The Obesity Paradox in Heart Failure: Accepting Reality and Making Rational Decisions

The Impact of Body Mass Index on Morbidity and Mortality in Iraqi Patients With Heart Failure

BACKGROUND

Obesity and heart failure (HF) are increasingly significant contributors to illness and death worldwide. While obesity appears to increase the risk of HF, it may paradoxically improve survival. This study aimed to investigate the impact of body mass index (BMI) on the mortality and morbidity of patients with HF.

METHODOLOGY

 A total of 122 patients including females (n=39) and males (n=83) diagnosed with HF were admitted to two cardiac units in Basrah, Iraq. The diagnosis was made based on Framingham Heart Failure Diagnostic Criteria. The BMI, baseline hemodynamics, and medical history were recorded, while the etiology and severity of HF were assessed at enrollment. The patients were followed up prospectively for hospital admission, and survival after one year of enrollment.

RESULTS

The mean age of patients with HF was 62.7 years (SD 10.25). They included based on BMI categories 49.2% of normal/underweight individuals, while 50.8% were overweight/obese. The most frequent etiology was ischemic heart disease in 63.9%. Echocardiography revealed that the prevalence of left ventricular ejection fraction (LVEF) < 50% was 62.29%. It was observed that obese/overweight patients were more likely to have diastolic HF (P=0.001), and more severe disease (P=0.014), and were more likely to be alive at the one-year mark (P=0.001) than underweight/normal ones. Furthermore, the underweight had the least favorable outcome than any of the other five BMI categories (P<0.0001). Moreover, obese/overweight individuals had higher hospitalization rates in the first six months than normal/underweight, though this was insignificant (P=0.15).

CONCLUSIONS

It appears that among Iraqis with heart failure, those who are overweight or obese had better outcomes at one year compared to normal or underweight. Further studies on a larger number of HF patients, and utilizing additional anthropometric indices and cardiorespiratory fitness to validate the observation of this study are warranted.

Is the obesity paradox in outpatients with heart failure reduced ejection fraction real?

Background

The obesity occurrence has achieved epidemic levels worldwide and several studies indicate a paradoxical similarity among obesity and the prognosis in heart failure (HF). The primary objective was to understand the association between body mass index (BMI) and heart failure with reduced ejection fraction (HFREF) of ischemic etiology in outpatients, using mortality as a parameter. The secondary objectives were to determine the differences in HF functional class, pharmacological therapy and evaluate the prognostic value of MAGGIC Score in this population.

Methods

We analyzed 1,556 medical records from the HF outpatient clinic of a quaternary hospital and 242 were selected according to the criteria. Most were male, average age 62.6 (56-70), BMI 18.5-24.9 = 35.1%, 25-29.9 = 37.2%, 30-34.9 = 17.8%, 35-39.9 = 7%; BMI <18.5 and >40 groups were eliminated from the central analyzes because of scarce testing.

Results

BMI 30-34.9 and BMI 18.5-24.9 had the best prognosis, BMI 25-29.9 had an average performance, and BMI -39.9 group provided the worst outcome (p = 0.123). In the subcategory analysis, BMI 30-34.9 group had a better prognosis compared to the BMI 35-39.9 group (p = 0.033). In the multivariate analysis The MAGGIC score was not able to foretell mortality in this population according to BMI.

Conclusion

In not hospitalized patients with HFREF of ischemic etiology, obesity was not a protective factor.

The Obesity Paradox in Chronic Heart Disease and Chronic Obstructive Pulmonary Disease

Obesity in recent years has become an epidemic. A high body mass index (BMI) is one of today's most crucial population health indicators. BMI does not directly quantify body fat but correlates well with easier body fat measurements. Like smoking, obesity impacts multiple organ systems and is a major modifiable risk factor for countless diseases. Despite this, reports have emerged that obesity positively impacts the prognosis of patients with chronic illnesses such as chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD), a phenomenon known as the Obesity Paradox. This article attempts to explain and summarize this phenomenon.

As it stands, two theories explain this paradox. The muscle mass hypothesis states that obese patients are better adapted to tide through acute exacerbations due to increased reserve because of greater muscle mass. The other theory focuses on brown adipose tissue and its anti-inflammatory effects on the body.

