Obese Subjects Show Sex-Specific Differences in Right Ventricular Hypertrophy

Obesity, Preserved Ejection Fraction Heart Failure, and Left Ventricular Remodeling

Owing to the overwhelming obesity epidemic, preserved ejection fraction heart failure commonly ensues in patients with severe obesity and the obese phenotype of preserved ejection fraction heart failure is now commonplace in clinical practice. Severe obesity and preserved ejection fraction heart failure share congruent cardiovascular, immune, and renal derangements that make it difficult to ascertain whether the obese phenotype of preserved ejection fraction heart failure is the convergence of two highly prevalent conditions or severe obesity enables the development and progression of the syndrome of preserved ejection fraction heart failure. Nevertheless, the obese phenotype of preserved ejection fraction heart failure provides a unique opportunity to assess whether sustained and sizeable loss of excess body weight via metabolic bariatric surgery reverses the concentric left ventricular remodeling that patients with preserved ejection fraction heart failure commonly display.

Adverse right ventricular remodelling, function, and stress responses in obesity: insights from cardiovascular magnetic resonance

AIMS

We aimed to determine the effect of increasing body weight upon right ventricular (RV) volumes, energetics, systolic function, and stress responses using cardiovascular magnetic resonance (CMR).

METHODS AND RESULTS

We first determined the effects of World Health Organization class III obesity [body mass index (BMI) > 40 kg/m2, n = 54] vs. healthy weight (BMI < 25 kg/m2, n = 49) upon RV volumes, energetics and systolic function using CMR. In less severe obesity (BMI 35 ± 5 kg/m2, n = 18) and healthy weight controls (BMI 21 ± 1 kg/m2, n = 9), we next performed CMR before and during dobutamine to evaluate RV stress response. A subgroup undergoing bariatric surgery (n = 37) were rescanned at median 1 year to determine the effects of weight loss. When compared with healthy weight, class III obesity was associated with adverse RV remodelling (17% RV end-diastolic volume increase, P < 0.0001), impaired cardiac energetics (19% phosphocreatine to adenosine triphosphate ratio reduction, P < 0.001), and reduction in RV ejection fraction (by 3%, P = 0.01), which was related to impaired energetics (R = 0.3, P = 0.04). Participants with less severe obesity had impaired RV diastolic filling at rest and blunted RV systolic and diastolic responses to dobutamine compared with healthy weight. Surgical weight loss (34 ± 15 kg weight loss) was associated with improvement in RV end-diastolic volume (by 8%, P = 0.006) and systolic function (by 2%, P = 0.03).

CONCLUSION

Increasing body weight is associated with significant alterations in RV volumes, energetic, systolic function, and stress responses. Adverse RV modelling is mitigated with weight loss. Randomized trials are needed to determine whether intentional weight loss improves symptoms and outcomes in patients with obesity and heart failure.

MiR 208a Regulates Mitochondrial Biogenesis in Metabolically Challenged Cardiomyocytes

Metabolic syndrome increases the risk for cardiovascular disease including metabolic cardiomyopathy that may progress to heart failure. The decline in mitochondrial metabolism is considered a critical pathogenic mechanism that drives this progression. Considering its cardiac specificity, we hypothesized that miR 208a regulates the bioenergetic metabolism in human cardiomyocytes exposed to metabolic challenges. We screened in silico for potential miR 208a targets focusing on mitochondrial outcomes, and we found that mRNA species for mediator complex subunit 7, mitochondrial ribosomal protein 28, stanniocalcin 1, and Sortin nexin 10 are rescued by the CRISPR deletion of miR 208a in human SV40 cardiomyocytes exposed to metabolic challenges (high glucose and high albumin-bound palmitate). These mRNAs translate into proteins that are involved in nuclear transcription, mitochondrial translation, mitochondrial integrity, and protein trafficking. MiR 208a suppression prevented the decrease in myosin heavy chain α isoform induced by the metabolic stress suggesting protection against a decrease in cardiac contractility. MiR 208a deficiency opposed the decrease in the mitochondrial biogenesis signaling pathway, mtDNA, mitochondrial markers, and respiratory properties induced by metabolic challenges. The benefit of miR 208a suppression on mitochondrial function was canceled by the reinsertion of miR 208a. In summary, miR 208a regulates mitochondrial biogenesis and function in cardiomyocytes exposed to diabetic conditions. MiR 208a may be a therapeutic target to promote mitochondrial biogenesis in chronic diseases associated with mitochondrial defects.

