Nutritional cardiomyopathy

Article written and reviewed by Dr Luca Moretti

Nutritional cardiomyopathy is not a single nosologic entity but an umbrella term applicable when myocardial dysfunction can be attributed to a defined nutritional deficiency or to the profound metabolic abnormalities accompanying undernutrition and refeeding. Thiamine, selenium and carnitine are the best-documented paradigms, but their mechanisms, hemodynamic phenotypes and strength of evidence differ markedly. A rigorous diagnosis therefore requires identification of the causal nutrient, the context that caused its depletion, and the evidence linking the deficiency to cardiac injury.

A low biochemical value does not automatically equal cardiomyopathy. Inflammation, hemodilution, hypoalbuminemia, organ failure and the acute phase alter circulating concentrations of many micronutrients; heart failure itself also reduces appetite, alters absorption and increases losses. The relationship may be causal, contributory or reverse. Clinical triangulation integrates exposure, a compatible phenotype, an appropriate biomarker, exclusion of alternatives and a temporally plausible response to correction.

The category includes very different presentations: wet beriberi may begin with vasodilation and high cardiac output, Shoshin beriberi may precipitate shock with extremely high lactate, selenium depletion may present as dilated ventricular dysfunction, and primary carnitine deficiency as a cardiomuscular metabolic disease. Severe undernutrition, by contrast, often produces a small heart, reduced myocardial mass, bradycardia and low output without necessarily meeting the definition of cardiomyopathy. The hemodynamic phenotype takes precedence over the generic label.

Clinical relevance derives from potential reversibility and urgency. A timely dose of thiamine can alter refractory collapse within hours, whereas waiting for a level sent to an outside laboratory can be fatal. At the opposite extreme, indiscriminate use of trace elements turns a precision diagnosis into an unproven and sometimes toxic practice. The correct principle is to recognize a well-founded clinical suspicion, obtaining samples before treatment when this does not cause delay.

Clinical and epidemiologic framework

There is no reliable global estimate of nutritional cardiomyopathy because studies use different definitions and select high-risk populations. Beriberi remains relevant where diets are poor or depend on unfortified refined grains and reappears in advanced health systems in the presence of vomiting, eating disorders, alcohol use, cancer, digestive surgery or incomplete artificial nutrition. Selenium-related forms are rare outside historical endemic areas, but have been documented in intestinal failure, parenteral nutrition and after malabsorptive procedures.

Malnutrition is not synonymous with a low body mass index. After risk screening, the GLIM criteria require at least one phenotypic criterion, such as unintentional weight loss, low BMI or reduced muscle mass, and at least one etiologic criterion, such as reduced intake or assimilation or inflammation. A patient with obesity who loses weight rapidly after surgery, or a critically ill patient with edema, may be profoundly depleted without appearing thin. The dynamic weight history is more informative than an anthropometric snapshot alone.

Risk increases when several depletion pathways overlap. Poor intake, diarrhea, intestinal resection, vomiting, increased requirements, renal losses and omission of additives from parenteral nutrition may coexist. Even prescribed adherence does not guarantee adequacy if the preparation, dose or route does not match residual absorption. The map of losses must be reconstructed for each nutrient and for the period preceding symptoms.

Modern cardiomyopathy guidelines include nutritional deficiencies among acquired causes to investigate in compatible phenotypes, not among residual explanations to invoke after a single test. The presence of a deficiency does not exclude a genetic variant, myocarditis, toxic exposure or endocrine etiology. In particular, a deficiency may lower the reserve of an already vulnerable myocardium and make an otherwise subclinical disease manifest. The multiple-hit model better describes many real cases.

Bioenergetics, microcirculation and remodeling

The heart derives ATP mainly from fatty-acid oxidation but rapidly adapts its substrate use to glucose, lactate and ketone bodies. Thiamine and carnitine act at different points in this network: thiamine as a cofactor for complexes linking glycolysis, the tricarboxylic acid cycle and the pentose phosphate pathway; carnitine in mitochondrial transport of long-chain fatty acids. Severe deficiency reduces metabolic flexibility and makes cardiac performance particularly sensitive to infection, fasting or increased demand.

