Toxic cardiomyopathies are cardiomyopathies in which structural and functional myocardial damage results from exposure to exogenous or endogenous substances capable of directly altering the cardiomyocyte, microcirculation, energy metabolism, neurohormonal system, electrical conduction or extracellular matrix. The term includes very different conditions: ventricular dysfunction from cancer therapies, alcoholic cardiomyopathy, stimulant-associated cardiomyopathy, damage from anabolic androgenic steroids, metal toxicity, cardiomyopathies caused by antimalarial agents, by some psychotropic medications, by immunomodulatory agents, by industrial substances or by environmental exposures. The common feature is not the morphological phenotype, but the causal relationship between toxic exposure and myocardial disease.
This category requires a particularly rigorous diagnosis because many patients have concurrent risk factors: hypertension, ischemic heart disease, diabetes, kidney disease, tachyarrhythmias, infections, genetic predisposition, multiple cancer treatments, malnutrition, alcohol consumption, occupational exposures or stimulant substance use. Toxic cardiomyopathy must not be diagnosed simply because the patient has been exposed to a potentially cardiotoxic substance; it is necessary to demonstrate temporal compatibility, biological plausibility, a coherent phenotype, exclusion of relevant alternative causes and, when possible, improvement after withdrawal or reduction of the exposure. At the same time, early recognition is decisive, because many forms are at least partially reversible if the causal agent is eliminated before fibrosis, apoptosis, necrosis, remodeling and advanced heart failure become dominant.
The epidemiology is heterogeneous and depends on the type of exposure. Cancer therapy-related toxicity is increasingly relevant because of improved survival among patients with malignancy and because of the use of anthracyclines, anti-HER2 therapies, tyrosine kinase inhibitors, proteasome inhibitors, immunotherapies and thoracic radiotherapy. Alcoholic cardiomyopathy accounts for a significant proportion of non-ischemic dilated cardiomyopathies in settings of chronic heavy alcohol consumption. Cardiomyopathies caused by cocaine, methamphetamine and anabolic androgenic steroids often affect younger individuals, with a risk of arrhythmias, hypertension, ischemia, heart failure and sudden death. Cardiomyopathies caused by metals, antimalarial agents or environmental toxins are rarer, but clinically important because they may be underdiagnosed and because removal of the toxic source can modify prognosis.
The etiological causes of toxic cardiomyopathies must be organized according to the nature of the exposure and the predominant mechanism of injury. Cancer therapies are the most extensively studied group. Anthracyclines, such as doxorubicin, daunorubicin, epirubicin and idarubicin, can cause dose-dependent ventricular dysfunction mediated by oxidative stress, mitochondrial damage, alteration of topoisomerase II beta in the cardiomyocyte, dysfunction of the sarcoplasmic reticulum, apoptosis and progressive loss of contractile cells. Toxicity may appear during treatment, in the following months or even years later, especially in subjects exposed during childhood, in women, in older adults, in patients with cardiovascular risk factors, previous heart disease, mediastinal radiotherapy or cardiotoxic treatment combinations.
Anti-HER2 therapies, particularly trastuzumab and other agents directed against human epidermal growth factor receptor 2 (HER2), can cause ventricular dysfunction by interfering with neuregulin-HER2-dependent myocardial survival pathways. Unlike anthracyclines, the damage is often less related to irreversible cell necrosis and may recover after withdrawal and cardiological therapy, but the risk increases when the patient has received anthracyclines or has cardiovascular vulnerability. Tyrosine kinase inhibitors may cause hypertension, ventricular dysfunction, ischemia, corrected QT interval (QTc) prolongation, thrombosis or microangiopathy according to the molecular target. Proteasome inhibitors, particularly carfilzomib, may be associated with heart failure, hypertension, ischemia and endothelial dysfunction. Immune checkpoint inhibitors may cause immune-mediated myocarditis, which is rare but potentially fulminant, with arrhythmias, conduction blocks and shock.
Ethyl alcohol is a classic cause of non-ischemic toxic cardiomyopathy. Damage depends on chronic heavy consumption, duration of exposure, genetic susceptibility, sex, nutritional status, vitamin deficiencies, coexposure to tobacco or other substances, hypertension and liver disease. Ethanol and its metabolite acetaldehyde alter protein synthesis, mitochondrial function, fatty acid oxidation, calcium homeostasis, oxidative stress, apoptosis and sarcomere structure. The typical result is dilated cardiomyopathy with reduced contractility, ventricular dilatation, functional mitral regurgitation, arrhythmias and heart failure. Alcohol toxicity may be worsened by thiamine, magnesium and other micronutrient deficiencies, but it cannot be reduced to a simple nutritional deficiency.
