Reduced peripheral skeletal muscle mass and abnormal reflex physiology in chronic heart failure

Association of Sarcopenia and Oxygen Uptake Efficiency Slope in Male Patients With Heart Failure

PURPOSE

Sarcopenia, the loss of muscle mass and function, is a common comorbidity in patients with heart failure (HF). The skeletal muscle modulates the respiratory response during exercise. However, whether ventilatory behavior is affected by sarcopenia is still unknown.

METHODS

We enrolled 169 male patients with HF. Muscle strength was measured by a handgrip dynamometer. Body composition was measured with dual-energy X-ray absorptiometry. Sarcopenia was defined by handgrip strength <27 kg and appendicular lean mass divided by height squared (ALM/height 2 ) <7.0 kg/m 2 . Oxygen uptake efficiency slope (OUES), ventilation (VE), oxygen uptake (VO 2 ), and carbon dioxide output (VCO 2 ) were measured by a cardiopulmonary exercise test.

RESULTS

Sarcopenia was identified in 29 patients (17%). At the first ventilatory threshold, VE/VO 2 (36.9 ± 5.9 vs 32.7 ± 6.5; P = .003) and VE/VCO 2 (39.8 ± 7.2 vs 35.3 ± 6.9; P = .004) were higher in patients with sarcopenia compared to those without sarcopenia. At the exercise peak, compared to patients without sarcopenia, patients with sarcopenia had lower OUES (1186 ± 295 vs 1634 ± 564; P < .001), relative VO 2 (16.2 ± 5.0 vs 19.5 ± 6.5 mL/kg/min; P = .01), and VE (47.3 ± 10.1 vs 63.0 ± 18.2 L/min; P < .0001), while VE/VCO 2 (42.9 ± 8.9 vs 38.7 ± 8.4; P = .025) was increased. OUES was positively correlated with ALM/height 2 ( r = 0.36; P < .0001) and handgrip strength ( r = 0.31; P < .001). Hemoglobin (OR = 1.149; 95% CI, 0.842-1.570; P = .038), ALM/height 2 (OR = 2.166; 95% CI, 1.338-3.504; P = .002), and VO 2peak (OR = 1.377; 95% CI, 1.218-1.557; P < .001) were independently associated with OUES adjusted by cofounders.

CONCLUSIONS

Our results suggest that sarcopenia is related to impaired ventilatory response during exercise in patients with HF.

Frailty, Sarcopenia, Cachexia, and Malnutrition in Heart Failure

With global aging, the number of patients with heart failure has increased markedly. Heart failure is a complex condition intricately associated with aging, organ damage, frailty, and cognitive decline, resulting in a poor prognosis. The relationship among frailty, sarcopenia, cachexia, malnutrition, and heart failure has recently received considerable attention. Although these conditions are distinct, they often exhibit a remarkably close relationship. Overlapping diagnostic criteria have been observed in the recently proposed guidelines and position statements, suggesting that several of these conditions may coexist in patients with heart failure. Therefore, a comprehensive understanding of these conditions is essential, and interventions must not only target these conditions individually, but also provide comprehensive management strategies. This review article provides an overview of the epidemiology, diagnostic methods, overlap, and prognosis of frailty, sarcopenia, cachexia, and malnutrition in patients with heart failure, incorporating insights from the FRAGILE-HF study data. Additionally, based on existing literature, this article discusses the impact of these conditions on the effectiveness of guideline-directed medical therapy for patients with heart failure. While recognizing these conditions early and promptly implementing interventions may be advantageous, further data, particularly from well-powered, large-scale, randomized controlled trials, are necessary to refine personalized treatment strategies for patients with heart failure.

Relationship between prehabilitation responsiveness and postoperative physical functional recovery in cardiovascular surgery

BACKGROUND

The purpose of this study was to examine the relationship between responsiveness to prehabilitation and postoperative recovery of physical function in cardiac surgery patients.

METHODS

Ninety-three cardiac surgery patients (mean age: 76.4 years) were included in this retrospective cohort study. Preoperative physical function was measured using the Short Physical Performance Battery (SPPB), and a prehabilitation exercise program was implemented for the SPPB domains with low scores. Among the patients, those whose SPPB score was over 11 from the start of prehabilitation and remained over 11 on the day before surgery were defined as the high-functioning group, and those whose SPPB score improved by 2 points or more from the start of prehabilitation and exceeded 11 points were defined as the responder group. Those whose SPPB score did not exceed 11 immediately before surgery were classified as non-responders. The characteristics of each group and postoperative recovery of physical function were investigated.

RESULTS

There were no serious adverse events during prehabilitation. Mean days of prehabilitation was 5.4 days. The responder group showed faster improvement in postoperative physical function and shorter time to ambulatory independence than the non-responder group. The non-responder group had lower preoperative skeletal muscle index, more severe preoperative New York Heart Association classification, and a history of musculoskeletal disease or stroke.

CONCLUSION

There were responders and non-responders to prehabilitation among cardiac surgery patients. Cardiac surgery patients who respond to prehabilitation had faster recovery of physical function. Further research is needed to determine what type of prehabilitation is more effective in postoperative recovery of physical function in cardiac surgery patients.

Neural control of the circulation during exercise in heart failure with reduced and preserved ejection fraction

Patients with heart failure with reduced (HFrEF) and preserved ejection fraction (HFpEF) exhibit severe exercise intolerance that may be due, in part, to inappropriate cardiovascular and hemodynamic adjustments to exercise. Several neural mechanisms and locally released vasoactive substances work in concert through complex interactions to ensure proper adjustments to meet the metabolic demands of the contracting skeletal muscle. Specifically, accumulating evidence suggests that disease-related alterations in neural mechanisms (e.g., central command, exercise pressor reflex, arterial baroreflex, and cardiopulmonary baroreflex) contribute to heightened sympathetic activation and impaired ability to attenuate sympathetic vasoconstrictor responsiveness that may contribute to reduced skeletal muscle blood flow and severe exercise intolerance in patients with HFrEF. In contrast, little is known regarding these important aspects of physiology in patients with HFpEF, though emerging data reveal heightened sympathetic activation and attenuated skeletal muscle blood flow during exercise in this patient population that may be attributable to dysregulated neural control of the circulation. The overall goal of this review is to provide a brief overview of the current understanding of disease-related alterations in the integrative neural cardiovascular responses to exercise in both HFrEF and HFpEF phenotypes, with a focus on sympathetic nervous system regulation during exercise.

Association between creatinine to body weight ratio and all-cause mortality: a cohort study of NHANES

Research on the relationship between the weight-adjusted skeletal muscle mass index and all-cause mortality is rare, and even rarer is the relationship between the creatinine/body weight (Cre/BW) ratio and all-cause mortality. Therefore, this study aimed to investigate the relationship between the Cre/BW ratio and mortality in individuals with normal renal function. This prospective study used data from the National Health and Nutrition Examination Survey (NHANES) database. A Cox hazard model was used to analyze the relationship between the Cre/BW ratio and mortality risk. In total, 45,459 participants were included, of which 49.97% were women, with an average age of 45.68 ± 18.08 years. The incidence of all-cause mortality was 10.9% among these participants during the median (interquartile range) follow-up of 9.6 (5.2, 14.2) years. After adjusting for all covariates, a U-shaped relationship was found between the Cre/BW ratio and all-cause mortality (P for nonlinearity <0.001), with the lowest risk observed at Cre/BW ratios (×100) between 0.821 and 0.987. In the threshold effect analysis, the Cre/BW ratio (×100) had a threshold value of 0.96. When the Cre/BW ratio (×100) was <0.96, all-cause mortality was negatively associated with the Cre/BW ratio (×100) (0.63 (0.41, 0.97)). In contrast, when the Cre/BW ratio (×100) was ≥0.96, the higher Cre/BW ratio was associated with a greater hazard ratio of all-cause mortality (1.67 (1.41, 1.97)). In conclusion, we report a U-shaped relationship between the Cre/BW ratio and all-cause mortality. Controlling the Cre/BW ratio within a certain range may reduce the risk of all-cause mortality.

Association of resting energy expenditure-based energy intake sufficiency with functional recovery, dysphagia, and 1-year mortality following heart failure: A prospective observational study

AIM

Evidence for the influence of resting energy expenditure (REE)-based energy intake on the outcomes of patients with heart failure (HF) is scarce. This study evaluates the relationship between REE-based energy intake sufficiency and clinical outcomes in hospitalized HF patients.

