Myocardial mechanics and cardiac biomarkers in adults with severe anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is associated with left ventricular (LV) atrophy and unexplained sudden death. Myocardial mechanics have not been well studied in adults with AN. Whether LV mass or illness duration, markers of AN severity, correlate with abnormal strain imaging is unknown.

METHODS

We performed a prospective study among patients hospitalized with severe AN (n = 29) [body mass index (BMI) < 14.5 kg/m2] and sex/age-matched controls (n = 16) (BMI > 18.5 kg/m2). LV ejection fraction (LVEF) was calculated via modified-biplane method and LV mass was derived using the truncated ellipsoid formula. Apical 2-, 3-, and 4-chamber images were used to generate regional strain mapping and global longitudinal strain (GLS). N-terminal brain natriuretic peptide (NT-proBNP) levels were measured and linear regression was used to determine independent predictors of strain.

RESULTS

Mean LVEF did not differ (65% ± 6.0 vs. 62% ± 4.4, p = 0.06), but LV mass was substantially reduced (61.6 ± 16.8 vs. 97.6 ± 19.1 g, p < .0001). GLS was similar (- 20.6 ± 3.8 vs. - 20.9 ± 2.8, p = 0.82), however, the basal strain was worse (-18.7 ± 4.8 vs. -21.9 ± 4.1, p = 0.03). Lower LV mass was associated with worsening GLS (r = - 0.40, p = 0.003), but not among controls (p = 0.89). Median (IQR) NT-proBNP (pg/ml) was higher in patients with AN [141 (59-257) vs. 35.5 (21-56.5) p = 0.0007]. Both increasing NT-proBNP and illness duration were associated with worsening strain patterns in AN (both p = .001).

CONCLUSIONS

While LVEF and GLS did not differ, regional strain variation was noted among patients with AN. Elevated NT-proBNP may reflect increased wall tension from LV atrophy. Whether strain heterogeneity can identify patients with AN, at risk for sudden death, requires further study.

Cardiac Remodeling and Its Determinants in Anorexia Nervosa Adolescents: Impact of Weight Recovery

Cardiovascular alterations in anorexia nervosa (AN) adolescents include bradycardia and decreased systolic blood pressure and left ventricular mass. However, their determinants remain poorly understood. We assessed the associations between morphological and functional left ventricular (LV) remodeling, autonomic control by heart rate variability (HRV) analysis, thyroid hormones and brain natriuretic peptide (BNP) levels in AN female adolescents without or with weight recovery (WR). Fifty-nine female adolescents including 16 AN patients without WR (mean age 13.9 years (10−16)), 10 AN patients with WR (15.7 years (12−18)) and 33 controls (14.1 years (10−18)) underwent night heart rate (HR) recording to measure HRV (and especially SD1/SD2, the ratio between instantaneous (SD1) and long-term (SD2) standard deviation of R-R intervals, reflecting sympatho-vagal balance), speckle tracking echocardiography to assess LV global longitudinal strain (GLS) and blood test for dosage of tri-iodothyronine (T3) hormone and NT-proBNP. Compared to controls, AN patients without WR presented with lower HR (55 ± 7 vs. 68 ± 6 bpm; p < 0.001), parasympathetic hyperactivity, and higher GLS (−19.2 ± 1.8 vs. −16.9 ± 2.8%; p = 0.009). These alterations were partly abolished in AN patients with WR. In a multivariate regression analysis, T3 was the main factor explaining the variance of SD1/SD2, a sympatho-vagal balance marker. NT-proBNP levels were not correlated with cardiac alterations. AN patients had parasympathetic hyperactivity linked with their rate of T3, and a higher GLS. These alterations were partly restored in AN patients with WR.