Selenium acts through selenoproteins, including glutathione peroxidase and thioredoxin reductase, which contribute to redox homeostasis and thyroid function. Severe depletion may reduce the ability to control peroxides and oxidative stress, but the transition from a low biomarker to human cardiomyopathy is not linear. In Keshan disease and Western cases, interactions with infections, inflammation, diet and individual susceptibility are likely. Antioxidant reserve is a determinant, not a universal explanation.

Protein-energy undernutrition reduces lean body mass, plasma volume, peripheral thyroid activity and sympathetic tone. The myocardium may atrophy in proportion to loss of body mass, while bradycardia and hypotension limit energy consumption. Edema may result from hypoalbuminemia, renal retention and increased permeability without necessarily indicating elevated filling pressures. The adaptive physiology must be distinguished from primary heart failure.

When nutrition is resumed abruptly, insulin shifts phosphate, potassium and magnesium into cells, reactivates ATP synthesis and increases thiamine requirements. At the same time, sodium and water excretion decreases. An atrophic or already dysfunctional heart must therefore face volume expansion and greater metabolic demand precisely when cofactors may be insufficient. The anabolic transition, rather than food itself, explains the risk of refeeding.

Thiamine, cardiac beriberi and Shoshin form

Thiamine is converted to thiamine diphosphate, a cofactor for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, branched-chain alpha-ketoacid dehydrogenase and transketolase. When availability becomes critical, pyruvate is diverted to lactate and aerobic ATP production decreases. Body stores are modest and persistently inadequate intake may cause depletion within a few weeks, more rapidly if requirements, losses or carbohydrate load increase.

Classic wet beriberi combines peripheral vasodilation, reduced systemic resistance, tachycardia, an initial increase in cardiac output, neurohormonal activation and sodium and water retention. The ventricle may appear hyperdynamic early and dilate as the condition progresses; right-sided failure, wide pulse pressure, warm extremities and edema point toward a high-output circulation. Anemia, sepsis, thyrotoxicosis and arteriovenous fistulas remain important alternatives.

The fulminant form, known as Shoshin beriberi, may instead present with profound hypotension, biventricular dysfunction, vasoconstriction, cyanosis, renal failure and disproportionate lactic acidosis. High and low output are not incompatible categories: the patient may transition from hyperdynamic vasodilation to contractile exhaustion and shock, while catecholamines and ventilation alter measurements. Refractory hyperlactatemia in an at-risk patient should prompt thiamine administration without waiting for a perfect hemodynamic pattern.

Contemporary settings include prolonged vomiting, hyperemesis gravidarum, anorexia or ARFID, cancer, dialysis, diarrhea, AIDS, bariatric surgery and parenteral nutrition without multivitamins. Loop diuretics may increase urinary excretion, but the clinical magnitude of their contribution varies and does not justify an automatic diagnosis. In harmful alcohol use, poor intake, reduced absorption and impaired hepatic storage coexist with direct myocardial toxicity, which may contribute to a distinct but overlapping alcoholic cardiomyopathy.

Neuropathy, confusion, ataxia or ocular abnormalities strengthen suspicion, but the didactic separation among dry beriberi, wet beriberi and Wernicke encephalopathy is incomplete. A patient may have only cardiovascular manifestations or a multisystem presentation. Lactate may be normal in nonfulminant beriberi and very high for many other reasons. No single finding has sufficient diagnostic sensitivity to exclude the deficiency.

When thiamine-deficiency cardiomyopathy is suspected, the decisive point remains obtaining an appropriate specimen if immediately available and administering parenteral thiamine at once. In high-risk patients, it precedes glucose loading when possible, but dangerous hypoglycemia must be corrected without delay, with thiamine given concomitantly or immediately afterward. A rapid fall in lactate and hemodynamic improvement support the diagnosis but do not eliminate the need to treat sepsis, ischemia, toxins or other concomitant causes.

