAT) in general, and in patients with T2D. Next, we summarize the evidence that these fat depots are elevated in patients with T2D, and discuss whether they might drive the high cardiometabolic risk in patients with T2D. Finally, we discuss the clinical potential of cardiac adipose tissues, address means to target this depot, and briefly touch upon underlying mechanisms and future research questions.

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

Obesity and diabetes can lead to heart failure with preserved ejection fraction (HFpEF), potentially because they both cause expansion and inflammation of epicardial adipose tissue and thus lead to microvascular dysfunction and fibrosis of the underlying left ventricle. The same process also causes an atrial myopathy, which is clinically evident as atrial fibrillation (AF); thus, AF may be the first manifestation of HFpEF. Many patients with apparently isolated AF have latent HFpEF or subsequently develop HFpEF. Most patients with obesity or diabetes who have AF and exercise intolerance have increased left atrial pressures at rest or during exercise, even in the absence of diagnosed HFpEF. Among patients with AF, those who also have latent HFpEF have increased risk for systemic thromboembolism and death. The identification of HFpEF in patients with obesity or diabetes alters the risk-to-benefit relationship of commonly prescribed treatments. Bariatric surgery and statins can ameliorate AF and reduce the risk for HFpEF. Conversely, antihyperglycaemic drugs that promote adipogenesis or cause sodium retention (insulin and thiazolidinediones) may increase the risk for heart failure in patients with an underlying ventricular myopathy. Patients with obesity and diabetes who undergo catheter ablation for AF are at increased risk for AF recurrence and for post-ablation increases in pulmonary venous pressures and worsening heart failure, especially if HFpEF coexists. Therefore, AF may be the earliest indicator of HFpEF in patients with obesity or type 2 diabetes, and recognition of HFpEF alters the management of these patients.

Inflammaging as a common ground for the development and maintenance of sarcopenia, obesity, cardiomyopathy and dysbiosis

Sarcopenia, obesity and their coexistence, obese sarcopenia (OBSP) as well as atherosclerosis-related cardio-vascular diseases (ACVDs), including chronic heart failure (CHF), are among the greatest public health concerns in the ageing population. A clear age-dependent increased prevalence of sarcopenia and OBSP has been registered in CHF patients, suggesting mechanistic relationships. Development of OBSP could be mediated by a crosstalk between the visceral and subcutaneous adipose tissue (AT) and the skeletal muscle under conditions of low-grade local and systemic inflammation, inflammaging. The present review summarizes the emerging data supporting the idea that inflammaging may serve as a mutual mechanism governing the development of sarcopenia, OBSP and ACVDs. In support of this hypothesis, various immune cells release pro-inflammatory mediators in the skeletal muscle and myocardium. Subsequently, the endothelial structure is disrupted, and cellular processes, such as mitochondrial activity, mitophagy, and autophagy are impaired. Inflamed myocytes lose their contractile properties, which is characteristic of sarcopenia and CHF. Inflammation may increase the risk of ACVD events in a hyperlipidemia-independent manner. Significant reduction of ACVD event rates, without the lowering of plasma lipids, following a specific targeting of key pro-inflammatory cytokines confirms a key role of inflammation in ACVD pathogenesis. Gut dysbiosis, an imbalanced gut microbial community, is known to be deeply involved in the pathogenesis of age-associated sarcopenia and ACVDs by inducing and supporting inflammaging. Dysbiosis induces the production of trimethylamine-N-oxide (TMAO), which is implicated in atherosclerosis, thrombosis, metabolic syndrome, hypertension and poor CHF prognosis. In OBSP, AT dysfunction and inflammation induce, in concert with dysbiosis, lipotoxicity and other pathophysiological processes, thus exacerbating sarcopenia and CHF. Administration of specialized, inflammation pro-resolving mediators has been shown to ameliorate the inflammatory manifestations. Considering all these findings, we hypothesize that sarcopenia, OBSP, CHF and dysbiosis are inflammaging-oriented disorders, whereby inflammaging is common and most probably the causative mechanism driving their pathogenesis.