Relation of Body Mass Index to Adverse Right Ventricular Mechanics

Although higher body mass index (BMI) is associated with adverse left ventricular morphology and functional remodeling, its possible association with right ventricular (RV) dysfunction has not been extensively evaluated. RV free wall longitudinal strain (RVLS) is emerging as an important tool to detect early RV dysfunction. This study aimed to investigate the independent effect of increased BMI on RVLS in a large sample of the general population without overt cardiac disease. We examined 1,085 participants (603 men, mean age 62 years) who voluntarily underwent an extensive cardiovascular health check-up. This included laboratory tests and speckle-tracking echocardiography to assess RVLS. The association between BMI and RVLS was determined by logistic regression analyses. The prevalence of abnormal RVLS (>-19.2%) was greatest in obese individuals (29.7%), followed by overweight (16.3%), and normal weight (10.6%, p <0.001). In multivariable analyses, BMI was significantly associated with abnormal RVLS (adjusted odds ratio [OR] = 1.07 per 1 kg/m², p = 0.033) independent of traditional cardiovascular risk factors, pertinent laboratory and echocardiographic parameters including RV size and pulmonary artery systolic pressure. In subgroup analyses, BMI was significantly associated with abnormal RVLS in men (adjusted OR 1.10 per 1 kg/m², p = 0.032) and younger (<65 years) participants (adjusted OR 1.13 per 1 kg/m², p = 0.011), but not in women and the elderly. In a sample of the general population, higher BMI was independently associated with subclinical RV dysfunction. Furthermore, an increased BMI may carry different risk for impaired RVLS depending on the age and sex.

The Obesity Paradox in Patients with Significant Tricuspid Regurgitation: Effects of Obesity on Right Ventricular Remodeling and Long-Term Prognosis

BACKGROUND

Obesity may cause right ventricular (RV) remodeling due to volume overload. However, obesity is also associated with better prognosis compared with normal weight in patients with various cardiac diseases. The aim of this study was to assess the impact of obesity on RV remodeling and long-term prognosis in patients with significant (moderate and severe) tricuspid regurgitation (TR).

METHODS

A total of 951 patients with significant TR (median age, 70 years; interquartile range, 61-77 years; 50% men) were divided into three groups according to body mass index (BMI): normal weight (BMI 18.5-24.9 kg/m²), overweight (BMI 25-29.9 kg/m²), and obese (BMI ≥ 30 kg/m²). Patients with congenital heart disease, peripheral edema, active endocarditis, and BMI < 18.5 kg/m² were excluded. RV size and function for each group were measured using transthoracic echocardiography and compared with reference values of healthy study populations. The primary end point was all-cause mortality. Event rates were compared across the three BMI categories.

RESULTS

Four hundred seventy-six patients (50%) with significant TR had normal weight, 356 (37%) were overweight, and 119 (13%) were obese. RV end-diastolic and end-systolic areas were larger in overweight and obese patients compared with normal-weight patients. However, no differences in RV systolic function were observed. During a median follow-up period of 5 years, 358 patients (38%) died. Five-year survival rates were significantly better in overweight and obese patients compared with patients with normal weight (65% and 67% vs 58%, respectively, P < .001 and P = .005). In multivariate analysis, overweight and obesity were independently associated with lower rates of all-cause mortality compared with normal weight (hazard ratios, 0.628 [95% CI, 0.493-0.800] and 0.573 [95% CI, 0.387-0.848], respectively).

CONCLUSIONS

In patients with significant TR, overweight and obese patients demonstrated more RV remodeling compared with patients with normal weight. Nevertheless, a higher BMI was independently associated with better long-term survival, confirming the obesity paradox in this context.

PI3Kα Pathway Inhibition With Doxorubicin Treatment Results in Distinct Biventricular Atrophy and Remodeling With Right Ventricular Dysfunction

Background

Cancer therapies inhibiting PI3Kα (phosphoinositide 3‐kinase‐α)–dependent growth factor signaling, including trastuzumab inhibition of HER2 (Human Epidermal Growth Factor Receptor 2), can cause adverse effects on the heart. Direct inhibition of PI3Kα is now in clinical trials, but the effects of PI3Kα pathway inhibition on heart atrophy, remodeling, and function in the context of cancer therapy are not well understood.