Selenium and Keshan disease

Keshan disease is an endemic cardiomyopathy described in a geographic belt of China characterized by selenium-poor soils and foods. Historical community studies and a subsequent meta-analysis showed a marked reduction in incidence with selenite, providing strong causal evidence for depletion in the exposed population. However, Keshan disease is not universally synonymous with isolated selenium deficiency: seasonal distribution, clinical variability and experimental data support the contribution of additional factors.

Interactions with enterovirus strains, oxidative stress, mycotoxins and dietary characteristics have been proposed. The most cautious formulation considers low selenium a fundamental determinant that increases myocardial vulnerability, while other stresses may precipitate necrosis and remodeling. Acute forms cause heart failure and shock; chronic forms may progress with dilation, arrhythmias and heart failure. The multifactorial nature of Keshan disease prevents mechanically applying its model to every patient with low selenium.

In nonendemic countries, reversible cardiomyopathies associated with severe deficiency have been described mainly during prolonged parenteral nutrition, Crohn disease, short bowel syndrome and malabsorptive bariatric bypasses. This evidence consists predominantly of cases and small series in which multiple deficiencies often coexisted. Reversibility after replacement is suggestive but does not prove that selenium was the only cause. Etiologic exclusion and review of the entire nutritional prescription are required.

Plasma or serum selenium partly reflects recent intake and circulating selenoproteins, but decreases during inflammation and may be influenced by albumin, renal function and the analytical method. C-reactive protein should be interpreted together with the measurement; glutathione peroxidase activity and selenoprotein P may add information but are not universally available. A contextualized biomarker is more useful than an isolated threshold.

Supplementation should be dosed according to severity, route, renal function, losses and composition of artificial nutrition, with scheduled reassessment. Selenium has a limited safety window: chronic excess may cause hair and nail fragility, gastrointestinal symptoms, garlic breath, neuropathy and other signs of selenosis. There is no evidence that supplementing selenium-replete individuals generally prevents cardiomyopathy or heart failure. Targeted replacement should not be turned into indiscriminate prevention.

Carnitine: primary deficiency and acquired depletion

Carnitine transports long-chain acyl groups across the inner mitochondrial membrane through the carnitine shuttle and helps maintain the acyl-CoA/CoA ratio. Primary systemic carnitine deficiency is an autosomal recessive disease caused by biallelic variants in SLC22A5, which encodes the OCTN2 transporter. The defect reduces renal reabsorption and cellular uptake, causing extremely low plasma concentrations and muscle depletion. It is not a common dietary deficiency.

The phenotype ranges from hypoketotic hypoglycemia and encephalopathy in infancy to skeletal myopathy, dilated or hypertrophic cardiomyopathy, arrhythmias and sudden death; some adults remain paucisymptomatic. Newborn screening may identify low free carnitine in the infant because of previously unrecognized maternal deficiency. Normal cardiac function at screening does not eliminate future risk without treatment. Variable penetrance requires family metabolic assessment.

Diagnosis integrates free and total carnitine, the acylcarnitine profile, urinary excretion and molecular testing. Markedly low free carnitine with inappropriate renal loss suggests OCTN2 deficiency; confirmation comes from biallelic pathogenic variants and, in unresolved cases, transport studies in fibroblasts. Organic acidemias and fatty-acid oxidation disorders may cause secondary deficiency with specific patterns. The metabolic signature precedes cardiologic attribution.

Treatment of primary deficiency is continuous oral levocarnitine, generally on the order of 100–200 mg/kg/day in divided doses according to GeneReviews, titrated to concentrations and tolerability under metabolic supervision. Muscle and cardiac function may recover if therapy precedes irreversible injury; discontinuation again exposes the patient to heart failure and arrhythmias. Diarrhea, cramps and trimethylamine-related body odor are manageable adverse effects. Permanent replacement therapy distinguishes this disease from transient deficiencies.

Acquired deficiencies occur with severe malnutrition, malabsorption, prematurity, tubular losses, hemodialysis, prolonged parenteral nutrition or drugs that promote excretion of carnitine esters. They are usually less profound, and cardiac involvement is much less consistent than in primary deficiency. Before prescribing high doses, the mechanism and significance of the value should be defined. Evidence does not support levocarnitine as universal heart-failure therapy.