METHODS

This prospective observational study included newly admitted patients with acute HF. REE was measured using indirect calorimetry at baseline and total energy consumption (TEE) was calculated by multiplying REE with activity index. Energy intake (EI) was recorded, and the patients were classified into two groups, namely, the energy intake sufficiency (i.e., EI/TEE ≥1) and energy intake deficiency groups (i.e., EI/TEE <1). The primary outcome was the performance of activities of daily living, assessed using the Barthel Index, at discharge. Other outcomes included dysphagia at discharge and all-cause 1-year mortality following discharge. Dysphagia was defined as a Food Intake Level Scale (FILS) score of <7. Multivariable analyses and Kaplan-Meier estimates were used to determine the association of energy sufficiency both at baseline and at discharge with the outcomes of interest.

RESULTS

The analysis included 152 patients (mean age, 79.7 years; 51.3% women); of them, 40.1% and 42.8% had inadequate energy intake both at baseline and at discharge, respectively. In multivariable analyses, energy intake sufficiency at discharge was significantly associated with the BI (β = 0.136, p = 0.002) and FILS score (odds ratio = 0.027, p < 0.001) at discharge. Moreover, energy intake sufficiency at discharge was associated with 1-year mortality after discharge (p < 0.001).

CONCLUSION

Adequate energy intake during hospitalization was associated with improved physical and swallowing functions and 1-year survival in HF patients. Adequate nutritional management is essential for hospitalized HF patients, suggesting that adequate energy intake may lead to optimal outcomes.

The ventilatory component of the muscle metaboreflex is overstimulated in transthyretin cardiac amyloidosis patients with poor aerobic capacity

Background: The exercise pressor reflex, i.e., metabo- and mechano-reflex, partially regulates the control of ventilation and cardiovascular function during exercise. Abnormal exercise pressor reflex response has been associated with exaggerated ventilatory drive, sympathovagal imbalance and exercise limitation in chronic heart failure patients. Whether metaboreflex is over-activated and participate to poor aerobic capacity in patients with hereditary transthyretin cardiac amyloidosis (CA-TTR) is unknown. Methods: Twenty-two CA-TTR patients (aged 76 ± 7, 68% male) with the V122I (p.Val142Ile) transthyretin underwent a thorough evaluation including heart rate variability metrics, electrochemical skin conductance (ESC), physical function cardiopulmonary exercise testing, and muscle metaboreflex assessment. Eleven control subjects were chosen for muscle metaboreflex assessment. Results: Age-matched controls (n = 11) and CA-TTR patients (n = 22) had similar metaboreflex sensitivity for heart rate, stroke volume, cardiac index and mean systemic arterial pressure. Compared with age-matched controls, metaboreflex sensitivity for systemic vascular resistance (-18.64% ± 6.91% vs 3.14% ± 23.35%) and minute-ventilation responses (-9.65% ± 14.83% vs 11.84% ± 23.1%) was markedly increased in CA-TTR patients. Values of ESC displayed positive correlations with stroke volume (r = 0.53, p = 0.011) and cardiac index (r = 0.51, p = 0.015) components of metaboreflex sensitivity, an inverse correlation with systemic vascular resistance (r = -0.55, p = 0.008) and a trend with mean arterial (r = -0.42, p = 0.052) components of metaboreflex sensitivity. Peak aerobic capacity (peak VO₂%) displayed an inverse correlation with the ventilation component of metaboreflex sensitivity (r = -0.62, p = 0.015). Conclusion: Consistent with the "muscle hypothesis" in heart failure, it is proposed that deterioration of skeletal muscle function in hereditary CA-TTR patients may activate muscle metaboreflex, leading to an increase in ventilation and sensation of breathlessness, the perception of fatigue, and overall sympathetic activation.

Prognostic Value of Spot Urinary Creatinine Concentration and Its Relationship with Body Composition Parameters in HF Patients

BACKGROUND

Low 24-h urinary excretion of creatinine in patients with heart failure (HF) is believed to reflect muscle wasting and is associated with a poor prognosis. Recently, spot urinary creatinine concentration (SUCR) has been suggested as a useful prognostic factor in selected HF cohorts. This more practical and cheaper approach has never been tested in an unselected HF population. Moreover, neither the relation between SUCR and body composition markers nor the association of SUCR with the markers of volume overload, which are known to worsen clinical outcome, has been studied so far. The aim of the study was to check the prognostic value of SUCR in HF patients after adjusting for body composition and indirect markers of volume overload.

METHODS

In 911 HF patients, morning SUCR was determined and body composition scanning using dual X-ray absorptiometry (DEXA) was performed. Univariable and multivariable predictors of log SUCR were analyzed. All participants were divided into quartiles of SUCR.

RESULTS

In univariable analysis, SUCR weakly correlated with fat-free mass (R = 0.09, p = 0.01). Stronger correlations were shown between SUCR and loop diuretic dose (R = 0.16, p < 0.0001), NTproBNP (R = -0.15, p < 0.0001) and serum sodium (R = 0.16, p < 0.0001). During 3 years of follow-up, 353 (38.7%) patients died. Patients with lower SUCR were more frequently female, and their functional status was worse. The lowest mortality was observed in the top quartile of SUCR. In the unadjusted Cox regression analysis, the relative risk of death in all three lower quartiles of SUCR was higher by roughly 80% compared to the top SUCR quartile. Apart from lower SUCR, the significant predictors of death were age and malnutrition but not body composition. After adjustment for loop diuretic dose and percent of recommended dose of mineralocorticoid receptor antagonists, the difference in mortality vanished completely.

CONCLUSIONS

Lower SUCR levels in HF patients are associated with a worse outcome, but this effect is not correlated with fat-free mass. Fluid overload-driven effects may link lower SUCR with higher mortality in HF.

Sympathetic and hemodynamic responses to exercise in heart failure with preserved ejection fraction

Excessive sympathetic activity during exercise causes heightened peripheral vasoconstriction, which can reduce oxygen delivery to active muscles, resulting in exercise intolerance. Although both patients suffering from heart failure with preserved and reduced ejection fraction (HFpEF and HFrEF, respectively) exhibit reduced exercise capacity, accumulating evidence suggests that the underlying pathophysiology may be different between these two conditions. Unlike HFrEF, which is characterized by cardiac dysfunction with lower peak oxygen uptake, exercise intolerance in HFpEF appears to be predominantly attributed to peripheral limitations involving inadequate vasoconstriction rather than cardiac limitations. However, the relationship between systemic hemodynamics and the sympathetic neural response during exercise in HFpEF is less clear. This mini review summarizes the current knowledge on the sympathetic (i.e., muscle sympathetic nerve activity, plasma norepinephrine concentration) and hemodynamic (i.e., blood pressure, limb blood flow) responses to dynamic and static exercise in HFpEF compared to HFrEF, as well as non-HF controls. We also discuss the potential of a relationship between sympathetic over-activation and vasoconstriction leading to exercise intolerance in HFpEF. The limited body of literature indicates that higher peripheral vascular resistance, perhaps secondary to excessive sympathetically mediated vasoconstrictor discharge compared to non-HF and HFrEF, drives exercise in HFpEF. Excessive vasoconstriction also may primarily account for over elevations in blood pressure and concomitant limitations in skeletal muscle blood flow during dynamic exercise, resulting in exercise intolerance. Conversely, during static exercise, HFpEF exhibit relatively normal sympathetic neural reactivity compared to non-HF, suggesting that other mechanisms beyond sympathetic vasoconstriction dictate exercise intolerance in HFpEF.

Could SGLT2 Inhibitors Improve Exercise Intolerance in Chronic Heart Failure?

Despite the constant improvement of therapeutical options, heart failure (HF) remains associated with high mortality and morbidity. While new developments in guideline-recommended therapies can prolong survival and postpone HF hospitalizations, impaired exercise capacity remains one of the most debilitating symptoms of HF. Exercise intolerance in HF is multifactorial in origin, as the underlying cardiovascular pathology and reactive changes in skeletal muscle composition and metabolism both contribute. Recently, sodium-related glucose transporter 2 (SGLT2) inhibitors were found to improve cardiovascular outcomes significantly. Whilst much effort has been devoted to untangling the mechanisms responsible for these cardiovascular benefits of SGLT2 inhibitors, little is known about the effect of SGLT2 inhibitors on exercise performance in HF. This review provides an overview of the pathophysiological mechanisms that are responsible for exercise intolerance in HF, elaborates on the potential SGLT2-inhibitor-mediated effects on these phenomena, and provides an up-to-date overview of existing studies on the effect of SGLT2 inhibitors on clinical outcome parameters that are relevant to the assessment of exercise capacity. Finally, current gaps in the evidence and potential future perspectives on the effects of SGLT2 inhibitors on exercise intolerance in chronic HF are discussed.

