Echocardiographic abnormalities in normotensive obese patients: relationship with visceral fat

Global epidemiology of heart failure

Heart failure (HF) is a heterogeneous clinical syndrome marked by substantial morbidity and mortality. The natural history of HF is well established; however, epidemiological data are continually evolving owing to demographic shifts, advances in treatment and variations in access to health care. Although the incidence of HF has stabilized or declined in high-income countries over the past decade, its prevalence continues to increase, driven by an ageing population, an increase in risk factors, the effectiveness of novel therapies and improved survival. This rise in prevalence is increasingly noted among younger adults and is accompanied by a shift towards HF with preserved ejection fraction. However, disparities exist in our epidemiological understanding of HF burden and progression in low-income and middle-income countries owing to the lack of comprehensive data in these regions. Therefore, the current epidemiological landscape of HF highlights the need for periodic surveillance and resource allocation tailored to geographically vulnerable areas. In this Review, we highlight global trends in the burden of HF, focusing on the variations across the spectrum of left ventricular ejection fraction. We also discuss evolving population-based estimates of HF incidence and prevalence, the risk factors for and aetiologies of this disease, and outcomes in different geographical regions and populations.

The effects of bariatric surgery on cardiac function: a systematic review and meta-analysis

INTRODUCTION

Obesity is associated with alterations in cardiac structure and haemodynamics leading to cardiovascular mortality and morbidity. Culminating evidence suggests improvement of cardiac structure and function following bariatric surgery.

OBJECTIVE

To evaluate the effect of bariatric surgery on cardiac structure and function in patients before and after bariatric surgery.

METHODS

Systematic review and meta-analysis of studies reporting pre- and postoperative cardiac structure and function parameters on cardiac imaging in patients undergoing bariatric surgery.

RESULTS

Eighty studies of 3332 patients were included. Bariatric surgery is associated with a statistically significant improvement in cardiac geometry and function including a decrease of 12.2% (95% CI 0.096-0.149; p < 0.001) in left ventricular (LV) mass index, an increase of 0.155 (95% CI 0.106-0.205; p < 0.001) in E/A ratio, a decrease of 2.012 mm (95% CI 1.356-2.699; p < 0.001) in left atrial diameter, a decrease of 1.16 mm (95% CI 0.62-1.69; p < 0.001) in LV diastolic dimension, and an increase of 1.636% (95% CI 0.706-2.566; p < 0.001) in LV ejection fraction after surgery.

CONCLUSION

Bariatric surgery led to reverse remodelling and improvement in cardiac geometry and function driven by metabolic and haemodynamic factors.

Assessment of Epicardial Fat in Children: Its Role as a Cardiovascular Risk Factor and How It Is Influenced by Lifestyle Habits

Epicardial adipose tissue (EAT) stands out as a distinctive repository of visceral fat, positioned in close anatomical and functional proximity to the heart. EAT has emerged as a distinctive reservoir of visceral fat, intricately interlinked with cardiovascular health, particularly within the domain of cardiovascular diseases (CVDs). The aim of our overview is to highlight the role of EAT as a marker for cardiovascular risk in children. We also explore the influence of unhealthy lifestyle habits as predisposing factors for the deposition of EAT. The literature data accentuate the consequential impact of lifestyle choices on EAT dynamics, with sedentary behavior and unwholesome dietary practices being contributory to a heightened cardiovascular risk. Lifestyle interventions with a multidisciplinary approach are therefore pivotal, involving a nutritionally balanced diet rich in polyunsaturated and monounsaturated fatty acids, regular engagement in aerobic exercise, and psychosocial support to effectively mitigate cardiovascular risks in children. Specific interventions, such as high-intensity intermittent training and circuit training, reveal favorable outcomes in diminishing the EAT volume and enhancing cardiometabolic health. Future clinical studies focusing on EAT in children are crucial for advancing our understanding and developing targeted strategies for cardiovascular risk management in this population.

Fat cardiomyopathy in patients with severe degree of obesity. Case report

Currently, the world is constantly increasing the number of people with obesity. As was shown by the Framingham study, obesity is a risk factor for many cardiovascular diseases. The effect of obesity on the structure and function of the heart is manifested in the form of cardiac remodeling, the effect on energy metabolism in the heart and infiltration of both myocardium with lipids, and an increase in the accumulation of adipose tissue in the pericardium, imbalance of adipokines and activation of inflammatory markers. Cardiac remodeling occurs primarily due to thickening of the left ventricle (LV) walls and an increase in the LV myocardium mass. Systolic dysfunction of the heart is less common in obese individuals compared with diastolic dysfunction. However, more modern methods (tissue Doppler, visualization of the deformation of the chambers of the heart strain imaging) reveal a subclinical decrease in systolic function in people with obesity. It is not fully known whether obesity is associated with systolic dysfunction, regardless of other risk factors. In any case, it has been proven that heart failure in people with obesity can develop independently of other risk factors. As an illustration, we give an example when the presence of obesity and concomitant pathology (arterial hypertension, diabetes) led to the development of systolic dysfunction with a decrease in the LV ejection fraction to 35% (fat cardiopathy), which show the potential for the influence of both obesity itself and in combination with concomitant diseases to lead to severe systolic heart failure.

Cardiac remodeling in patients with childhood-onset craniopharyngioma-results of HIT-Endo and KRANIOPHARYNGEOM 2000/2007

Hypothalamic obesity caused by childhood-onset craniopharyngioma results in long-term cardiovascular morbidity. Knowledge about clinical markers and risk factors for cardiovascular morbidity is scarce. A cross-sectional study on transthoracic echocardiographic parameters was performed to determine the associations with clinical and anthropometric parameters in 36 craniopharyngioma patients. BMI correlated with the thickness of interventricular septum in diastole (IVSd) (r = 0.604, p < 0.001) and left ventricular posterior wall thickness in diastole (LVPWd) (r = 0.460, p = 0.011). In multivariate analyses on risk factors for cardiac remodeling, sex hormone replacement therapy, BMI, and male gender were positively correlated with increased left ventricular internal diameter in diastole (LVIDd), R² = 0.596, F = 10.323, p < 0.001. BMI and insulin resistance were selected as significant independent determinants of IVSd, produced R² = 0.655, F = 29.441, p < 0.001. Due to a wide range of disease duration, 17 pediatric and 19 adult patients were analyzed separately. In the adult subgroup (age at study ≥ 18 years), BMI correlated with IVSd (r = 0.707, p = 0.003), LVPWd (r = 0.592, p = 0.020), and LVIDd (r = 0.571, p = 0.026). In the pediatric subgroup (age at study < 18 years), no correlation between transthoracic echocardiography (TTE) parameters and BMI was observed. Only LVIDd correlated with disease duration (r = 0.645, p < 0.001). All cardiac functions were within the normal range, indicating no association with functional impairments.Conclusion: Cardiac remodeling in patients with craniopharyngioma correlated with the degree of hypothalamic obesity, disease duration, sex hormone replacement therapy, male gender, and insulin resistance. As echocardiography has limited sensitivity in patients with obesity, further research on more sensitive techniques for cardiac diagnostics in craniopharyngioma patients is warranted. What is Known: •Long-term prognosis in survivors of craniopharyngioma is impaired by obesity and cardiovascular disease. •Associations between echocardiographic findings and clinical and anthropometric parameters after craniopharyngioma are not yet analyzed. What is New: •In patients with childhood-onset craniopharyngioma, cardiac remodeling was associated with hypothalamic obesity, duration of disease, male gender sex hormone replacement, and insulin resistance. •Due to reduced echocardiographic sensitivity caused by obesity-related technical limitations, more sensitive cardiac diagnostics should be considered.