Doxorubicin Exposure Causes Subacute Cardiac Atrophy Dependent on the Striated Muscle-Specific Ubiquitin Ligase MuRF1

Background Anthracycline chemotherapeutics, such as doxorubicin, are used widely in the treatment of numerous malignancies. The primary dose-limiting adverse effect of anthracyclines is cardiotoxicity that often presents as heart failure due to dilated cardiomyopathy years after anthracycline exposure. Recent data from animal studies indicate that anthracyclines cause cardiac atrophy. The timing of onset and underlying mechanisms are not well defined, and the relevance of these findings to human disease is unclear. Methods and Results Wild-type mice were sacrificed 1 week after intraperitoneal administration of doxorubicin (1-25 mg/kg), revealing a dose-dependent decrease in cardiac mass ( R2=0.64; P<0.0001) and a significant decrease in cardiomyocyte cross-sectional area (336±29 versus 188±14 µm2; P<0.0001). Myocardial tissue analysis identified a dose-dependent upregulation of the ubiquitin ligase, MuRF1 (muscle ring finger-1; R2=0.91; P=0.003) and a molecular profile of muscle atrophy. To investigate the determinants of doxorubicin-induced cardiac atrophy, we administered doxorubicin 20 mg/kg to mice lacking MuRF1 (MuRF1-/-) and wild-type littermates. MuRF1-/- mice were protected from cardiac atrophy and exhibited no reduction in contractile function. To explore the clinical relevance of these findings, we analyzed cardiac magnetic resonance imaging data from 70 patients in the DETECT-1 cohort and found that anthracycline exposure was associated with decreased cardiac mass evident within 1 month and persisting to 6 months after initiation. Conclusions Doxorubicin causes a subacute decrease in cardiac mass in both mice and humans. In mice, doxorubicin-induced cardiac atrophy is dependent on MuRF1. These findings suggest that therapies directed at preventing or reversing cardiac atrophy might preserve the cardiac function of cancer patients receiving anthracyclines.

Evidence of direct cardiac damage following high-intensity exercise in chronic energy restriction: A case report and literature review

RATIONALE

Following prolonged endurance events such as marathons, elevated levels of cardiospecific biomarkers are commonly reported. Although transiently raised levels are generally not considered to indicate clinical myocardial damage, comprehension of this phenomenon remains incomplete. The popularity of high-intensity interval training highlights a paucity of research measuring cardiac biomarker response to this type of exercise. This a posteriori case report discusses the elevation of cardiac troponins (cTn) associated with short interval, high-intensity exercise.

PATIENT CONCERNS

In this case report, an apparently healthy 29-year-old recreationally active female presented clinically raised cardiac troponin I (cTnI) levels (>0.04 ng/mL), after performing high-intensity cycle ergometer sprints. As creatine kinase (CK) is expressed by multiple organs (e.g., skeletal muscle, brain, and myocardium), cTnI assays were performed to determine any changes in total serum CK levels not originating from skeletal muscle damage.

DIAGNOSIS

A posteriori the individual's daily energy expenditure indicated chronically low-energy availability. Psychometric testing suggested that the individual scored positive for disordered eating, highly for fatigue levels, and low in mental health components.

OUTCOMES

The current case report provides novel evidence of elevated cTnI occurring as a result of performing short duration, high intensity, cycle ergometer exercise in an individual with self-reported chronically depleted energy balance. A schematic to identify potentially "at risk" individuals is presented.

LESSONS

Considering this as a case report, results cannot be generalized; however, the main findings suggest that individuals who habitually restrict their calorie intake below their bodies' daily energy requirements, may have elevated biomarkers of exercise induced myocardial stress from performing high-intensity exercise.

Serum Albumin and Prealbumin in Calorically Restricted, Nondiseased Individuals: A Systematic Review

PURPOSE

Undernutrition is often suspected in patients when serum albumin or prealbumin levels are low. We asked whether these measures are indeed low in undernourished people if no inflammatory illness is present.

METHODS

We did a systematic review to identify otherwise healthy subjects who were severely nutrient-deprived due to poor access to food or unwillingness to eat. We excluded children and pregnant women. We tabulated available measures of nutrient intake, anthropometry, serum albumin and prealbumin, and, when available, changes in these measures during nutritional intervention.

RESULTS

In otherwise healthy subjects, serum albumin and prealbumin levels remained normal despite marked nutrient deprivation until the extremes of starvation, that is, body mass index <12 or more than 6 weeks of starvation.