Phosphate, magnesium and other micronutrients

Phosphate is essential for ATP, 2,3-diphosphoglycerate, membranes and signaling. Severe hypophosphatemia can reduce contractility and promote arrhythmias, hemolysis, diaphragmatic weakness and impaired oxygen delivery; clinical studies have documented reversible depression of myocardial performance particularly at the lowest levels. The phenomenon is often acute and metabolic rather than a chronic structural cardiomyopathy. Intracellular depletion may precede the serum nadir after nutrition is started.

Magnesium and potassium modulate membrane potential and electrical stability. Vomiting, diarrhea, diuretics, purging and refeeding can cause a combined decline, increasing ectopy, torsades de pointes and risk of cardiac arrest. Hypomagnesemia often makes potassium correction refractory. These abnormalities explain an arrhythmic presentation or contractile depression, but do not justify calling every event magnesium cardiomyopathy.

Copper participates in cytochrome c oxidase, superoxide dismutase and collagen cross-linking. Human deficiency is well recognized for anemia, neutropenia and myeloneuropathy after malabsorption, bariatric surgery or excess zinc; isolated cardiomyopathy, however, is supported mainly by experimental models and rare reports. Measuring copper and ceruloplasmin makes sense in a coherent context, while accounting for inflammation and cholestasis. The strength of cardiac causality remains lower than for thiamine or selenium.

Vitamin D deficiency is common in obesity, malabsorption, after bariatric surgery and in numerous chronic diseases; status is assessed with 25-hydroxyvitamin D and deficiency should be treated for appropriate bone and mineral indications. Low concentrations observed in heart failure are, however, influenced by adiposity, reduced physical activity, inflammation and renal dysfunction, while supplementation trials have not demonstrated reliable reductions in heart-failure hospitalizations or mortality. Coexisting hypovitaminosis therefore does not justify diagnosing a vitamin D cardiomyopathy or replacing validated cardiovascular therapies with cholecalciferol.

Zinc is essential for numerous enzymes and deficiency frequently accompanies malnutrition and inflammation, but there is no validated human phenotype of zinc-deficiency cardiomyopathy. Low serum values during acute illness do not demonstrate tissue depletion; prolonged high doses may induce copper deficiency. Supplementation should therefore respond to nutritional indications, not presumed cardioprotection. The balance among trace elements makes isolated unmonitored treatments risky.

Cobalt illustrates another important boundary. As a component of cobalamin it is not treated as an autonomous trace element, whereas excessive exposure to cobalt salts caused the historical beer-drinkers' cardiomyopathy and may now arise, rarely, from metal prostheses. This is toxicity, often confounded by alcohol use and malnutrition, not nutritional deficiency. Likewise, ipecac and other emetics can cause toxic cardiomyopathy in eating disorders.

Undernutrition, malabsorption and artificial nutrition

In severe undernutrition, the cardiovascular system reduces expenditure through sinus bradycardia, hypotension, lower stroke volume and reduced ventricular mass. Pericardial effusion, mitral valve prolapse and repolarization abnormalities may accompany anorexia nervosa, but many findings regress with weight recovery. A normal ejection fraction does not exclude low output because the ventricle is small; true reduction requires evaluation for deficiencies, myocarditis, medications or pre-existing disease. The starvation heart is primarily a fragile systemic adaptation.

Self-induced vomiting, laxatives and diuretics add dehydration, alkalosis, hypokalemia and hypomagnesemia. QTc is not invariably prolonged by anorexia itself, but medications and electrolytes may make it dangerous. Syncope, chest pain, extreme bradycardia, hypotension, electrolyte imbalance or signs of heart failure require urgent assessment and an appropriate level of care. Medical stability comes before outpatient nutritional rehabilitation.

Celiac disease, inflammatory bowel disease, pancreatic insufficiency, cholestasis, resections and short bowel reduce absorption with different profiles. Suspicion cannot be exhausted by ordering a standard panel: residual anatomy, site of absorption, steatorrhea, stoma losses and dietary composition must be correlated. A deficiency may persist despite oral supplements if the route is inadequate. Treatment of malabsorption is part of causal cardiac therapy.