Sympathomimetic stimulants, such as cocaine, methamphetamine and related substances, damage the heart through multiple pathways. Cocaine blocks catecholamine reuptake, increases sympathetic tone, heart rate, blood pressure and oxygen demand, induces coronary vasoconstriction, endothelial dysfunction, thrombosis, ischemia, myocarditis, arrhythmias and hypertrophy. Methamphetamine increases release and reduces reuptake of dopamine, norepinephrine and serotonin, producing prolonged catecholaminergic stimulation, hypertension, tachycardia, hyperthermia, vasospasm, oxidative stress, mitochondrial damage, inflammation and fibrosis. The phenotype may be dilated, hypertrophic, ischemic, arrhythmic or mixed. The central pathophysiological point is that the myocardium is repeatedly exposed to adrenergic crises, microvascular ischemia and direct toxicity.
Anabolic androgenic steroids can produce cardiomyopathy through pathological myocardial hypertrophy, fibrosis, diastolic dysfunction, systolic dysfunction, hypertension, dyslipidemia, thrombosis, endothelial damage and electrical remodeling. The typical phenotype may mimic athletic adaptation, but if excessive wall thickness, dilated cavities, reduced strain, fibrosis, arrhythmias, hypertension or heart failure coexist, the condition becomes pathological. Distinction from physiological athlete’s heart is essential: in athletic adaptation, function, reserve, regression with detraining and absence of fibrosis support a benign interpretation; in chronic anabolic steroid exposure, myocardial growth may become disorganized, fibrotic and proarrhythmic.
Some metals and environmental toxins can cause cardiomyopathy. Cobalt is the modern paradigm, historically associated with beer drinkers’ cardiomyopathy in specific industrial contexts and more recently described in patients with metal-on-metal hip prostheses or corrosion of prosthetic components. Cobalt toxicity can produce dilated or restrictive cardiomyopathy, hypothyroidism, neuropathy, visual disturbances, hearing loss, polycythemia and systemic symptoms. The mechanism includes mitochondrial damage, oxidative stress, interference with cellular enzymes, alteration of thyroid metabolism and direct cardiomyocyte toxicity. Arsenic, lead, mercury, carbon monoxide and solvents can also contribute to cardiovascular damage, with mechanisms varying among hypoxia, oxidative stress, endothelial dysfunction, hypertension, arrhythmias and myocardial injury.
Antimalarial agents such as chloroquine and hydroxychloroquine can rarely cause cardiomyopathy due to acquired lysosomal storage. The damage derives from interference with lysosomal function, accumulation of autophagic and phospholipid material, cardiomyocyte vacuolization and characteristic ultrastructural alterations. The phenotype may be hypertrophic, restrictive, dilated or mixed, often associated with conduction disturbances, atrioventricular blocks, bundle branch blocks, arrhythmias, heart failure and sometimes skeletal muscle involvement. The risk increases with prolonged exposure, high cumulative dose, kidney failure, older age and concomitant use of other medications that alter conduction or QTc.
Other non-oncological medicines can damage the heart directly or indirectly. Some antipsychotics and antidepressants may promote arrhythmias, QTc prolongation, myocarditis, cardiomyopathy or heart failure through autonomic, metabolic, inflammatory or ionic effects. Clozapine is classically associated with early myocarditis and, more rarely, late cardiomyopathy. Some older antiretrovirals, particularly older nucleoside analogues, have been associated with mitochondrial toxicity. Some immunomodulatory and anti-inflammatory agents may worsen heart failure through salt and water retention, hypertension or direct toxicity. Lithium, digoxin and other medicines mainly produce electrical toxicity, but in vulnerable patients persistent arrhythmia or bradyarrhythmia may precipitate tachycardia-induced or low-output cardiomyopathy.
The pathogenetic mechanisms can be grouped into several common pathways. The first is mitochondrial damage, present with anthracyclines, alcohol, methamphetamine, antimalarial agents, some antiretrovirals and metals. The cardiomyocyte loses energetic efficiency, produces more reactive oxygen species, manages calcium and membrane potential less effectively, activates apoptosis or necrosis and develops contractile dysfunction. The second is oxidative stress, in which free radicals and lipid peroxidation damage membranes, sarcomeres, DNA, sarcoplasmic reticulum and mitochondria. The third is adrenergic neurotoxicity, typical of stimulants and catecholaminergic states, which produces tachycardia, hypertension, vasospasm, calcium toxicity and remodeling.
