Cardiac cachexia

Article written and reviewed by Dr Luca Moretti

Cardiac cachexia is a multifactorial metabolic syndrome associated with heart failure, characterized by involuntary loss of edema-free weight and muscle tissue, with or without a reduction in fat. It is not equivalent to simply being underweight, nor is it resolved by indiscriminately increasing calories, because anorexia, inflammation, congestion, inactivity, and anabolic-catabolic imbalance act simultaneously. There is still no single cardiology definition. The historical criterion uses nonedematous loss of at least 6% over 6-12 months; the general Evans consensus requires a chronic disease, loss of at least 5% over 12 months or a BMI below 20 kg/m², and at least three features among reduced strength, fatigue, anorexia, low lean mass, and biochemical abnormalities. The decisive finding is the weight trajectory after correction of congestion. Edema and ascites may conceal months of catabolism, whereas a rapid decrease during diuresis often represents water and must not be labeled cachexia.

Cachexia, malnutrition, sarcopenia, and frailty are distinct but overlapping entities. Malnutrition describes a deficit in intake or assimilation with consequences for body composition; sarcopenia is defined primarily by reduced strength, confirmed by low muscle mass or quality; frailty indicates multisystem vulnerability to a stressor. Cachexia may occur with a normal or elevated BMI when loss occurs from a higher previous weight. Sarcopenic obesity may also conceal severe muscle depletion behind adiposity and edema, making assessment based on BMI alone inadequate. It is a marker of advanced heart failure, reduced treatment tolerance, and operative risk, but does not automatically demonstrate irreversibility. Early screening allows correctable causes to be treated and prevents missing the window for rehabilitation, an LVAD, or transplantation.

Etiology, pathogenesis, and pathophysiology

Reduced cardiac output and congestion activate the sympathetic nervous system, renin-angiotensin-aldosterone, vasopressin, and the hypothalamic-pituitary-adrenal axis; these systems temporarily support perfusion and blood pressure, but chronic exposure promotes vasoconstriction, lipolysis, insulin resistance, and proteolysis. The anabolic response to insulin, growth hormone, and IGF-1 becomes attenuated; androgen deficiency, inactivity, and aging further reduce synthesis and regeneration; the anabolic-catabolic imbalance affects skeletal muscle, adipose tissue, and, in the most advanced phenotypes, the myocardium and bone. Effective neurohormonal therapy may attenuate some catabolic signals, but there is no evidence that any single heart failure drug cures cachexia. Control of the cardiac syndrome creates the conditions for nutrition and activity to have an effect.

TNF, IL-1, IL-6, and other inflammatory pathways activate NF-κB, the ubiquitin-proteasome system, and autophagy and inhibit protein synthesis. Oxidative stress and reduced perfusion alter muscle mitochondria, capillarization, and oxidative metabolism; myostatin limits growth and differentiation and may increase in the muscle of patients with advanced heart failure. Its relationship with follistatin, PI3K-AKT, and myogenic factors contributes to reduced fiber cross-sectional area and a poor response to anabolic stimulation; inflammation is neither uniform nor specific. Elevated CRP or cytokines support the catabolic phenotype, but infection, obesity, CKD, and comorbidities limit their individual diagnostic value.

Muscle develops a reduction in oxidative fibers, capillary density, and mitochondrial function, with early anaerobic metabolism and metabolite accumulation. Ergoreflexes increase ventilation and sympathetic activity, contributing to the disproportion between dyspnea and cardiac measurements; inactivity causes deconditioning, but does not explain everything: cellular abnormalities persist even after adjustment for age and functional class. Each hospitalization adds bed rest, possible corticosteroid use, inflammation, and reduced intake, accelerating the loss of mass and power. Inspiratory muscles and the diaphragm may weaken, increasing the work of breathing and limitation. Strength and performance decline before weight loss becomes evident.

Right-sided failure and tricuspid regurgitation raise hepatic and intestinal venous pressure. Wall edema, reduced mucosal flow, fullness, nausea, and postprandial pain reduce intake and may alter absorption and barrier function. Translocation of bacterial products has been proposed as an inflammatory stimulus, but does not constitute a validated clinical test. The association between intestinal congestion, right atrial pressure, and cachexia is robust in observational terms and makes decongestion a component of etiological treatment. Hepatic congestion, cholestasis, and hypoalbuminemia often accompany the right-sided phenotype. Low albumin may reflect inflammation, dilution, losses, liver disease, or malnutrition and does not identify the mechanism on its own.