After bariatric surgery, persistent vomiting and rapid weight loss make thiamine an emergency, while procedures with a substantial malabsorptive component increase the long-term risk of selenium, copper and other deficiencies. ASMBS guidelines recommend procedure-specific screening, supplementation and follow-up. A patient who develops dyspnea or dysfunction should not be dismissed as deconditioned. Post-bariatric surveillance continues even when the weight outcome appears excellent.

Complete parenteral nutrition should provide vitamins and trace elements daily, adapting them to losses, cholestasis, renal failure and duration. Historical thiamine and selenium deficiencies occurred when preparations or additives were incomplete; today they may recur during commercial shortages, prescribing errors or interruptions. Contamination and excess are the mirror problem. Bag reconciliation verifies the formulation actually infused, not merely the one theoretically prescribed.

Refeeding syndrome

Refeeding syndrome is a complication of caloric resumption after depletion, not an inevitable consequence of nutritional recovery. ASPEN proposes classification according to the percentage reduction in phosphate, potassium or magnesium within five days and considers severe cases those with marked decline or organ dysfunction, including when associated with thiamine deficiency. This definition facilitates surveillance but is not a universally validated gold standard. Clinical risk should be assessed before the first dextrose intake.

Prolonged negligible intake, substantial weight loss, low BMI, alcohol use, eating disorders, cancer, malabsorption and previous low electrolytes increase risk. Intravenous fluids and medications in dextrose also provide carbohydrate and may initiate metabolic transition before nutrition is formally recorded. A normal serum level before feeding does not guarantee adequate stores. Pre-refeeding assessment therefore includes history, examination, balance and the trajectory of laboratory values.

In at-risk patients, ASPEN recommends thiamine before dextrose, monitoring of phosphate, potassium and magnesium, and a cautious caloric start with monitored progression; protocols and rates should be adapted to age, severity, renal and cardiac function. In high-risk patients, electrolytes may require checks every twelve hours during the first three days. Individualized prescribing avoids both excessive slowness, which prolongs malnutrition, and unmonitored progression.

Cardiac manifestations include tachycardia, edema, rapid weight gain, congestion, arrhythmias, hypotension and respiratory failure. Sodium and water expansion can precipitate pulmonary edema even without new myocardial injury, while hypophosphatemia and hypomagnesemia simultaneously impair contractility and rhythm. Treatment corrects electrolytes and thiamine, reduces or temporarily pauses caloric advancement in evolving cases and manages fluids and organ failure. The combined metabolic cause requires coordinated intervention.

Prevention does not consist of indiscriminately administering large amounts of electrolytes. Intravenous phosphate can cause hypocalcemia, calcium-phosphate salt precipitation, hypotension and renal injury; magnesium and potassium become dangerous in renal failure. Even parenteral thiamine, although very safe, requires the ability to manage rare hypersensitivity reactions. Close monitoring makes necessary therapy safe.

Clinical manifestations and hemodynamics

Symptoms are nonspecific: dyspnea, asthenia, edema, palpitations, chest pain, syncope and exercise intolerance. Extracardiac clues suggest etiology, such as neuropathy and confusion in thiamine deficiency, myopathy and hypoketotic hypoglycemia in carnitine deficiency, diarrhea or a stoma in malabsorption, and dermatitis or hematologic abnormalities in multiple deficiencies. Absence of classic signs does not exclude any cause. Multisystem phenotyping increases diagnostic probability.

The high-output profile includes warm extremities, bounding pulse, tachycardia, widened pulse pressure and congestion despite elevated output. Invasive measurement can document a high cardiac index and low resistance when the picture remains uncertain, but therapy and catecholamines rapidly alter the state. In advanced beriberi, output may normalize or decrease. Measurement over time is more informative than a single hemodynamic snapshot.

The low-output profile of undernutrition combines cool skin, hypotension, bradycardia, low pulse pressure and reduced exercise capacity, often without primary congestion. Shoshin beriberi, although arising from a different metabolic mechanism, may culminate in tachycardic low output with lactate elevation and organ injury. Sepsis, adrenal insufficiency, pulmonary embolism, tamponade and ischemic cardiogenic shock must be treated in parallel until excluded. Time to therapy does not allow serial diagnostic waiting.