Analysis of long non-coding RNA and mRNA profiles in epicardial adipose tissue of patients with atrial fibrillation

Accumulating studies have suggested that epicardial adipose tissue (EAT) play an important role in the pathogenesis of atrial fibrillation (AF), but few have characterized the underlying mechanism between their interactions. Recent evidence suggested that bioactive molecules secreted from EAT, including exosomes carrying long non-coding RNAs (lncRNAs), may modulate atrial remodeling. LncRNAs are associated with cardiovascular disorders, including AF, but their roles in EAT remain elusive. The aim of the present study was to investigate the expression profile of lncRNAs in EAT with AF. Differentially expressed lncRNAs and nearby mRNAs interaction networks were constructed. Epicardial adipose samples were collected from patients with persistent non-valvular AF (n = 6) and sinus rhythm (SR) (n = 6), and the expression of lncRNAs and mRNAs were profiled using RNA-sequencing method. A total of 46,577 transcripts, including 35,552 protein-coding pattern, corresponding to 15,404 genes in EAT, among which, 655 mRNAs (265 upregulated and 390 downregulated) and 57 lncRNAs (17 upregulated and 40 downregulated) were differentially expressed between AF and SR (P < 0.05; fold change>1.5). GO enrichment, KEGG pathway analysis and interaction network construction showed that these differentially expressed lncRNAs were enriched in functional categories, including metabolism and stress response, which might contribute to the pathogenesis of AF. Our study demonstrated a differentially expressed lncRNA profile in EAT with AF, and provide a novel insight into the interactions between EAT and AF.

Disease-treatment interactions in the management of patients with obesity and diabetes who have atrial fibrillation: the potential mediating influence of epicardial adipose tissue

Both obesity and type 2 diabetes are important risk factors for atrial fibrillation (AF), possibly because they both cause an expansion of epicardial adipose tissue, which is the source of proinflammatory adipocytokines that can lead to microvascular dysfunction and fibrosis of the underlying myocardium. If the derangement of epicardial fat adjoins the left atrium, the result is an atrial myopathy, which is clinically manifest as AF. In patients with AF, there is a close relationship between epicardial fat volume and the severity of electrophysiological abnormalities in the adjacent myocardial tissues, and epicardial fat mass predicts AF in the general population. The expansion of epicardial adipose tissue in obesity and type 2 diabetes may also affect the left ventricle, impairing its distensibility and leading to heart failure with a preserved ejection fraction (HFpEF). Patients with obesity or type 2 diabetes with AF often have HFpEF, but the diagnosis may be missed, if dyspnea is attributed to increased body mass or to the arrhythmia. The expected response to the treatment for obesity, diabetes or AF may be influenced by their effects on epicardial inflammation and the underlying atrial and ventricular myopathy. Bariatric surgery and metformin reduce epicardial fat mass and ameliorate AF, whereas insulin promotes adipogenesis and cardiac fibrosis, and its use is accompanied by an increased risk of AF. Rate control strategies for AF may impair exercise tolerance, because they allow for greater time for ventricular filling in patients who cannot tolerate volume loading because of cardiac fibrosis and HFpEF. At the same time, both obesity and diabetes decrease the expected success rate of rhythm control strategies for AF (e.g., electrical cardioversion or catheter ablation), because increased epicardial adipose tissue volumes and cardiac fibrosis are important determinants of AF recurrence following these procedures.

Metabolic Stress and Cardiovascular Disease in Diabetes Mellitus: The Role of Protein O-GlcNAc Modification

Mammalian cells metabolize glucose primarily for energy production, biomass synthesis, and posttranslational glycosylation; and maintaining glucose metabolic homeostasis is essential for normal physiology of cells. Impaired glucose homeostasis leads to hyperglycemia, a hallmark of diabetes mellitus. Chronically increased glucose in diabetes mellitus promotes pathological changes accompanied by impaired cellular function and tissue damage, which facilitates the development of cardiovascular complications, the major cause of morbidity and mortality of patients with diabetes mellitus. Emerging roles of glucose metabolism via the hexosamine biosynthesis pathway (HBP) and increased protein modification via O-linked β-N-acetylglucosamine (O-GlcNAcylation) have been demonstrated in diabetes mellitus and implicated in the development of diabetic cardiovascular complications. This review will discuss the biological outcomes of the glucose metabolism via the hexosamine biogenesis pathway and protein O-GlcNAcylation in regulating cellular homeostasis, and highlight the regulations and contributions of elevated O-GlcNAcylation to the pathogenesis of diabetic cardiovascular disease.