Method and Results

Pharmacological PI3Kα inhibition and heart‐specific genetic deletion of p110α, the catalytic subunit of PI3Kα, was characterized in conjunction with anthracycline (doxorubicin) treatment in female murine models. Biventricular changes in heart morphological characteristics and function were analyzed, with molecular characterization of signaling pathways. Both PI3Kα inhibition and anthracycline therapy promoted heart atrophy and a combined effect of distinct right ventricular dilation, dysfunction, and cardiomyocyte remodeling in the absence of pulmonary arterial hypertension. Congruent findings of right ventricular dilation and dysfunction were seen with pharmacological and genetic suppression of PI3Kα signaling when combined with doxorubicin treatment. Increased p38 mitogen‐activated protein kinase activation was mechanistically linked to heart atrophy and correlated with right ventricular dysfunction in explanted failing human hearts.

Conclusions

The PI3Kα pathway promotes heart atrophy in mice. The right ventricle is specifically at risk for dilation and dysfunction in the setting of PI3K inhibition in conjunction with chemotherapy. Inhibition of p38 mitogen‐activated protein kinase is a proposed therapeutic target to minimize this mode of cardiotoxicity.

Association between Cardiac Remodeling and Metabolic Alteration in an Experimental Model of Obesity Induced by Western Diet

The high consumption of fat and sugar contributes to the development of obesity and co-morbidities, such as dyslipidemia, hypertension, and cardiovascular disease. The aim of this study was to evaluate the association between dyslipidemia and cardiac dysfunction induced by western diet consumption. Wistar rats were randomly divided into two experimental groups and fed ad libitum for 20 weeks with a control diet (Control, n = 12) or a high-sugar and high-fat diet (HSF, n = 12). The HSF group also received water + sucrose (25%). Evaluations included feed and caloric intake; body weight; plasma glucose; insulin; uric acid; HOMA-IR; lipid profile: [total cholesterol (T-chol), high-density lipoprotein (HDL), non-HDL Chol, triglycerides (TG)]; systolic blood pressure, and Doppler echocardiographic. Compared to the control group, animals that consumed the HSF diet presented higher weight gain, caloric intake, feed efficiency, insulin, HOMA-IR, and glucose levels, and lipid profile impairment (higher TG, T-chol, non-HDL chol and lower HDL). HSF diet was also associated with atrial-ventricular structural impairment and systolic-diastolic dysfunction. Positive correlation was also found among the following parameters: insulin versus estimated LV mass (r = 0.90, p = 0.001); non-HDL versus deceleration time (r = 0.46, p = 0.02); TG versus deceleration time (r = 0.50, p = 0.01). In summary, our results suggest cardiac remodeling lead by western diet is associated with metabolic parameters.

Cardiovascular Disease Risk in Patients with Rheumatic Diseases

Evidence suggests the greater than 1.5 increased risk of cardiovascular disease (CVD) in rheumatoid arthritis (RA) is related to an accelerated burden of subclinical atherosclerosis that develops before the diagnosis of RA. Dyslipidemia in RA is better quantified by lipoproteins and apolipoproteins than cholesterol levels. Current risk factors likely underestimate CVD risk partly by underestimating prior risk factor levels. To reduce CVD risk in RA, control disease activity and aggressively treat CVD risk factors. Some of the two-fold higher risk of heart failure and total mortality in RA may be due to myocardial disease caused by inflammation.

The impact of cardiovascular risk factors on cardiac structure and function: Insights from the UK Biobank imaging enhancement study

Aims

The UK Biobank is a large-scale population-based study utilising cardiovascular magnetic resonance (CMR) to generate measurements of atrial and ventricular structure and function. This study aimed to quantify the association between modifiable cardiovascular risk factors and cardiac morphology and function in individuals without known cardiovascular disease.

Methods

Age, sex, ethnicity (non-modifiable) and systolic blood pressure, diastolic blood pressure, smoking status, exercise, body mass index (BMI), high cholesterol, diabetes, alcohol intake (modifiable) were considered important cardiovascular risk factors. Multivariable regression models were built to ascertain the association of risk factors on left ventricular (LV), right ventricular (RV), left atrial (LA) and right atrial (RA) CMR parameters.