Automatic quantification of myocardium and pericardial fat from coronary computed tomography angiography: a multicenter study

OBJECTIVES

To develop a deep learning-based method for simultaneous myocardium and pericardial fat quantification from coronary computed tomography angiography (CCTA) for the diagnosis and treatment of cardiovascular disease (CVD).

METHODS

We retrospectively identified CCTA data obtained between May 2008 and July 2018 in a multicenter (six centers) CVD study. The proposed method was evaluated on 422 patients' data by two studies. The first overall study involves training model on CVD patients and testing on non-CVD patients, as well as training on non-CVD patients and testing on CVD patients. The second study was performed using the leave-center-out approach. The method performance was evaluated using Dice similarity coefficient (DSC), Jaccard index (JAC), 95% Hausdorff distance (HD95), mean surface distance (MSD), residual mean square distance (RMSD), and the center of mass distance (CMD). The robustness of the proposed method was tested using the nonparametric Kruskal-Wallis test and post hoc test to assess the equality of distribution of DSC values among different tests.

RESULTS

The automatic segmentation achieved a strong correlation with contour (ICC and R > 0.97, p value < 0.001 throughout all tests). The accuracy of the proposed method remained high through all the tests, with the median DSC higher than 0.88 for pericardial fat and 0.96 for myocardium. The proposed method also resulted in mean MSD, RMSD, HD95, and CMD of less than 1.36 mm for pericardial fat and 1.00 mm for myocardium.

CONCLUSIONS

The proposed deep learning-based segmentation method enables accurate simultaneous quantification of myocardium and pericardial fat in a multicenter study.

KEY POINTS

• Deep learning-based myocardium and pericardial fat segmentation method tested on 422 patients' coronary computed tomography angiography in a multicenter study. • The proposed method provides segmentations with high volumetric accuracy (ICC and R > 0.97, p value < 0.001) and similar shape as manual annotation by experienced radiologists (median Dice similarity coefficient ≥ 0.88 for pericardial fat and 0.96 for myocardium).

Obesity Phenotypes, Diabetes, and Cardiovascular Diseases

This review addresses the interplay between obesity, type 2 diabetes mellitus, and cardiovascular diseases. It is proposed that obesity, generally defined by an excess of body fat causing prejudice to health, can no longer be evaluated solely by the body mass index (expressed in kg/m²) because it represents a heterogeneous entity. For instance, several cardiometabolic imaging studies have shown that some individuals who have a normal weight or who are overweight are at high risk if they have an excess of visceral adipose tissue-a condition often accompanied by accumulation of fat in normally lean tissues (ectopic fat deposition in liver, heart, skeletal muscle, etc). On the other hand, individuals who are overweight or obese can nevertheless be at much lower risk than expected when faced with excess energy intake if they have the ability to expand their subcutaneous adipose tissue mass, particularly in the gluteal-femoral area. Hence, excessive amounts of visceral adipose tissue and of ectopic fat largely define the cardiovascular disease risk of overweight and moderate obesity. There is also a rapidly expanding subgroup of patients characterized by a high accumulation of body fat (severe obesity). Severe obesity is characterized by specific additional cardiovascular health issues that should receive attention. Because of the difficulties of normalizing body fat content in patients with severe obesity, more aggressive treatments have been studied in this subgroup of individuals such as obesity surgery, also referred to as metabolic surgery. On the basis of the above, we propose that we should refer to obesities rather than obesity.

Obesity and Mechanisms of its Negative Impact on the Cardiovascular System

Currently, the number of obese people in the world is constantly increasing. Obesity has a direct negative impact on the heart and blood vessels, which can be considered not only as an appropriate response to an increase in the volume of circulating blood due to an increase in body weight, but also as a side tissue reaction of the myocardium to hormonal and metabolic changes inherent in obesity. Our review is devoted to the description of the mechanisms of influence of obesity on the structural and functional parameters of the heart, which create prerequisites for the development of cardiovascular diseases, as well as the existing contradictions. Currently, the accumulated data suggest that an excessive amount of adipose tissue, in addition to metabolic disorders, including insulin resistance, imbalance of adipokines and inflammation markers, leading to the development of lipotoxicity, can directly penetrate the myocardium and cause violations of its contractile properties, as well as affect the conduction of excitation pulses and provoke the development of rhythm and conduction disorders. The development of endothelial dysfunction in obesity ultimately leads to the development of atherosclerosis and coronary heart disease. In addition, obesity contributes to the emergence of risk factors for hypertension, diabetes, atrial fibrillation, chronic heart failure, obstructive sleep apnea syndrome. Given the differences in the literature on the effect of obesity on long-term outcomes in patients with cardiovascular diseases, it is important to conduct prospective studies on the role of individual factors and their combinations that affect the mortality of patients with cardiovascular diseases.

Cardiac Structure and Function in Morbidly Obese Parturients: An Echocardiographic Study

BACKGROUND

The increasing prevalence of obesity worldwide is a major threat to global health. Cardiac structural and functional changes are well documented for obesity as well as for pregnancy, but there is limited literature on morbidly obese parturients. We hypothesized that there are both cardiac structural and functional differences between morbidly obese pregnant women and pregnant women of normal body mass index (BMI).

METHODS

This prospective cross-sectional study was performed in 2 referral maternity units in Cape Town, South Africa, over a 3-month period. Forty morbidly obese pregnant women of BMI ≥40 kg·m (group O) were compared to 45 pregnant women of BMI ≤30 kg·m (group N). Cardiac structure and function were assessed by transthoracic echocardiography, according to the recommendations of the British Society of Echocardiography. The 2-sample t-test with unequal variances was used for the comparison of the mean values between the groups.

RESULTS

Acceptable echocardiographic images were obtained in all obese women. Statistical significance was defined as P < .0225 after applying the Benjamini-Hochberg correction for multiple testing. Mean (standard deviation) mean arterial pressure was higher in group O (91 [8.42] vs 84 [9.49] mm Hg, P < .001). There were no between-group differences in heart rate, stroke volume, or cardiac index (84 [12] vs 79 [13] beats·minute, P = .103; 64.4 [9.7] vs 59.5 [13.5] mL, P = .069; 2551 [474] vs 2729 [623] mL·minute·m, P = .156, for groups O and N, respectively). Stroke volume index was lower, and left ventricular mass was higher in group O (30.14 [4.51] vs 34.25 [7.00] mL·m, P = .003; 152 [24] vs 115 [29] g, P < .001). S' septal was lower in group O (8.43 [1.20] vs 9.25 [1.64] cm·second, P = .012). Considering diastolic function, isovolumetric relaxation time was significantly prolonged in group O (73 [15] vs 61 [15] milliseconds, P < .001). The septal tissue Doppler index E' septal was lower in group O (9.08 [1.69] vs 11.28 [3.18], P < .001). There were no between-group differences in E' average (10.7 [2.3] vs 12.0 [2.7], P = .018, O versus N) or E/E' average (7.85 [1.77] vs 7.27 [1.68], P = .137, O versus N). Right ventricular E'/A' was lower in group O (1.07 [0.47] vs 1.29 [0.32], P = .016).

CONCLUSIONS

Cardiac index did not differ between obese pregnant women and those with normal BMI. Their increased left ventricular mass and lower stroke volume index could indicate a limited adaptive reserve. Obese women had minor decreases in septal left ventricular tissue Doppler velocity, but the E/E' average values did not suggest clinically significant diastolic dysfunction.

