Subclinical Myocardial Impairment in Metabolic Diseases

Single-nucleus transcriptomics reveal cardiac cell type-specific diversification in metabolic disease transgenic pigs

Cardiac damage is widely present in patients with metabolic diseases, but the exact pathophysiological mechanisms involved remain unclear. The porcine heart is an ideal material for cardiovascular research due to its similarities to the human heart. This study evaluated pathological features and performed single-nucleus RNA sequencing (snRNA-seq) on myocardial samples from both wild-type and metabolic disease-susceptible transgenic pigs (previously established). We found that transgenic pigs exhibited lipid metabolism disturbances and myocardial injury after a high-fat high-sucrose diet intervention. snRNA-seq reveals the cellular landscape of healthy and metabolically disturbed pig hearts and identifies the major cardiac cell populations affected by metabolic diseases. Within metabolic disorder hearts, metabolically active cardiomyocytes exhibited impaired function and reduced abundance. Moreover, massive numbers of reparative LYVE1+ macrophages were lost. Additionally, proinflammatory endothelial cells were activated with high expression of multiple proinflammatory cytokines. Our findings provide insights into the cellular mechanisms of metabolic disease-induced myocardial injury.

Association between Obesity and Atrial Function in Patients with Non-Valvular Atrial Fibrillation: An Echocardiographic Study

Background: Obesity is a public health problem which prevalence has increased worldwide and is associated with different degrees of hemodynamic alterations and structural cardiac changes. The aim of the study is to investigate the impact of body mass index (BMI) on left atrial function using standard and advanced echocardiography in a population of patients with non-valvular atrial fibrillation (AF). Methods: 395 adult patients suffering from non-valvular AF, divided into three tertiles based on BMI value, carry out a cardiological examination with standard and advanced echocardiography. Results: Peak atrial longitudinal strain (PALS), a measure of left atrial function, is lower in the tertile with highest BMI (14.3 ± 8.2%) compared to both the first (19 ± 11.5%) and the second tertile (17.7 ± 10.6%) in a statistically significant manner (p < 0.002). Furthermore, BMI is significantly associated independent with the PALS by multilinear regression analysis, even after correction of the data for CHA2DS2-VASc score, left ventricular mass index, left ventricular ejection fraction, E/E' ratio and systolic pulmonary arterial pressure (coefficient standardized β = -0.127, p < 0.02; Cumulative R2 = 0.41, SEE = 0.8%, p < 0.0001). Conclusions: BMI could be considered an additional factor in assessing cardiovascular risk in patients with non-valvular atrial fibrillation, in addition to the well-known CHA2DS2-VASc score.

Prevalence of diabetic cardiomyopathy in patients with type 2 diabetes in a large academic medical center

BACKGROUND

Diabetic cardiomyopathy (DbCM) is characterized by asymptomatic stage B heart failure (SBHF) caused by diabetes-related metabolic alterations. DbCM is associated with an increased risk of progression to overt heart failure (HF). The prevalence of DbCM in patients with type 2 diabetes (T2D) is not well established. This study aims to determine prevalence of DbCM in adult T2D patients in real-world clinical practice.

METHODS

Retrospective multi-step review of electronic medical records of patients with the diagnosis of T2D who had echocardiogram at UC San Diego Medical Center (UCSD) within 2010-2019 was conducted to identify T2D patients with SBHF. We defined "pure" DbCM when SBHF is associated solely with T2D and "mixed" SBHF when other medical conditions can contribute to SBHF. "Pure" DbCM was diagnosed in T2D patients with echocardiographic demonstration of SBHF defined as left atrial (LA) enlargement (LAE), as evidenced by LA volume index ≥ 34 mL/m2, in the presence of left ventricular ejection fraction (LVEF) ≥ 45%, while excluding overt HF and comorbidities that can contribute to SBHF.

RESULTS

Of 778,314 UCSD patients in 2010-2019, 45,600 (5.9%) had T2D diagnosis. In this group, 15,182 T2D patients (33.3%) had echocardiogram and, among them, 13,680 (90.1%) had LVEF ≥ 45%. Out of 13,680 patients, 4,790 patients had LAE. Of them, 1,070 patients were excluded due to incomplete data and/or a lack of confirmed T2D according to the American Diabetes Association recommendations. Thus, 3,720 T2D patients with LVEF ≥ 45% and LAE were identified, regardless of HF symptoms. In this group, 1,604 patients (43.1%) had overt HF and were excluded. Thus, 2,116 T2D patients (56.9% of T2D patients with LVEF ≥ 45% and LAE) with asymptomatic SBHF were identified. Out of them, 1,773 patients (83.8%) were diagnosed with "mixed" SBHF due to comorbidities such as hypertension (58%), coronary artery disease (36%), and valvular heart disease (17%). Finally, 343 patients met the diagnostic criteria of "pure" DbCM, which represents 16.2% of T2D patients with SBHF, i.e., at least 2.9% of the entire T2D population in this study.

CONCLUSIONS

Our findings provide insights into prevalence of DbCM in real-world clinical practice and indicate that DbCM affects a significant portion of T2D patients.

Classification, Diagnosis, and Treatment of Obesity-Related Heart Diseases

Evidence-based medicine shows that obesity is associated with a wide range of cardiovascular (CV) diseases. Obesity can lead to changes in cardiac structure and function, which can lead to obese cardiomyopathy, subclinical cardiac dysfunction, and even heart failure. It also increases the risk of atrial fibrillation and sudden cardiac death. Many invasive and noninvasive diagnostic methods can detect obesity-related heart disease at an early stage, so that appropriate measures can be selected to prevent adverse CV events. However, studies have shown a protective effect of obesity on clinical outcomes of CV disease, a phenomenon that has been termed the obesity paradox. The "obesity paradox" essentially refers to the fact that the classification of obesity defined by body mass index (BMI) does not consider the impact of obesity heterogeneity on CV disease prognosis, but simply puts subjects with different clinical and biochemical characteristics into the same category. In any case, indicators such as waist-to-hip ratio, ectopic body fat qualitative and quantitative, and CV fitness have been shown to be able to distinguish different CV risks in patients with the same BMI, which is convenient for early intervention in an appropriate way. A multidisciplinary approach, including lifestyle modification, evidence-based generic and novel pharmacotherapy, and surgical intervention, can improve CV outcomes in overweight/obese patients.