Results

4,651 participants were included in the analysis. All modifiable risk factors had significant effects on differing atrial and ventricular parameters. BMI was the modifiable risk factor most consistently associated with subclinical changes to CMR parameters, particularly in relation to higher LV mass (+8.3% per SD [4.3 kg/m2], 95% CI: 7.6 to 8.9%), LV (EDV: +4.8% per SD, 95% CI: 4.2 to 5.4%); ESV: +4.4% per SD, 95% CI: 3.5 to 5.3%), RV (EDV: +5.3% per SD, 95% CI: 4.7 to 5.9%; ESV: +5.4% per SD, 95% CI: 4.5 to 6.4%) and LA maximal (+8.6% per SD, 95% CI: 7.4 to 9.7%) volumes. Increases in SBP were associated with higher LV mass (+6.8% per SD, 95% CI: 5.9 to 7.7%), LV (EDV: +4.5% per SD, 95% CI: 3.6 to 5.4%; ESV: +2.0% per SD, 95% CI: 0.8 to 3.3%) volumes. The presence of diabetes or high cholesterol resulted in smaller volumes and lower ejection fractions.

Conclusions

Modifiable risk factors are associated with subclinical alterations in structure and function in all four cardiac chambers. BMI and systolic blood pressure are the most important modifiable risk factors affecting CMR parameters known to be linked to adverse outcomes.

Cardiac and Metabolic Variables in Obese Dogs

Background

The etiology of obesity‐related cardiac dysfunction (ORCD) is linked to metabolic syndrome in people. Studies have indicated that obese dogs have components of metabolic syndrome, warranting evaluation for ORCD in obese dogs.

Objectives

To evaluate cardiac structure and function and metabolic variables in obese dogs compared to ideal weight dogs.

Animals

Forty‐six healthy, small‐breed (<25 pounds), obese dogs (n = 29) compared to ideal weight dogs (n = 17).

Methods

A cross‐sectional study of cardiac structure and function by standard and strain echocardiographic measurements and quantification of serum metabolic variables (insulin:glucose ratios, lipid analysis, adiponectin, inflammatory markers).

Results

Compared to the ideal weight controls, obese dogs had cardiac changes characterized by an increased interventricular septal width in diastole to left ventricular internal dimension in diastole ratio, decreased ratios of peak early to peak late left ventricular inflow velocities, and ratios of peak early to peak late mitral annular tissue velocities, and increased fractional shortening and ejection fraction percentages. The left ventricular posterior wall width in diastole to left ventricular internal dimension in diastole ratios were not significantly different between groups. Systolic blood pressure was not significantly different between groups. Obese dogs had metabolic derangements characterized by increased insulin:glucose ratios, dyslipidemias with increased cholesterol, triglyceride, and high‐density lipoprotein concentrations, decreased adiponectin concentrations, and increased concentrations of interleukin 8 and keratinocyte‐derived chemokine‐like inflammatory cytokines.

Conclusions and Clinical Importance

Compared to ideal weight controls, obese dogs have alterations in cardiac structure and function as well as insulin resistance, dyslipidemia, hypoadiponectinemia, and increased concentrations of inflammatory markers. These findings warrant additional studies to investigate inflammation, dyslipidemia, and possibly systemic hypertension as potential contributing factors for altered cardiac function.

Two-dimensional echocardiographic right ventricle measurements adjusted to body mass index and surface area in a normal population

BACKGROUND

To determine reference echocardiographic values in a normal population and assess their correlation with body mass index (BMI) and body surface area.

METHODS

An expert cardiologist performed two-dimensional echocardiography with triplicate right ventricle (RV) size measurements in 80 subjects with normal heart condition. Results were correlated with anthropometric data.

RESULTS

Base-to-apex length in four-chamber view (RVD3) and above-pulmonic valve in short-axis view in males, as well as mid-RV diameter in standard four-chamber view (RVD), basal RV diameter, and mid RV diameter in RV-focused four-chamber view in females, were significantly correlated with BMI. All RV variables were significantly correlated with BMI in 20-30-year-old subjects. All RV variables except RVD3 and above-aortic valve in short-axis view (proximal) were significantly correlated with BMI in 35-55-year-old subjects. All RV parameters were significantly correlated with body surface area, except for RVD and in 20-35-year-old subjects.