Obesity, Echocardiographic Changes and Framingham Risk Score in the Spectrum of Gout: A Cross-Sectional Study

Objectives

This study aims to establish cardiovascular risk in obese and non-obese patients in stages of gout by using Framingham risk score (FRS) and transthoracic echocardiography.

Patients and methods

This single-center cross-sectional study encompassed 201 patients (160 males, 41 females; mean age 56.9±13 years; range 20 to 89 years) including 52 asymptomatic hyperuricemia, 86 gouty arthritis without tophi, and 63 gouty tophi patients. Body Mass Index (BMI) and FRS were calculated. Left atrium (LA), interventricular septum, posterior wall (PW) of the left ventricle, fractional shortening (FS), mitral annular systolic velocity (S'), mitral annular early diastolic velocity (E') and transmitral to mitral annular early diastolic velocity ratio (E/E') were measured. Data were analyzed by Kolmogorov-Smirnov test, Shapiro-Wilk test, t-test, Mann-Whitney U test, analysis of variance test and multiple linear regression models.

Results

There was no significant difference in FRS, FS, S', E' and E/E' between obese and non-obese patients with asymptomatic hyperuricemia, gouty arthritis without tophi or gouty tophi. Obese patients in the three disease gradations had larger LA (p=0.007, p=0.004, p=0.039) and thicker PW (p=0.002, p=0.037, p=0.007). Increased BMI independently predicted the thickening of the PW in asymptomatic hyperuricemia (R2=0.319), gouty arthritis without tophi (R2=0.093) and gouty tophi (R2=0.068).

Conclusion

Despite the lack of difference in FRS and functional systolic and diastolic parameters between obese and non-obese patients in the spectrum of gout, morphological heart changes were more pronounced in obese patients. In gouty tophi, it is possible that higher urate load together with chronic inflammation contribute for the alterations, as obesity worsens them.

Effect of epicardial fat and metabolic syndrome on reverse atrial remodeling after ablation for atrial fibrillation

BACKGROUND

Metabolic syndrome/epicardial adipose tissue (EAT) plays an important role in atrial fibrillation (AF). Although reverse atrial remodeling (RAR) often occurs after AF ablation, the effects of EAT on RAR remain unknown.

METHODS

Study subjects were 104 patients in whom transthoracic echocardiography (TTE) was performed before AF ablation and 3, 6, and 12 months afterward. EAT was assessed in terms of its thickness adjacent to the right ventricular anterior wall in the TTE parasternal view. RAR was defined as >10% reduction in the left atrial volume (LAV) index by the 3-month follow-up examination.

RESULTS

Postablation RAR occurred in 57/104 (55%) patients. RAR absence was associated with a relatively thick EAT (4.92 ± 1.65 vs. 3.92 ± 1.17 mm, P = 0.0005), small LAV index (24.6 ± 7.5 vs. 28.8 ± 10.6 mL/m2, P = 0.0233), and metabolic syndrome (62% vs. 28%, P = 0.0006). Metabolic syndrome and EAT were shown to be independent predictors of RAR absence. Thick EAT was significantly associated with AF recurrence after ablation (5.05 ± 2.19 mm vs. 4.17 ± 1.16 mm for no AF recurrence group, P = 0.0116), but metabolic syndrome was not (48% vs. 42%, P = 0.6189). Despite no change in body weight, EAT thickness decreased significantly by 12 months in patients without AF recurrence (4.17 ± 1.16 vs. 3.65 ± 1.16 mm, P < 0.0001).

CONCLUSIONS

EAT and metabolic syndrome appear to be strongly associated with RAR absence, but only the thick EAT was significantly associated with the postablation AF recurrence. Our findings, especially the thinning of EAT, suggest that thick EAT lead to AF vulnerability but that EAT reduction favorably affects ablation outcome.

Multimarker Assessment of Diastolic Dysfunction in Metabolic Syndrome Patients

BACKGROUND

Metabolic syndrome (MetS) has been associated with left ventricular diastolic dysfunction (LVDD) with preserved systolic function. This study aims at identifying the predictive factors for LVDD in MetS patients.

METHODS

The studied group comprised 72 consecutive hospitalized patients (2010-2011) diagnosed with MetS based on AHA/NHLBI/IDF 2009 definition, free of cardiovascular disease (36.11% males, age 59.19 ± 5.26 years), who underwent echocardiographic examination. Laboratory measurements of high-sensitivity C-reactive protein (hs-CRP), fibrinogen (Fbg) and interleukin-6 (IL-6), 8-isoprostaglandin-F2alpa (8-isoPGF2α), uric acid, glutathione peroxidases, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were measured.

RESULTS

LVDD was identified in 47 (65.27%) of the MetS patients. The diastolic blood pressure (DBP) was the strongest prediction factor for LVDD (areas under the receiver operating curve [AUC]: 0.73, odds ratios [OR]: 1.065). The number of MetS criteria was also significantly predictive for LVDD (AUC: 0.65, OR: 2.029, P < 0.04). IL-6, hs-CRP, Fbg, and NT-proBNP were predictive for LVDD when receiver operating curve (ROC) analyses were used. The multimarker model comprising age, sex, SBP and DBP, waist, circumference, triglycerides along with hs-CRP, IL-6, and NT-proBNP had the best predictive capacity (AUC: 0.88, P = 0.0001). In multivariate analysis, IL-6 remained an independent predictive biomarker for LVDD (OR: 2.045).

CONCLUSION

Both MetS components and biomarkers of inflammation (IF) are predictive factors for LVDD. The best predictive multimarker model for LVDD in MetS patients is composed of waist, triglycerides (TGL), SBP, DBP, fasting glucose, IL-6, hs-CRP, and NT-proBNP. IL-6 remains an independent predictive biomarker for LVDD in MetS patients, underlining the importance of IF in the evolution of MetS to subclinical cardiac damage.

Obesity and atrial fibrillation: A comprehensive review of the pathophysiological mechanisms and links

Obesity is a worldwide health problem with epidemic proportions that has been associated with atrial fibrillation (AF). Even though the underlying pathophysiological mechanisms have not been completely elucidated, several experimental and clinical studies implicate obesity in the initiation and perpetuation of AF. Of note, hypertension, diabetes mellitus, metabolic syndrome, coronary artery disease, and obstructive sleep apnea, represent clinical correlates between obesity and AF. In addition, ventricular adaptation, diastolic dysfunction, and epicardial adipose tissue appear to be implicated in atrial electrical and structural remodeling, thereby promoting the arrhythmia in obese subjects. The present article provides a concise overview of the association between obesity and AF, and highlights the underlying pathophysiological mechanisms.

Heart failure and atrial fibrillation: from basic science to clinical practice

Heart failure (HF) and atrial fibrillation (AF) are two growing epidemics associated with significant morbidity and mortality. They often coexist due to common risk factors and shared pathophysiological mechanisms. Patients presenting with both HF and AF have a worse prognosis and present a particular therapeutic challenge to clinicians. This review aims to appraise the common pathophysiological background, as well as the prognostic and therapeutic implications of coexistent HF and AF.

Chronic high-fat diet-induced obesity decreased survival and increased hypertrophy of rats with experimental eccentric hypertrophy from chronic aortic regurgitation

Background

The composition of a diet can influence myocardial metabolism and development of left ventricular hypertrophy (LVH). The impact of a high-fat diet in chronic left ventricular volume overload (VO) causing eccentric LVH is unknown. This study examined the effects of chronic ingestion of a high-fat diet in rats with chronic VO caused by severe aortic valve regurgitation (AR) on LVH, function and on myocardial energetics and survival.