The fourth pathway is endothelial and microvascular toxicity. Fluoropyrimidines, cocaine, methamphetamine, radiotherapy, inhibitors of vascular endothelial growth factor (VEGF) and metals can alter vasodilation, promote vasospasm, hypertension, thrombosis or microvascular ischemia. The fifth pathway is immune-mediated inflammation, particularly important in myocarditis caused by immune checkpoint inhibitors and in some hypersensitivity reactions. The sixth is intracellular accumulation, as in hydroxychloroquine- or chloroquine-induced cardiomyopathy. The seventh is indirect hemodynamic remodeling, in which a substance causes hypertension, tachyarrhythmia, valvular disease, ischemia or endocrine alterations that secondarily produce cardiomyopathy.
The final pathophysiology depends on the predominant mechanism. Diffuse cellular damage produces dilated cardiomyopathy with reduced left ventricular ejection fraction (LVEF). Lysosomal accumulation or toxic hypertrophy produces a hypertrophic or restrictive phenotype. Coronary vasoconstriction and thrombosis produce ischemic necrosis and scar. Inflammation produces myocarditis and arrhythmias. Electrical toxicity produces tachycardias, bradyarrhythmias, torsades de pointes and secondary cardiomyopathy. In many patients, several mechanisms coexist: a subject who consumes alcohol, cocaine and anabolic steroids may simultaneously present myocyte toxicity, hypertension, ischemia, arrhythmias and fibrosis.
The logical sequence of toxic damage can be described as follows: a cardiotoxic substance reaches the myocardium or alters the cardiovascular system; the cardiomyocyte undergoes energetic, oxidative, adrenergic, immunological, microvascular or lysosomal stress; contractile or electrical function declines; the ventricle activates compensatory responses such as hypertrophy, dilatation, tachycardia and neurohormonal systems; if exposure continues, fibrosis, cell loss, remodeling and heart failure develop; if exposure is interrupted early, part of the damage may regress. Reversibility is therefore inversely proportional to duration of exposure, toxic load, fibrosis and severity of remodeling.
The clinical presentation of toxic cardiomyopathies is variable and depends on the substance, dose, duration, individual vulnerability, comorbidities and dominant mechanism. The history must be much more detailed than in a generic non-ischemic cardiomyopathy. It is necessary to reconstruct previous or ongoing cancer treatments, thoracic radiotherapy, alcohol consumption, stimulant use, exposure to anabolic androgenic steroids, supplements purchased outside controlled channels, chronic antimalarial therapy, antipsychotics, antidepressants, antiretrovirals, immunomodulators, previous chemotherapy, occupational substances, metals, metal-on-metal orthopedic prostheses, industrial exposures and environmental intoxications. The question must be explicit, non-judgmental and repeated in a clinically useful way, because many exposures are not reported spontaneously.
The most frequent symptom is exertional dyspnea, reflecting reduced ventricular reserve, increased filling pressures, diastolic dysfunction, pulmonary hypertension or ischemia. It may be progressive, as in alcoholic cardiomyopathy or late anthracycline toxicity, or acute, as in immunotherapy-related myocarditis, stimulant toxicity or heart failure during cancer treatment. Orthopnea, paroxysmal nocturnal dyspnea, dependent edema, weight gain and reduced exercise tolerance indicate congestive heart failure. In patients with malignancy, these symptoms may be confused with anemia, deconditioning, infection, pulmonary toxicity or cancer progression, so cardiological assessment must be proactive.
Palpitations are common and may reflect atrial fibrillation, ectopy, ventricular tachycardias, adrenergic sinus tachycardia, QTc prolongation or conduction disturbances. Cocaine, methamphetamine, antidepressants, antipsychotics, antimalarial agents, alcohol and some cancer therapies can promote electrical instability. Syncope is a warning sign because it may depend on ventricular tachycardia, torsades de pointes, atrioventricular block, hypotension, ischemia or pulmonary embolism. In a patient exposed to hydroxychloroquine or chloroquine for years, syncope and conduction blocks should raise suspicion of lysosomal cardiotoxicity; in a patient using stimulants, syncope and chest pain should also suggest ischemia, vasospasm and malignant arrhythmias.
Chest pain may derive from coronary ischemia, vasospasm, myocarditis, pericarditis, severe hypertension, aortic dissection, pulmonary embolism or increased myocardial demand. Cocaine is associated with vasoconstriction, thrombosis, infarction, arrhythmias and dissection; methamphetamine with vasospasm, hypertension and ischemia; fluoropyrimidines with coronary vasospasm and ischemia; immune checkpoint inhibitors with myocarditis that may mimic infarction. Chest pain in a patient exposed to cardiotoxic substances must not be automatically attributed to cardiomyopathy: it must be managed as a possible coronary, myocarditic or aortic emergency.