We performed a literature review on research articles published in English from 1983 to the present in the following databases - PubMed, Elsevier, and Google Scholar. The following search strings and Medical Subject Headings (MeSH) terms were used: "Obesity," "Heart Failure," "COPD," and "Cardio-Respiratory Fitness." In this review, we looked at the obesity paradox in Heart Failure and COPD. We summarized the current literature on the Obesity Paradox and reviewed its relationship with Cardio-Respiratory Fitness.

Malnutrition outweighs the effect of the obesity paradox

BACKGROUND

High body mass index (BMI) is paradoxically associated with better outcome in patients with heart failure (HF). The effects of malnutrition on this phenomenon across the whole spectrum of HF have not yet been studied.

METHODS

In this observational study, patients were classified by guideline diagnostic criteria to one of three heart failure subtypes: reduced (HFrEF), mildy reduced (HFmrEF), and preserved ejection fraction (HFpEF). Data were retrieved from the Viennese-community healthcare provider network between 2010 and 2020. The relationship between BMI, nutritional status reflected by the prognostic nutritional index (PNI), and survival was assessed. Patients were classified by the presence (PNI < 45) or absence (PNI ≥ 45) of malnutrition.

RESULTS

Of the 11 995 patients enrolled, 6916 (58%) were classified as HFpEF, 2809 (23%) HFmrEF, and 2270 HFrEF (19%). Median age was 70 years (IQR 61-77), and 67% of patients were men. During a median follow-up time of 44 months (IQR 19-76), 3718 (31%) of patients died. After adjustment for potential confounders, BMI per IQR increase was independently associated with better survival (adj. hazard ratio [HR]: 0.91 [CI 0.86-0.97], P = 0.005), this association remained significant after additional adjustment for HF type (adj. HR: 0.92 [CI 0.86-0.98], P = 0.011). PNI was available in 10 005 patients and lowest in HFrEF patients. PNI was independently associated with improved survival (adj. HR: 0.96 [CI 0.95-0.97], P < 0.001); additional adjustment for HF type yielded similar results (adj. HR: 0.96 [CI 0.96-0.97], P < 0.001). Although obese patients experienced a 30% risk reduction, malnutrition at least doubled the risk for death with 1.8- to 2.5-fold higher hazards for patients with poor nutritional status compared with normal weight well-nourished patients.

CONCLUSIONS

The obesity paradox seems to be an inherent characteristic of HF regardless of phenotype and nutritional status. Yet malnutrition significantly changes trajectory of outcome with regard to BMI alone: obese patients with malnutrition have a considerably worse outcome compared with their well-nourished counterparts, outweighing protective effects of high BMI alone. In this context, routine recommendation towards weight loss in patients with obesity and HF should generally be made with caution and focus should be shifted on nutritional status.

Collider Bias in Observational Studies: Consequences for Medical Research–Part 30 of a Series on Evaluation of Scientific Publications

BACKGROUND

The findings of observational studies can be distorted by a number of factors. Socalled confounders are well known, but distortion by collider bias (CB) has received little attention in medical research to date. The goal of this article is to present the principle of CB, and measures that can be taken to avoid it, by way of a few illustrative examples.

METHODS

The findings of a selective review of the literature on CB are explained with illustrative examples.

RESULTS

The simplest case of a collider variable is one that is caused by at least two other variables. An example of CB is the observation that, among persons with diabetes, obesity is associated with lower mortality, even though it is associated with higher mortality in the general population. The false protective association between obesity and mortality arises from the restriction of the study population to persons with diabetes.

CONCLUSION

CB is a distortion that arises through restriction on or stratification by a collider variable, or through statistical adjustment for a collider variable in a regression model. CB can arise in many ways. The graphic representation of causal structures helps to identify potential sources of CB. It is important to distinguish confounders from colliders, as methods that serve to correct for confounding can themselves cause bias when applied to colliders. There is no generally applicable method for correcting CB.

The obesity paradox and diabetes

BACKGROUND

Obesity has been proven to be a risk factor for type 2 diabetes mellitus (T2DM) through numerous pathogenetic mechanisms. Unexpectedly, some studies suggest that subjects with overweight/obesity and T2DM have better clinical outcome than their normal weight peers. This finding is described as "obesity paradox" and calls into question the importance of weight loss in this specific population.