Methods

Male Wistar rats were divided in four groups: Shams on control or high-fat (HF) diet (15 rats/group) and AR rats fed with the same diets (ARC (n = 56) and ARHF (n = 32)). HF diet was started one week before AR induction and the protocol was stopped 30 weeks later.

Results

As expected, AR caused significant LV dilation and hypertrophy and this was exacerbated in the ARHF group. Moreover, survival in the ARHF group was significantly decreased compared the ARC group. Although the sham animals on HF also developed significant obesity compared to those on control diet, this was not associated with heart hypertrophy. The HF diet in AR rats partially countered the expected shift in myocardial energy substrate preference usually observed in heart hypertrophy (from fatty acids towards glucose). Systolic function was decreased in AR rats but HF diet had no impact on this parameter. The response to HF diet of different fatty acid oxidation markers as well as the increase in glucose transporter-4 translocation to the plasma membrane compared to ARC was blunted in AR animals compared to those on control diet.

Conclusions

HF diet for 30 weeks decreased survival of AR rats and worsened eccentric hypertrophy without affecting systolic function. The expected adaptation of myocardial energetics to volume-overload left ventricle hypertrophy in AR animals seemed to be impaired by the high-fat diet suggesting less metabolic flexibility.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2261-14-123) contains supplementary material, which is available to authorized users.

Long-term obesity promotes alterations in diastolic function induced by reduction of phospholamban phosphorylation at serine-16 without affecting calcium handling

Few studies have evaluated the relationship between the duration of obesity, cardiac function, and the proteins involved in myocardial calcium (Ca(2+)) handling. We hypothesized that long-term obesity promotes cardiac dysfunction due to a reduction of expression and/or phosphorylation of myocardial Ca(2+)-handling proteins. Thirty-day-old male Wistar rats were distributed into two groups (n = 10 each): control (C; standard diet) and obese (Ob; high-fat diet) for 30 wk. Morphological and histological analyses were assessed. Left ventricular cardiac function was assessed in vivo by echocardiographic evaluation and in vitro by papillary muscle. Cardiac protein expression of sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a), calsequestrin, L-type Ca(2+) channel, and phospholamban (PLB), as well as PLB serine-16 phosphorylation (pPLB Ser(16)) and PLB threonine-17 phosphorylation (pPLB Thr(17)) were determined by Western blot. The adiposity index was higher (82%) in Ob rats than in C rats. Obesity promoted cardiac hypertrophy without alterations in interstitial collagen levels. Ob rats had increased endocardial and midwall fractional shortening, posterior wall shortening velocity, and A-wave compared with C rats. Cardiac index, early-to-late diastolic mitral inflow ratio, and isovolumetric relaxation time were lower in Ob than in C. The Ob muscles developed similar baseline data and myocardial responsiveness to increased extracellular Ca(2+). Obesity caused a reduction in cardiac pPLB Ser(16) and the pPLB Ser(16)/PLB ratio in Ob rats. Long-term obesity promotes alterations in diastolic function, most likely due to the reduction of pPLB Ser(16), but does not impair the myocardial Ca(2+) entry and recapture to SR.

Serial changes in adipocytokines and cardiac function in a rat model of the metabolic syndrome

Obesity is associated with high chronic cardiac workload due to the need to supply more blood to peripheral tissue, and frequently leads to left ventricular (LV) dysfunction. The present study examined serial changes in cardiac function in the SHR/NDmcr-cp (SHR/cp) strain, an experimental model of obesity plus hypertension and metabolic syndrome. Transthoracic echocardiography was used to define cardiac dimensions and function in male spontaneously hypertensive rats (SHR/lean), SHR/cp and Wistar-Kyoto rats. We also assessed age-related changes in plasma and LV adipocytokine levels in this model. Although there were no significant differences in LV end-diastolic diameter and end-systolic diameter among the three rat strains until 24 weeks of age, these parameters were significantly higher and LV fractional shortening (%FS) was significantly lower in SHR/cp compared with SHR/lean at 32 weeks of age. At the same age, pronounced interstitial fibrosis and infiltration of macrophages and T lymphocytes into the LV was noted in SHR/cp relative to the other strains. In the myocardium, adiponectin levels were significantly lower and resistin levels and the expression of proinflammatory cytokines (tumour necrosis factor-α and interleukin-6) were significantly higher in SHR/cp than SHR/lean at 32 weeks of age. Using echocardiography, we demonstrated reduced systolic function in 32-week-old SHR/cp. Changes in myocardial cytokine concentrations could be involved in worsening of cardiac function in our animal model of metabolic syndrome.

Expression of proteins associated with adipocyte lipolysis was significantly changed in the adipose tissues of the obese spontaneously hypertensive/NDmcr-cp rat

BACKGROUND

The etiology of the metabolic syndrome is complex, and is determined by the interplay of both genetic and environmental factors. The present study was designed to identify genes and proteins in the adipose tissues with altered expression in the spontaneously hypertensive/NIH -corpulent rat, SHR/NDmcr-cp (CP) and to find possible molecular targets associated with the pathogenesis or progression of obesity related to the metabolic syndrome.

METHODS

We extracted RNAs and proteins from the epididymal adipose tissues in CP, SHR/Lean (Lean), and Wistar Kyoto (WKY) rats and performed microarray analysis and two-dimensional difference in gel electrophoresis (2D-DIGE) linked to a matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS).

RESULTS

The results showed different mRNA and protein expression levels in the adipose tissue: oligo DNA microarray identified 33 genes that were significantly (P < 0.01) up-regulated and 17 genes significantly down-regulated in CP compared with WKY and Lean rats at both 6 and 25 weeks of age. The affected genes-proteins were associated with lipolytic enzymes stimulated by peroxisome proliferator-activated receptor (PPAR) signaling. Further analysis using the 2D-DIGE connected with MALDI-TOF/TOF analysis, the expression of monoglyceride lipase (MGLL) was significantly up-regulated and that of carboxylesterase 3 (CES3) was significantly down-regulated in 6- and 25-week-old CP compared with age-matched control (WKY and Lean rats).

CONCLUSIONS

Our results suggest the possible involvement of proteins associated with adipocyte lipolysis in obesity related to the metabolic syndrome.

Decreased plasma B-type natriuretic peptide levels in obesity are not explained by altered left ventricular hemodynamics

SUMMARY

BACKGROUND

Although obesity has been reported to be associated with decreased plasma B-type natriuretic peptide (BNP) levels, it is unknown whether the reduced BNP levels in obesity results from decreased left ventricular (LV) hemodynamic load.

METHODS

We examined the relationships between body mass index (BMI), plasma BNP levels, and LV systolic and diastolic function (ejection fraction [EF] and end-diastolic pressure [EDP]) in 271 consecutive patients undergoing cardiac catheterization for coronary artery disease. When patients were grouped by tertile of BMI, with increasing tertiles of BMI, there was a progressive increase in EDP (lower, middle, and upper tertiles of BMI, 13.5 ± 5.8, 14.9 ± 5.3, and 16.3 ± 5.4 mmHg, respectively; p for trend <0.01) and a progressive decrease in log BNP levels (lower, middle, and upper tertiles of BMI, 3.52 ± 1.29, 2.96 ± 1.08, and 2.87 ± 1.21 ln[pg/ml], respectively, p for trend < 0.001). There was no clear difference in EF across BMI tertiles (p for trend >0.1). Plasma BNP levels correlated positively with EDP (r = 0.38, p < 0.001). In multivariate linear regression including EDP and known correlates of plasma BNP levels, BMI correlated negatively with BNP levels (standardized β = -0.31, p < 0.001).