Alcoholic cardiomyopathy typically presents with a chronic dilated pattern. The patient may report years of heavy consumption, progressive reduction in functional capacity, edema, dyspnea, palpitations, episodes of atrial fibrillation, hypertension, sleep disturbances, malnutrition, neuropathy, liver disease or pancreatitis. Physical examination may show tachycardia, irregular rhythm, third heart sound, functional murmurs, crackles, hepatomegaly, ascites, edema, tremor, signs of liver disease or nutritional deficiencies. Alcohol can also cause acute arrhythmias after episodic heavy intake, without advanced structural cardiomyopathy; distinguishing acute arrhythmia from chronic cardiomyopathy is part of the assessment.
Anthracycline- or cancer therapy-related toxicity may initially be asymptomatic. LVEF may decrease before dyspnea appears, and global longitudinal strain (GLS) may worsen before LVEF. The patient may report only fatigue, reduced exertional capacity or tachycardia, symptoms easily overlapping with the effects of malignancy and its treatments. When orthopnea, pulmonary edema, hypotension or overt heart failure appear, damage may already be more advanced. For this reason, cardio-oncology emphasizes baseline and serial surveillance in patients at risk, not late diagnosis based on symptoms.
Stimulant-associated cardiomyopathies often affect younger patients and may present with severe heart failure, hypertension, tachycardia, chest pain, agitation, hyperthermia, stroke, dissection, arrhythmias or cardiac arrest. Methamphetamine can produce severe dilated cardiomyopathy with intracardiac thrombi and pulmonary hypertension; cocaine may alternate acute ischemia, myocarditis, fibrosis and chronic dysfunction. The history may be difficult because the patient may minimize or deny the exposure. Signs such as mydriasis, hypertension, tachycardia, agitation, weight loss, skin lesions, psychiatric disturbances or a history of repeated emergency department visits may guide suspicion.
Anabolic androgenic steroids should be suspected in subjects who practice bodybuilding, strength sports or physical enhancement programs, especially if they present with hypertension, acne, androgenetic alopecia, gynecomastia, infertility, testicular atrophy, mood changes, dyslipidemia, polycythemia or disproportionate muscle growth. Cardiac presentation may include ventricular hypertrophy, diastolic dysfunction, reduced LVEF, arrhythmias, ischemia, thrombosis or heart failure. The patient may appear athletic and young, but have a heart with fibrosis and reduced functional reserve.
Cobalt toxicity should be considered in patients with metal-on-metal hip prostheses, prosthesis revision, joint pain or noise, metallosis, elevated cobalt levels, hearing loss, visual disturbances, neuropathy, hypothyroidism, polycythemia or systemic symptoms associated with unexplained cardiomyopathy. The condition may be progressive and confused with idiopathic cardiomyopathy. The key is to connect the heart and orthopedic history, because the patient rarely associates a hip prosthesis with heart failure.
Hydroxychloroquine or chloroquine toxicity often presents after long exposure. Symptoms include dyspnea, edema, syncope, palpitations, conduction blocks, muscle weakness and, sometimes, retinopathy or myopathy. Echocardiography may show hypertrophy, a restrictive phenotype or dysfunction; electrocardiogram (ECG) may show blocks and conduction abnormalities. Diagnosis is often delayed because the treatment is perceived as relatively safe and because the phenotype may mimic amyloidosis, Fabry disease or hypertrophic cardiomyopathy. Duration of exposure is a fundamental clinical clue.
Physical examination must look for signs of heart failure, but also traces of systemic toxicity. In patients with malignancy, nutritional status, anemia, infections, effusions and signs of thrombosis are assessed. In patients with alcohol exposure, liver disease, neuropathy, nutritional deficiencies and hypertension are sought. In patients using stimulants, adrenergic signs, skin lesions, hyperthermia, hypertension and altered mental status are sought. In patients with metal exposure, neuropathy, sensory disturbances, thyroid abnormalities and prostheses are assessed. In patients taking antimalarial agents, myopathy, retinopathy and conduction disturbances are sought. The examination must therefore be toxicological as well as cardiological.
The diagnosis of toxic cardiomyopathy requires a rational sequence: identifying the cardiac phenotype, documenting the exposure, establishing temporal and biological plausibility, excluding alternative causes, assessing reversibility and defining risk. There are no universal diagnostic criteria valid for all toxic cardiomyopathies, because the mechanisms differ. Cardio-oncology guidelines provide detailed operational definitions for cardiovascular dysfunction related to cancer treatments, whereas for alcohol, stimulants, metals, antimalarial agents and other exposures the diagnosis remains clinical and instrumental, supported by imaging, laboratory testing, toxicology, history and response to withdrawal.