OBJECTIVE

This article is a narrative overview on the obesity and type 2 diabetes mellitus, particularly regarding the obesity paradox in T2DM patients.

METHODS

We used as sources MEDLINE/PubMed, CINAHL, EMBASE, and Cochrane Library, from inception to March 2020; we chose 30 relevant papers regarding the association of obesity with clinical outcome and mortality of patients affected by T2DM.

RESULTS

Many studies report that in patients with T2DM, overweight and obesity are associated with a better prognosis than underweight or normal weight, suggesting the presence of an obesity paradox. However, these studies have numerous limitations due to their mainly retrospective nature and to numerous confounding factors, such as associated pathologies, antidiabetic treatments, smoking habit, lack of data about distribution of body fat or weight history.

CONCLUSION

Literature data regarding the phenomenon of obesity paradox in T2DM patients are controversial due to the several limitations of the studies; therefore in the management of patients with overweight/obesity and T2DM is recommended referring to the established guidelines, which indicate diet and physical activity as the cornerstone of the treatment.

LEVEL OF EVIDENCE

Level V: narrative review.

Time-updated resting heart rate predicts mortality in patients with COPD

High resting heart rate (RHR) is associated with higher mortality in the general population and in cardiovascular disease. Less is known about the association of RHR with outcome in chronic obstructive pulmonary disease (COPD). In particular, the time-updated RHR (most recent value before the event) appears informative. This is the first study to investigate the association of time-updated RHR with mortality in COPD. We compared the baseline and time-updated RHR related to survival in 2218 COPD patients of the German COSYCONET cohort (COPD and Systemic Consequences-Comorbidities Network). Patients with a baseline RHR > 72 beats per minute (bmp) had a significantly (p = 0.049) higher all-cause mortality risk (adjusted hazard ratio (HR) of 1.37 (1.00-1.87) compared to baseline RHR ≤ 72 bpm. The time-updated RHR > 72 bpm was markedly superior (HR 1.79, 1.30-2.46, p = 0.001). Both, increased baseline and time-updated RHR, were independently associated with low FEV1, low TLCO, a history of diabetes, and medication with short-acting beta agonists (SABAs). In conclusion, increased time-updated RHR is associated with higher mortality in COPD independent of other predictors and superior to baseline RHR. Increased RHR is linked to lung function, comorbidities and medication. Whether RHR is an effective treatment target in COPD, needs to be proven in controlled trials.

Body mass index and clinical outcomes in patients after ischaemic stroke in South Korea: a retrospective cohort study

OBJECTIVES

Although obesity is a risk factor for stroke, its impact on mortality in patients with stroke remains unclear. In this study, we aimed to evaluate the relationship between body mass index (BMI) and mortality due to ischaemic stroke among adults aged 20 years and above in Korea.

DESIGN

Retrospective cohort study.

SETTING

A tertiary-hospital-based stroke registry linked to the death records.

PARTICIPANTS

3599 patients admitted for ischaemic stroke from January 2007 to June 2013.

OUTCOME MEASURES

The HRs for all-cause and stroke-related mortality were calculated using Cox proportional hazards models. Progression from stroke-related mortality was assessed using the Fine-Grey competing risk model, treating other-cause mortality as a competing risk. Adjustments were made for age, gender, smoking status, Charlson comorbidity index, cardiovascular or non-cardiovascular comorbidities, stroke severity, severity related to other medical conditions, complications and enrolment year. We repeated the analysis with stratification based on age groups (less than 65 vs 65 years and above).

RESULTS

For stroke-related mortality, there was no significant difference among the four BMI groups. The risk of all-cause mortality was 36% higher in the underweight group than in the normal weight group (long-term HR=1.36, 95% CI: 1.04 to 1.79), whereas the mortality risk of the obese group was significantly lower (HR=0.66, 95% CI: 0.54 to 0.81). Although this relationship was not estimated in the younger group, it was found that obesity had a protective effect on the all-cause mortality in the elderly (long-term HR=0.66, 95% CI: 0.52 to 0.83).

CONCLUSIONS

Obesity is more likely to reduce mortality risk than normal weight, especially in elderly patients.