CONCLUSIONS

We found that increased BMI was associated with LV diastolic abnormalities without change in systolic function and that patients with increased BMI had reduced plasma BNP levels despite having elevated EDP. These results suggest that the reduced BNP levels in obesity are not explained by altered LV hemodynamics.

Arterial stiffness, body fat compartments, central hemodynamics, renal function and left atrial size

BACKGROUND

Left atrial (LA) size is an important predictor of stroke, death, and atrial fibrillation. It was demonstrated recently that body fat, arterial stiffness and renal functions are associated with LA diameter. However, data are lacking for comprehensive assessments of all these risk factors in a single population. Therefore, the aim of the present study was to investigate the association between LA size and different fat descriptors, central hemodynamics, arterial stiffness, and renal function in healthy subjects.

METHODS

To this end, body fat percentage, abdominal, subcutaneous fat, and general descriptors of body fat were estimated in 162 healthy subjects (mean age 51 years). Echocardiography was performed to assess LA diameter. Arterial stiffness and peripheral and central hemodynamics were estimated by digital volume pulse analysis and pulse wave analysis. Glomerular filtration rate was estimated by MDRD formula.

RESULTS

There were significant (p < 0.05) bivariate correlations between LA diameter and all descriptors of body fat (except subcutaneous fat). Arterial stiffness and estimated glomerular filtration rate (eGFR) were also significantly correlated with LA size. Multiple regression analysis including all significant confounders, such as sex, mean arterial pressure, arterial stiffness, eGFR and body fat descriptors, explained 35% of variance in LA diameter.

CONCLUSIONS

In conclusion, the present study reveals significant, independent relationships between body fat, arterial stiffness, and LA size.

Obesity in heart failure: impact on survival and treatment modalities

Heart failure (HF) and obesity are commonly seen in the USA. Although obesity is associated with traditional cardiovascular disease, its relationship with HF is complex. Obesity is an accepted risk factor for incident HF. However, in patients with established HF, there exists a paradoxical correlation, with escalating BMI incrementally protective against adverse outcomes. Despite this relationship, patients with HF may desire to lose weight to reduce comorbidities or to improve quality of life. Thus far, studies have shown that intentional weight loss in obese patients with HF does not increase risk, with strategies including dietary modification, physical activity, pharmacotherapy, and/or surgical intervention.

Improvement in cardiovascular indices after Roux-en-Y gastric bypass or sleeve gastrectomy for morbid obesity

BACKGROUND

Morbidly obese patients display cardiac abnormalities which are partially reversed after weight loss. The aim of the present study was to assess the potential difference in cardiovascular disease indices between patients who underwent either gastric bypass surgery or sleeve gastrectomy.

METHODS

Thirty-seven morbidly obese patients who underwent either Roux-en-Y gastric bypass (RYGB) (n = 14) or SG (n = 23) were examined before, 3 and 6 months after surgery. Indices of cardiac autonomic nervous system activity were evaluated, namely baroreflex sensitivity (BRS) and heart rate variability (HRV). A complete echocardiographic study was performed in a subgroup of 17 patients (RYGB 8, SG 9) preoperatively and 6 months after surgery, evaluating epicardial fat thickness, aortic distensibility, left ventricular (LV) Tei index, left atrium diameter, ejection fraction, and LV mass.

RESULTS

All subjects experienced significant (p < 0.001) and similar weight loss independently of the type of operation. BRS and HRV indices improved significantly and to the same degree after surgery in both groups. In the echocardiographic study, all parameters improved significantly at 6 months in comparison with the baseline values. In addition, the RYGB group displayed significantly greater reduction in epicardial fat thickness (p = 0.007) and also tended to have a better LV performance as expressed by the lower values of the Tei index (p = 0.06) compared to the SG group 6 months after surgery.

CONCLUSIONS

Both RYGB and SG exert comparable effects on weight loss and improvement of cardiovascular parameters. RYGB displays a more beneficial influence on epicardial fat thickness and left ventricular performance than SG.

Beneficial cardiac effects of caloric restriction are lost with age in a murine model of obesity

Obesity is associated with increased diastolic stiffness and myocardial steatosis and dysfunction. The impact of aging on the protective effects of caloric restriction (CR) is not clear. We studied 2-month (younger) and 6-7-month (older)-old ob/ob mice and age-matched C57BL/6J controls (WT). Ob/ob mice were assigned to diet ad libitum or CR for 4 weeks. We performed echocardiograms, myocardial triglyceride assays, Oil Red O staining, and measured free fatty acids, superoxide, NOS activity, ceramide levels, and Western blots. In younger mice, CR restored diastolic function, reversed myocardial steatosis, and upregulated Akt phosphorylation. None of these changes was observed in the older mice; however, CR decreased oxidative stress and normalized NOS activity in these animals. Interestingly, myocardial steatosis was not associated with increased ceramide, but CR altered the composition of ceramides. In this model of obesity, aging attenuates the benefits of CR on myocardial structure and function.

Cathepsin K knockout mitigates high-fat diet-induced cardiac hypertrophy and contractile dysfunction

The cysteine protease cathepsin K has been implicated in pathogenesis of cardiovascular disease. We hypothesized that ablation of cathepsin K protects against obesity-associated cardiac dysfunction. Wild-type mice fed a high-fat diet exhibited elevated heart weight, enlarged cardiomyocytes, increased left ventricular wall thickness, and decreased fractional shortening. All these changes were reconciled in cathepsin K knockout mice. Cathepsin K knockout partly reversed the impaired cardiomyocyte contractility and dysregulated calcium handling associated with high-fat diet. Additionally, cathepsin K knockout alleviated whole-body glucose intolerance and improved insulin-stimulated Akt phosphorylation in high-fat diet-fed mice. High-fat feeding increased the expression of cardiac hypertrophic proteins and apoptotic markers, which were inhibited by cathepsin K knockout. Furthermore, high-fat feeding resulted in cathepsin K release from lysosomes into the cytoplasm. In H9c2 myoblasts, silencing of cathepsin K inhibited palmitic acid-induced release of cytochrome c from mitochondria and expression of proapoptotic signaling molecules. Collectively, our data indicate that cathepsin K contributes to the development of obesity-associated cardiac hypertrophy and may represent a potential target for the treatment to obesity-associated cardiac anomalies.

Heart failure epicardial fat increases atrial arrhythmogenesis

BACKGROUND

Obesity is an important risk factor for atrial fibrillation (AF) and heart failure (HF). The effects of epicardial fat on atrial electrophysiology were not clear. This study was to evaluate whether HF may modulate the effects of epicardial fat on atrial electrophysiology.

METHODS

Conventional microelectrodes recording was used to record the action potential in left (LA) and right (RA) atria of healthy (control) rabbits before and after application of epicardial fat from control or HF (ventricular pacing of 360-400 bpm for 4 weeks) rabbits. Adipokine profiles were checked in epicardial fat of control and HF rabbits.

RESULTS

The LA 90% of AP duration was prolonged by control epicardial fat (from 77 ± 6 to 87 ± 7 ms, p<0.05, n=7), and by HF epicardial fat (from 78 ± 3 to 98 ± 4 ms, p<0.001, n=9). However, control or HF epicardial fat did not change the AP morphology in RA. HF epicardial fat increased the contractility in LA (61 ± 11 vs. 35 ± 6 mg, p=0.001), but not in RA. Control fat did not change the LA or RA contractility. Moreover, control and HF epicardial fat induced early and delayed afterdepolarizations in LA and RA, but only HF epicardial fat provoked spontaneous activity and burst firing in LA (n=3/9, 33.3% vs. n=0/7, 0%, n=0/9, 0%, p<0.05). Compared to control fat, HF epicardial fat, had lower resistin, C-reactive protein and serum amyloid A, but similar interleukin-6, leptin, monocyte chemotactic protein-1, adiponectin and adipsin.