Associations between long-term averages of metabolic parameters in adulthood and cardiac structure and function in later life

The effects of long-term levels of body mass index (BMI), blood pressure (BP), plasma lipids and fasting blood glucose (FBG) on the cardiac structure and function in later life in general population are to evaluate. We included adult participants without heart failure from Framingham Heart Study. The respective averages over a span of 30-36 years of seven parameters were pooled into linear regression models simultaneously to evaluate their associations with subsequent left atrial internal dimension (LAID), left ventricular mass index (LVMi), internal dimension (LVID), ejection fraction (LVEF), global longitudinal strain (GLS) and mitral inflow velocity to early diastolic mitral annular velocity (E/é). In 1838 participants (56.0% female, mean age 66.1 years), per 1-standard deviation (SD) increment of mean BMI correlated with larger LAID and LVID (β 0.05~0.17, standard error [SE] 0.01 for all), greater LVMi (β [SE], 1.49 [0.46]), worse E/é (β [SE], 0.28 [0.05]). Per 1-SD increment of mean systolic BP correlated with greater LVMi (β [SE], 4.70 [0.69]), LVEF (β [SE], 0.73 [0.24]), E/é (β [SE], 0.52 [0.08]), whereas increase of mean diastolic BP correlated with smaller LVMi (β [SE], -1.61 [0.62]), LVEF (β [SE], -0.46 [0.22]), E/é (β [SE], -0.30 [0.07]). Per 1-SD increment of mean high density lipoprotein cholesterol (HDL-c) correlated with smaller LVID (β [SE], -0.03 [0.01]) and better systolic function (LVEF, β [SE], 0.63 [0.19]; GLS, β [SE], -0.20 [0.10]). The variabilities of BMI, BP and HDL-c also correlated with certain cardiac measurements. In long-term, BMI affected the size and mass of heart chambers, systolic and diastolic BP differently influenced left ventricular mass and function, higher HDL-c linked to better systolic function. Clinical trial registration: URL: https://clinicaltrials.gov . Identifier: NCT00005121.

Increased Left Atrial Stiffness is Significantly Associated with Paroxysmal Atrial Fibrillation in Diabetic Patients

Purpose

Atrial fibrillation (AF) and diabetes mellitus (DM) are common pathogenic diseases. Diabetes is an independent risk factor for AF, and coexisting AF is a risk factor for the diabetic pa-tient's progression. The purpose of this study was to see if two-dimensional-speckle tracking echocardiography (2D-STE) might provide valuable criteria for determining the risk of AF in diabetic patients.

Patients and Methods

This retrospective study compared 30 adult diabetic patients with documented paroxysmal atrial fibrillation (PAF) with 30 age- and sex-matched diabetic patients without PAF. Inclusion criteria were: age ≥18 years, sinus rhythm, diabetes mellitus type 2, and the ability to sign the informed consent. Exclusion criteria included: moderate or severe valvular disease, previous myocardial infarction, left ventricular ejection fraction (LVEF) <50%, congenital heart disease, a history of cardiac surgery, paced atrial or ventricular rhythm, inadequate echocardiography imaging. The medical history, clinical, biochemical data and the results of the transthoracic cardiac ultrasound examination were registered during their evaluation at the outpatients cardiology clinics.

Results

The mean age of the patients was 62.5±1.7 years, 60% were men. Diabetic patients who experienced PAF episodes demonstrated significantly impaired left atrial (LA) deformation patterns, with decreased LA strains and increased LA stiffness (p < 0.05).

Conclusion

The present study demonstrates that LA strains and LA stiffness are significantly associated with the occurrence of PAF in diabetic patients. As 2D-STE of the LA is more sensitive than routine echocardiographic examination, it should be performed in patients suspected of being suffering from PAF.

Echocardiographic Assessment of Patients with Glycogen Storage Disease in a Single Center

Glycogen storage disease (GSD) is a hereditary metabolic disorder caused by enzyme deficiency resulting in glycogen accumulation in the liver, muscle, heart, or kidney. GSD types II, III, IV, and IX are associated with cardiac involvement. However, cardiac manifestation in other GSD types is unclear. This study aimed to describe whether energy deprivation and the toxic effects of accumulated glycogen affect the heart of patients with GSD. We evaluated the left ventricle (LV) wall mass, LV systolic and diastolic function and myocardial strain with conventional echocardiography and two-dimensional speckle-tracking echocardiography (2D STE) in 62 patients with GSD type I, III, VI and IX who visited the Wonju Severance Hospital in 2021. Among the GSD patients, the echocardiographic parameters of 55 pediatrics were converted into z-scores and analyzed. Of the patients, 43 (62.3%), 7 (11.3%) and 12 (19.4%) patients were diagnosed with GSD type I, type III, and type IX, respectively. The median age was 9 years (range, 1-36 years), with 55 children under 18 years old and seven adults over 18 years. For the 55 pediatric patients, the echocardiographic parameters were converted into a z-score and analyzed. Multiple linear regression analysis showed that the BMI z-score (p = 0.022) and CK (p = 0.020) predicted increased LV mass z-score, regardless of GSD type. There was no difference in the diastolic and systolic functions according to myocardial thickness; however, 2D STE showed a negative correlation with the LV mass (r = -0.28, p = 0.041). Given that patients with GSD tend to be overweight, serial evaluation with echocardiography might be required for all types of GSD.

The worsening effect of anemia on left ventricular function and global strain in type 2 diabetes mellitus patients: a 3.0 T CMR feature tracking study

OBJECTIVE

To explore the additive effects of anemia on left ventricular (LV) global strains in patients with type 2 diabetes mellitus (T2DM) with or without anemia via cardiac magnetic resonance (CMR) feature tracking technology.

MATERIALS AND METHODS

236 T2DM patients with or without anemia and 67 controls who underwent CMR examination were retrospectively enrolled. LV function parameters, LV global radial peak strain (GRPS), longitudinal peak strain (GLPS), and circumferential peak strain (GCPS) were used to analyze the function and global strain of the heart. One-way analysis of variance and the chi-square test were used for intergroup analysis. Multivariable linear regression analysis was performed for the two T2DM groups to explore factors associated with LV global strains.