Arrhythmias more often result from electrolytes, medications, QT prolongation or an underlying cardiomyopathic substrate than from the name of the deficiency. Atrial fibrillation may accompany dilation and congestion; ventricular tachycardias and torsades de pointes require immediate correction of potassium and magnesium and withdrawal of implicated medications. An electrical phenotype without severe dysfunction has also been described in primary carnitine deficiency. Rhythm management proceeds simultaneously with nutritional diagnosis.

Biochemical diagnosis and causal pathway

History should quantify intake, composition, supplements, alcohol, vomiting, diarrhea, weight loss, digestive procedures, enteral or parenteral nutrition, medications and food access. The timing between exposure and symptoms should be reconstructed and product formulations verified. A recent food diary does not necessarily represent months of depletion. Nutritional chronology determines which tests to order and how to interpret the result.

Whole blood thiamine diphosphate measured by chromatography or mass spectrometry is generally the most useful direct biomarker; plasma thiamine is more sensitive to recent intake. Erythrocyte transketolase activity is a historical functional test, now less available and influenced by analytical variables. The specimen should be collected before treatment if this can be done immediately, protected and handled according to laboratory requirements. Urgent empirical therapy should not be delayed by sampling.

For selenium, the specimen and laboratory reference interval, C-reactive protein, albumin and renal function are needed. A very low level in a patient with short bowel and trace-element-free nutrition differs from a modest reduction during sepsis. Similar acute-phase interferences apply to copper and zinc, and ceruloplasmin increases with inflammation and estrogens. Preanalytical quality includes appropriate tubes and avoidance of trace-element contamination.

When primary carnitine deficiency is suspected, free, acylated and total carnitine are measured together with the acylcarnitine profile, glucose, ketones, ammonia, transaminases and CK. Urinary loss and the reabsorption fraction help distinguish OCTN2 deficiency from poor intake. Genetic testing of SLC22A5 confirms most cases and guides family cascade testing. Metabolic counseling is necessary before interpreting an uncertain variant.

The acute panel includes complete blood count, sodium, potassium, magnesium, phosphate, ionized calcium, creatinine, transaminases, albumin, glucose, blood gas analysis, lactate, troponin and natriuretic peptides. The values are nonspecific: BNP may rise with high-output congestion and troponin with shock; albumin is a negative acute-phase reactant, not an isolated measure of nutritional status. Integrated interpretation distinguishes hemodynamic consequence, depletion and inflammation.

Causal diagnosis becomes convincing when there is a strong risk context, a deficiency measured with an appropriate method, a biologically compatible phenotype, improvement within a compatible time frame, and no better alternative explanation. Response is not always immediate: lactate and thiamine-related vasodilation may change within hours, whereas recovery of mass and function requires weeks or months. Failure to recover requires reassessment of adherence, absorption and diagnosis. Differential reversibility is part of the reasoning process, not absolute retrospective proof.

Imaging and differential diagnosis

Echocardiography measures dimensions, mass, ejection fraction, right ventricular function, valves, effusion and estimated pressures. In beriberi it may show hyperdynamic function, dilation or biventricular dysfunction; in selenium deficiency the dilated phenotype predominates, while primary carnitine deficiency can produce dilated or hypertrophic phenotypes; undernutrition often shows small chambers and reduced mass. No finding is pathognomonic. Echocardiographic discordance between severe shock and modest structural abnormalities may suggest a metabolic-vascular component.

Cardiac magnetic resonance quantifies volumes and function and assesses edema, fibrosis, infiltration or patterns compatible with myocarditis and genetic cardiomyopathies. Late gadolinium enhancement does not identify a specific deficiency; absence of scar may support potential reversibility but does not prove a nutritional etiology. In unstable patients, CMR follows treatment and stabilization. Tissue characterization serves mainly to exclude competing substrates.