CONCLUSIONS

HF epicardial fat increases atrial arrhythmogenesis, which may contribute to the higher atrial arrhythmia in obesity.

The relationship among central obesity, systemic inflammation, and left ventricular diastolic dysfunction as determined by structural equation modeling

The purpose of this study was to investigate the associations among central obesity, inflammation, and left ventricular (LV) diastolic dysfunction by structural equation modeling. Echocardiographic parameters were assessed in 102 otherwise-healthy adults over age 30. The participants were classified as having LV diastolic dysfunction by echocardiographic findings including mitral inflow E/A ratio <1, deceleration time >220 cm/s, or decreased peak annular early diastolic velocity in tissue Doppler imaging or otherwise the control group. Serum C-reactive protein (CRP) and lipid profile were also measured. The homeostasis model of insulin resistance (HOMA) was calculated. Central obesity was assessed by computerized tomography (CT) at the L4 level. In a multivariate regression analysis, the relationship between visceral adipose tissue (VAT) and LV diastolic dysfunction became insignificant when CRP was introduced into the model, although CRP itself was significantly associated with LV diastolic dysfunction (odds ratio (OR): 1.32, 95% confidence interval (CI): 1.01-1.72, P = 0.04). A significant correlation was also found between VAT and CRP (r = 0.70; P < 0.001). We then performed path analysis as illustrated by the structural equation model. This proved our hypotheses that VAT might affect LV diastolic dysfunction through the effect of CRP (total fat load with inflammation (B = 1.133, P < 0.001) and that inflammation might affect LV diastolic dysfunction (B = 0.373. P < 0.001)). Using structural equation modeling, we concluded that higher amounts of VAT were associated with low-grade inflammation and this may lead to subclinical LV diastolic dysfunction in otherwise-healthy subjects.

The influence of body composition, fat distribution, and sustained weight loss on left ventricular mass and geometry in obesity

Alterations in left ventricular mass and geometry vary along with the degree of obesity, but mechanisms underlying such covariation are not clear. In a case-control study, we examined how body composition and fat distribution relate to left ventricular structure and examine how sustained weight loss affects left ventricular mass and geometry. At the 10-year follow-up of the Swedish obese subjects (SOS) study cohort, we identified 44 patients with sustained weight losses after bariatric surgery (surgery group) and 44 matched obese control patients who remained weight stable (obese group). We also recruited 44 matched normal weight subjects (lean group). Dual-energy X-ray absorptiometry, computed tomography, and echocardiography were performed to evaluate body composition, fat distribution, and left ventricular structure. BMI was 42.5 kg/m(2), 31.5 kg/m(2), and 24.4 kg/m(2) for the obese, surgery, and lean groups, respectively. Corresponding values for left ventricular mass were 201.4 g, 157.7 g, and 133.9 g (P < 0.001). In multivariate analyses, left ventricular diastolic dimension was predicted by lean body mass (β = 0.03, P < 0.001); left ventricular wall thickness by visceral adipose tissue (β = 0.11, P < 0.001) and systolic blood pressure (β = 0.02, P = 0.019); left ventricular mass by lean body mass (β = 1.23, P < 0.001), total body fat (β = 1.15, P < 0.001) and systolic blood pressure (β = 2.72, P = 0.047); and relative wall thickness by visceral adipose tissue (β = 0.02, P < 0.001). Left ventricular adjustment to body size is dependent on body composition and fat distribution, regardless of blood pressure levels. Obesity is associated with concentric left ventricular remodeling and sustained 10-year weight loss results in lower cavity size, wall thickness and mass.

Bariatric surgery to unload the stressed heart: a metabolic hypothesis

Obesity is an independent risk factor for cardiovascular disease. Data from the Framingham Study have reported a higher incidence of heart failure in obese individuals compared with a normal cohort. The body initially copes with the abundance of fuel present in an obese milieu by storing it in adipose tissue. However, when the storage capacity is exceeded, the excess energy is taken up and stored ectopically as fat in vital organs such as the heart. Indeed, intramyocardial lipid overload is present in hearts of obese patients, as well as in hearts of animal models of obesity, and is associated with a distinct gene expression profile and cardiac dysfunction. By imposing a metabolic stress on the heart, obesity causes it to hypertrophy and ultimately to fail. Conventional measures to treat obesity include diet, exercise, and drugs. More recently, weight loss surgery (WLS) has achieved increasing prominence because of its ability to reduce the neurohumoral load, normalize metabolic dysregulation, and improve overall survival. The effects of WLS on systemic metabolic, neurohumoral, and hemodynamic parameters are well described and include an early normalization of serum glucose and insulin levels as well as reduction in blood pressure. WLS is also associated with reverse cardiac remodeling, regression of left ventricular hypertrophy, and improved left ventricular and right ventricular function. By targeting the source of the excess energy, we hypothesize that WLS improves contractile function by limiting exogenous substrate availability to the metabolically overloaded heart. These changes have also been found to be associated with increased levels of adiponectin and improved insulin sensitivity. Taken together, the sustained beneficial effects of WLS on left ventricular mass and function highlight the need to better understand the mechanism by which obesity regulates cardiovascular physiology.

Favorable changes in cardiac geometry and function following gastric bypass surgery: 2-year follow-up in the Utah obesity study

OBJECTIVES

The objective of this study was to test the hypothesis that gastric bypass surgery (GBS) would favorably impact cardiac remodeling and function.

BACKGROUND

GBS is increasingly used to treat severe obesity, but there are limited outcome data.

METHODS

We prospectively studied 423 severely obese patients undergoing GBS and a reference group of severely obese subjects that did not have surgery (n = 733).

RESULTS

At a 2-year follow up, GBS subjects had a large reduction in body mass index compared with the reference group (-15.4 ± 7.2 kg/m(2) vs. -0.03 ± 4.0 kg/m(2); p < 0.0001), as well as significant reductions in waist circumference, systolic blood pressure, heart rate, triglycerides, low-density lipoprotein cholesterol, and insulin resistance. High-density lipoprotein cholesterol increased. The GBS group had reductions in left ventricular (LV) mass index and right ventricular (RV) cavity area. Left atrial volume did not change in GBS but increased in reference subjects. In conjunction with reduced chamber sizes, GBS subjects also had increased LV midwall fractional shortening and RV fractional area change. In multivariable analysis, age, change in body mass index, severity of nocturnal hypoxemia, E/E', and sex were independently associated with LV mass index, whereas surgical status, change in waist circumference, and change in insulin resistance were not.

CONCLUSIONS

Marked weight loss in patients undergoing GBS was associated with reverse cardiac remodeling and improved LV and RV function. These data support the use of bariatric surgery to prevent cardiovascular complications in severe obesity.

Sex differences in obesity-related changes in left ventricular morphology: the Strong Heart Study

OBJECTIVES

It is unclear whether there are sex differences in the relations of left ventricular mass to body composition and fat distribution in nonobese or obese hypertensive and nonhypertensive individuals and whether the obesity-related increase in left ventricular mass is similar in men and women.