RESULTS

The T2DM group with anemia was oldest and had a lowest hemoglobin (Hb) concentration, lowest estimated glomerular filtration rate, highest LV end-systolic volume index, highest end-diastolic volume index and highest LV mass index than the control group and T2DM without anemia group (all P ≤ 0.001). Besides, The LV global peak strains in all three directions worsened successively from the control group to the T2DM without anemia group to the T2DM with anemia group (all p < 0.001). Among all clinical indices, the decrease in Hb was independently associated with the worsening in GRPS (β = 0.237, p = 0.001), GCPS (β = 0.326, p < 0.001), and GLPS (β = 0.265, p < 0.001).

CONCLUSION

Anemia has additive deleterious effects on LV function and LV global strains in patients with T2DM. Regular detection and early intervention of anemia might be beneficial for T2DM patients.

Heart failure with preserved ejection fraction (HFpEF) in type 2 diabetes mellitus: from pathophysiology to therapeutics

Type 2 diabetes mellitus (T2DM or T2D) is a devastating metabolic abnormality featured by insulin resistance, hyperglycemia, and hyperlipidemia. T2D provokes unique metabolic changes and compromises cardiovascular geometry and function. Meanwhile, T2D increases the overall risk for heart failure (HF) and acts independent of classical risk factors including coronary artery disease, hypertension, and valvular heart diseases. The incidence of HF is extremely high in patients with T2D and is manifested as HF with preserved, reduced, and midrange ejection fraction (HFpEF, HFrEF, and HFmrEF, respectively), all of which significantly worsen the prognosis for T2D. HFpEF is seen in approximately half of the HF cases and is defined as a heterogenous syndrome with discrete phenotypes, particularly in close association with metabolic syndrome. Nonetheless, management of HFpEF in T2D remains unclear, largely due to the poorly defined pathophysiology behind HFpEF. Here, in this review, we will summarize findings from multiple preclinical and clinical studies as well as recent clinical trials, mainly focusing on the pathophysiology, potential mechanisms, and therapies of HFpEF in T2D.

2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure" replaces the "2013 ACCF/AHA Guideline for the Management of Heart Failure" and the "2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure." The 2022 guideline is intended to provide patient-centric recommendations for clinicians to prevent, diagnose, and manage patients with heart failure.

METHODS

A comprehensive literature search was conducted from May 2020 to December 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (PubMed), EMBASE, the Cochrane Collaboration, the Agency for Healthcare Research and Quality, and other relevant databases. Additional relevant clinical trials and research studies, published through September 2021, were also considered. This guideline was harmonized with other American Heart Association/American College of Cardiology guidelines published through December 2021. Structure: Heart failure remains a leading cause of morbidity and mortality globally. The 2022 heart failure guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with heart failure, with the intent to improve quality of care and align with patients' interests. Many recommendations from the earlier heart failure guidelines have been updated with new evidence, and new recommendations have been created when supported by published data. Value statements are provided for certain treatments with high-quality published economic analyses.

2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure

AIM

The "2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure" replaces the "2013 ACCF/AHA Guideline for the Management of Heart Failure" and the "2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure." The 2022 guideline is intended to provide patient-centric recommendations for clinicians to prevent, diagnose, and manage patients with heart failure.

METHODS

A comprehensive literature search was conducted from May 2020 to December 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (PubMed), EMBASE, the Cochrane Collaboration, the Agency for Healthcare Research and Quality, and other relevant databases. Additional relevant clinical trials and research studies, published through September 2021, were also considered. This guideline was harmonized with other American Heart Association/American College of Cardiology guidelines published through December 2021.

STRUCTURE

Heart failure remains a leading cause of morbidity and mortality globally. The 2022 heart failure guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with heart failure, with the intent to improve quality of care and align with patients' interests. Many recommendations from the earlier heart failure guidelines have been updated with new evidence, and new recommendations have been created when supported by published data. Value statements are provided for certain treatments with high-quality published economic analyses.

Strategies for Imaging Metabolic Remodeling of the Heart in Obesity and Heart Failure

PURPOSE OF REVIEW

Define early myocardial metabolic changes among patients with obesity and heart failure, and to describe noninvasive methods and their applications for imaging cardiac metabolic remodeling.

RECENT FINDINGS

Metabolic remodeling precedes, triggers, and sustains functional and structural remodeling in the stressed heart. Alterations in cardiac metabolism can be assessed by using a variety of molecular probes. The glucose tracer analog, 18F-FDG, and the labeled tracer 11C-palmitate are still the most commonly used tracers to assess glucose and fatty acid metabolism, respectively. The development of new tracer analogs and imaging agents, including those targeting the peroxisome proliferator-activated receptor (PPAR), provides new opportunities for imaging metabolic activities at a molecular level. While the use of cardiac magnetic resonance spectroscopy in the clinical setting is limited to the assessment of intramyocardial and epicardial fat, new technical improvements are likely to increase its usage in the setting of heart failure. Noninvasive imaging methods are an effective tool for the serial assessment of alterations in cardiac metabolism, either during disease progression, or in response to treatment.

The impact of short-term hyperglycemia and obesity on biventricular and biatrial myocardial function assessed by speckle tracking echocardiography in a population of women with gestational diabetes mellitus

BACKGROUND AND AIMS

To compare biventricular and biatrial myocardial strain indices assessed by two-dimensional speckle tracking echocardiography (2D-STE) in women with gestational diabetes mellitus (GDM) and those with uncomplicated pregnancy at the third trimester of pregnancy and in post-partum.

METHODS AND RESULTS

30 consecutive GDM women and 30 age-, ethnicity- and gestational week-matched controls without any comorbidity were examined in this prospective case-control study. All women underwent obstetric visit, blood tests and transthoracic echocardiography (TTE) implemented with 2D-STE analysis of all cardiac chambers at 36-38 weeks' gestation. TTE and 2D-STE were repeated at 6-10 weeks after delivery. At 36-38 weeks' gestation, GDM women, compared to controls, had significantly higher body mass index (BMI), blood pressure values and inflammatory markers. TTE showed increased left ventricular (LV) mass and impaired LV diastolic function in GDM women, whereas there was no significant difference between the groups in ejection fraction. 2D-STE revealed that biventricular global longitudinal strain (GLS) and biatrial reservoir strain indices were significantly lower in GDM women than controls. Third trimester BMI was inversely correlated with LV-GLS (r = -0.86) and was independently associated with reduced LV-GLS (less negative than -20%) in GDM women in post-partum (OR 1.81, 95%CI 1.14-2.89). A BMI value ≥ 30 kg/m² had 100% sensitivity and 99.5% specificity for identifying GDM women with impaired LV-GLS in post-partum (AUC = 0.97).