Comparison of sarcopenia and cachexia in men with chronic heart failure: results from the Studies Investigating Co-morbidities Aggravating Heart Failure (SICA-HF)

AIMS

Changes in heart failure (HF) patients' body composition may be associated with reduced exercise capacity. The aim of the present study was to determine the overlap in wasting syndromes in HF (cachexia and sarcopenia) and to compare their functional impact.

METHODS AND RESULTS

We prospectively enrolled 207 ambulatory male patients with clinically stable chronic HF. All patients underwent a standardized protocol examining functional capacity, body composition, and quality of life (QoL). Cachexia was present in 39 (18.8%) of 207 patients, 14 of whom also fulfilled the characteristics of sarcopenia (sarcopenia + cachexia group, 6.7%), whereas 25 did not (cachectic HF group, 12.1%). Sarcopenia without cachexia was present in 30 patients (sarcopenic HF group, 14.4%). A total of 44 patients (21.3%) presented with sarcopenia; however, 138 patients showed no signs of wasting (no wasting group, 66%). Patients with sarcopenia had lower strength and exercise capacity than both the no wasting and the cachectic HF group. Handgrip strength, quadriceps strength, peak oxygen uptake (VO₂ ), distance in the 6-minute walk test (6MWT), and QoL results were lowest in the sarcopenia + cachexia group vs. the no wasting group (P < 0.05 for all). Likewise, the sarcopenic HF group showed lower handgrip strength, quadriceps strength, 6MWT, peak VO₂ , and QoL results vs. the no wasting group (P < 0.05 for all).

CONCLUSION

Losing muscle with or without weight loss appears to have a more pronounced role than weight loss alone with regard to functional capacity and QoL among male patients with chronic HF.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01872299.

The Impact of Body Mass Index on the Link Between Depressive Symptoms and Health Outcome in Patients With Heart Failure

BACKGROUND

Depressive symptoms are predictors of shorter cardiac event-free survival, whereas increased body mass index (BMI) is associated with longer cardiac event-free survival in patients with heart failure (HF). However, the impact of BMI on the link between depressive symptoms and cardiac event-free survival is unexplored. The purpose of this study was to determine whether the relationship between depressive symptoms and cardiac event-free survival differs among HF patients stratified by BMI tertiles.

METHODS

A total of 297 outpatients with HF completed the Patient Health Questionnaire-9 to assess depressive symptoms. Body mass index was calculated as weight in kilograms divided by height in meters squared. Patients were followed for 1 year to determine cardiac event-free survival. Cox proportional hazard regression with survival curves was used to determine the relationships among depressive symptoms, BMI, and cardiac event-free survival.

RESULTS

Both depressive symptoms (P < .001) and lower BMI (P = .002) are independent predictors of shorter cardiac event-free survival after controlling for age, gender, etiology, total comorbidity scores, ejection fraction, New York Heart Association functional class, and prescribed medications. Patients with depressive symptoms had shorter cardiac event-free survival compared with patients without depressive symptoms in the lowest (P = .001) and middle (P = .036) BMI tertiles. There was no difference in cardiac event-free survival between patients with and without depressive symptoms in the highest tertile (P = .894).

CONCLUSIONS

Higher BMI has a protective role in the adverse effect of depressive symptoms on health outcomes in patients with HF.

Association of Plasma Small-Molecule Intermediate Metabolites With Age and Body Mass Index Across Six Diverse Study Populations

BACKGROUND

Older age and obesity are associated with metabolic dysregulation; the mechanism by which these factors impact metabolism across the lifespan is important, but relatively unknown. We evaluated a panel of amino acids (AAs) and acylcarnitines (ACs) to identify effects of age and adiposity (body mass index) on circulating small-molecule metabolites in a meta-analysis of six diverse study populations.

METHODS

Targeted metabolic profiling was performed in six independent studies, representing 739 subjects with a broad range of age, body mass index, health states, and ethnic origin. Principal components analysis was performed on log-normalized values for AAs and ACs separately, generating one AC factor and two AA factors for each study. A common AC factor consisted primarily of acetylcarnitine, medium-chain AC, and several long-chain AC. AA Factor 1 consisted primarily of large neutral AAs. Glycine was its own factor.