Effects of age and gender on body composition indices as predictors of mortality in middle-aged and old people

To determine whether body composition indices interact with age and gender as a predictor of all-cause mortality, 1200 participants at least 40 years of age were recruited in 2009 and 2010. A multi-frequency bioelectrical impedance analysis device was used to measure each participant's body composition indices, including the fat mass index (FMI), fat free mass index (FFMI), skeletal muscle mass index (SMMI), and visceral fat area index (VFAI). A baseline questionnaire was used to collect demographic information about lifestyle habits, socioeconomic status, and medical conditions. All claimed records of death from 2009 to 2018 in the National Health Insurance Research Databank were identified. The all-cause mortality rate was 8.67% after a mean follow-up period of 5.86 ± 2.39 person-years. The Cox proportional hazard model analysis showed significantly negative associations between FFMI or SMMI with all-cause mortality in the total group and those aged ≥ 65 y/o. The FFMI and SMMI were negative predictors of mortality in both genders. The FMI and VFAI were positive predictors of mortality exclusively in females. In conclusion, the SMMI is a better predictor of mortality than the BMI, FMI, and FFMI, especially in older adults. A higher fat mass or visceral fat distribution may predict higher mortality in females.

Endocrine system dysfunction and chronic heart failure: a clinical perspective

Chronic heart failure (CHF) leads to an excess of urgent ambulatory visits, recurrent hospital admissions, morbidity, and mortality regardless of medical and non-medical management of the disease. This excess of risk may be attributable, at least in part, to comorbid conditions influencing the development and progression of CHF. In this perspective, the authors examined and described the most common endocrine disorders observed in patients with CHF, particularly in individuals with reduced ejection fraction, aiming to qualify the risks, quantify the epidemiological burden and discuss about the potential role of endocrine treatment. Thyroid dysfunction is commonly observed in patients with CHF, and sometimes it could be the consequence of certain medications (e.g., amiodarone). Male and female hypogonadism may also coexist in this clinical context, contributing to deteriorating the prognosis of these patients. Furthermore, growth hormone deficiency may affect the development of adult myocardium and predispose to CHF. Limited recommendation suggests to screen endocrine disorders in CHF patients, but it could be interesting to evaluate possible endocrine dysfunction in this setting, especially when a high suspicion coexists. Data referring to long-term safety and effectiveness of endocrine treatments in patients with CHF are limited, and their impact on several "hard" endpoints (such as hospital admission, all-cause, and cardiovascular mortality) are still poorly understood.

Examination of the Relationship and Dissociation Between Minimum Minute Ventilation/Carbon Dioxide Production and Minute Ventilation vs. Carbon Dioxide Production Slope

BACKGROUND

Minute ventilation/carbon dioxide production (V̇E/V̇CO₂) is a variable of cardiopulmonary exercise testing (CPET), which is evaluated by arterial CO₂pressure and ventilation-perfusion mismatch via invasive methods. This study evaluated substitute non-invasively obtained variables for minimum V̇E/V̇CO₂(Min) and V̇E vs. V̇CO₂slope (Slope) and the relationship between Min and Slope.Methods and Results:This study enrolled 1,052 patients with heart disease who underwent CPET and impedance cardiography simultaneously. At first, the correlations between the end-tidal CO₂pressure (PETCO₂), tidal volume/respiratory rate (TV/RR) ratio, V̇E and V̇CO₂Y-intercept (Y-int), and cardiac index (CI) and the Min and Slope were investigated. Second, the correlation between Min and Slope was investigated. PETCO₂showed the largest correlation value among the 4 variables. These 4 variables could reveal 84.2% and 81.9% of Min and Slope, respectively. Although Slope correlated with Min (R=0.868) and predicted 78.9% of Min, considering these 4 variables, Slope+Y-int was more strongly correlated with Min (R=0.940); the Slope+Y-int revealed 90.6% of the Min relationship in the multiple regression analysis.

CONCLUSIONS

Over 80% of the Min and Slope values were revealed with the above-mentioned 4 variables collected non-invasively. The formula, Min∝Slope+Y-int, can reveal >90% of the Min/Slope relationships, and the Y-int may be a crucial factor to clarify the relationship between Min and Slope.

Role of systemic inflammation in functional recovery, dysphagia, and 1-y mortality in heart failure: A prospective cohort study

OBJECTIVES

This study evaluated the relationship between systemic inflammation and clinical outcomes in people hospitalized with acute heart failure (AHF).

METHODS

We prospectively enrolled people newly hospitalized with AHF after excluding those with concomitant infectious or inflammatory diseases. Systemic inflammation was evaluated using the modified Glasgow Prognostic Score (mGPS) at hospitalization, and participants were classified into low-grade and high-grade inflammation groups (mGPS 0-1 and 2, respectively). The primary outcome measure was functional recovery, evaluated using the Barthel Index gain. Secondary outcome measures were dysphagia at discharge and all-cause 1-y mortality after discharge. Multivariable analyses and Kaplan-Meier estimates were used to determine the association between systemic inflammation and study outcomes.

RESULTS

A total of 184 participants (mean age, 79.1 y; 48.4% female, 51.6% male) were included; 148 (80.4%) and 36 (19.6%), respectively, had low-grade and high-grade inflammation. Participants with high-grade inflammation were significantly older, had lower body mass index and muscle strength, and had lower nutrient intake, swallowing status, and Barthel Index than those with low-grade inflammation. In multivariable analyses, mGPS was significantly associated with Barthel Index gain (β = -0.229, P = 0.004) and Food Intake Level Scale (odds ratio = 5.067, P = 0.034) at discharge; mGPS was associated with 1-y mortality after discharge (P = 0.003).

CONCLUSIONS

Baseline systemic inflammation was negatively associated with improvements in physical function and dysphagia and with 1-y survival in people with AHF. These findings highlight the importance of focusing on the assessment of systemic inflammation to accurately predict the functional prognosis of people with AHF.

Pathobiological Relationship of Excessive Dietary Intake of Choline/L-Carnitine: A TMAO Precursor-Associated Aggravation in Heart Failure in Sarcopenic Patients

The microecological environment of the gastrointestinal tract is altered if there is an imbalance between the gut microbiota phylases, resulting in a variety of diseases. Moreover, progressive age not only slows down physical activity but also reduces the fat metabolism pathway, which may lead to a reduction in the variety of bacterial strains and bacteroidetes' abundance, promoting firmicutes and proteobacteria growth. As a result, dysbiosis reduces physiological adaptability, boosts inflammatory markers, generates ROS, and induces the destruction of free radical macromolecules, leading to sarcopenia in older patients. Research conducted at various levels indicates that the microbiota of the gut is involved in pathogenesis and can be considered as the causative agent of several cardiovascular diseases. Local and systematic inflammatory reactions are caused in patients with heart failure, as ischemia and edema are caused by splanchnic hypoperfusion and enable both bacterial metabolites and bacteria translocation to enter from an intestinal barrier, which is already weakened, to the blood circulation. Multiple diseases, such as HF, include healthy microbe-derived metabolites. These key findings demonstrate that the gut microbiota modulates the host's metabolism, either specifically or indirectly, by generating multiple metabolites. Currently, the real procedures that are an analogy to the symptoms in cardiac pathologies, such as cardiac mass dysfunctions and modifications, are investigated at a minimum level in older patients. Thus, the purpose of this review is to summarize the existing knowledge about a particular diet, including trimethylamine, which usually seems to be effective for the improvement of cardiac and skeletal muscle, such as choline and L-carnitine, which may aggravate the HF process in sarcopenic patients.

The ergoreflex: how the skeletal muscle modulates ventilation and cardiovascular function in health and disease

The control of ventilation and cardiovascular function during physical activity is partially regulated by the ergoreflex, a cardiorespiratory reflex activated by physical activity. Two components of the ergoreflex have been identified: the mechanoreflex, which is activated early by muscle contraction and tendon stretch, and the metaboreflex, which responds to the accumulation of metabolites in the exercising muscles. Patients with heart failure (HF) often develop a skeletal myopathy with varying degrees of severity, from a subclinical disease to cardiac cachexia. HF‐related myopathy has been associated with increased ergoreflex sensitivity, which is believed to contribute to dyspnoea on effort, fatigue and sympatho‐vagal imbalance, which are hallmarks of HF. Ergoreflex sensitivity increases significantly also in patients with neuromuscular disorders. Exercise training is a valuable therapeutic option for both HF and neuromuscular disorders to blunt ergoreflex sensitivity, restore the sympatho‐vagal balance, and increase tolerance to physical exercise. A deeper knowledge of the mechanisms mediating ergoreflex sensitivity might enable a drug or device modulation of this reflex when patients cannot exercise because of advanced skeletal myopathy.