Impact of Epicardial Adipose Tissue, Left Ventricular Myocardial Fat Content, and Interstitial Fibrosis on Myocardial Contractile Function

Background Current understanding of metabolic heart disease consists of a myriad of different pathophysiological mechanisms. Epicardial adipose tissue (EAT) is increasingly recognized as metabolically active and associated with adverse cardiovascular outcomes. The present study aimed to investigate the effect of increased EAT volume index on left ventricular (LV) myocardial fat content and burden of interstitial myocardial fibrosis and their subsequent effects on LV myocardial contractile function. Methods and Results A total of 40 volunteers (mean age, 35±10 years; 26 males) of varying body mass index (25.0±4.1 kg/m²; range, 19.3-36.3 kg/m²) and without diabetes mellitus or hypertension were prospectively recruited. EAT volume index, LV myocardial fat content, and extracellular volume were quantified by magnetic resonance imaging. LV myocardial contractile function was quantified by speckle tracking echocardiography global longitudinal strain on the same day as magnetic resonance imaging examination. Mean total EAT volume index, LV myocardial fat content, and extracellular volume were 30.0±19.6 cm³/m², 5.06%±1.18%, and 27.5%±0.5%, respectively. On multivariable analyses, increased EAT volume index and insulin resistance were independently associated with both increased LV myocardial fat content content and higher burden of interstitial myocardial fibrosis. Furthermore, increased EAT volume index was independently associated with LV global longitudinal strain. Conclusions Increased EAT volume index and insulin resistance were independently associated with increased myocardial fat accumulation and interstitial myocardial fibrosis. Increased EAT volume index was associated with detrimental effects on myocardial contractile function as evidenced by a reduction in LV global longitudinal strain.

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

Aims

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

Methods and results

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

Conclusions

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

Redox State in Atrial Fibrillation Pathogenesis and Relevant Therapeutic Approaches

BACKGROUND

Myocardial redox state is a critical determinant of atrial biology, regulating cardiomyocyte apoptosis, ion channel function, and cardiac hypertrophy/fibrosis and function. Nevertheless, it remains unclear whether the targeting of atrial redox state is a rational therapeutic strategy for atrial fibrillation prevention.

OBJECTIVE

To review the role of atrial redox state and anti-oxidant therapies in atrial fibrillation.

METHOD

Published literature in Medline was searched for experimental and clinical evidence linking myocardial redox state with atrial fibrillation pathogenesis as well as studies looking into the role of redoxtargeting therapies in the prevention of atrial fibrillation.

RESULTS

Data from animal models have shown that altered myocardial nitroso-redox balance and NADPH oxidases activity are causally involved in the pathogenesis of atrial fibrillation. Similarly experimental animal data supports that increased reactive oxygen / nitrogen species formation in the atrial tissue is associated with altered electrophysiological properties of atrial myocytes and electrical remodeling, favoring atrial fibrillation development. In humans, randomized clinical studies using redox-related therapeutic approaches (e.g. statins or antioxidant agents) have not documented any benefits in the prevention of atrial fibrillation development (mainly post-operative atrial fibrillation risk).

CONCLUSION

Despite strong experimental and translational data supporting the role of atrial redox state in atrial fibrillation pathogenesis, such mechanistic evidence has not been translated to clinical benefits in atrial fibrillation risk in randomized clinical studies using redox-related therapies.

Adipose Tissue Dysfunction as Determinant of Obesity-Associated Metabolic Complications

Obesity is a critical risk factor for the development of type 2 diabetes (T2D), and its prevalence is rising worldwide. White adipose tissue (WAT) has a crucial role in regulating systemic energy homeostasis. Adipose tissue expands by a combination of an increase in adipocyte size (hypertrophy) and number (hyperplasia). The recruitment and differentiation of adipose precursor cells in the subcutaneous adipose tissue (SAT), rather than merely inflating the cells, would be protective from the obesity-associated metabolic complications. In metabolically unhealthy obesity, the storage capacity of SAT, the largest WAT depot, is limited, and further caloric overload leads to the fat accumulation in ectopic tissues (e.g., liver, skeletal muscle, and heart) and in the visceral adipose depots, an event commonly defined as “lipotoxicity.” Excessive ectopic lipid accumulation leads to local inflammation and insulin resistance (IR). Indeed, overnutrition triggers uncontrolled inflammatory responses in WAT, leading to chronic low-grade inflammation, therefore fostering the progression of IR. This review summarizes the current knowledge on WAT dysfunction in obesity and its associated metabolic abnormalities, such as IR. A better understanding of the mechanisms regulating adipose tissue expansion in obesity is required for the development of future therapeutic approaches in obesity-associated metabolic complications.