RESULTS

Metabolic profiling and factor analysis identified clusters of related metabolites of lipid and AA metabolism that were consistently associated with age and body mass in a series of studies with a broad range of age, body mass index, and health status. An inverse association of glycine with body mass index and male gender supports its role as a marker of favorable metabolic health.

CONCLUSIONS

An important focus of future investigations should be to determine whether these clusters of metabolic intermediates are possible early predictors of health outcomes associated with body mass; are involved with accelerated aging; are involved in the causative pathway of aging; and how modification of these metabolic pathways impact the biology of aging.

The Obesity Paradox and Heart Failure: A Systematic Review of a Decade of Evidence

There is scientific consensus that obesity increases the risk of cardiovascular diseases, including heart failure. However, among persons who already have heart failure, outcomes seem to be better in obese persons as compared with lean persons: this has been termed the obesity paradox, the mechanisms of which remain unclear. This study systematically reviewed the evidence of the relationship between heart failure mortality (and survival) and weight status. Search of the PubMed/MEDLINE and EMBASE databases was done according to the PRISMA protocol. The initial search identified 9879 potentially relevant papers, out of which ten studies met the inclusion criteria. One study was a randomized clinical trial and 9 were observational cohort studies: 6 prospective and 3 retrospective studies. All studies used the BMI, WC, or TSF as measure of body fatness and NYHA Classification of Heart Failure and had single outcomes, death, as study endpoint. All studies included in review were longitudinal studies. All ten studies reported improved outcomes for obese heart failure patients as compared with their normal weight counterparts; worse prognosis was demonstrated for extreme obesity (BMI > 40 kg/m(2)). The findings of this review will be of significance in informing the practice of asking obese persons with heart failure to lose weight. However, any such recommendation on weight loss must be consequent upon more conclusive evidence on the mechanisms of the obesity paradox in heart failure and exclusion of collider bias.

The role of adiponectin signaling in metabolic syndrome and cancer

The increased prevalence of obesity has mandated extensive research focused on mechanisms responsible for associated clinical complications. Emerging from the focus on adipose tissue biology as a vitally important adipokine is adiponectin which is now believed to mediate anti-diabetic, anti-atherosclerotic, anti-inflammatory, cardioprotective and cancer modifying actions. Adiponectin mediates these primarily beneficial effects via direct signaling effects and via enhancing insulin sensitivity via crosstalk with insulin signaling pathways. Reduced adiponectin action is detrimental and occurs in obesity via decreased circulating levels of adiponectin action or development of adiponectin resistance. This review will focus on cellular mechanisms of adiponectin action, their crosstalk with insulin signaling and the resultant role of adiponectin in cardiovascular disease, diabetes and cancer and reviews data from in vitro cell based studies through animal models to clinical observations.

Direct effects of adipokines on the heart: focus on adiponectin

Cardiovascular disease, including heart failure, is a principal cause of death in individuals with obesity and diabetes. However, the mechanisms of obesity- and diabetes-induced heart disease are multifaceted and remain to be clearly defined. Of relevance to this review, there is currently great research and clinical interest in the endocrine effects of adipokines on the myocardium and their role in heart failure. We will discuss the potential significance of adipokines in the pathogenesis of heart failure via their ability to regulate remodeling events including metabolism, hypertrophy, fibrosis, and cell death. As an excellent example, we will first focus on adiponectin which is best known to confer numerous cardioprotective effects. However, we comprehensively discuss the existing literature that highlights it would be naive to assume that this was always the case. We also focus on lipocalin-2 which mediates pro-inflammatory and pro-apoptotic effects. It is important when studying actions of adipokines to integrate cellular and mechanistic analyses and translate these to physiologically relevant in vivo models and clinical studies. However, assimilating studies on numerous cardiac remodeling events which ultimately dictate cardiac dysfunction into a unifying conclusion is challenging. Nevertheless, there is undoubted potential for the use of adipokines as robust biomarkers and appropriate therapeutic targets in heart failure.

Mandatory oral glucose tolerance tests identify more diabetics in stable patients with chronic heart failure: a prospective observational study

BACKGROUND

Many patients with chronic heart failure (CHF) are believed to have unrecognized diabetes, which is associated with a worse prognosis. This study aimed to describe glucose tolerance in a general stable CHF population and to identify determinants of glucose tolerance focusing on body composition and skeletal muscle strength.