CONCLUSION

Women with GDM, compared to women with uncomplicated pregnancy, have significantly lower biventricular and biatrial myocardial deformation indices. These abnormalities may be persistent in post-partum in GDM women with obesity.

Longitudinal CMR assessment of cardiac global longitudinal strain and hemodynamic forces in a mouse model of heart failure

To longitudinally assess left ventricle (LV) global longitudinal strain (GLS) and hemodynamic forces during the early stages of cardiac dysfunction in a mouse model of heart failure with preserved ejection fraction (HFpEF). Cardiac MRI measurements were performed in control mice (n = 6), and db/db mice (n = 7), whereby animals were scanned four times between the age of 11-15 weeks. After the first scan, the db/db animals received a doxycycline intervention to accelerate progression of HFpEF. Systolic function was evaluated based on a series of prospectively ECG-triggered short-axis CINE images acquired from base to apex. Cardiac GLS and hemodynamic forces values were evaluated based on high frame rate retrospectively gated 2-, 3-, and 4-chamber long-axis CINE images. Ejection fraction (EF) was not different between control and db/db animals, despite that cardiac output, as well as end systolic and end diastolic volume were significantly higher in control animals. Whereas GLS parameters were not significantly different between groups, hemodynamic force root mean square (RMS) values, as well as average hemodynamic forces and the ratio between hemodynamic forces in the inferolateral-anteroseptal and apical-basal direction were lower in db/db mice compared to controls. More importantly, hemodynamic forces parameters showed a significant interaction effect between time and group. Our results indicated that hemodynamic forces parameters were the only functional outcome measure that showed distinct temporal differences between groups. As such, changes in hemodynamic forces reflect early alterations in cardiac function which can be of added value in (pre)clinical research on HFpEF.

Inflammation in Metabolic Cardiomyopathy

Overlapping pandemics of lifestyle-related diseases pose a substantial threat to cardiovascular health. Apart from coronary artery disease, metabolic disturbances linked to obesity, insulin resistance and diabetes directly compromise myocardial structure and function through independent and shared mechanisms heavily involving inflammatory signals. Accumulating evidence indicates that metabolic dysregulation causes systemic inflammation, which in turn aggravates cardiovascular disease. Indeed, elevated systemic levels of pro-inflammatory cytokines and metabolic substrates induce an inflammatory state in different cardiac cells and lead to subcellular alterations thereby promoting maladaptive myocardial remodeling. At the cellular level, inflammation-induced oxidative stress, mitochondrial dysfunction, impaired calcium handling, and lipotoxicity contribute to cardiomyocyte hypertrophy and dysfunction, extracellular matrix accumulation and microvascular disease. In cardiometabolic patients, myocardial inflammation is maintained by innate immune cell activation mediated by pattern recognition receptors such as Toll-like receptor 4 (TLR4) and downstream activation of the NLRP3 inflammasome and NF-κB-dependent pathways. Chronic low-grade inflammation progressively alters metabolic processes in the heart, leading to a metabolic cardiomyopathy (MC) phenotype and eventually to heart failure with preserved ejection fraction (HFpEF). In accordance with preclinical data, observational studies consistently showed increased inflammatory markers and cardiometabolic features in patients with HFpEF. Future treatment approaches of MC may target inflammatory mediators as they are closely intertwined with cardiac nutrient metabolism. Here, we review current evidence on inflammatory processes involved in the development of MC and provide an overview of nutrient and cytokine-driven pro-inflammatory effects stratified by cell type.

Role of skeletal muscle perfusion and insulin resistance in the effect of dietary sodium on heart function in overweight

Aims

Weight excess and insulin resistance predispose to heart failure. High sodium consumption may contribute to the development of cardiac impairment in insulin‐resistant individuals by promoting inadequate skeletal muscle microvascular perfusion response to insulin. We sought to investigate the association of dietary sodium reduction with muscle perfusion, insulin sensitivity, and cardiac function in overweight/obese insulin‐resistant (O‐IR) normotensive subjects.

Methods and results

Fifty O‐IR individuals with higher than recommended sodium intake were randomized to usual or reduced sodium diet for 8 weeks; 25 lean, healthy subjects served as controls for pre‐intervention measurements. Echocardiography and muscle perfusion were performed during fasting and under stable euglycaemic–hyperinsulinaemic clamp conditions. O‐IR patients demonstrated subclinical cardiac dysfunction as evidenced by lower left ventricular global longitudinal strain (GLS), e′ tissue velocity, and left atrial strain and reduced muscle perfusion. The intervention arm showed improvements in insulin resistance [glucose infusion rate (GIR)], GLS, e′, atrial strain, and muscle perfusion in fasting conditions, as well as improved responses of GLS and muscle perfusion to insulin during clamp. Significant interactions were found between the allocation to low‐salt diet and improvement in muscle perfusion on change in GIR at follow‐up (P = 0.030), and between improvement in muscle perfusion and change in GIR on change in GLS response to insulin at follow‐up (P = 0.026). Mediation analysis revealed that the relationship between the reduction of sodium intake and improvement in GLS was mediated by improvements in muscle perfusion and GIR (decrease in beta coefficient from −0.29 to −0.16 after the inclusion of mediator variables to the model).

Conclusions

The reduction of dietary sodium in the normotensive O‐IR population improves cardiac function, and this effect may be associated with the concomitant improvements in skeletal muscle perfusion and insulin resistance. These findings might contribute to refining heart failure preventive strategies.

Cardiopulmonary Pathophysiological Aspects in the Context of COVID-19 and Obesity

Obesity is a significant public health concern associated with high morbidity. Obese patients are at risk of severe COVID-19 infection, and obesity is a high-risk factor for admission to the intensive care unit. We aimed to write a narrative review of cardiac and pulmonary pathophysiological aspects of obese patients in the context of COVID-19 infection. Obesity affects lung volume, with a decrease in expiratory reserve volume, which is associated with a decrease in lung and chest wall compliance, an increase in airway resistance, and an increase in work of breathing. Obesity affects cardiac structure and hemodynamics. Obesity is a risk factor for hypertension and cardiovascular disorders. Moreover, obesity is associated with a low-grade inflammatory state, endothelial dysfunction, hyperinsulinemia, and metabolic disorders. Obesity is associated with severe COVID-19 and invasive mechanical ventilation. These previous cardiopulmonary pathological aspects may explain the clinical severity in obese patients with COVID-19. Obese patients are at risk of severe COVID-19 infection. Understanding cardiorespiratory pathophysiological aspects may help physicians manage patients in hospitals.