Intake decreases because of dyspnea during meals, anorexia, altered taste and smell, xerostomia, dental problems, dysphagia, depression, isolation, or financial difficulties. Polypharmacy, nausea, and multiple restrictions may turn a theoretically cardioprotective diet into an inadequate regimen; energy expenditure is not invariably elevated: fever, catecholamines, and the work of breathing may increase it, whereas loss of mass and inactivity reduce it. Indirect calorimetry, when available, avoids assuming universal hypermetabolism. CKD, COPD, diabetes, hyperthyroidism, infections, malignancies, and malabsorption add their own mechanisms. Defining cachexia as cardiac therefore requires plausibly causal heart failure and exclusion of relevant alternatives.

Clinical manifestations

The central manifestation is an involuntary, progressive loss of dry weight. Looser clothing, reduced circumferences, bony prominence, and loss of temporal or interosseous tissue may precede formal recognition; grip strength declines, rising from a chair becomes difficult, and gait speed and independence decrease. Fatigue and dyspnea arise jointly from the heart, muscle, anemia, lungs, and motivation and are nonspecific; the patient may retain peripheral edema and appear to have a normal weight. Current weight and inspection must be compared with premorbid values, photographs, records, and caregiver reports.

Anorexia, early satiety, nausea, distension, and abdominal discomfort are common in right-sided congestion. Dysgeusia, xerostomia, and dyspnea make meals tiring; orthopnea and oxygen therapy may interfere further; a brief food diary identifies amounts, distribution, protein, supplements, and specific obstacles, but is affected by recall and underestimation. Who prepares meals and the financial ability to obtain them are part of the clinical history. Diarrhea, steatorrhea, vomiting, dysphagia, or persistent pain must not automatically be attributed to heart failure. They require gastroenterological or oncological assessment according to the presentation.

Overlapping sarcopenia manifests with low strength and reduced mass, even without fat loss. According to EWGSOP2, low strength makes the diagnosis probable, low quantity or quality confirms it, and reduced performance defines its severe form. Physical frailty often combines slowness, weakness, exhaustion, low activity, and weight loss, but also includes cognitive, psychological, and social domains in multidimensional models. Not all frail patients are cachectic, and vice versa. Falls, fear of movement, and dependence in daily activities fuel immobility. Delirium and repeated hospitalizations may produce abrupt steps of deterioration.

The advanced phenotype includes hypotension, high diuretic doses, refractory congestion, drug intolerance, hyponatremia, and renal or hepatic injury; cachexia is one of the signals for referral to an advanced heart failure center. The congested right heart may present with elevated jugular venous pressure, hepatomegaly, ascites, and edema alongside muscle loss. In this context, total body weight underestimates the severity of catabolism. It is well described in HFrEF, but wasting and sarcopenia also occur in HFpEF, congenital heart disease, valvular disease, and pulmonary hypertension; ejection fraction is not a diagnostic criterion.

Depression, anxiety, and loss of enjoyment of food may aggravate anorexia. Cognitive impairment compromises the purchase, preparation, and intake of medications and meals, whereas caregiver burden influences the sustainability of the program. Pressure injuries, slow healing, and recurrent infections indicate reduced reserve; quality of life worsens because of fatigue, body image, dependence, and conflict between poor appetite and pressure to eat. Assessment must avoid judgments of nonadherence. Symptoms, restrictions, and social determinants often explain insufficient intake more than the patient's willingness does.

Investigations and diagnosis

The first measure is to reconstruct usual weight, recent maximum weight, percentage loss, duration, and intentionality, distinguishing phases of decongestion; the most reliable dry weight is that after stabilization, compared with measurements under similar volume conditions. BMI, arm and calf circumferences, and skinfolds are accessible but influenced by edema, age, and fat distribution. A loss greater than 5% over 12 months is clinically relevant, but the threshold and associated criteria must be stated. Daily weight is used to assess volume; composition changes more slowly. Confusing the two signals generates false diagnoses during diuresis and delays the true diagnosis during retention.

Nutritional screening uses validated tools such as NRS-2002 in hospitalized patients, MUST in various settings, and MNA-SF in older adults; a positive result requires a full assessment by qualified personnel and does not equate to a diagnosis of cachexia. The GLIM criteria diagnose malnutrition after screening when at least one phenotypic criterion, among weight loss, low BMI, or reduced muscle mass, coexists with one etiological criterion, among reduced intake or assimilation and inflammation. SGA or dietetic assessment integrates history, examination, and function. GNRI, CONUT, and PNI have prognostic value in cardiac cohorts, but depend on albumin, cholesterol, or lymphocytes and do not replace etiological judgment.