METHODS

A prospective observational study was set up. Inclusion criteria were diagnosis of CHF, stable condition and absence of glucose-lowering medication. Patients underwent a 2 h oral glucose tolerance test (OGTT), isometric strength testing of the upper leg and dual energy x-ray absorptiometry. Health-related quality of life and physical activity level were assessed by questionnaire.

RESULTS

Data of 56 participants were analyzed. Despite near-normal fasting glucose values, 55% was classified as prediabetic, 14% as diabetic, and 20% as normal glucose tolerant. Of all newly diagnosed diabetic patients, 79% were diagnosed because of 2 h glucose values only and none because of HbA1c. Univariate mixed model analysis revealed ischaemic aetiology, daily physical activity, E/E', fat trunk/fat limbs and extension strength as possible explanatory variables for the glucose curve during the glucose tolerance test. When combined in one model, only fat trunk/fat limbs and E/E' remained significant predictors. Furthermore, fasting insulin was correlated with fat mass/height2 (r = 0.51, p < 0.0001), extension strength (r = -0.33, p < 0.01) and triglycerides (r = 0.39, p < 0.01).

CONCLUSIONS

Our data confirm that a large majority of CHF patients have impaired glucose tolerance. This glucose intolerance is related to fat distribution and left ventricular end-diastolic pressure.

Body mass index, diabetes, and mortality in French women: explaining away a "paradox"

BACKGROUND

Obesity is associated with increased mortality in the general population but, paradoxically, with decreased mortality in persons with diabetes.

METHODS

Among 88,373 French women participating in the E3N-EPIC study who were free of diabetes in 1990, we estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) of mortality for body mass index (BMI) levels by diabetes status.

RESULTS

During an average 16.7 years of follow-up, 2421 cases of diabetes were identified and 3750 deaths occurred. For overweight/obese versus normal-weight women, the HR of mortality was 1.42 (95% CI = 1.32-1.53) in women without diabetes and 0.69 (0.40-1.18) in women with incident diabetes. As BMI increased, mortality among women without diabetes increased and that among women with diabetes decreased.

CONCLUSIONS

We found the obesity "paradox" among women with and without incident diabetes in the same population. Selection bias may be a simple explanation for this "paradox."

Insulin resistance protects the heart from fuel overload in dysregulated metabolic states

Reversing impaired insulin sensitivity has been suggested as treatment for heart failure. However, recent clinical evidence suggests the opposite. Here we present a line of reasoning in support of the hypothesis that insulin resistance protects the heart from the consequences of fuel overload in the dysregulated metabolic state of obesity and diabetes. We discuss pathways of myocardial fuel toxicity, as well as several layers of defense against fuel overload. Our reassessment of the literature suggests that in the heart, insulin-sensitizing agents result in an elimination of some of the defenses, leading to cytotoxic damage. In contrast, a normalization of fuel supply should either prevent or reverse the process. Taken together, we offer a new perspective on insulin resistance of the heart.

New echocardiographic techniques in the evaluation of left ventricular function in obesity

OBJECTIVE

Obesity has reached global epidemic proportions and is associated with numerous comorbidities, including major cardiovascular (CV) diseases.

DESIGN AND METHODS

It has many adverse effects on hemodynamics and CV structure and function: it increases total blood volume and cardiac output, and the cardiac workload is greater. Typically, obese patients have a higher cardiac output but a lower level of total peripheral resistance at any given level of arterial pressure. Most of the increase in cardiac output in obesity is caused by stroke volume, although heart rate typically mildly increases also due to enhanced sympathetic activation.

RESULTS

Over the last few years, experimental investigations have unraveled some important pathogenetic mechanisms that may underlie a specific form of "obesity cardiomyopathy." Bariatric surgery represents an effective alternative to treat obesity when nonsurgical weight loss programs (diet + behavior modifications + regular exercise) have failed. A great numbers of questions are still open in the global comprehension of the pathophysiological interactions between obesity and heart.