METHODS

We examined sex differences in the relations between left ventricular mass and both body composition and fat distribution, in the presence or absence of obesity in 1068 men and 1851 women (65%) of the Strong Heart Study cohort, without prevalent cardiovascular disease or severe chronic kidney disease. Fat-free mass (FFM) and adipose mass were estimated by bioelectric impedance analysis and fat distribution by waist-to-hip ratio (WHR).

RESULTS

Adipose mass was significantly higher in women than in men for any weight category (P < 0.0001). After adjusting for age, hypertension, systolic blood pressure (BP) and diabetes, both left ventricular mass/height (LVMi) and left ventricular mass (LVM)/FFM were greater in obese women than obese men (P < 0.0001). Relative wall thickness was also greater in women than in men (P < 0.0001). LVM was independently related to Doppler-stroke volume, FFM and systolic BP in both sexes, with WHR and adipose mass contributing to variance of LVM in women but not in men (both P < 0.03).

CONCLUSION

Obesity influences left ventricular geometry substantially more in women than in men, possibly due to biological factors specifically associated with female adiposity.

Epicardial fat and its association with cardiovascular risk: a cross-sectional observational study

Background:

The association between visceral obesity and cardiovascular risk has been well described. Some studies show a proportional relationship between the presence of visceral obesity and epicardial fat. Measuring the amount of epicardial adipose tissue (EAT) can be a novel parameter that is inexpensive and easy to obtain and may be helpful in cardiovascular risk stratification. However, the relationship between epicardial fat and cardiac function and that between epicardial fat and cardiac risk factors is less well described.

Objectives:

To evaluate the association between echocardiographic epicardial fat and the morphologic and physiologic changes observed at echocardiography and to evaluate the association between epicardial fat and cardiac risk factors. A cross-sectional study of 97 echocardiographic studies (females, n = 42) was conducted. Two groups were identified: epicardial fat ≥ 5 mm (group I) and <5 mm (group II).

Results:

Epicardial fat >5 mm was associated with LA enlargement, with lower ejection fraction, increased left ventricular mass, and abnormal diastolic function. On a multivariable regression analysis, all these parameters also correlated individually with EAT thickness independent of age. Hyperglycemia (DM), systolic hypertension, and lipid parameters for metabolic syndrome showed a trend for positive association, but this was not statistically significant. The association was not significant even for higher cutoff limits of EAT thickness.

Conclusion:

Epicardial fat >5 mm is associated with cardiac abnormalities on echocardiography. This is a sensitive assessment of body fat distribution, is easily available at echocardiography, and is simple to acquire at no added cost. Further studies looking at the appropriate cut-off thickness of EAT and the sites of measurement to be used are needed. Comparison of this simple and inexpensive measure with other measures of obesity, such as waist-hip ratio, body mass index, Dexa scan of visceral fat, and magnetic resonance imaging of visceral, are needed.

Assessment of atrial electromechanical delay by tissue Doppler echocardiography in obese subjects

Our aim was to evaluate whether atrial electromechanical delay measured by tissue Doppler imaging (TDI), which is an early predictor of atrial fibrillation (AF) development, is prolonged in obese subjects. A total of 40 obese and 40 normal-weight subjects with normal coronary angiograms were included in this study. P-wave dispersion (PWD) was calculated on the 12-lead electrocardiogram (ECG). Systolic and diastolic left ventricular (LV) functions, inter- and intra-atrial electromechanical delay were measured by TDI and conventional echocardiography. Inter- and intra-atrial electromechanical delay were significantly longer in the obese subjects compared with the controls (44.08 ± 10.06 vs. 19.35 ± 5.94 ms and 23.63 ± 6.41 vs. 5.13 ± 2.67 ms, P < 0.0001 for both, respectively). PWD was higher in obese subjects (53.40 ± 5.49 vs. 35.95 ± 5.93 ms, P < 0.0001). Left atrial (LA) diameter, LA volume index and LV diastolic parameters were significantly different between the groups. Interatrial electromechanical delay was correlated with PWD (r = 0.409, P = 0.009), high-sensitivity C-reactive protein (hsCRP) levels (r = 0.588, P < 0.0001). Interatrial electromechanical delay was positively correlated with LA diameter, LA volume index, and LV diastolic function parameters consisting of mitral early wave (E) deceleration time (DT) and isovolumetric relaxation time (IVRT; r = 0.323, P = 0.042; r = 0.387, P = 0.014; r = 0.339, P = 0.033; r = 0.325, P = 0.041; respectively) and, negatively correlated with mitral early (E) to late (A) wave ratio (E/A) (r = -0.380, P = 0.016) and myocardial early-to-late diastolic wave ratio (E(m)/A(m)) (r = -0.326, P = 0.040). This study showed that atrial electromechanical delay is prolonged in obese subjects. Prolonged atrial electromechanical delay is due to provoked low-grade inflammation as well as LA enlargement and early LV diastolic dysfunction in obese subjects.

Cardiac remodeling in a rat model of diet-induced obesity

The mechanisms by which diet-induced obesity cause remodeling and cardiac dysfunction are still unknown. Interstitial collagen and myocardial ultrastructure are important in the development of left ventricular hypertrophy, and are essential to the adaptive and maladaptive changes associated with obesity. Thus, the accumulation of collagen and ultrastructural damage may contribute to cardiac dysfunction in obesity. The purpose of the present study was to investigate cardiac function in a rat model of diet-induced obesity and to test the hypothesis that cardiac dysfunction induced by obesity is related to myocardial collagen deposition and ultrastructural damage. Thirty-day-old male Wistar rats were fed standard (control [C]) and hypercaloric diets (obese [Ob]) for 15 weeks. Cardiac function was evaluated by echocardiogram and isolated left ventricle papillary muscle. Cardiac morphology was assessed by histology and electron microscopy. Compared with C rats, Ob rats had increased body fat, systolic blood pressure and area under the curve for glucose, leptin and insulin plasma concentrations. Echocardiographic indexes indicated that Ob rats had increased left ventricular mass, increased systolic stress and depressed systolic function. Analysis of the isolated papillary muscle was consistent with higher myocardial stiffness in Ob compared with C rats. The Ob rats had an increase in myocardial collagen and marked ultrastructural changes compared with C rats. Obesity promotes pathological cardiac remodeling with systolic dysfunction and an increase in myocardial stiffness, which, in turn, is probably related to afterload elevation and cardiac fibrosis. Obesity also causes damage to myocardial ultrastructure, but its effect on myocardial function needs to be further clarified.

The effect of surgical weight reduction on left ventricular structure and function in severe obesity

The aim of this study was to examine the effect of surgical weight reduction on cardiac structure and function and to seek the determinants of these changes. Sixty-six severely obese adults (BMI >or=35 kg/m(2)) who received bariatric surgery underwent echocardiographic examination before and 3 months after surgery. At 3 months after surgery, BMI and systolic blood pressure (BP) decreased (43.3 +/- 6.3 to 34.1 +/- 5.6 kg/m(2), P < 0.001, and 146 +/- 12 to 130 +/- 14 mm Hg, P < 0.001, respectively). In left ventricular (LV) geometry, the relative wall thickness (RWT) and LV mass index decreased significantly (0.43 +/- 0.05 to 0.35 +/- 0.05, P < 0.001, and 50 +/- 11 to 39 +/- 11 g/m(2.7), P < 0.001, respectively) without changes in chamber size. Multivariate analyses showed change in systolic BP to be an independent predictor for the changes in RWT and LV mass index. In myocardial performance, peak systolic mitral annular velocity and all diastolic indexes showed significant improvements. We concluded that LV hypertrophy and function improved rapidly after bariatric surgery in severely obese adults. BP reduction was the major determinant for the regression of LV hypertrophy in the early stage of surgical weight reduction.