Early benefits of bariatric surgery on subclinical cardiac function: Contribution of visceral fat mobilization

AIMS

We explored the early effects of bariatric surgery on subclinical myocardial function in individuals with severe obesity and preserved left ventricular (LV) ejection fraction.

METHODS

Thirty-eight patients with severe obesity [body mass index (BMI) ≥35 kg/m²] and preserved LV ejection fraction (≥50%) who underwent bariatric surgery (biliopancreatic diversion with duodenal switch [BPD-DS]) (Surgery group), 19 patients with severe obesity managed with usual care (Medical group), and 18 age and sex-matched non-obese controls (non-obese group) were included. Left ventricular global longitudinal strain (LV GLS) was evaluated with echocardiography speckle tracking imaging. Abnormal myocardial function was defined as LV GLS <18%.

RESULTS

Age of the participants was 42 ± 11 years with a BMI of 48 ± 8 kg/m² (mean ± standard deviation); 82% were female. The percentage of total weight loss at 6 months after bariatric surgery was 26.3 ± 5.2%. Proportions of hypertension (61 vs. 30%, P = 0.0005), dyslipidemia (42 vs. 5%, P = 0.0001) and type 2 diabetes (40 vs. 13%, P = 0.002) were reduced postoperatively. Before surgery, patients with obesity displayed abnormal subclinical myocardial function vs. non-obese controls (LV GLS, 16.3 ± 2.5 vs. 19.6 ± 1.7%, P < 0.001). Six months after bariatric surgery, the subclinical myocardial function was comparable to non-obese (LV GLS, 18.2 ± 1.9 vs. 19.6 ± 1.7%, surgery vs. non-obese, P = NS). On the contrary, half of individuals with obesity managed medically worsened their myocardial function during the follow-up (P = 0.002). Improvement in subclinical myocardial function following bariatric surgery was associated with changes in abdominal visceral fat (r = 0.43, P < 0.05) and inflammatory markers (r = 0.45, P < 0.01), whereas no significant association was found with weight loss or change in insulin sensitivity (HOMA-IR) (P > 0.05). In a multivariate model, losing visceral fat mass was independently associated with improved subclinical myocardial function.

CONCLUSIONS

Bariatric surgery was associated with significant improvement in the metabolic profile and in subclinical myocardial function. Early improvement in subclinical myocardial function following bariatric surgery was related to a greater mobilization of visceral fat depot, linked to global fat dysfunction and cardiometabolic morbidity.

Reduced mechanical function of the left atrial predicts adverse outcome in pregnant women with clustering of metabolic risk factors

INTRODUCTION

The left atrial (LA) strain and strain rate are sensitive indicators of LA function. However, they are not widely used for the evaluation of pregnant women with metabolic diseases. The aim of this study was to assess the LA strain and strain rate of pregnant women with clustering of metabolic risk factors and to explore its prognostic effect on adverse pregnancy outcomes.

MATERIALS AND METHODS

Sixty-three pregnant women with a clustering of metabolic risk factors (CMR group), fifty-seven women with pregnancy-induced hypertension (PIH group), fifty-seven women with gestational diabetes mellitus (GDM group), and fifty matched healthy pregnant women (control group) were retrospectively evaluated. LA function was evaluated with two-dimensional speckle-tracking imaging. Iatrogenic preterm delivery caused by severe preeclampsia, placental abruption, and fetal distress was regarded as the primary adverse outcome.

RESULTS

The CMR group showed the lowest LA strain during reservoir phase (LASr), strain during contraction phase (LASct) and peak strain rate during conduit phase (pLASRcd) among the three groups (P < 0.05). LA strain during conduit phase (LAScd) and peak strain rate during reservoir phase (pLASRr) in the CMR group were lower than those in the control and GDM groups (P < 0.05). Multivariable Cox regression analysis demonstrated systolic blood pressure (HR = 1.03, 95% CI 1.01-1.05, p = 0.001) and LASr (HR = 0.86, 95% CI 0.80-0.92, p < 0.0001) to be independent predictors of iatrogenic preterm delivery. An LASr cutoff value ≤ 38.35% predicted the occurrence of iatrogenic preterm delivery.

CONCLUSIONS

LA mechanical function in pregnant women with metabolic aggregation is deteriorated. An LASr value of 38.35% or less may indicate the occurrence of adverse pregnancy outcomes.

Obesity cardiomyopathy: evidence, mechanisms, and therapeutic implications

The prevalence of heart failure is on the rise and imposes a major health threat, in part, due to the rapidly increased prevalence of overweight and obesity. To this point, epidemiological, clinical, and experimental evidence supports the existence of a unique disease entity termed “obesity cardiomyopathy,” which develops independent of hypertension, coronary heart disease, and other heart diseases. Our contemporary review evaluates the evidence for this pathological condition, examines putative responsible mechanisms, and discusses therapeutic options for this disorder. Clinical findings have consolidated the presence of left ventricular dysfunction in obesity. Experimental investigations have uncovered pathophysiological changes in myocardial structure and function in genetically predisposed and diet-induced obesity. Indeed, contemporary evidence consolidates a wide array of cellular and molecular mechanisms underlying the etiology of obesity cardiomyopathy including adipose tissue dysfunction, systemic inflammation, metabolic disturbances (insulin resistance, abnormal glucose transport, spillover of free fatty acids, lipotoxicity, and amino acid derangement), altered intracellular especially mitochondrial Ca²⁺ homeostasis, oxidative stress, autophagy/mitophagy defect, myocardial fibrosis, dampened coronary flow reserve, coronary microvascular disease (microangiopathy), and endothelial impairment. Given the important role of obesity in the increased risk of heart failure, especially that with preserved systolic function and the recent rises in COVID-19-associated cardiovascular mortality, this review should provide compelling evidence for the presence of obesity cardiomyopathy, independent of various comorbid conditions, underlying mechanisms, and offer new insights into potential therapeutic approaches (pharmacological and lifestyle modification) for the clinical management of obesity cardiomyopathy.