CONCLUSION

Conventional two-dimensional Doppler echocardiography, integrated by relative new technological ultrasonic approaches, represents the reference technique to study and possibly clarify both the very complex hemodynamic changes induced by obesity and those relative to obesity treatment.

Left ventricular assist device effects on metabolic substrates in the failing heart

BACKGROUND

Heart failure patients have inadequate nutritional intake and alterations in metabolism contributing to an overall energy depleted state. Left ventricular assist device (LVAD) support is a common and successful intervention in patients with end-stage heart failure. LVAD support leads to alterations in cardiac output, functional status, neurohormonal activity and transcriptional profiles but the effects of LVADs on myocardial metabolism are unknown. This study set out to measure cardiac metabolites in non-failing hearts, failing hearts, and hearts post-LVAD support.

METHODS

The study population consisted of 8 non-ischemic failing (at LVAD implant) and 8 post-LVAD hearts, plus 8 non-failing hearts obtained from the tissue bank at the University of Colorado. NMR spectroscopy was utilized to evaluate differences in myocardial energy substrates. Paired and non-paired t-tests were used to determine differences between the appropriate groups.

RESULTS

Glucose and lactate values both decreased from non-failing to failing hearts and increased again significantly in the (paired) post-LVAD hearts. Glutamine, alanine, and aromatic amino acids decreased from non-failing to failing hearts and did not change significantly post-LVAD. Total creatine and succinate decreased from non-failing to failing hearts and did not change significantly post-LVAD.

DISCUSSION

Measured metabolites related to glucose metabolism are diminished in failing hearts, but recovered their values post-LVAD. This differed from the amino acid levels, which decreased in heart failure but did not recover following LVAD. Creatine and the citric acid cycle intermediate succinate followed a similar pattern as the amino acid levels.

Adiposity facilitates increased strength capacity in heart failure patients with reduced ejection fraction

BACKGROUND

Obesity is associated with relatively improved prognosis among heart failure (HF) patients. Mechanisms explaining this so-called "obesity paradox" have been unclear. We hypothesized that increased adiposity may contribute to increased strength capacity, and may thereby facilitate clinical benefits.

METHODS AND RESULTS

In a controlled, cross-sectional study, adults aged ≥ 50 years with HF with reduced ejection fraction (HFREF) (LVEF ≤ 40%) were compared to age matched controls. Body composition was determined by dual-energy X-ray absorptiometry (DXA). Aerobic (cardiopulmonary exercise testing), maximum strength (one repetition maximum [1RM]), and power (submaximal resistance/time) were assessed. 70 adults (31 HFREF, 39 controls; mean age 66.2 ± 9.6 years) were studied. Peak oxygen consumption (VO2) (15.4 ± 4.2 vs. 23.4 ± 6.6 ml O2 · kg(-1) · min(-1), p<0.0001), 1RM (154.8 ± 52.0 vs. 195.3 ± 56.8 kg, p<0.01) and power (226.4 ± 99.2 vs. 313.3 ± 130.6, p<0.01) were lower in HFREF vs. controls. 1 RM correlated with total fat (r=0.56, p<0.01), leg fat (r=0.45, p<0.05) and arm fat (r=0.39, p<0.05) in HFREF. Moreover, among HFREF patients with a high (≥ 30 kg/m(2)) body mass index (BMI), 1RM and fat mass were significantly greater than those with lower (<30 kg/m(2)) BMIs. Correlations between 1 RM and total fat (r=0.65, p<0.05) and leg fat (r=0.64, p<0.05) were particularly notable in the high BMI subgroup.

CONCLUSION

Increased adiposity correlates with relatively greater strength in HFREF patients which may explain some of the clinical benefits that result from obesity.

The obesity paradox in chronic disease: facts and numbers

Body size, particularly large, is a matter of concern among the lay public. Whether this is justified depends upon the state of health and should be judged individually. For patients with established chronic disease, there is sufficient evidence to support the benefits of large body size, i.e., the obesity paradox. This uniform finding is shared over a variety of cardiovascular, pulmonary, and renal diseases and is counterintuitive to the current concepts on ideal body weight. The scientific community has to increase the awareness about differences for optimal body size in health and disease. Simultaneously, clinicians have to be aware about body weight dynamics implications and should interpret the changes in the context of an underlying disease in order to implement the best available management.