The first level includes detailed toxicological history, physical examination, 12-lead electrocardiogram (ECG), transthoracic echocardiography, troponin, B-type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP), complete blood count, creatinine, electrolytes, liver function, blood glucose, glycated hemoglobin, lipid profile, thyroid function, ferritin and transferrin saturation when indicated, screening for infections or myocarditis if the presentation suggests it, targeted toxicological tests when useful and ischemic assessment according to age, symptoms and risk. The ECG may show tachycardia, atrial fibrillation, long QTc, blocks, hypertrophy, ischemia or arrhythmias. Echocardiography must measure LVEF, volumes, GLS, diastolic function, right ventricle, pulmonary pressures, valves and thrombi.
Cardiac magnetic resonance (CMR) is the most useful second-level examination when the phenotype is unclear, when the aim is to distinguish myocarditis, ischemia, infiltration, accumulation, fibrosis or non-ischemic cardiomyopathy, or when echocardiography is insufficient. CMR can show dilatation, hypertrophy, edema, fibrosis, late gadolinium enhancement (LGE), ischemic or non-ischemic patterns, infiltration, thrombi and right ventricular function. In anthracycline toxicity it can document remodeling and fibrosis; in immunotherapy-related myocarditis, edema and LGE; in antimalarial toxicity, hypertrophy and an accumulation pattern; in methamphetamine exposure, fibrosis and dilatation; in alcoholic cardiomyopathy, a pattern of non-ischemic dilated cardiomyopathy. The value of CMR is greater when the differential diagnosis is broad.
Coronary assessment is necessary when the presentation may be ischemic. Chest pain, elevated troponin, ST-T abnormalities, risk factors, exposure to cocaine, methamphetamine, fluoropyrimidines or thoracic radiotherapy should prompt consideration of coronary computed tomography or coronary angiography according to clinical probability and urgency. The diagnosis of toxic cardiomyopathy must not lead to ignoring coronary artery disease, vasospasm, thrombosis or infarction. In particular, cocaine and methamphetamine can produce both chronic cardiomyopathy and acute coronary syndrome; the two conditions may coexist.
For patients exposed to cancer therapies, the European Society of Cardiology (ESC) cardio-oncology guidelines define cancer therapy-related cardiovascular toxicity on the basis of symptoms, changes in LVEF, GLS and biomarkers. Risk must be assessed before therapy, considering age, pre-existing heart disease, risk factors, type of malignancy, therapeutic regimen, cumulative anthracycline dose, thoracic radiotherapy, combinations and baseline biomarkers. During treatment, echocardiography, GLS, troponin and natriuretic peptides are used according to risk to identify subclinical damage before overt heart failure.
cardio-oncology operational definition of cancer therapy-related dysfunction
For alcoholic cardiomyopathy, in the absence of universal official diagnostic criteria, according to the clinical literature diagnosis requires documenting non-ischemic dilated cardiomyopathy in a patient with chronic heavy alcohol consumption and absence of a sufficient alternative cause. Quantification must be precise, including grams per day, duration in years, pattern of consumption, episodes of heavy intake, periods of abstinence, liver comorbidity and nutrition. Echocardiography usually shows ventricular dilatation and reduced LVEF; CMR helps exclude ischemia, myocarditis, infiltration or another cardiomyopathy. Improvement after abstinence supports the diagnosis, but it must not be awaited before starting treatment.
For stimulants and anabolic androgenic steroids, diagnosis requires a specific history and often targeted toxicological tests. Urine tests can document recent exposure to cocaine or amphetamines, but do not always clarify chronic exposure or synthetic substances. For anabolic steroids, history, clinical signs, endocrine profile and, when necessary, specialist testing can support suspicion. Imaging must distinguish dilated cardiomyopathy, pathological hypertrophy, ischemia, myocarditis, thrombi, pulmonary hypertension and fibrosis. The diagnosis is more robust if function improves after cessation of exposure, but some forms remain persistent.
For metal toxicity, diagnosis requires a link between exposure and the clinical picture. When cobalt from a prosthesis is suspected, orthopedic history, type of implant, hip pain or dysfunction, prosthesis imaging, blood cobalt and chromium levels, thyroid function, neurology, audiology, ophthalmology and cardiology are assessed. The mere presence of a prosthesis is not enough, but unexplained cardiomyopathy with elevated levels and systemic symptoms makes the suspicion strong. For other metals or industrial exposures, occupational history, occupational medicine and clinical toxicology are needed.