Effects of obesity and diabesity on heart rhythm in the Zucker rat

Obesity and type 2 diabetes mellitus are risk factors for hypertension, coronary heart disease, cardiac arrhythmias including atrial fibrillation, heart failure and sudden cardiac death. The effects of obesity and diabesity on heart rhythm were investigated in the Zucker diabetic fatty (ZDF) and Zucker fatty (ZF) compared to the Zucker lean (ZL) control rat. In vivo biotelemetry techniques were used to assess the electrocardiogram and other cardiac and metabolic parameters. ZDF rats were characterized by age-dependent elevations in fasting and non-fasting blood glucose, glucose intolerance and weight gain and ZF rats were characterized by smaller elevations in fasting and non-fasting blood glucose and greater weight gain compared to ZL rats. Heart rate (HR) was progressively reduced in ZDF, ZF and ZL rats. At 195 days (6.5 months) of age there were significant differences in HR between ZDF (265 ± 8 bpm, n = 10), ZF (336 ± 9 bpm, n = 10) and ZL (336 ± 10 bpm, n = 10) rats and significant differences in HRV between ZDF (22 ± 1 bpm, n = 10), ZF (27 ± 1 bpm, n = 10) and ZL (31 ± 1 bpm, n = 10) rats. Power spectral analysis revealed no significant (P > 0.05) differences in HRV at low frequencies, reduced HRV at high frequencies and increased sympathovagal balance in ZDF compared to ZF and ZL rats. HR was reduced by ageing and additionally reduced by diabesity in the absence of changes in physical activity and body temperature. Reductions in HRV associated with altered sympathovagal drive might partly underlie disturbed HR in the ZDF rat. Possible explanations for reduced HR and future mechanistic studies are discussed.

Cardiac Morphology, Function, and Hemodynamics in Patients With Morbid Obesity and Nonalcoholic Steatohepatitis

Background

The patients with nonalcoholic fatty liver disease demonstrate an increased cardiovascular risk. The adverse influence of liver abnormalities on cardiac function are among many postulated mechanisms behind this association. The aim of the study was to evaluate cardiac morphology and function in patients with morbid obesity referred for bariatric surgery with liver biopsy.

Methods and Results

We evaluated with echocardiography 171 consecutive patients without known cardiac disease (median age 42 [interquartile range, 37–48] years, median body mass index 43.7 [interquartile range, 41.0–47.5], 67% female patients. Based on the liver biopsy results, there were 44 patients with nonalcoholic steatohepatitis (NASH), 69 patients with isolated steatosis, and 58 patients without steatosis. Patients with NASH demonstrated signs of left ventricular concentric remodeling and hyperdynamic circulation, including indexed left ventricular end‐diastolic diameter [cm/m²]: NASH 1.87 [0.22]; isolated steatosis 2.03 [0.33]; without steatosis 2.01 [0.19], P=0.001; relative wall thickness: NASH 0.49±0.05, isolated steatosis 0.47±0.06, without steatosis 0.46±0.06, P=0.011; cardiac index [L/m²]: NASH 3.05±0.54, isolated steatosis 2.80±0.44, without steatosis 2.79±0.50, P=0.013. After adjustment for sex, age, blood pressure, and heart rate, most of the measures of the left ventricular systolic and diastolic function, left atrial size, right ventricular function, and right ventricular size did not differ between groups.

Conclusions

In a group of patients with extreme obesity, NASH was associated with left ventricular concentric remodeling and hyperdynamic circulation. Increased cardiac output in NASH may represent an additional risk factor for incident cardiovascular events in this population.

Molecular Mechanisms of Obesity-Linked Cardiac Dysfunction: An Up-Date on Current Knowledge

Obesity is defined as excessive body fat accumulation, and worldwide obesity has nearly tripled since 1975. Excess of free fatty acids (FFAs) and triglycerides in obese individuals promote ectopic lipid accumulation in the liver, skeletal muscle tissue, and heart, among others, inducing insulin resistance, hypertension, metabolic syndrome, type 2 diabetes (T2D), atherosclerosis, and cardiovascular disease (CVD). These diseases are promoted by visceral white adipocyte tissue (WAT) dysfunction through an increase in pro-inflammatory adipokines, oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and adverse changes in the gut microbiome. In the heart, obesity and T2D induce changes in substrate utilization, tissue metabolism, oxidative stress, and inflammation, leading to myocardial fibrosis and ultimately cardiac dysfunction. Peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of carbohydrate and lipid metabolism, also improve insulin sensitivity, triglyceride levels, inflammation, and oxidative stress. The purpose of this review is to provide an update on the molecular mechanisms involved in obesity-linked CVD pathophysiology, considering pro-inflammatory cytokines, adipokines, and hormones, as well as the role of oxidative stress, inflammation, and PPARs. In addition, cell lines and animal models, biomarkers, gut microbiota dysbiosis, epigenetic modifications, and current therapeutic treatments in CVD associated with obesity are outlined in this paper.

Impact of Pregnancy on Ventricular Strain in Women with Repaired Tetralogy of Fallot

Increasing numbers of women with repaired tetralogy of Fallot (rTOF) are reaching reproductive age and seek counseling regarding their cardiovascular risks related to pregnancy. Therefore, the aim of this study was to characterize changes in left ventricular (LV) strain in women with rTOF during pregnancy and in the postpartum period. Seventeen pregnancies in women with rTOF were included (mean age at repair = 3.2 years ± 5.5 years; mean age at delivery = 32.7 ± 4 years). Echocardiograms from three time periods were analyzed; baseline (prior to conception or in the first trimester), third trimester, and 4-6 weeks postpartum. Sixty-five percent of the patients had at least mild pulmonary regurgitation. Eight patients (47%) had undergone at least one pulmonary valve replacement. There were no changes in LV ejection fraction (EF) or circumferential strain across the three time periods. Significant differences were present in longitudinal strain within the three time points (p = 0.01). Postpartum strain decreased in magnitude compared to the third trimester value (- 17.7 ± 4.1 vs. - 21 ± 5, p-value = 0.003) but was not different when compared to baseline strain (- 17.7 ± 4.1 vs. - 19.4 ± 3.4; p-value = 0.15). In conclusion, in women with rTOF, changes in longitudinal strain were observed during pregnancy with a return to baseline after delivery; EF did not change. These findings provide evidence that pregnancy does not adversely impact LV mechanics in the short term in this potentially vulnerable patient population.