Obesity and preclinical changes of cardiac geometry and function

Overweight and obesity are rapidly increasing in prevalence due to adoption of the westernized life style in Korea. Obesity is strongly associated with the development of cardiovascular risk factors such as diabetes, hypertension, and dyslipidemia. In addition, accumulating evidence suggests that obesity per se has a direct effect on cardiac functional and structural changes that may not be the result of atherosclerosis. In this review, we focus on the view that obesity can influence on the structural and functional changes of the heart, drawing evidence from human and animal studies. We also review influencing factors such as physical, neurohormonal, and metabolic alterations that are associated with changes of the heart in obesity.

Glucose, obesity, metabolic syndrome, and diabetes relevance to incidence of heart failure

Heart failure (HF) is common, results in poor clinical outcomes, and is associated with large health care costs. The incidence of HF continues to rise, with approximately 670,000 new cases per year and a 20% lifetime risk of HF for persons 40 years and older in the U.S. Risk factors for HF have been identified, and thus preventative strategies should have a positive effect on disease burden, morbidity, and mortality. Although coronary artery disease and hypertension have traditionally been considered among the most important modifiable risk factors for the development of HF, recent studies have highlighted the importance of increasingly prevalent metabolic risk factors: glucose, diabetes, obesity, and the metabolic syndrome. This report will present evidence for the link between glucose, diabetes, obesity, metabolic syndrome, and incident HF. Furthermore, we will discuss how risk factor modification and other preventive therapies may help curb the rising incidence of HF.

Determinants of left ventricular mass in obesity; a cardiovascular magnetic resonance study

BACKGROUND

Obesity is linked to increased left ventricular mass, an independent predictor of mortality. As a result of this, understanding the determinants of left ventricular mass in the setting of obesity has both therapeutic and prognostic implications. Using cardiovascular magnetic resonance our goal was to elucidate the main predictors of left ventricular mass in severely obese subjects free of additional cardiovascular risk factors.

METHODS

38 obese (BMI 37.8 +/- 6.9 kg/m2) and 16 normal weight controls subjects, (BMI 21.7 +/- 1.8 kg/m2), all without cardiovascular risk factors, underwent cardiovascular magnetic resonance imaging to assess left ventricular mass, left ventricular volumes and visceral fat mass. Left ventricular mass was then compared to serum and anthropometric markers of obesity linked to left ventricular mass, i.e. height, age, blood pressure, total fat mass, visceral fat mass, lean mass, serum leptin and fasting insulin level.

RESULTS

As expected, obesity was associated with significantly increased left ventricular mass (126 +/- 27 vs 90 +/- 20 g; p < 0.001). Stepwise multiple regression analysis showed that over 75% of the cross sectional variation in left ventricular mass can be explained by lean body mass (beta = 0.51, p < 0.001), LV stroke volume (beta = 0.31 p = 0.001) and abdominal visceral fat mass (beta = 0.20, p = 0.02), all of which showed highly significant independent associations with left ventricular mass (overall R2 = 0.77).

CONCLUSION

The left ventricular hypertrophic response to obesity in the absence of additional cardiovascular risk factors is mainly attributable to increases in lean body mass, LV stroke volume and visceral fat mass. In view of the well documented link between obesity, left ventricular hypertrophy and mortality, these findings have potentially important prognostic and therapeutic implications for primary and secondary prevention.

Pericardial fat, intrathoracic fat, and measures of left ventricular structure and function: the Framingham Heart Study

BACKGROUND

Pericardial fat has been implicated in the pathogenesis of obesity-related cardiovascular disease. Whether the associations of pericardial fat and measures of cardiac structure and function are independent of the systemic effects of obesity and visceral adiposity has not been fully explored.

METHODS AND RESULTS

Participants from the Framingham Heart Study (n=997; 54.4% women) underwent chest and abdominal computed tomography and cardiovascular magnetic resonance imaging between 2002 and 2005. Pericardial fat, intrathoracic fat, and visceral adipose tissue quantified from multidetector computed tomography, along with body mass index and waist circumference, were examined in relation to cardiovascular magnetic resonance measures of left ventricular (LV) mass, LV end-diastolic volume, and left atrial dimension. In women, pericardial fat (r=0.20 to 0.35, P<0.001), intrathoracic fat (r=0.25 to 0.37, P<0.001), visceral adipose tissue (r=0.24 to 0.45, P<0.001), body mass index (r=0.36 to 0.53, P<0.001), and waist circumference (r=0.30 to 0.48, P<0.001) were directly correlated with LV mass, LV end-diastolic volume, and left atrial dimension. In men, pericardial fat (r=0.19 to 0.37, P<0.001), intrathoracic fat (r=0.17 to 0.31, P<0.001), visceral adipose tissue (r=0.19 to 0.36, P<0.001), body mass index (r=0.32 to 0.44, P<0.001), and waist circumference (r=0.34 to 0.44, P<0.001) were directly correlated with LV mass and left atrial dimension, but LV end-diastolic volume was not consistently associated with adiposity measures. Associations persisted after multivariable adjustment but not after additional adjustment for body weight and visceral adipose tissue, except for pericardial fat and left atrial dimension in men.

CONCLUSIONS

Pericardial fat is correlated with cardiovascular magnetic resonance measures, but the association is not independent of or stronger than other ectopic fat stores or proxy measures of visceral adiposity. An important exception is left atrial dimension in men. These results suggest that the systemic effects of obesity on cardiac structure and function may outweigh the local pathogenic effects of pericardial fat.

Association between sleep-disordered breathing, aminoterminal pro-brain natriuretic peptide (NT-proBNP) levels and insulin resistance in morbidly obese young women

OBJECTIVE

Sleep-disordered breathing (SDB) is often encountered in morbid obesity (MO) in conjunction with insulin resistance (IR) and several cardio-vascular risk factors. Aminoterminal pro-brain natriuretic peptide (NT-proBNP) is a promising marker for left ventricular dysfunction (LVD) in MO. The aim of this study was to look for possible correlations between SDB, IR, heart structure and function indexes and NT-proBNP levels in MO female subjects.

MATERIALS AND METHODS

Cross-sectional study involving 110 MO (44.5+/-0.7 kg m(-2)) apparently healthy, young (37.8+/-1.0 y.o.) female patients. NT-proBNP was measured using an ELISA kit (Roche). Echo-cardiograms were performed to quantify left ventricular ejection fraction values (LVEF), cardiac output (CO), left ventricular mass (LVM), left atria size (LA) and left ventricular filling pressures (the E/Em ratio). The Berlin Questionnaire (BQ) was used to assess the risk of SDB. IR and sensitivity were assessed using the HOMA index and adiponectin measurements, respectively.

RESULTS

All patients had a normal LVEF (>50%). Hypertension and Type 2 diabetes mellitus prevalences were 34.5 and 4.5% (respectively). Log-transformed NT-proBNP levels correlated with BQ categories (P<0.0005), creatinine (P<0.001), age (P<0.05), LVM (P<0.001), CO (P<0.001), LA (P<0.0005) and E/Em (P<0.01). NT-proBNP levels, LVD and LVM increased significantly along with BQ scores (P<0.0001). Stepwise multiple regression analysis identified BQ and log-transformed HOMA as independent variables predicting as much as 48.0% of log-transformed NT-proBNP's variability (dependent variable).

CONCLUSIONS

NT-proBNP levels are independently predicted by SDB and IR in asymptomatic MO women. Additionally, SDB worsens along with LVH and diastolic dysfunction. Larger prospective studies are warranted.