Exercise intolerance in pulmonary arterial hypertension: insight into central and peripheral pathophysiological mechanisms

Exercise intolerance is a cardinal symptom of pulmonary arterial hypertension (PAH) and strongly impacts patients' quality of life (QoL). Although central cardiopulmonary impairments limit peak oxygen consumption (V' O2peak ) in patients with PAH, several peripheral abnormalities have been described over the recent decade as key determinants in exercise intolerance, including impaired skeletal muscle (SKM) morphology, convective O2 transport, capillarity and metabolism indicating that peripheral abnormalities play a greater role in limiting exercise capacity than previously thought. More recently, cerebrovascular alterations potentially contributing to exercise intolerance in patients with PAH were also documented. Currently, only cardiopulmonary rehabilitation has been shown to efficiently improve the peripheral components of exercise intolerance in patients with PAH. However, more extensive studies are needed to identify targeted interventions that would ultimately improve patients' exercise tolerance and QoL. The present review offers a broad and comprehensive analysis of the present literature about the complex mechanisms and their interactions limiting exercise in patients and suggests several gaps in knowledge that need to be addressed in the future for a better understanding of exercise intolerance in patients with PAH.

Comparison of Different Intensity Modes of Neuromuscular Electrical Stimulation in the Rehabilitation of Elderly Patients with Decompensated Chronic Heart Failure

Aim        To compare effects of neuromuscular electrostimulation (NMES) with various intensity of induced muscle contractions on its tolerance and effect on physical work ability in elderly patients admitted for chronic heart failure (CHF).Material and methods        The study included 22 patients older than 60 years admitted for decompensated CHF. NMES was performed from the 2nd or 3d day of stay in the hospital to the discharge from the hospital. Patients choose the stimulation regimen themselves based on the result of the first session: the high intensity to achieve maximum tolerable muscle contractions (group 1) or the lower intensity to achieve visible/ palpable muscle contractions (group 2). Prior to the onset and after the completion of the training, the 6-min walk test (6MWT) was performed and the general condition of the patient was assessed with a visual analogue scale (VAS).Results   More patients, mostly women, chose the less intensive NMES (14 vs. 8). The groups did not differ in age, comorbidity, and functional condition. Both groups achieved considerable increases in the 6MWT distance (7.3 [5.6; 176] and 9.8 [7.0; 9.9] %, respectively, p&gt;0.05) and VAS scores without a significant difference between the groups. Among the patients who were compliant with continuing NMES after the discharge from the hospital, 69% were patients of the group of the less intensive stimulation.Conclusion            The less intensive NMES (with achieving visible muscle contractions) was characterized by better tolerance and better compliance in elderly patients with decompensated CHF compared to the more intensive NMES (with achieving maximum contractions), but the less intensive NMES was not inferior to the more intensive NMES in effectiveness.

Catabolic/Anabolic Imbalance Is Accompanied by Changes of Left Ventricular Steroid Nuclear Receptor Expression in Tachycardia-Induced Systolic Heart Failure in Male Pigs

BACKGROUND

Steroid hormones play an important role in heart failure (HF) pathogenesis, and clinical data have revealed disordered steroidogenesis in male patients with HF. However, there is still a lack of studies on steroid hormones and their receptors during HF progression. Therefore, a porcine model of tachycardia-induced cardiomyopathy corresponding to HF was used to assess steroid hormone concentrations in serum and their nuclear receptor levels in heart tissue during the consecutive stages of HF.

METHODS AND RESULTS

Male pigs underwent right ventricular pacing and developed a clinical picture of mild, moderate, or severe HF. Serum concentrations of dehydroepiandrosterone, testosterone, dihydrotestosterone, estradiol, aldosterone, and cortisol were assessed by enzyme-linked immunosorbent assay. Androgen receptor, estrogen receptor alpha, mineralocorticoid receptor, and glucocorticoid receptor messenger RNA levels in the left ventricle were determined by qPCR.The androgen level decreased in moderate and severe HF animals, while the corticosteroid level increased. The estradiol concentration remained stable. The quantitative real-time polymerase chain reaction revealed the downregulation of androgen receptor in consecutive stages of HF and increased expression of mineralocorticoid receptor messenger RNA under these conditions.

CONCLUSIONS

In the HF pig model, deteriorated catabolic/anabolic balance, manifested by upregulation of aldosterone and cortisol and downregulation of androgen signaling on the ligand level, was augmented by changes in steroid hormone receptor expression in the heart tissue.

Muscle wasting as an independent predictor of survival in patients with chronic heart failure

BACKGROUND

Skeletal muscle wasting is an extremely common feature in patients with heart failure, affecting approximately 20% of ambulatory patients with even higher values during acute decompensation. Its occurrence is associated with reduced exercise capacity, muscle strength, and quality of life. We sought to investigate if the presence of muscle wasting carries prognostic information.

METHODS

Two hundred sixty-eight ambulatory patients with heart failure (age 67.1 ± 10.9 years, New York Heart Association class 2.3 ± 0.6, left ventricular ejection fraction 39 ± 13.3%, and 21% female) were prospectively enrolled as part of the Studies Investigating Co-morbidities Aggravating Heart Failure. Muscle wasting as assessed using dual-energy X-ray absorptiometry was present in 47 patients (17.5%).

RESULTS

During a mean follow-up of 67.2 ± 28.02 months, 95 patients (35.4%) died from any cause. After adjusting for age, New York Heart Association class, left ventricular ejection fraction, creatinine, N-terminal pro-B-type natriuretic peptide, and iron deficiency, muscle wasting remained an independent predictor of death (hazard ratio 1.80, 95% confidence interval 1.01-3.19, P = 0.04). This effect was more pronounced in patients with heart failure with reduced than in heart failure with preserved ejection fraction.

CONCLUSIONS

Muscle wasting is an independent predictor of death in ambulatory patients with heart failure. Clinical trials are needed to identify treatment approaches to this co-morbidity.

Recent advances in exercise pressor reflex function in health and disease

Autonomic alterations at the onset of exercise are critical to redistribute cardiac output towards the contracting muscles while preventing a fall in arterial pressure due to excessive vasodilation within the contracting muscles. Neural mechanisms responsible for these adjustments include central command, the exercise pressor reflex, and arterial and cardiopulmonary baroreflexes. The exercise pressor reflex evokes reflex increases in sympathetic activity to the heart and systemic vessels and decreases in parasympathetic activity to the heart, which increases blood pressure (BP), heart rate, and total peripheral resistance through vasoconstriction of systemic vessels. In this review, we discuss recent advancements in our understanding of exercise pressor reflex function in health and disease. Specifically, we discuss emerging evidence suggesting that sympathetic vasoconstrictor drive to the contracting and non-contracting skeletal muscle is differentially controlled by central command and the metaboreflex in healthy conditions. Further, we discuss evidence from animal and human studies showing that cardiovascular diseases, including hypertension, diabetes, and heart failure, lead to an altered exercise pressor reflex function. We also provide an update on the mechanisms thought to underlie this altered exercise pressor reflex function in each of these diseases. Although these mechanisms are complex, multifactorial, and dependent on the etiology of the disease, there is a clear consensus that several mechanisms are involved. Ultimately, approaches targeting these mechanisms are clinically significant as they provide alternative therapeutic strategies to prevent adverse cardiovascular events while also reducing symptoms of exercise intolerance.

Relationship between ventilatory pattern and peak VO2 and area M regulates the respiratory system during exercise

BACKGROUND

Exertional dyspnea is a major symptom of heart failure. We investigated the tidal volume (TV)-the respiratory rate (RR) regulation according to the peak O₂ uptake (VO₂) during cardiopulmonary exercise testing (CPET) for clarifying exercise ventilatory pattern.

METHODS

We enrolled 1111 patients (66±13 years old, 68% men) who had undergone CPET at our hospital. We investigated the relationship between TV and RR and drew the TV/height-RR figure according to the %peak VO₂.

RESULTS

During exercise, TV was greater, illustrated as higher %peak VO₂. However, RR was weakly correlated with %peak VO₂. Adjusted with age, height, sex, each point of RR, and %peak VO₂, TV during exercise highly correlated with age, height, each point of RR, and % peak VO₂ (R=0.726 to 0.821, p<0.01). In the figure, regardless of the %peak VO₂, TV/height and RR values were linearly related at rest, as well as at the point of anaerobic threshold, respiratory compensation, and peak exercise point, with each of these lines converging onto a single area (area M). The TV-RR slope values at early phase were also lower at lower %peak VO₂.

CONCLUSIONS

We identified three ventilatory regularities during exercise. First, TV increases as greater %peak VO₂. Second, the line relating TV/height and RR at each reference point during the incremental exercise test converged onto area M. Finally, the TV-RR slope at the early exercise phase was lower in patients with a lower %peak VO₂. These ventilatory regularities may assist in elucidating the excise ventilatory pattern and help the diagnosis of exertional dyspnea.