Usefulness and clinical relevance of left ventricular global longitudinal systolic strain in patients with heart failure with preserved ejection fraction

In recent years, several studies have shown the usefulness and clinical relevance of left ventricular global longitudinal systolic strain (GLS) in different cardiovascular diseases. In line with this, the role of GLS in patients with heart failure with preserved ejection fraction (HFpEF) has achieved great importance in this predominant form of heart failure in the last years. In this regard, GLS has shown to be not only a sensitive parameter to detect subtle myocardial abnormalities but also a parameter of clinical and prognostic relevance in patients with HFpEF. In this review, we analyze the current evidence concerning the clinical relevance of GLS in patients with HFpEF and we discuss the potential usefulness of GLS in this complex and heterogeneous condition for which so far no effective therapy exists.

The association of the metabolic syndrome with target organ damage: focus on the heart, brain, and central arteries

INTRODUCTION

The metabolic syndrome (MetS) is an adverse metabolic state composed of obesity, hyperglycemia/pre-diabetes, hypertension, and dyslipidemia. It substantially increases the risk of type 2 diabetes, cardiovascular disease (CVD) and mortality, and has a huge impact on public health.

AREA COVERED

The present review gives an update on the definition and prevalence of MetS, and its impact on cardiac structure and function as well as on the brain and central arteries. The association with CVD and mortality risk is discussed. Focus is mainly directed toward the subclinical target organ damage related to MetS. Data is also critically reviewed to provide evidence on the incremental prognostic value of overall MetS over its individual components.

EXPERT COMMENTARY

MetS is a clinical risk condition associated with subclinical and clinical CVD and mortality. Roughly, 30% of the world population suffer from MetS. As all components of the MetS are modifiable, optimal preventive and therapeutic measures should be initiated to improve CV risk control, particularly aggressively treating hypertension and hyperglycemia, and encouraging people to adopt healthy lifestyle as early as possible is of great importance.

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.

Early detection of left atrial and bi-ventricular myocardial strain abnormalities by MRI feature tracking in normotensive or hypertensive T2DM patients with preserved LV function

BACKGROUND

Previous studies have found that impaired global myocardial systolic strain is associated with cardiovascular events in T2DM patients. However, the effect of hypertension (HT) on left atrial (LA), right ventricular (RV) and left ventricular (LV) myocardial deformation in hypertensive T2DM patients has not been fully studied by cardiac magnetic resonance feature tracking (CMR-FT). Our aim was to assess LA, RV and LV strain in T2DM patients with T2DM-HT and without hypertension using CMR-FT and to determine the underlying relationships with clinical parameters.

METHODS

A total of 27 T2DM patients, 23 T2DM-HT patients and 31 controls were studied. LA, LV and RV strain was evaluated using CMR-FT. The clinical and biochemical parameters of the patients were collected.

RESULTS

The T2DM patients had reduced LA global circumferential strain (LAGCS), radial strain (LAGRS), longitudinal strain (LAGLS) and right ventricular longitudinal strain (RVGLS) compared with the controls (LAGCS: 27.2 ± 2.1% vs 33.5 ± 2.4%; LAGRS: - 28.6 ± 1.1% vs - 31.9 ± 1.3%; LAGLS: 24.3 ± 1.3% vs 31.4 ± 1.5; RVGLS: - 21.4 ± 1.2% vs - 26.3 ± 1.1%, p < 0.05 for all). The T2DM-HT patients had greater LAGCS, LAGRS and LAGLS than the T2DM patients (LAGCS: 40.4 ± 3.8% vs 27.2 ± 2.1%; LAGRS: - 36.8 ± 2.0% vs - 28.6 ± 1.1%; LAGLS: 32.3 ± 2.4% vs 24.3 ± 1.3%, p < 0.05 for all). In the diabetic patients, LAGCS was associated with microalbuminuria levels (standardized ß = - 0.289, p = 0.021), and LAGCS, LAGRS and LAGLS were correlated with diuretic treatment (standardized ß =0.440, - 0.442, and 0.643, p < 0.05 for all).

CONCLUSIONS

CMR-FT may be considered a promising tool for the early detection of abnormal LA and RV myocardial strain. LA and RV strain values are impaired in T2DM patients. The amelioration of LA strain might be associated with hypertensive compensation or antihypertensive treatment, which requires to be confirmed in larger trials.

Short-term echocardiographic evaluation by global longitudinal strain in patients with heart failure treated with sacubitril/valsartan

AIMS

The angiotensin receptor neprilysin inhibitor (ARNI) sacubitril/valsartan reduces mortality and hospitalizations in patients with heart failure and reduced ejection fraction (HFrEF). Favourable effects on haemodynamic and functional parameters have been observed in patients with HFrEF undergoing ARNI therapy, using standard transthoracic echocardiography. Global longitudinal strain (GLS) assessment uses a semi-automatic procedure to provide a reliable and repeatable method that improves the detection of early changes of contractile function. We aimed to assess the effects of ARNI on GLS and myocardial mechanics in patients with HFrEF.

METHODS AND RESULTS

Thirty patients with New York Heart Association class II-III HFrEF were treated with ARNI and monitored using standard echocardiographic examination and GLS measurements at baseline, 3 months, and 6 months. ARNI therapy resulted in a significant reduction of ventricular volumes and a significant increase in left ventricular ejection fraction at 6 months but not 3 months by standard transthoracic echocardiography (left ventricular ejection fraction from 28 ± 8% at baseline to 34 ± 12% at 6 months, P < 0.001). Non-significant differences in the size of the left atrium, right ventricular function, and pulmonary pressures were found at 6 months. By using GLS, there was a progressive improvement of all strain parameters by 3 months. The improvement showed a progressive trend over time and maintained significance at 6 months: GLS 4ch -7.2 ± 4.8% at baseline vs. -7.5 ± 3.9% at 3 months (P = 0.025) and - 9.2 ± 5.2% at 6 months (P = 0.0001); AVG GLS -6.9 ± 4.3 at baseline vs. -7.9 ± 4.2 at 3 months (P = 0.04) and - 8.8 ± 4.4 at 6 months (P = 0.035); GLS endo 8.2 ± 4.8 at baseline vs. -9.0 ± 4.8 at 3 months (P = 0.05) and - 10.1 ± 5.1 at 6 months (P = 0.001).

CONCLUSIONS

Sacubitril/valsartan induces an early benefit on left ventricular remodelling, which is captured by myocardial strain and not by standard echocardiography. Strain method represents a practical tool to assess early and minimal variations of left ventricular systolic function.