CONCLUSIONS

In these otherwise healthy subjects, serum albumin and prealbumin levels are not "markers of nutritional status." The "markers" failed to identify subjects with severe protein-calorie malnutrition until extreme starvation. That is, they failed to identify healthy individuals who would benefit from nutrition support, becoming abnormal only when starvation was already obvious. In contrast, serum albumin and prealbumin levels are known to fall promptly with injury or illness regardless of nutrient intake. They are negative acute-phase reactants. When these measures are low in sick patients, this cannot be assumed to reflect nutritional deprivation. Decisions about nutrition support should be based on evidence of meaningful benefit from this treatment rather than on assessment of "nutritional markers."

INTERACTING DISCIPLINES: Cardiac natriuretic peptides and obesity: perspectives from an endocrinologist and a cardiologist

Since their discovery in 1981, the cardiac natriuretic peptides (cNP) atrial natriuretic peptide (also referred to as atrial natriuretic factor) and brain natriuretic peptide have been well characterised in terms of their renal and cardiovascular actions. In addition, it has been shown that cNP plasma levels are strong predictors of cardiovascular events and mortality in populations with no apparent heart disease as well as in patients with established cardiac pathology. cNP secretion from the heart is increased by humoral and mechanical stimuli. The clinical significance of cNP plasma levels has been shown to differ in obese and non-obese subjects. Recent lines of evidence suggest important metabolic effects of the cNP system, which has been shown to activate lipolysis, enhance lipid oxidation and mitochondrial respiration. Clinically, these properties lead to browning of white adipose tissue and to increased muscular oxidative capacity. In human association studies in patients without heart disease higher cNP concentrations were observed in lean, insulin-sensitive subjects. Highly elevated cNP levels are generally observed in patients with systolic heart failure or high blood pressure, while obese and type-2 diabetics display reduced cNP levels. Together, these observations suggest that the cNP system plays a role in the pathophysiology of metabolic vascular disease. Understanding this role should help define novel principles in the treatment of cardiometabolic disease.

Heart hormones fueling a fire in fat

Our view of how adipose tissue metabolism is regulated recently experienced a change in focus and breadth, meaning that some of the key controlling factors were not fully in the picture. The catecholamines of the sympathetic nervous system are well-known activators of β-adrenergic receptors in adipocytes to increase lipolysis. They also drive energy expenditure in brown adipose tissue and, importantly, the “browning” of cells in white adipose depots. However, this is clearly not the whole story. In earlier work, we established a pathway from β-adrenergic receptors to p38 MAP kinase to drive the transcription of brown adipocyte genes and respiratory uncoupling. Now we recently discovered that cardiac natriuretic peptides (NPs) stimulate a similar “browning” of human and mouse adipocytes. NPs activate the guanylyl cyclase coupled NP receptor A and activation of protein kinase G. Importantly, this pathway also depends upon p38 MAPK. These two pathways work together, additively increasing expression of brown adipocyte marker genes, as well as reflexively controlling each other’s components. We discuss these findings and how the control of body fat by these cardiac hormones, in conjunction with the sympathetic nervous system, has implications for obesity as well as cardiovascular disease, including hypertension and heart failure.

Research on cachexia, sarcopenia and skeletal muscle in cardiology

BACKGROUND

The awareness of cardiac cachexia, i.e. involuntary weight loss in patients with underlying cardiovascular disease, has increased over the last two decades.

METHODS AND RESULTS

This mini-review looks at recent research in the cardiovascular literature that is relevant to the areas of interest of the Journal of Cachexia, Sarcopenia and Muscle. It identifies significant research in the last 3 years on the obesity paradox, the causes and effects of skeletal muscle wasting, animal models of cachexia and emerging treatment ideas in cardiac cachexia.

CONCLUSIONS

Assuming a similar literature in the fields of cancer, chronic obstructive pulmonary disease, chronic renal failure and chronic liver failure, the emergence of cachexia as a vibrant area of clinical and experimental research seems assured.