Redistribution of cardiac output during exercise by functional mitral regurgitation in heart failure: compensatory O2 peripheral uptake to delivery failure

This is an analysis involving 134 heart failure patients with reduced ejection fraction versus 80 controls investigated during functional evaluation with gas exchange and hemodynamic, addressing the severe mitral regurgitation phenotype and testing the hypothesis that the backward cardiac output redistribution to the lung during exercise impairs delivery and overexpresses peripheral extraction. This information is new and has important implications in the management of heart failure.

Exercise intolerance and fatigue in chronic heart failure: is there a role for group III/IV afferent feedback?

Exercise intolerance and early fatiguability are hallmark symptoms of chronic heart failure. While the malfunction of the heart is certainly the leading cause of chronic heart failure, the patho-physiological mechanisms of exercise intolerance in these patients are more complex, multifactorial and only partially understood. Some evidence points towards a potential role of an exaggerated afferent feedback from group III/IV muscle afferents in the genesis of these symptoms. Overactivity of feedback from these muscle afferents may cause exercise intolerance with a double action: by inducing cardiovascular dysregulation, by reducing motor output and by facilitating the development of central and peripheral fatigue during exercise. Importantly, physical inactivity appears to affect the progression of the syndrome negatively, while physical training can partially counteract this condition. In the present review, the role played by group III/IV afferent feedback in cardiovascular regulation during exercise and exercise-induced muscle fatigue of healthy people and their potential role in inducing exercise intolerance in chronic heart failure patients will be summarised.

The Role of Cardiac Rehabilitation in Reducing Major Adverse Cardiac Events in Heart Transplant Patients

BACKGROUND

Methods for reducing major adverse cardiac events (MACE) in patients after heart transplantation (HTx) are critical for long-term quality outcomes.

METHODS AND RESULTS

Patients with cardiopulmonary exercise testing prior to HTx and at least 1 session of cardiac rehabilitation (CR) after HTx were included. Exercise sessions were evaluated as ≥ 23 or < 23 sessions based on recursive partitioning. We included 140 patients who had undergone HTx (women: n = 41 (29%), age: 52 ± 12 years, body mass index: 27 ± 5 kg/m²). Mean follow-up was 4.1 ± 2.7 years, and 44 patients (31%) had a MACE: stroke (n = 1), percutaneous intervention (n = 5), heart failure (n = 6), myocardial infarction (n = 1), rejection (n = 16), or death (n = 15). CR was a significant predictor of MACE, with ≥ 23 sessions associated with a ∼ 60% reduction in MACE risk (hazard ratio [HR]: 0.42, 95% CI: 0.19-0.94, P = 0.035). This remained after adjusting for age, sex and history of diabetes (HR: 0.41, 95% CI: 0.18-0.94, P = 0.035) as well as body mass index and pre-HTx peak oxygen consumption (HR: 0.40, 95% CI: 0.18-0.92, P = 0.031).

CONCLUSIONS

After adjustment for covariates of age, sex, diabetes, body mass index, and pre-HTx peak oxygen consumption, CR attendance of ≥ 23 exercise sessions was predictive of lower MACE risk following HTx. In post-HTx patients, CR was associated with MACE prevention and should be viewed as a critical tool in post-HTx treatment strategies.

Anabolic Hormone Deficiencies in Heart Failure with Reduced or Preserved Ejection Fraction and Correlation with Plasma Total Antioxidant Capacity

BACKGROUND

While anabolic hormone deficit is a common finding in heart failure with reduced ejection fraction (HFrEF), few data are available in heart failure with preserved ejection fraction (HFpEF).

METHODS

Blood samples were collected for metabolic (total cholesterol, HDL cholesterol, LDL cholesterol, creatinine, and glucose) and hormonal (IGF-1, DHEA-S, TSH, fT3, fT4, and T) determination, comparing 30 patients with HFpEF and 20 patients with HFrEF. Total antioxidant capacity was evaluated by using the spectrophotometric method using the latency time in the appearance of the radical species of a chromogen (LAG, sec) as a parameter proportional to antioxidant content of the sample. Echocardiographic parameters were also assessed in the two groups.

RESULTS

A high prevalence of testosterone (32% in HFrEF and 72% in HFpEF, p < 0.05) and DHEA-S deficiencies was observed in HFpEF patients. Echocardiographic parameters did not correlate with hormone values. A significant direct correlation between T (r ² = 0.25, p < 0.05) and DHEA-S (r ² = 0.19, p < 0.05) with LAG was observed only in HFpEF.

CONCLUSION

Anabolic hormone deficiency is clearly shown in HFpEF, as already known in HFrEF. Although longitudinal studies are required to confirm the prognostic value of this observation, our data suggest different mechanisms in modulating antioxidants in the two conditions, with possible therapeutic implications.

Impaired Exercise Tolerance in Heart Failure: Role of Skeletal Muscle Morphology and Function

PURPOSE OF REVIEW

To discuss the impact of deleterious changes in skeletal muscle morphology and function on exercise intolerance in patients with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), as well as the utility of exercise training and the potential of novel treatment strategies to preserve or improve skeletal muscle morphology and function.

RECENT FINDINGS

Both HFrEF and HFpEF patients exhibit a reduction in percent of type I (oxidative) muscle fibers and oxidative enzymes coupled with abnormal mitochondrial respiration. These skeletal muscle abnormalities contribute to impaired oxidative metabolism with an earlier shift towards glycolytic metabolism during exercise that is strongly associated with exercise intolerance. In both HFrEF and HFpEF patients, peripheral "non-cardiac" factors are important determinants of the improvement in exercise tolerance following aerobic exercise training. Adjunctive strategies that include nutritional supplementation with amino acids and/or anabolic drugs to stimulate anabolic molecular pathways in skeletal muscle show great promise for improving exercise tolerance and treating heart failure-associated sarcopenia, but these efforts remain early in their evolution, with no immediate clinical applications. There is consistent evidence that heart failure is associated with multiple skeletal muscle abnormalities which impair oxygen uptake and utilization and contribute greatly to exercise intolerance. Exercise training induces favorable adaptations in skeletal muscle morphology and function that contribute to improvements in exercise tolerance in patients with HFrEF. The contribution of skeletal muscle adaptations to improved exercise tolerance following exercise training in HFpEF remains unknown and warrants further investigation.

Restoring pulsatility and peakVO2 in the era of continuous flow, fixed pump speed, left ventricular assist devices: 'A hypothesis of pump's or patient's speed?'

Despite significant improvement in survival and functional capacity after continuous flow left ventricular assist device implantation, the patient's quality of life may remain limited by complications such as aortic valve insufficiency, thromboembolic episodes and gastrointestinal bleeding attributed to high shear stress continuous flow with attenuated or absence of pulsatile flow and by a reduced peak oxygen consumption (peakVO₂) primarily associated with a fixed pump speed operation. Revision of current evidence suggests that high technology pump speed algorithms, a 'hypothesis of decreasing pump's speed' to promote pulsatile flow and a 'hypothesis of increasing pump's speed' to increase peakVO₂, may only partially reverse these barriers. A 'hypothesis of increasing patient's speed' is introduced, suggesting that exercise training may further contribute to the patient's recovery, enhancing peakVO₂ and pulsatile flow by improving skeletal muscle oxidative capacity and strength, peripheral vasodilatory and ventilatory responses, favour changes in preload/afterload and facilitate native flow, formulating the rationale for further studies in the field.

Compression of morbidity in a progeroid mouse model through the attenuation of myostatin/activin signalling

BACKGROUND

One of the principles underpinning our understanding of ageing is that DNA damage induces a stress response that shifts cellular resources from growth towards maintenance. A contrasting and seemingly irreconcilable view is that prompting growth of, for example, skeletal muscle confers systemic benefit.

METHODS

To investigate the robustness of these axioms, we induced muscle growth in a murine progeroid model through the use of activin receptor IIB ligand trap that dampens myostatin/activin signalling. Progeric mice were then investigated for neurological and muscle function as well as cellular profiling of the muscle, kidney, liver, and bone.