Activin type II receptor signaling in cardiac aging and heart failure

Activin type II receptor (ActRII) ligands have been implicated in muscle wasting in aging and disease. However, the role of these ligands and ActRII signaling in the heart remains unclear. Here, we investigated this catabolic pathway in human aging and heart failure (HF) using circulating follistatin-like 3 (FSTL3) as a potential indicator of systemic ActRII activity. FSTL3 is a downstream regulator of ActRII signaling, whose expression is up-regulated by the major ActRII ligands, activin A, circulating growth differentiation factor-8 (GDF8), and GDF11. In humans, we found that circulating FSTL3 increased with aging, frailty, and HF severity, correlating with an increase in circulating activins. In mice, increasing circulating activin A increased cardiac ActRII signaling and FSTL3 expression, as well as impaired cardiac function. Conversely, ActRII blockade with either clinical-stage inhibitors or genetic ablation reduced cardiac ActRII signaling while restoring or preserving cardiac function in multiple models of HF induced by aging, sarcomere mutation, or pressure overload. Using unbiased RNA sequencing, we show that activin A, GDF8, and GDF11 all induce a similar pathologic profile associated with up-regulation of the proteasome pathway in mammalian cardiomyocytes. The E3 ubiquitin ligase, Smurf1, was identified as a key downstream effector of activin-mediated ActRII signaling, which increased proteasome-dependent degradation of sarcoplasmic reticulum Ca2+ ATPase (SERCA2a), a critical determinant of cardiomyocyte function. Together, our findings suggest that increased activin/ActRII signaling links aging and HF pathobiology and that targeted inhibition of this catabolic pathway holds promise as a therapeutic strategy for multiple forms of HF.

The adipo-fibrokine activin A is associated with metabolic abnormalities and left ventricular diastolic dysfunction in obese patients

Aims

Left ventricular diastolic dysfunction (LVDD) is common in obese subjects, and a relationship between epicardial adipose tissue (EAT), increased adipocytokines, and cardiovascular diseases has been reported. This study sought to examine as to whether the adipo‐fibrokine activin A is a link between increased EAT, the metabolic syndrome (MetS), and LVDD in severely obese subjects.

Methods and results

In 236 obese subjects (ø body mass index 39.8 ± 7.9 kg/m²) with a variable degree of the MetS and in 60 healthy non‐obese controls (ø body mass index 24.8 ± 3.4 kg/m²), serum activin A levels were measured and correlated with parameters of the MetS, epicardial fat thickness (EFT), and echocardiographic parameters of LVDD. Activin A levels were higher in obese than in non‐obese subjects (362 ± 124 vs. 301 ± 94 pg/mL, P = 0.0004), increased with the number of MetS components (from 285 ± 82 with no MetS component, 323 ± 94 with one or two MetS components, to 403 ± 131 pg/mL with ≥3 MetS components, P < 0.0001) and correlated with EFT (r = 0.41, P < 0.001). Furthermore, activin A levels were related to several parameters of LVDD [e.g. left atrial size (382 ± 117 vs. 352 125 pg/mL, P = 0.024), E/e′ (394 ± 108 vs. 356 ± 127 pg/mL, P = 0.005)]. LVDD was highest in MetS obese subjects with high EFT (44.3%) compared with MetS obese subjects with low EFT (27.0%), non‐MetS obese subjects with high EFT (24.2%), and non‐MetS obese subjects with low EFT (10.6%, P < 0.0001).

Conclusions

In severe obesity, activin A was significantly related to EFT, MetS, and LVDD, implicating MetS‐related alterations in the secretory profile of EAT in the pathogenesis of obesity‐related heart disease.