For hydroxychloroquine and chloroquine, diagnosis is based on prolonged exposure, compatible phenotype, conduction disturbances, suggestive imaging and exclusion of infiltrative or storage diseases. Endomyocardial biopsy can be decisive in uncertain cases, showing myocyte vacuolization, lamellar inclusions and curvilinear bodies on ultrastructural examination. However, biopsy is not necessary in every case if clinical probability is high and the therapeutic decision is clear. Early withdrawal is essential because reversibility is variable and conduction disturbances may persist.
The differential diagnosis includes ischemic cardiomyopathy, genetic dilated cardiomyopathy, viral or autoimmune myocarditis, tachycardia-induced cardiomyopathy, hypertensive cardiomyopathy, valvular cardiomyopathy, amyloidosis, Fabry disease, hemochromatosis, cardiac sarcoidosis, thyrotoxicosis, hypothyroidism, thiamine deficiency, peripartum cardiomyopathy, inflammatory cardiomyopathies and mitochondrial diseases. A patient exposed to a toxic substance may still have latent genetic cardiomyopathy unmasked by toxic stress. For this reason, genetic counseling should also be considered in familial, early-onset, severe or non-reversible cases.
Rhythm monitoring is essential when palpitations, syncope, long QTc, proarrhythmic substances, antimalarial agents, antipsychotics, stimulants, alcohol or fibrosis are present. Holter ECG, prolonged monitoring or loop recorder can document atrial fibrillation, ventricular tachycardias, pauses, blocks or ectopic burden. In patients with stimulant- or methamphetamine-associated cardiomyopathy, intracardiac thrombi must be sought, because severe dilatation and low LVEF increase embolic risk. In patients with cancer therapy-related toxicity, ventricular dysfunction, myocarditis, ischemia, hypertension and arrhythmias must be distinguished, because each mechanism requires a specific pathway.
The treatment of toxic cardiomyopathies is based on a non-negotiable principle: removing or reducing the causal exposure whenever possible. No heart failure therapy can stably compensate for ongoing toxicity. This principle must be applied with clinical judgment: in alcohol and stimulants it means complete cessation; in anabolic androgenic steroids, withdrawal; in metals, removal or revision of the source when indicated; in antimalarial agents, withdrawal and therapeutic substitution; in cancer therapies, balancing cancer control and cardiac risk through shared decision-making between cardiology and oncology. Cardiological treatment supports recovery, but etiological therapy is interruption of the injury.
When heart failure with reduced LVEF is present, validated heart failure therapies are used: angiotensin receptor-neprilysin inhibitor (ARNI), angiotensin-converting enzyme inhibitor (ACE inhibitor) or angiotensin receptor blocker, beta-blocker, mineralocorticoid receptor antagonist, sodium-glucose cotransporter 2 (SGLT2) inhibitor, diuretics for congestion, correction of iron deficiency, blood pressure control, diabetes management, cardiac rehabilitation and treatment of comorbidities. Titration must be personalized because some patients have hypotension, cancer cachexia, alcoholic liver disease, kidney failure, dehydration, arrhythmias or medication interactions. Therapy should be started early when dysfunction is documented, not only when advanced heart failure appears.
In cancer therapy-related toxicity, management depends on severity of dysfunction, symptoms, type of anticancer therapy, risk of cancer progression and available alternatives. The ESC guidelines recommend baseline risk assessment, surveillance with echocardiography, GLS and biomarkers in appropriate patients, and early treatment of dysfunction with heart failure medications. For high-risk anthracycline therapy, prevention strategies such as control of risk factors, liposomal formulations, dexrazoxane in selected contexts and reduction of cumulative exposure may be considered. For anti-HER2 therapies, temporary interruption and restart after recovery may be possible in selected cases, under close surveillance. For immunotherapy-related myocarditis, withdrawal of immunotherapy, high-dose corticosteroids and specialist immunosuppression in refractory cases are required.
In alcoholic cardiomyopathy, complete abstinence is the most important prognostic measure. Reduction of consumption may not be sufficient in patients with established cardiomyopathy, because even persistent exposure can maintain myocardial damage, arrhythmias and hypertension. Abstinence can improve LVEF, symptoms and survival, especially if started before fibrosis and advanced heart failure. Treatment must include heart failure therapy, support for alcohol use disorder, nutrition, thiamine when indicated, electrolyte correction, treatment of hypertension, management of atrial fibrillation and liver involvement. Dependence must be treated as part of cardiological therapy, not as a separate problem.