RESULTS

We show that muscle of Ercc1^Δ/- progeroid mice undergoes severe wasting (decreases in hind limb muscle mass of 40-60% compared with normal mass), which is largely protected by attenuating myostatin/activin signalling using soluble activin receptor type IIB (sActRIIB) (increase of 30-62% compared with untreated progeric). sActRIIB-treated progeroid mice maintained muscle activity (distance travel per hour: 5.6 m in untreated mice vs. 13.7 m in treated) and increased specific force (19.3 mN/mg in untreated vs. 24.0 mN/mg in treated). sActRIIb treatment of progeroid mice also improved satellite cell function especially their ability to proliferate on their native substrate (2.5 cells per fibre in untreated progeroids vs. 5.4 in sActRIIB-treated progeroids after 72 h in culture). Besides direct protective effects on muscle, we show systemic improvements to other organs including the structure and function of the kidneys; there was a major decrease in the protein content in urine (albumin/creatinine of 4.9 sActRIIB treated vs. 15.7 in untreated), which is likely to be a result in the normalization of podocyte foot processes, which constitute the filtration apparatus (glomerular basement membrane thickness reduced from 224 to 177 nm following sActRIIB treatment). Treatment of the progeric mice with the activin ligand trap protected against the development of liver abnormalities including polyploidy (18.3% untreated vs. 8.1% treated) and osteoporosis (trabecular bone volume; 0.30 mm³ in treated progeroid mice vs. 0.14 mm³ in untreated mice, cortical bone volume; 0.30 mm³ in treated progeroid mice vs. 0.22 mm³ in untreated mice). The onset of neurological abnormalities was delayed (by ~5 weeks) and their severity reduced, overall sustaining health without affecting lifespan.

CONCLUSIONS

This study questions the notion that tissue growth and maintaining tissue function during ageing are incompatible mechanisms. It highlights the need for future investigations to assess the potential of therapies based on myostatin/activin blockade to compress morbidity and promote healthy ageing.

Heart Failure With Preserved Ejection Fraction: A Review of Cardiac and Noncardiac Pathophysiology

Heart failure with preserved ejection fraction (HFpEF) is one of the largest unmet clinical needs in 21st-century cardiology. It is a complex disorder resulting from the influence of several comorbidities on the endothelium. A derangement in nitric oxide bioavailability leads to an intricate web of physiological abnormalities in the heart, blood vessels, and other organs. In this review, we examine the contribution of cardiac and noncardiac factors to the development of HFpEF. We zoom in on recent insights on the role of comorbidities and microRNAs in HFpEF. Finally, we address the potential of exercise training, which is currently the only available therapy to improve aerobic capacity and quality of life in HFpEF patients. Unraveling the underlying mechanisms responsible for this improvement could lead to new biomarkers and therapeutic targets for HFpEF.

Randomized controlled trials - mechanistic studies of testosterone and the cardiovascular system

Testosterone deficiency is common in men with cardiovascular disease (CVD), and randomized placebo-controlled trials (RCTs) have reported beneficial effects of testosterone therapy on exercise-induced cardiac ischemia in chronic stable angina, functional exercise capacity, maximum oxygen consumption during exercise (VO_2max) and muscle strength in chronic heart failure (CHF), shortening of the Q-T interval, and improvement of some cardiovascular risk factors. Testosterone deficiency is associated with an adverse CV risk profile and mortality. Clinical and scientific studies have provided mechanistic evidence to support and explain the findings of the RCTs. Testosterone is a rapid-onset arterial vasodilator within the coronary circulation and other vascular beds including the pulmonary vasculature and can reduce the overall peripheral systemic vascular resistance. Evidence has demonstrated that testosterone mediates this effect on vascular reactivity through calcium channel blockade (L-calcium channel) and stimulates potassium channel opening by direct nongenomic mechanisms. Testosterone also stimulates repolarization of cardiac myocytes by stimulating the ultra-rapid potassium channel-operated current. Testosterone improves cardiac output, functional exercise capacity, VO_2max and vagally mediated arterial baroreceptor cardiac reflex sensitivity in CHF, and other mechanisms. Independent of the benefit of testosterone on cardiac function, testosterone substitution may also increase skeletal muscle glucose metabolism and enhance muscular strength, both factors that could contribute to the improvement in functional exercise capacity may include improved glucose metabolism and muscle strength. Testosterone improves metabolic CV risk factors including body composition, insulin resistance, and hypercholesterolemia by improving both glucose utilization and lipid metabolism by a combination of genomic and nongenomic actions of glucose uptake and utilization expression of the insulin receptor, glucose transporters, and expression on regulatory enzymes of key metabolic pathways. The effect on high-density lipoprotein-cholesterol (HDL-C) differs between studies in that it has been found to fall, rise, or have no change in levels. Testosterone replacement can suppress the levels of circulating pro-inflammatory cytokines and stimulate the production of interleukin-10 (IL-10) which has anti-inflammatory and anti-atherogenic actions in men with CVD. No effect on C-reactive protein has been detected. No adverse effects on clotting factors have been detected. RCTs have not clearly demonstrated any significant evidence that testosterone improves or adversely affects the surrogate markers of atherosclerosis such as reduction in carotid intima thickness or coronary calcium deposition. Any effect of testosterone on prevention or amelioration of atherosclerosis is likely to occur over years as shown in statin therapy trials and not months as used in testosterone RCTs. The weight of evidence from long-term epidemiological studies supports a protective effect as evidenced by a reduction in major adverse CV events (MACEs) and mortality in studies which have treated men with testosterone deficiency. No RCT where testosterone has been replaced to the normal healthy range has reported a significant benefit or adverse effect on MACE nor has any recent meta-analysis.

Dilated cardiomyopathy-mediated heart failure induces a unique skeletal muscle myopathy with inflammation

Background

Skeletal muscle myopathy and exercise intolerance are diagnostic hallmarks of heart failure (HF). However, the molecular adaptations of skeletal muscles during dilated cardiomyopathy (DCM)-mediated HF are not completely understood.

Methods

Skeletal muscle structure and function were compared in wild-type (WT) and cardiac myosin binding protein-C null mice (t/t), which develop DCM-induced HF. Cardiac function was examined by echocardiography. Exercise tolerance was measured using a graded maximum treadmill running test. Hindlimb muscle function was assessed in vivo from measurements of plantar flexor strength. Inflammatory status was evaluated from the expression of inflammatory markers and the presence of specific immune cell types in gastrocnemius muscles. Muscle regenerative capacityat days 3, 7, and 14 after eccentric contraction-induced injury was determined from the number of phenotypically new and adult fibers in the gastrocnemius, and functional recovery of plantar flexion torque.

Results

t/t mice developed DCM-induced HF in association with profound exercise intolerance, consistent with previous reports. Compared to WT, t/t mouse hearts show significant hypertrophy of the atria and ventricles and reduced fractional shortening, both systolic and diastolic. In parallel, the skeletal muscles of t/t mice exhibit weakness and myopathy. Compared to WT, plantar flexor muscles of t/t null mice produce less peak isometric plantar torque (Po), develop torque more slowly (+ dF/dt), and relax more slowly (− dF/dt, longer half-relaxation times,1/2RT). Gastrocnemius muscles of t/t mice have a greater number of fibers with smaller diameters and central nuclei. Oxidative fibers, both type I and type IIa, show significantly smaller cross-sectional areas and more central nuclei. These fiber phenotypes suggest ongoing repair and regeneration under homeostatic conditions. In addition, the ability of muscles to recover and regenerate after acute injury is impaired in t/t mice.

Conclusions

Our studies concluded that DCM-induced HF induces a unique skeletal myopathy characterized by decreased muscle strength, atrophy of oxidative fiber types, ongoing inflammation and damage under homeostasis, and impaired regeneration after acute muscle injury. Furthermore, this unique myopathy in DCM-induced HF likely contributes to and exacerbates exercise intolerance. Therefore, efforts to develop therapeutic interventions to treat skeletal myopathy during DCM-induced HF should be considered.

Electronic supplementary material

The online version of this article (10.1186/s13395-019-0189-y) contains supplementary material, which is available to authorized users.

Iron deficiency as energetic insult to skeletal muscle in chronic diseases

Specific skeletal myopathy constitutes a common feature of heart failure, chronic obstructive pulmonary disease, and type 2 diabetes mellitus, where it can be characterized by the loss of skeletal muscle oxidative capacity. There is evidence from in vitro and animal studies that iron deficiency affects skeletal muscle functioning mainly in the context of its energetics by limiting oxidative metabolism in favour of glycolysis and by alterations in both carbohydrate and fat catabolic processing. In this review, we depict the possible molecular pathomechanisms of skeletal muscle energetic impairment and postulate iron deficiency as an important factor causally linked to loss of muscle oxidative capacity that contributes to skeletal myopathy seen in patients with heart failure, chronic obstructive pulmonary disease, and type 2 diabetes mellitus.

Low skeletal muscle mass is associated with low aerobic capacity and increased mortality risk in patients with coronary heart disease - a CARE CR study

BACKGROUND

In patients with chronic heart failure, there is a positive linear relationship between skeletal muscle mass (SMM) and peak oxygen consumption ( V ˙ O_2peak ); an independent predictor of all-cause mortality_. We investigated the association between SMM and V ˙ O_2peak in patients with coronary heart disease (CHD) without a diagnosis of heart failure.