MRI-based assessment and characterization of epicardial and paracardial fat depots in the context of impaired glucose metabolism and subclinical left-ventricular alterations

OBJECTIVE:

To analyze the associations between epicardial and paracardial fat and impaired glucose tolerance as well as left ventricular (LV) alterations.

METHODS:

400 subjects underwent 3 T MRI and fat depots were delineated in the four chamber-view of the steady-state free precession cine sequence (repetition time: 29.97 ms; echo time 1.46 ms). LV parameters were also derived from MRI. Oral glucose tolerance tests were performed.

RESULTS:

Epi- and paracardial fat was derived in 372 (93%) subjects (220 healthy controls, 100 persons with prediabetes, 52 with diabetes). Epi- and paracardial fat increased from normal glucose tolerance (NGT) to prediabetes and diabetes (7.7 vs 9.2 vs 10.3 cm² and 14.3 vs 20.3 vs 27.4 cm², respectively; all p < 0.001). However, the association between impaired glucose metabolism and cardiac fat attenuated after adjustment, mainly confounded by visceral adipose tissue (VAT). 93 subjects (27%) had LV impairment, defined as late gadolinium enhancement, ejection fraction < 55% or LV concentricity index > 1.3 g ml^-1 . Mean epicardial fat was higher in subjects with LV impairment (11.0 vs 8.1 cm², p < 0.001). This association remained independent after adjustment for traditional risk factors and VAT [β: 1.13 (0.22; 2.03), p = 0.02].

CONCLUSION:

Although epicardial and paracardial fat are increased in prediabetes and diabetes, the association is mostly confounded by VAT. Epicardial fat is independently associated with subclinical LV impairment in subjects without known cardiovascular disease.

ADVANCES IN KNOWLEDGE:

This study contributes to the picture of epicardial fat as a pathogenic local fat depot that is independently associated with MR-derived markers of left ventricular alterations.

Linking Arrhythmias and Adipocytes: Insights, Mechanisms, and Future Directions

Obesity and atrial fibrillation have risen to epidemic levels worldwide and may continue to grow over the next decades. Emerging evidence suggests that obesity promotes atrial and ventricular arrhythmias. This has led to trials employing various strategies with the ultimate goal of decreasing the atrial arrhythmic burden in obese patients. The effectiveness of these interventions remains to be determined. Obesity is defined by the expansion of adipose mass, making adipocytes a prime candidate to mediate the pro-arrhythmogenic effects of obesity. The molecular mechanisms linking obesity and adipocytes to increased arrhythmogenicity in both the atria and ventricles remain poorly understood. In this focused review, we highlight areas of potential molecular interplay between adipocytes and cardiomyocytes. The effects of adipocytes may be direct, local or remote. Direct effect refers to adipocyte or fatty infiltration of the atrial and ventricular myocardium itself, possibly causing increased dispersion of normal myocardial electrical signals and fibrotic substrate of adipocytes that promote reentry or adipocytes serving as a direct source of aberrant signals. Local effects may originate from nearby adipose depots, specifically epicardial adipose tissue (EAT) and pericardial adipose tissue, which may play a role in the secretion of adipokines and chemokines that can incite inflammation given the direct contact and disrupt the conduction system. Adipocytes can also have a remote effect on the myocardium arising from their systemic secretion of adipokines, cytokines and metabolites. These factors may lead to mitochondrial dysfunction, oxidative stress, autophagy, mitophagy, autonomic dysfunction, and cardiomyocyte death to ultimately produce a pro-arrhythmogenic state. By better understanding the molecular mechanisms connecting dysfunctional adipocytes and arrhythmias, novel therapies may be developed to sever the link between obesity and arrhythmias.

Is echocardiographic epicardial fat thickness increased in patients with coronary artery disease? A systematic review and meta-analysis

Background

The relation of epicardial fat thickness (EFT) to coronary artery disease (CAD) has recently been reported in multiple studies. Echocardiography is a safe and relatively inexpensive and accessible approach to assess regional EFT, which can be performed easily in many centers.

Objective

To determine the association between echocardiographic EFT and the presence or the absence of CAD.