In stimulant-associated cardiomyopathies, cessation of cocaine, methamphetamine or other substances is indispensable. LVEF may improve significantly after abstinence, especially if fibrosis is not extensive, but recovery is not guaranteed. Treatment includes heart failure therapy, blood pressure control, arrhythmia management, anticoagulation if thrombus or a specific indication is present, ischemic assessment, psychiatric support and dependence programs. In acute presentations with hypertension, chest pain, agitation or ischemia, therapy must manage vasospasm, adrenergic demand, temperature, electrolytes and arrhythmic risk. Follow-up must be realistic: relapse of use is a cardiac toxic relapse.
In anabolic androgenic steroid-associated cardiomyopathy, withdrawal is the first intervention. Ventricular function may improve, but hypertrophy, fibrosis, diastolic dysfunction or endocrine alterations may persist. Treatment includes heart failure therapy, blood pressure control, correction of dyslipidemia, management of polycythemia if present, endocrine assessment of the hypothalamic-pituitary-gonadal axis, psychological support and rhythm monitoring. In athletic subjects, safe return to activity must be distinguished from the risk of arrhythmias or heart failure; aesthetic or performance normalization does not coincide with cardiac recovery.
In cobalt toxicity, therapy requires removal of the source when indicated, often revision of the responsible prosthesis, together with heart failure treatment and management of systemic manifestations. Chelation has a limited role and does not replace removal of the source. Cardiac recovery is variable and depends on duration of exposure, levels, systemic damage and severity of cardiomyopathy. Early diagnosis is decisive because advanced metal-related cardiomyopathy may not fully recover even after levels normalize.
In hydroxychloroquine or chloroquine toxicity, withdrawal is mandatory when suspicion is strong or diagnosis is confirmed, in agreement with the specialist managing the underlying disease. Heart failure, arrhythmias and conduction disturbances are treated. Pacemaker or defibrillator may be necessary in cases of advanced blocks, syncope, tachyarrhythmias or persistent risk. Functional recovery may occur, but is not constant; toxicity recognized late may progress despite withdrawal, especially if lysosomal and fibrotic damage is advanced.
Arrhythmia management follows the type of disturbance. Long QTc requires withdrawal or reduction of QT-prolonging medications, correction of potassium and magnesium, assessment of interactions and monitoring. Atrial fibrillation requires rate or rhythm control and anticoagulation according to risk. Ventricular tachycardias require exclusion of ischemia, correction of toxicity, selected antiarrhythmic medications, ablation or implantable defibrillator according to indications. In patients with reversible substances, the decision on a permanent defibrillator must consider potential recovery after abstinence or withdrawal, but must not leave patients with high immediate risk unprotected.
Prognosis depends on the causal agent, duration of exposure, cumulative dose, fibrosis, LVEF, right ventricle, arrhythmias, ischemia, age, comorbidities and the real possibility of interrupting exposure. More favorable forms are those recognized early, with subclinical reduction in GLS or mild LVEF reduction, without extensive fibrosis and with complete removal of the toxic agent. Unfavorable factors include prolonged exposure, persistent consumption, relapses, advanced dilated cardiomyopathy, extensive LGE, thrombi, pulmonary hypertension, fulminant myocarditis, shock, active malignancy, kidney failure, severe liver disease and poor adherence.
Follow-up must be calibrated to risk. After withdrawal or modification of exposure, echocardiography, GLS, biomarkers and CMR when indicated assess recovery or progression. In patients with malignancy, surveillance continues even after the end of therapy, especially if they have been exposed to anthracyclines or thoracic radiotherapy. In patients with alcohol, stimulant or anabolic steroid exposure, follow-up must include relapse prevention, because the heart may improve and then worsen again. In patients with metal or antimalarial toxicity, surveillance must document the course of function, conduction and systemic toxicity. Clinical recovery must not be declared only because symptoms improve: structural, electrical and biological recovery must be demonstrated.
The complications of toxic cardiomyopathies depend on the mechanism of injury and persistence of exposure. The most frequent is heart failure. In dilated forms caused by alcohol, anthracyclines, methamphetamine or mixed toxicity, the ventricle dilates, LVEF decreases, filling pressures increase and pulmonary congestion, edema, fatigue, hospitalizations and reduced survival appear. Ongoing toxicity fuels remodeling, while early withdrawal may allow reverse remodeling. When fibrosis and cell loss are advanced, recovery becomes incomplete.
Arrhythmias are a cross-cutting complication. Alcohol, cocaine, methamphetamine, antipsychotics, antidepressants, antimalarial agents, cancer therapies, metals and heart failure can promote atrial fibrillation, supraventricular tachycardias, ventricular ectopy, ventricular tachycardia, ventricular fibrillation, torsades de pointes and bradyarrhythmias. The mechanism may be direct electrical, ischemic, fibrotic, adrenergic, metabolic or related to long QTc. Sudden death may occur even before the patient develops overt heart failure, especially in the presence of stimulants, long QTc, myocarditis or fibrosis.