DXA quantifies appendicular lean mass and fat with a low radiation dose, but does not perfectly distinguish water from tissue. BIA is portable and estimates impedance and phase angle, but congestion violates its assumptions and requires measurements in a stable state. CT and magnetic resonance imaging measure muscle area and quality at standard levels and can reuse previously acquired images, avoiding additional radiation; muscle ultrasound assesses thickness and architecture at the bedside, but cutoffs and reproducibility depend on the protocol. No technology has a universal threshold specific to cardiac cachexia. Method, side, site, hydration, sex, and ethnicity must be documented in serial measurements.

Handgrip, the five-times sit-to-stand test, and quadriceps strength assess the muscular domain. Gait speed, the Short Physical Performance Battery, and Timed Up and Go describe performance, but congestion, arthritis, neuropathy, and motivation affect the result. The six-minute walk test and cardiopulmonary exercise testing quantify overall capacity; a reduced peak VO2 does not separate the cardiac from the muscular component, whereas the VE/VCO2 slope, oscillation, and blood pressure response add prognostic information. Functional assessment is repeated after stabilization; a test performed during pulmonary edema or infection does not represent usual reserve.

Laboratory testing includes complete blood count, ferritin and transferrin saturation, electrolytes, renal and liver function, blood glucose, TSH, CRP, and albumin; vitamins, folate, B12, zinc, or other tests are targeted. Natriuretic peptides and troponin define cardiac burden, not cachexia. Albumin and prealbumin are acute-phase proteins, influenced by inflammation, hydration, the liver, and losses. Low values have prognostic significance but do not directly measure caloric intake. Anemia, iron status, thyroid function, and treatable deficiencies may explain some of the weakness. Biomarkers such as cytokines, myostatin, ghrelin, and IGF-1 remain primarily research tools.

The differential diagnosis investigates malignancies, chronic infections, COPD, CKD, primary liver disease, hyperthyroidism, adrenal insufficiency, and gastrointestinal, rheumatological, and neurological diseases. History, examination, and symptoms guide imaging, endoscopy, and specific tests without indiscriminate screening. Medications may cause nausea, altered taste, diarrhea, or anorexia; alcohol and substances add malabsorption or toxicity; medication review must not eliminate drugs that improve prognosis without demonstrating a plausible relationship. The final formulation should indicate the criterion used, dry weight loss, composition and strength, nutritional status, inflammation, congestion, and competing causes; a simple label is not sufficient to design the intervention.

Treatment and prognosis

The first treatment is to optimize heart failure and correct the precipitant. Euvolemia, perfusion, rhythm, ischemia, valves, and therapy that modifies prognosis reduce symptoms and catabolic signals; the right heart and abdominal congestion require particular attention. Diuretics improve satiety and absorption when they reduce intestinal edema, but excessive use causes hypotension, AKI, and electrolyte loss; the nutritional response is reassessed after decongestion, not assumed from weight loss alone. Iron status, anemia, thyroid disorders, infections, depression, pain, dental problems, and dysphagia are treated as indicated. Removing correctable obstacles may be more effective than adding a supplement.

A dietitian estimates intake, requirements, preferences, and accessibility and designs small, frequent meals with high energy and protein density. Oral supplements are added when food does not meet targets and are selected considering sodium, volume, potassium, diabetes, and renal status. The 2026 AHA document generally proposes protein at 1-1.2 g/kg/day in cardiac cachexia and 1.2-2.0 g/kg/day in critically ill patients, individualized according to renal function, metabolic phase, and tolerance. Higher intakes have not demonstrated additional benefit; energy requirements are preferably measured or estimated cautiously and adjusted to the trend. Rigid targets based on edematous weight overfeed some patients and undertreat others.

Sodium and fluid restriction is calibrated to congestion, avoiding regimens so severe that they reduce palatability and calories; the dietary pattern must remain cardioprotective, but the immediate priority in a depleted patient is to achieve safe and sufficient intake. In stable hospitalized patients, early enteral feeding is preferred if oral intake fails; in uncontrolled shock or suspected intestinal ischemia, the risk changes. Parenteral nutrition is reserved for an unusable or insufficient gastrointestinal tract and entails infection, glycemic, and volume risks. Small trials and analyses of malnourished patients with heart failure suggest benefit from individualized interventions, but do not prove that nutrition alone reverses metabolic cachexia or always improves survival.