Methods

This was a systematic review and meta-analysis conducted on literature available in electronic databases up to March 2018. The articles measuring EFT by echocardiography in the right ventricular (RV) free wall were included in the study. The quality of the enrolled items was assessed using the Methodological Index for Non-Randomized Studies (MINORS) checklist. The analyses were performed using the Comprehensive Meta-Analysis version 2 software. Cochran’s Q test and I² index were used to evaluate heterogeneity.

Results

This meta-analysis was performed on 13 studies involving 2,436 patients (1,622 with CAD, and 814 without CAD). The maximum EFT reported by echocardiography was 12.9±2.7 mm in the CAD group and 8.4±2.5 mm in the non-CAD group. The minimum EFT reported by echocardiography was 2.2±1.8 mm in the CAD group and 1.8±1.4 mm in the non-CAD group. The heterogeneity was found among the researched studies (I²=91.8%, p=0.000, Q-value=146.43, df [Q] =12) using the random effect model. The patients with CAD had a significantly higher echocardiographic EFT than those without CAD (SMD=1.03, 95% CI= 0.70–1.37, p=0.000).

Conclusion

According to the findings of this meta-analysis, the echocardiographic EFT in the subjects with CAD was significantly higher than that of those without CAD. The measurement of echocardiographic EFT seems to be an acceptable strategy for risk stratification of heart diseases considering ease of use, cost-effectiveness and non-exposure characteristics, compared to other imaging interventions.

Epicardial adipose tissue feeding and overfeeding the heart

Epicardial adipose tissue is a particular visceral fat depot with unique anatomic, biomolecular, and genetic features. Epicardial fat displays both physiological and pathological properties. Epicardial fat expresses genes and secretes cytokines actively involved in the thermogenesis and regulation of lipid and glucose metabolism of the adjacent myocardium. A disequilibrium between epicardial fat feeding and overfeeding the myocardium with free fatty acids leads to intramyocardial fat infiltration causing organ damage and clinical consequences. The upregulation of epicardial fat proinflammatory and lipogenic genes contributes to the fat build up in the proximal coronary arteries. Epicardial fat is a measurable and modifiable risk factor that can serve as a novel and additional tool for cardiovascular risk stratification. Pharmacologically targeting epicardial fat with drugs such as glucagon peptide-like 1 analogs or sodium glucose transport 2 inhibitors reduces the epicardial fat burden and induces beneficial cardiometabolic effects. Assessment and manipulation of epicardial fat transcriptome might open new avenues in the prevention of cardiometabolic diseases.

Epicardial adipose tissue as a metabolic transducer: role in heart failure and coronary artery disease

Obesity and diabetes are strongly associated with metabolic and cardiovascular disorders including dyslipidemia, coronary artery disease, hypertension, and heart failure. Adipose tissue is identified as a complex endocrine organ, which by exerting a wide array of regulatory functions at the cellular, tissue and systemic levels can have profound effects on the cardiovascular system. Different terms including "epicardial," "pericardial," and "paracardial" have been used to describe adipose tissue deposits surrounding the heart. Epicardial adipose tissue (EAT) is a unique and multifaceted fat depot with local and systemic effects. The functional and anatomic proximity of EAT to the myocardium enables endocrine, paracrine, and vasocrine effects on the heart. EAT displays a large secretosome, which regulates physiological and pathophysiological processes in the heart. Perivascular adipose tissue (PVAT) secretes adipose-derived relaxing factor, which is a "cocktail" of cytokines, adipokines, microRNAs, and cellular mediators, with a potent effect on paracrine regulation of vascular tone, vascular smooth muscle cell proliferation, migration, atherosclerosis-susceptibility, and restenosis. Although there are various physiological functions of the EAT and PVAT, a phenotypic transformation can lead to a major pathogenic role in various cardiovascular diseases. The equilibrium between the physiological and pathophysiological properties of EAT is very delicate and susceptible to the influences of intrinsic and extrinsic factors. Various adipokines secreted from EAT and PVAT have a profound effect on the myocardium and coronary arteries; targeting these adipokines could be an important therapeutic approach to counteract cardiovascular disease.