Ischemia and infarction are particularly relevant complications in exposures that cause vasospasm, thrombosis or endothelial damage. Cocaine, methamphetamine, fluoropyrimidines, thoracic radiotherapy and inhibitors of angiogenic pathways can increase ischemic risk through different mechanisms. Ischemia can worsen an already present toxic cardiomyopathy or be the first clinical event. Distinction between toxic myocardial dysfunction and ischemic damage is essential because coronary management can change prognosis.
Immune-mediated myocarditis is a rare but high-mortality complication of cancer immunotherapies. It may present with elevated troponin, chest pain, dyspnea, arrhythmias, conduction blocks, shock or association with myositis and myasthenia. The damage derives from immune activation against shared antigens or altered tolerance mechanisms. Treatment must be rapid because the course may be fulminant. In this scenario, the main complication is not only reduced LVEF, but the combination of inflammatory necrosis and electrical instability.
Restrictive or storage cardiomyopathy may complicate prolonged exposure to antimalarial agents and some toxins. The ventricle becomes thickened, stiff and poorly relaxing, with high filling pressures, dilated atria, congestion and conduction disturbances. Late diagnosis is frequent because the presentation mimics infiltrative diseases. Complications include refractory heart failure, atrioventricular blocks, need for pacemaker and incomplete recovery after withdrawal.
Intracardiac thrombi and embolic events may occur in toxic cardiomyopathies with severely reduced LVEF, dilated ventricle, regional akinesia, atrial fibrillation or methamphetamine exposure. Blood stagnates in the ventricular cavity, especially at the apex, and can form thrombi capable of embolizing to the brain, kidneys, spleen, intestine or limbs. Prevention requires active search for thrombi using echocardiography, contrast or CMR in high-risk patients and anticoagulation when indicated.
Pulmonary hypertension may complicate methamphetamine exposure, advanced left-sided cardiomyopathy, concomitant lung disease, emboli or vascular toxicity. When the right ventricle is involved, prognosis worsens because systemic congestion, edema, hepatomegaly, ascites and reduced tolerance to medications appear. Distinction between substance-related precapillary pulmonary hypertension and postcapillary pulmonary hypertension from left-sided heart failure is important because treatments differ.
Valvular diseases are often functional. Ventricular dilatation causes mitral and tricuspid regurgitation through annular remodeling and displacement of the papillary muscles. Pulmonary hypertension and right ventricular dilatation worsen tricuspid regurgitation. These valvular diseases increase volume overload and worsen congestion and prognosis. If the ventricle recovers after withdrawal of the toxic agent, regurgitation may decrease; if dilatation becomes chronic, it may persist.
Systemic complications condition the heart. Alcohol can cause liver disease, malnutrition, arrhythmias, hypertension and autonomic neuropathy. Stimulants can cause stroke, aortic dissection, malignant hypertension, kidney failure, infections and psychiatric disorders. Anabolic steroids can cause dyslipidemia, polycythemia, hypertension, thrombosis and endocrine alterations. Cobalt can cause neuropathy, hearing loss, visual disturbances and hypothyroidism. These complications are not accessory, because they can worsen heart failure, arrhythmias, adherence to therapy and eligibility for devices or transplantation.
Relapses are frequent when exposure resumes. A patient with alcoholic cardiomyopathy may improve with abstinence and deteriorate rapidly when consumption resumes. The same applies to methamphetamine, cocaine and anabolic steroids. In patients with malignancy, restarting a cardiotoxic therapy may be necessary for cancer control and requires intensive surveillance. In metal toxicity, the source may continue to release ions if not removed. Relapse prevention is therefore part of prognosis, not generic advice.
Progression toward end-stage heart failure is the final complication of unrecognized or non-reversible forms. The patient may require a defibrillator, resynchronization therapy, ventricular assist device, transplantation or cardiological palliative care. Eligibility for advanced therapies may be limited by active malignancy, uncontrolled dependence, liver disease, infections, neurological damage, systemic disease or persistent exposure. Early diagnosis is not only useful for treating the heart, but for preventing a potentially modifiable toxicity from becoming terminal cardiomyopathy.
The most important clinical complication is failure to recognize the exposure. If the history does not investigate remote cancer therapies, alcohol, stimulants, anabolic steroids, antimalarial agents, metal-on-metal prostheses and industrial work, the cardiomyopathy is labeled idiopathic and the toxic agent continues to act. Every non-ischemic cardiomyopathy must therefore include an essential toxicological assessment. Identifying the cause is not a classificatory detail: it is often the only possibility of modifying the natural history of the disease.