Cardiac rehabilitation combines aerobic exercise, strength, balance, and functional activities after stabilization; intensity starts from actual capacity; short or interval sessions and slow progression limit dyspnea, falls, and dropout. Resistance training provides the most direct stimulus to strength, whereas aerobic exercise improves perfusion, oxidative capacity, and independence. Mechanistic studies show reduced myostatin and improved regenerative pathways, but specific outcomes in severe cachexia remain poorly defined. Respiratory physiotherapy and inspiratory muscle training are selected for documented weakness; bed rest is interrupted early when hemodynamics allow.

Ghrelin, analogs, testosterone, growth hormone, megestrol, cannabinoids, myostatin modulators, and anti-inflammatory drugs have been studied in small samples or other diseases. Improvements in appetite or mass do not equate to clinical benefit, and risks such as retention, thrombosis, arrhythmias, and toxicity are relevant. There is no approved pharmacological therapy specifically for cardiac cachexia. Anabolic steroids or appetite stimulants must not be used routinely outside other indications or protocols. Beta-blockade, RAAS inhibition, ARNIs, and SGLT2 inhibitors follow the heart failure phenotype, with monitoring of blood pressure, volume, and weight; the initial decline from diuresis or SGLT2 inhibitors must not be confused with progression of cachexia.

The development of cachexia requires prompt referral for advanced therapy. An LVAD or transplantation may correct hemodynamics and allow recovery of weight and muscle, but depletion, frailty, and right-sided failure increase complications and may narrow eligibility. Prehabilitation integrates nutrition, exercise, and psychosocial support without delaying a necessary procedure; reversibility is assessed through trends, response to stabilization, and absence of an uncontrollable competing disease. Prognosis is unfavorable, and weight or muscle loss predicts mortality independently of several cardiac markers. Stage, rate of decline, organs involved, and the possibility of causal therapy define individual risk.

Complications

Loss of strength reduces walking, coughing, transfers, and the ability to eat. Falls, fractures, pressure injuries, and dependence generate further immobility and a cycle of deterioration; respiratory muscle weakness increases ventilatory fatigue and difficulty weaning after intubation. An infection or procedure that would be tolerable with normal reserve may precipitate persistent disability; reduced mass alters creatinine-based estimation of renal function, which may appear reassuring. Cystatin C and combined assessment are useful when the decision depends on actual filtration.

Impaired immunity, fragile skin, and devices increase infections and slow healing. Hypoalbuminemia and edema promote dehiscence, exudate, and injuries, but correcting the albumin value alone does not change the mechanism. Anemia, deficiencies, and osteoporosis amplify fatigue and fracture risk. Anticoagulation makes falls more dangerous and requires prevention, not immobilization. Sarcopenia and frailty increase delirium, length of hospitalization, and rehabilitation needs. Multidimensional geriatric assessment may define interventions and care.

Refeeding a severely depleted patient may cause hypophosphatemia, hypokalemia, hypomagnesemia, sodium retention, arrhythmias, and heart failure. Initial intake, thiamine, electrolytes, and volume are managed according to risk; refeeding syndrome may also occur with oral nutrition or intravenous glucose and is not prevented by calorie counting alone. Monitoring is closer in the first few days. Overfeeding increases CO2, blood glucose, steatosis, and fluid load; the goal is progressive recovery, not a rapid increase in total body weight.

Hydrophilic and lipophilic drugs may change their distribution with loss of water, fat, and albumin; impaired liver and kidney function alter clearance. Hypotension and low mass make previously stable doses less tolerable; polypharmacy increases nausea, xerostomia, interactions, and the burden of meals. Deprescribing means removing treatments that are inconsistent with benefit and goals, preserving those that improve prognosis as long as they are tolerated. Herbal supplements and high-protein products may contain sodium, potassium, or pharmacological substances. They are recorded and assessed like any other therapy.

Advanced cachexia may make an LVAD, transplantation, or surgery unfeasible and increases infection, bleeding, right-sided failure, and prolonged rehabilitation. For this reason, specialist assessment must not wait until BMI is very low. When reversibility is unlikely, palliative care addresses dyspnea, nausea, anxiety, taste, conflicts over food, and realistic goals. Forcing feeding may increase suffering and aspiration without restoring function in the terminal phase; caregiver support includes explaining that reduced appetite is part of the disease. Decisions about artificial nutrition, ICDs, and hospitalizations must be shared on the basis of foreseeable benefits and preferences.