Increased activin A levels in prediabetes and association with carotid intima-media thickness: a cross-sectional analysis from I-Lan Longitudinal Aging Study

Activin A and its binding protein follistatin may be crucial in glucose homeostasis, as multifunctional proteins mediating inflammatory and anti-inflammatory effects. However, clinical data on the activin A level in prediabetes, and the association between the circulating activin A level and carotid intima-media thickness (cIMT), are lacking. We aimed to investigate activin A and follistatin levels and their associations with cIMT. In total, 470 inhabitants of I-Lan county (235 men; mean age 69 ± 9 years) with measurements of serum activin A and follistatin levels were included. Patients with prediabetes and diabetes had significantly increased activin A concentrations compared with those in the normal glycemic group (both p < 0.001). A multivariable logistic regression model demonstrated that the circulating activin A level was associated with prediabetes and diabetes independently of other risk factors. Moreover, the circulating activin A levels were associated positively with cIMT in prediabetes (r_s = 0.264, p = 0.001). In conclusion, activin A level, but not follistatin, was elevated independent of demographic variables with borderline significance and was correlated positively with cIMT in prediabetes. Activin A and follistatin levels were elevated in diabetes. In addition, elevated activin A was an independent risk factor for prediabetes and diabetes.

Mechanisms and Drug Development in Atrial Fibrillation

Atrial fibrillation is a highly prevalent cardiac arrhythmia and the most important cause of embolic stroke. Although genetic studies have identified an increasing assembly of AF-related genes, the impact of these genetic discoveries is yet to be realized. In addition, despite more than a century of research and speculation, the molecular and cellular mechanisms underlying AF have not been established, and therapy for AF, particularly persistent AF, remains suboptimal. Current antiarrhythmic drugs are associated with a significant rate of adverse events, particularly proarrhythmia, which may explain why many highly symptomatic AF patients are not receiving any rhythm control therapy. This review focuses on recent advances in AF research, including its epidemiology, genetics, and pathophysiological mechanisms. We then discuss the status of antiarrhythmic drug therapy for AF today, reviewing molecular mechanisms, and the possible clinical use of some of the new atrial-selective antifibrillatory agents, as well as drugs that target atrial remodeling, inflammation and fibrosis, which are being tested as upstream therapies to prevent AF perpetuation. Altogether, the objective is to highlight the magnitude and endemic dimension of AF, which requires a significant effort to develop new and effective antiarrhythmic drugs, but also improve AF prevention and treatment of risk factors that are associated with AF complications.

Potentiation of Insulin Signaling Contributes to Heart Failure in Type 2 Diabetes: A Hypothesis Supported by Both Mechanistic Studies and Clinical Trials

The heightened risk of heart failure in type 2 diabetes cannot be explained by the occurrence of clinically overt myocardial ischemic events or hyperglycemia. Experimentally, insulin exerts detrimental effects on the heart, vasculature, kidneys, and adipose tissue that can lead to heart failure. In both randomized clinical trials and observational studies, antihyperglycemic drugs that act through insulin signaling (i.e., sulfonylureas, thiazolidinediones, and incretins) increase the risk or worsen the clinical course of heart failure, whereas drugs that ameliorate hyperinsulinemia and do not signal through insulin (i.e., metformin and sodium-glucose cotransporter 2 inhibitors) reduce the risk of heart failure.

Interplay between epicardial adipose tissue, metabolic and cardiovascular diseases

Cardiovascular disease is the primary cause of death in obese and diabetic patients. In these groups of patients, the alterations of epicardial adipose tissue (EAT) contribute to both vascular and myocardial dysfunction. Therefore, it is of clinical interest to determine the mechanisms by which EAT influences cardiovascular disease. Two key factors contribute to the tight intercommunication among EAT, coronary arteries and myocardium. One is the close anatomical proximity between these tissues. The other is the capacity of EAT to secrete cytokines and other molecules with paracrine and vasocrine effects on the cardiovascular system. Epidemiological studies have demonstrated that EAT thickness is associated with not only metabolic syndrome but also atherosclerosis and heart failure. The evaluation of EAT using imaging modalities, although effective, presents several disadvantages including radiation exposure, limited availability and elevated costs. Therefore, there is a clinical interest in EAT as a source of new biomarkers of cardiovascular and endocrine alterations. In this review, we revise the mechanisms involved in the protective and pathological role of EAT and present the molecules released by EAT with greater potential to become biomarkers of cardiometabolic alterations.