CONCLUSIONS

RV echocardiographic values must be adjusted to anthropometric characteristics for proper diagnosis and management of cardiac disorders. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:204-210, 2017.

Improvements in ECG accuracy for diagnosis of left ventricular hypertrophy in obesity

OBJECTIVES

The electrocardiogram (ECG) is the most commonly used tool to screen for left ventricular hypertrophy (LVH), and yet current diagnostic criteria are insensitive in modern increasingly overweight society. We propose a simple adjustment to improve diagnostic accuracy in different body weights and improve the sensitivity of this universally available technique.

METHODS

Overall, 1295 participants were included-821 with a wide range of body mass index (BMI 17.1-53.3 kg/m(2)) initially underwent cardiac magnetic resonance evaluation of anatomical left ventricular (LV) axis, LV mass and 12-lead surface ECG in order to generate an adjustment factor applied to the Sokolow-Lyon criteria. This factor was then validated in a second cohort (n=520, BMI 15.9-63.2 kg/m(2)).

RESULTS

When matched for LV mass, the combination of leftward anatomical axis deviation and increased BMI resulted in a reduction of the Sokolow-Lyon index, by 4 mm in overweight and 8 mm in obesity. After adjusting for this in the initial cohort, the sensitivity of the Sokolow-Lyon index increased (overweight: 12.8% to 30.8%, obese: 3.1% to 27.2%) approaching that seen in normal weight (37.8%). Similar results were achieved in the validation cohort (specificity increased in overweight: 8.3% to 39.1%, obese: 9.4% to 25.0%) again approaching normal weight (39.0%). Importantly, specificity remained excellent (>93.1%).

CONCLUSIONS

Adjusting the Sokolow-Lyon index for BMI (overweight +4 mm, obesity +8 mm) improves the diagnostic accuracy for detecting LVH. As the ECG, worldwide, remains the most widely used screening tool for LVH, implementing these findings should translate into significant clinical benefit.

Early cardiac changes induced by a hypercaloric Western-type diet in “subclinical” obesity

“Obesity cardiomyopathy” effects have been widely described; however, the specific contribution of metabolic changes and altered adipokine secretion are still uncharacterized. Moreover, a diagnosis based on body mass index might not be the most accurate to identify increased adiposity and its outcomes. In this study, we aimed to determine the impact of a Western-type diet [hypercaloric diet (HCD)] ingestion on biventricular structure and function, as well as the metabolic and endocrine changes that occur before the establishment of overt obesity. Wistar rats were fed for 6 wk with a regular diet or HCD. At the end of the protocol, metabolic tests, cardiac structure, and functional evaluation were performed, and blood and tissue samples collected to perform histological, molecular biology, and functional studies. The animals that ingested the HCD presented increased adiposity and larger adipocyte cross-sectional area, but similar body weight compared with the regular diet group. At the cardiac level, HCD induced biventricular cardiomyocyte hypertrophy, fibrosis, increased stiffness, and impaired relaxation. Galectin-3 plasma expression was likewise elevated in the same animals. The nutritional modulation also altered the secretory pattern of the adipose tissue, originating a proinflammatory systemic environment. In this study, we observed that before “clinical” overweight or frank obesity is established, the ingestion of a HCD-induced cardiac remodeling manifests by increased biventricular stiffness and diastolic dysfunction. The mechanism triggering the cardiac alterations appears to be the proinflammatory environment promoted by the adipose tissue dysfunction. Furthermore, galectin-3, a profibrotic molecule, might be a potential biomarker for the myocardial alterations promoted by the HCD before overweight or obesity.

The paradox of obesity cardiomyopathy and the potential for weight loss as a therapy

Obesity is an independent risk factor for developing heart failure and the combination of the two disease states will prove to be a significant health burden over the coming years. Obesity is likely to contribute to the development of heart failure through a variety of mechanisms, including structural and functional changes, lipotoxicity and steatosis and altered substrate selection. However, once heart failure has developed, it seems that obesity confers a beneficial influence on prognosis in what has been termed the 'obesity paradox'. This may be a statistical phenomenon, but it should be considered that there is truly a protective state in the physiology of obesity. There is little evidence regarding the impact of weight loss in obese heart failure and whether or not this is beneficial. There have been small studies regarding the cardiovascular effects of both dietary weight loss and bariatric surgery, but few in heart failure. This is an important and increasingly relevant clinical question which must be addressed.