METHODS

Male patients with CHD underwent maximal cardiopulmonary exercise testing and dual X-ray absorptiometry assessment. V ˙ O_2peak, the ventilatory anaerobic threshold and peak oxygen pulse were calculated. SMM was expressed as appendicular lean mass (lean mass in both arms and legs) and reported as skeletal muscle index (SMI; kg m^-2 ), and as a proportion of total body mass (appendicular skeletal mass [ASM%]). Low SMM was defined as a SMI <7·26 kg m^-2 , or ASM% <25·72%. Five-year all-cause mortality risk was calculated using the Calibre 5-year all-cause mortality risk score.

RESULTS

Sixty patients were assessed. Thirteen (21·7%) had low SMM. SMI and ASM% correlated positively with V ˙ O_2peak (r = 0·431 and 0·473, respectively; P<0·001 for both). SMI and ASM% predicted 16·3% and 12·9% of the variance in V ˙ O_2peak , respectively. SMI correlated most closely with peak oxygen pulse (r = 0·58; P<0·001). SMI predicted 40·3% of peak V ˙ O₂ /HR variance. ASM% was inversely associated with 5-year all-cause mortality risk (r = -0·365; P = 0·006).

CONCLUSION

Skeletal muscle mass was positively correlated with V ˙ O_2peak in patients with CHD. Peak oxygen pulse had the strongest association with SMM. Low ASM% was associated with a higher risk of all-cause mortality. The effects of exercise and nutritional strategies aimed at improving SMM and function in CHD patients should be investigated.

The ‘aerobic/resistance/inspiratory muscle training hypothesis in heart failure’

Evidence from large multicentre exercise intervention trials in heart failure patients, investigating both moderate continuous aerobic training and high intensity interval training, indicates that the ‘crème de la crème’ exercise programme for this population remains to be found. The ‘aerobic/resistance/inspiratory (ARIS) muscle training hypothesis in heart failure’ is introduced, suggesting that combined ARIS muscle training may result in maximal exercise pathophysiological and functional benefits in heart failure patients. The hypothesis is based on the decoding of the ‘skeletal muscle hypothesis in heart failure’ and on revision of experimental evidence to date showing that exercise and functional intolerance in heart failure patients are associated not only with reduced muscle endurance, indication for aerobic training (AT), but also with reduced muscle strength and decreased inspiratory muscle function contributing to weakness, dyspnoea, fatigue and low aerobic capacity, forming the grounds for the addition of both resistance training (RT) and inspiratory muscle training (IMT) to AT. The hypothesis will be tested by comparing all potential exercise combinations, ARIS, AT/RT, AT/IMT, AT, evaluating both functional and cardiac indices in a large sample of heart failure patients of New York Heart Association class II–III and left ventricular ejection fraction ≤35% ad hoc by the multicentre randomized clinical trial, Aerobic Resistance, InSpiratory Training OutcomeS in Heart Failure (ARISTOS-HF trial).

The Impact of Cardiovascular Diseases on Cardiovascular Regulation During Exercise in Humans: Studies on Metaboreflex Activation Elicited by the Post-exercise Muscle Ischemia Method

BACKGROUND

Hemodynamics during dynamic exercise is finely regulated by some neural mechanisms. One of these mechanisms is the metabolic part of the exercise pressor reflex, i.e. the muscle metaboreflex. Hemodynamic response during the metaboreflex is characterised by the recruitment of the reserves in cardiac inotropism, pre-load, after-load and chronotropism. If one of these reserves is exhausted, then the cardiovascular response is achieved by recruiting one of the other reserves, thereby indicating a remarkable plasticity of the control of circulation.

CONCLUSION

In this review, the effects of a number of cardiovascular diseases - such as heart failure, heart failure with preserved ejection fraction, hypertension, type 1 and type 2 diabetes mellitus, obesity and metabolic syndrome - on hemodynamics during the metaboreflex are reviewed.

Evaluation of Skeletal Muscle Function and Effects of Early Rehabilitation during Acute Heart Failure: Rationale and Study Design

Background

Acute heart failure (AHF) is associated with disturbances of the peripheral perfusion leading to the dysfunction of many organs. Consequently, an episode of AHF constitutes a “multiple organ failure” which may also affect the skeletal muscles. However, the abnormalities within skeletal muscles during AHF have not been investigated so far. The aim of this project is to comprehensively evaluate skeletal muscles (at a functional and tissue level) during AHF.

Methods

The study will include ≥63 consecutive AHF patients who will be randomized into 2 groups: ≥42 with cardiac rehabilitation group versus ≥21 with standard pharmacotherapy alone. The following tests will be conducted on the first and last day of hospitalization, at rest and after exercise, and 30 days following the discharge: clinical evaluation, medical interview, routine physical examination, echocardiography, and laboratory tests (including the assessment of NT-proBNP, inflammatory markers, and parameters reflecting the status of the kidneys and the liver); hemodynamic evaluation, noninvasive determination of cardiac output and systemic vascular resistance using the impedance cardiography; evaluation of biomarkers reflecting myocyte damage, immunochemical measurements of tissue-specific enzymatic isoforms; evaluation of skeletal muscle function, using surface electromyography (sEMG) (maximum tonus of the muscles will be determined along with the level of muscular fatigability); evaluation of muscle tissue perfusion, assessed on the basis of the oxygenation level, with noninvasive direct continuous recording of perfusion in peripheral tissues by local tissue oximetry, measured by near-infrared spectroscopy (NIRS).

Results and Conclusions

Our findings will demonstrate that the muscle tissue is another area of the body which should be taken into consideration in the course of treatment of AHF, requiring a development of targeted therapeutic strategies, such as a properly conducted rehabilitation.

Peripheral vascular function, oxygen delivery and utilization: the impact of oxidative stress in aging and heart failure with reduced ejection fraction

The aging process appears to be a precursor to many age-related diseases, perhaps the most impactful of which is cardiovascular disease (CVD). Heart disease, a manifestation of CVD, is the leading cause of death in the USA, and heart failure (HF), a syndrome that develops as a consequence of heart disease, now affects almost six million American. Importantly, as this is an age-related disease, this number is likely to grow along with the ever-increasing elderly population. Hallmarks of the aging process and HF patients with a reduced ejection fraction (HFrEF) include exercise intolerance, premature fatigue, and limited oxygen delivery and utilization, perhaps as a consequence of diminished peripheral vascular function. Free radicals and oxidative stress have been implicated in this peripheral vascular dysfunction, as a redox imbalance may directly impact the function of the vascular endothelium. This review aims to bring together studies that have examined the impact of oxidative stress on peripheral vascular function and oxygen delivery and utilization with both healthy aging and HFrEF.

Iron limitation promotes the atrophy of skeletal myocytes, whereas iron supplementation prevents this process in the hypoxic conditions

There is clinical evidence that patients with heart failure and concomitant iron deficiency have increased skeletal muscle fatigability and impaired exercise tolerance. It was expected that a skeletal muscle cell line subjected to different degrees of iron availability and/or concomitant hypoxia would demonstrate changes in cell morphology and in the expression of atrophy markers. L6G8C5 rat skeletal myocytes were cultured in normoxia or hypoxia at optimal, reduced or increased iron concentrations. Experiments were performed to evaluate the iron content in cells, cell morphology, and the expression of muscle specific atrophy markers [Atrogin1 and muscle-specific RING-finger 1 (MuRF1)], a gene associated with the atrophy/hypertrophy balance [mothers against decapentaplegic homolog 4 (SMAD4)] and a muscle class-III intermediate filament protein (Desmin) at the mRNA and protein level. Hypoxic treatment caused, as compared to normoxic conditions, an increase in the expression of Atrogin-1 (P<0.001). Iron-deficient cells exhibited morphological abnormalities and demonstrated a significant increase in the expression of Atrogin-1 (P<0.05) and MuRF1 (P<0.05) both in normoxia and hypoxia, which indicated activation of the ubiquitin proteasome pathway associated with protein degradation during muscle atrophy. Depleted iron in cell culture combined with hypoxia also induced a decrease in SMAD4 expression (P<0.001) suggesting modifications leading to atrophy. In contrast, cells cultured in a medium enriched with iron during hypoxia exhibited inverse changes in the expression of atrophy markers (both P<0.05). Desmin was upregulated in cells subjected to both iron depletion and iron excess in normoxia and hypoxia (all P<0.05), but the greatest augmentation of mRNA expression occurred when iron depletion was combined with hypoxia. Notably, in hypoxia, an increased expression of Atrogin-1 and MuRF1 was associated with an increased expression of transferrin receptor 1, reflecting intracellular iron demand (R=0.76, P<0.01; R=0.86, P<0.01). Hypoxia and iron deficiency when combined exhibited the most detrimental impact on skeletal myocytes, especially in the context of muscle atrophy markers. Conversely, iron supplementation in in vitro conditions acted in a protective manner on these cells.