Coronary artery disease, valvular disease, tachycardia-induced cardiomyopathy, myocarditis, sepsis, thyrotoxicosis, pheochromocytoma, severe anemia and arteriovenous fistula can mimic parts of the presentation. In young patients with unexplained dysfunction, mitochondrial cardiomyopathies and other inherited metabolic diseases should be considered; these are not simple dietary deficiencies. Identification of a low vitamin level does not end the workup. A phenotype-guided differential diagnosis prevents delays in identifying other treatable causes.

Endomyocardial biopsy does not usually diagnose a deficiency, and reported findings are nonspecific, such as degeneration, edema, necrosis or fibrosis. It is reserved for conventional scenarios in which a histologic diagnosis may alter treatment, for example certain fulminant myocarditides or infiltrative diseases. Tissue trace-element analysis is not standard either. The biochemical-clinical evidence remains central.

Treatment, safety and prognosis

When severe cardiac beriberi is suspected, parenteral thiamine is administered immediately, before glucose when possible or concomitantly if hypoglycemia requires immediate correction, together with support of vital functions. Published regimens vary with severity and concurrent neurologic risk; no single cardiologic dose has been validated in trials. High initial doses are commonly used in fulminant presentations, followed by daily and then oral therapy, while also correcting magnesium required for enzymatic activation. The variability of protocols does not justify delay or underdosing in shock.

Heart failure is treated according to congestion, blood pressure and output, but the physiology requires caution. Vasodilators may worsen already vasoplegic beriberi, whereas repeated fluid loading aggravates edema and dilation; diuretics are useful for congestion but may worsen electrolyte abnormalities and depletion. Vasopressors and inotropes serve as a bridge until causal correction. Titrated hemodynamic support is based on ultrasound, perfusion and serial response.

Selenium is replaced when deficiency is documented or highly probable, choosing the oral or parenteral route according to absorption and urgency. The dose should not be extrapolated from Keshan prevention campaigns and requires monitoring to avoid accumulation, particularly with renal failure or changes in artificial nutrition. A multinutrient formulation may be necessary but makes it more difficult to attribute the response. A reassessment plan should be written before the first dose.

In primary carnitine deficiency, levocarnitine is lifesaving and should not be stopped when the patient improves; fasting and catabolism require an emergency plan with carbohydrate provision and metabolic supervision. In acquired depletion, the cause is corrected and supplementation provided when levels, symptoms and risk justify it. In the absence of deficiency, products containing carnitine or coenzymes do not replace evidence-based cardiomyopathy therapy. Precision of indication protects against cost, adverse effects and false reassurance.

Nutritional recovery is managed by a team integrating cardiology, clinical nutrition, gastroenterology or metabolic medicine and, when necessary, psychiatry. Caloric, protein and micronutrient targets are progressively adapted to refeeding risk, renal function, congestion and absorptive capacity. Daily weight during the acute phase does not by itself distinguish rebuilt tissue from water. Longitudinal body composition and physical function complete the assessment.

Follow-up includes symptoms, examination, weight and muscle trajectory, electrolytes, specific biomarkers, ECG and echocardiography. Frequency depends on the condition: close during refeeding, periodic during parenteral nutrition and lifelong in primary carnitine deficiency. Improvement in ejection fraction does not prove complete normalization of risk if fibrosis or arrhythmias persist. Documentation of recovery also requires stability after correction of the cause.

Prognosis is excellent in many forms treated early, but prolonged shock, necrosis, multiple deficiencies and concomitant myocardial disease may leave residual dysfunction. A dramatic response to thiamine or selenium should not lead to discontinuing investigation of the cause of depletion, otherwise recurrence remains likely. Prevention means ensuring adequate diet, follow-up after surgery, complete composition of artificial nutrition and stable access to care. Correction of vulnerability is as important as cardiac recovery.

Empirical supplementation has precise limits. Urgent thiamine in a compatible presentation has an exceptionally favorable benefit-risk ratio; selenium, copper, zinc, phosphate and carnitine instead require more selective indications, dosing and monitoring. Interactions, contamination, renal failure and nonstandardized products can turn a supplement into a problem. The medicine of nutritional cardiomyopathy does not consist of giving more micronutrients, but of practicing targeted etiologic replacement and verifying that the causal mechanism has truly been removed.