Early Stages of Obesity-related Heart Failure Are Associated with Natriuretic Peptide Deficiency and an Overall Lack of Neurohormonal Activation: The Copenhagen Heart Failure Risk Study

Objective

This study evaluated the associations between the natriuretic peptide activity and the neurohormonal response in non-obese and obese outpatients with and without heart failure (HF).

Background

Obesity-related HF may be a distinct subtype of HF. Obesity is associated with lower plasma concentrations of natriuretic peptides. The associations between obesity and neurohormonal activation estimated by mid-regional pro-adrenomedullin (MR-proADM) and copeptin in patients with HF is not elucidated.

Methods

This prospective cohort-study included 392 outpatients ≥60years, plus ≥1 risk-factor(-s) for HF (hypertension, ischemic heart disease, atrial fibrillation, diabetes, chronic kidney disease), and without known HF. Patients were categorized 'non-obese' BMI = 18.5-29.9 kg/m2 (n = 273) and 'obese' BMI ≥ 30 kg/m2 (n = 119). The diagnosis of HF required signs, symptoms, and abnormal echocardiography. NT-proBNP, MR-proANP, MR-proADM, and copeptin were analyzed.

Results

Obese patients were younger, had a higher prevalence of diabetes and chronic kidney disease, but a lower prevalence of atrial fibrillation. A total of 39 (14.3%) non-obese and 26 (21.8%) obese patients were diagnosed with HF. In obese patients, HF was not associated with higher plasma concentrations of NT-proBNP (Estimate: 0.063; 95%CI: -0.037-1.300; P = 0.064), MR-proANP (Estimate: 0.207; 95%CI: -0.101-0.515; P = 0.187), MR-proADM (Estimate: 0.112; 95%CI: -0.047-0.271; P = 0.168), or copeptin (Estimate: 0.093; 95%CI: -0.333-0.518; P = 0.669). Additionally, obese patients with HF had lower plasma concentrations of NT-proBNP (Estimate: -0.998; 95%CI: -1.778-0.218; P = 0.012), and MR-proANP (Estimate: -0.488; 95%CI: -0.845-0.132; P = 0.007) compared to non-obese patients with HF, whereas plasma concentrations of MR-proADM (Estimate: 0.066; 95%CI: -0.119-0.250; P = 0.484) and copeptin (Estimate: 0.140; 95%CI: -0.354-0.633; P = 0.578) were comparable.

Conclusions

Patients with obesity-related HF have natriuretic peptide deficiency and lack of increased plasma concentrations of MR-proADM and copeptin suggesting that patients with obesity-related HF have a blunted overall neurohormonal activity.

Myocardial Strain in the Assessment of Patients With Heart Failure: A Review

Importance

The cornerstones of imaging in heart failure (HF) are the measurement of systolic and diastolic function and left ventricular (LV) filling pressure.

Observations

Ejection fraction and the assessment of LV filling pressure and diastolic dysfunction using the ratio of early transmitral flow and LV relaxation (E/e') are conventional imaging markers of LV function. Despite their extensive use in HF guidelines, both have significant detractions, especially in an era when HF with preserved ejection fraction is becoming the dominant presentation. In contrast, strain imaging has provided a new window into myocardial mechanics. Myocardial strain is now well validated, robust, and can easily be performed on most modern echocardiography machines. This Review summarizes the evidence in 9 situations across the stages of HF where LV global longitudinal strain and other strain parameters may provide information on risk prediction, diagnosis, assessment of treatment response, and follow-up.

Conclusions and Relevance

The evolution of myocardial deformation imaging from research tool to clinical practice will provide clinicians with a useful additional imaging parameter to facilitate the assessment and risk evaluation of patients with HF.

Choosing an Adequate Test to Determine Fitness for Air Travel in Obese Individuals

BACKGROUND

Air travel is physically demanding and, because obesity is rising, physicians increasingly need to assess whether such patients can fly safely. Our aim was to compare the diagnostic accuracy of two routinely used exercise tests, 50-m walk test and 6-min walk test, and hypoxic challenge testing (HCT) in obese individuals. We further explored the diagnostic potential of perceived dyspnea as measured with the Borg scale because this is often recorded subsequent to walking tests.

METHODS

In this prospective study, we examined 21 obese participants (10 women, age 51 ± 15 [mean  ±  SD], BMI 36 ± 5  kg/m²). The most prevalent comorbidity was COPD (n = 11). The reference standard for in-flight hypoxia, defined as oxygen saturation below 90%, was established in an altitude chamber. Diagnostic accuracy of each index test was estimated by area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 21 participants, 13 (9 with COPD) were identified with in-flight hypoxia. HCT was the only test separating the reference groups significantly with AUC 0.87 (95% CI,  0.62-0.96). Neither of the walking tests predicted noticeably above chance level: 50 m walk test had an AUC of 0.63 (0.36-0.84) and 6MWT had an AUC of 0.64 (0.35-0.86). We further observed good prognostic ability of subjective dyspnea assessment when recorded after 6MWT with an AUC of 0.80 (0.55-0.93).

CONCLUSIONS

In-flight hypoxia in obese individuals can be predicted by HCT but not by simple walking tests.

Manifestations and mechanisms of myocardial lipotoxicity in obesity

Environmental and socioeconomic changes over the past thirty years have contributed to a dramatic rise in the worldwide prevalence of obesity. Heart disease is amongst the most serious health risks of obesity, with increases in both atherosclerotic coronary heart disease and heart failure among obese individuals. In this review, we focus on primary myocardial alterations in obesity that include hypertrophic remodelling and diastolic dysfunction. Obesity-associated perturbations in myocardial and systemic lipid metabolism are important contributors to cardiovascular complications of obesity. Accumulation of excess lipid in nonadipose cells of the cardiovascular system can cause cell dysfunction and cell death, a process known as lipotoxicity. Lipotoxicity has been modelled in mice using high-fat diet feeding, inbred lines with mutations in leptin receptor signalling, and in genetically engineered mice with enhanced myocardial fatty acid uptake, altered lipid droplet homoeostasis or decreased cardiac fatty acid oxidation. These studies, along with findings in cell culture model systems, indicate that the molecular pathophysiology of lipid overload involves endoplasmic reticulum stress, alterations in autophagy, de novo ceramide synthesis, oxidative stress, inflammation and changes in gene expression. We highlight recent advances that extend our understanding of the impact of obesity and altered lipid metabolism on cardiac function.