Is Exercise Training Appropriate for Patients With Advanced Heart Failure Receiving Continuous Inotropic Infusion? A Review

Exercise-based rehabilitation programs have been reported to have beneficial effects for patients with heart failure. However, there is little evidence about whether this is the case in patients with more severe heart failure. In particular, there is a question in the clinical setting whether patients with advanced heart failure and continuous inotropic infusion should be prescribed exercise training. In contrast, many studies conclude that prolonged immobility associated with heart failure profoundly impairs physical function and promotes muscle wasting that could further hasten the course of heart failure. By contrast, exercise training has various effects not only in improving exercise capacity but also on vascular function, skeletal muscle, and autonomic balance. In this review, we summarize the effectiveness and discuss methods of exercise training in patients with advanced heart failure receiving continuous inotropic agents such as dobutamine.

Androgen status in non-diabetic elderly men with heart failure

PURPOSE

We aimed at evaluating androgen status (serum testosterone [TT] and estimated free testosterone [eFT]) and its determinants in non-diabetic elderly men with heart failure (HF). Additionally, we investigated its associations with body composition and long-term survival.

METHODS

Seventy three non-diabetic men with HF and 20 healthy men aged over 55 years were studied. Echocardiography, 6-min walk test, grip strength, body composition measurement by DEXA method were performed. TT, sex hormone binding globulin, NT-proBNP, and adipokines (adiponectin and leptin) were measured. All-cause mortality was evaluated at six years of follow-up.

RESULTS

Androgen status (TT, eFT) was similar in elderly men with HF compared to healthy controls (4.79 ± 1.65 vs. 4.45 ± 1.68 ng/ml and 0.409 ± 0.277 vs. 0.350 ± 0.204 nmol/l, respectively). In HF patients, TT was positively associated with NT-proBNP (r= 0.371, p = 0.001) and adiponectin levels (r = 0.349, p = 0.002), while inverse association was noted with fat mass (r = -0.413, p < 0.001). TT and eFT were independently determined by age, total fat mass and adiponectin levels in elderly men with HF (p < 0.05 for all). Androgen status was not predictor for all-cause mortality at six years of follow-up.

CONCLUSIONS

In non-diabetic men with HF, androgen status is not altered and is not predictive of long-term outcome.

The Mechanoreflex and Hemodynamic Response to Passive Leg Movement in Heart Failure

BACKGROUND

Sensitization of mechanosensitive afferents, which contribute to the exercise pressor reflex, has been recognized as a characteristic of patients with heart failure (HF); however, the hemodynamic implications of this hypersensitivity are unclear.

OBJECTIVES

The present study used passive leg movement (PLM) and intrathecal injection of fentanyl to blunt the afferent portion of this reflex arc to better understand the role of the mechanoreflex on central and peripheral hemodynamics in HF.

METHODS

Femoral blood flow (FBF), mean arterial pressure, femoral vascular conductance, HR, stroke volume, cardiac output, ventilation, and muscle oxygenation of the vastus lateralis were assessed in 10 patients with New York Heart Association class II HF at baseline and during 3 min of PLM both with fentanyl and without (control).

RESULTS

Fentanyl had no effect on baseline measures but increased (control vs fentanyl, P < 0.05) the peak PLM-induced change in FBF (493 ± 155 vs 804 ± 198 ΔmL·min(-1)) and femoral vascular conductance (4.7 ± 2 vs 8.5 ± 3 ΔmL·min(-1)·mm Hg)(-1) while norepinephrine spillover (103% ± 19% vs 58% ± 17%Δ) and retrograde FBF (371 ± 115 vs 260 ± 68 ΔmL·min(-1)) tended to be reduced (P < 0.10). In addition, fentanyl administration resulted in greater PLM-induced increases in muscle oxygenation, suggestive of increased microvascular perfusion. Fentanyl had no effect on the ventilation, mean arterial pressure, HR, stroke volume, or cardiac output response to PLM.

CONCLUSIONS

Although movement-induced central hemodynamics were unchanged by afferent blockade, peripheral hemodynamic responses were significantly enhanced. Thus, in patients with HF, a heightened mechanoreflex seems to augment peripheral sympathetic vasoconstriction in response to movement, a phenomenon that may contribute to exercise intolerance in this population.

Long-Term Exercise Training in Patients With Advanced Chronic Heart Failure: SUSTAINED BENEFITS ON LEFT VENTRICULAR PERFORMANCE AND EXERCISE CAPACITY

PURPOSE

In moderately impaired, stable chronic heart failure (CHF) patients, exercise training (ET) enhances exercise capacity. In contrast, the therapeutic benefits of regular ET in patients with advanced CHF, especially in the long-term, are limited or conflicting. Therefore, the aim of the present investigation was to elucidate whether ET performed over 12 months would improve left ventricular performance and exercise capacity in patients with advanced CHF.

METHODS

Thirty-seven patients with CHF and New York Heart Association (NYHA) class IIIb were randomized to a sedentary lifestyle or daily ET on a cycle ergometer (in-hospital and home-based at 50%-60% of maximal exercise capacity). Cardiopulmonary exercise testing and echocardiography were performed at baseline, 3, 6, and 12 months.

RESULTS

Exercise training resulted in continuous decreases in left ventricular end-diastolic diameter at 3, 6, and 12 months versus baseline (all P < .05). This was accompanied by a significant increase in resting left ventricular ejection fraction from 24.1% ± 1.2% at baseline to 38.4% ± 2.0% at 12-month followup (P < .05). Moreover, ET patients increased exercise capacity measured by maximal oxygen uptake (Equation is included in full-text article.)O2max at 3, 6, and 12 months compared with baseline: 15.3 ± 0.8 mL/min/kg, 17.8 ± 0.8 mL/min/kg, 19.0 ± 0.7 mL/min/kg, and 19.5 ± 0.9 mL/min/kg, respectively (all P < .05 vs baseline). This was associated with a reduced NYHA classification.

CONCLUSIONS

Exercise training over 12 months resulted in an improvement in exercise capacity and reversing of left ventricular remodeling in patients with advanced CHF (NYHA IIIb). These beneficial adaptations continued to improve up to 6 months and remained stable thereafter.

The challenge of frailty and sarcopenia in heart failure with preserved ejection fraction

Frailty is a clinical state in which there is an increase in an individual's vulnerability for developing increased dependency and/or mortality when exposed to stressors. Frailty is often accompanied by heart failure with preserved ejection fraction (HFpEF), and frailty is likely to affect its clinical features and outcomes. Frail patients with HFpEF are frequently associated with sarcopenia (ie, muscle loss and weakness), which is a major component of the pathophysiology of frailty. Sarcopenia is a systemic skeletal muscle disease that impairs the function of limb skeletal muscles, as well as respiratory muscles, and this results in further functional decline. In addition, sarcopenia may contribute to cardiovascular remodelling and dysfunction, leading to the development of HFpEF through several metabolic and endocrine abnormalities. Although there is no established strategy for frail patients with HFpEF, a multidisciplinary approach, including various types of muscular training and nutritional intervention, may provide beneficial effects for these patients.

Effects of Six Months Training on Physical Capacity and Metaboreflex Activity in Patients with Multiple Sclerosis

Patients with multiple sclerosis (MS) have an increased systemic vascular resistance (SVR) response during the metaboreflex. It has been hypothesized that this is the consequence of a sedentary lifestyle secondary to MS. The purpose of this study was to discover whether a 6-month training program could reverse this hemodynamic dysregulation. Patients were randomly assigned to one of the following two groups: the intervention group (MSIT, n = 11), who followed an adapted training program; and the control group (MSCTL, n = 10), who continued with their sedentary lifestyle. Cardiovascular response during the metaboreflex was evaluated using the post-exercise muscle ischemia (PEMI) method and during a control exercise recovery (CER) test. The difference in hemodynamic variables such as stroke volume (SV), cardiac output (CO), and SVR between the PEMI and the CER tests was calculated to assess the metaboreflex response. Moreover, physical capacity was measured during a cardiopulmonary test till exhaustion. All tests were repeated after 3 and 6 months (T3 and T6, respectively) from the beginning of the study. The main result was that the MSIT group substantially improved parameters related to physical capacity (+5.31 ± 5.12 ml·min⁻¹/kg in maximal oxygen uptake at T6) in comparison with the MSCTL group (−0.97 ± 4.89 ml·min⁻¹/kg at T6; group effect: p = 0.0004). However, none of the hemodynamic variables changed in response to the metaboreflex activation. It was concluded that a 6-month period of adapted physical training was unable to reverse the hemodynamic dys-regulation in response to metaboreflex activation in these patients.