Cardiomyopathies are diseases of the heart muscle in which the myocardium shows structural, functional, electrical or molecular abnormalities that are not explained exclusively by coronary artery disease, arterial hypertension, valvular heart disease or congenital heart disease sufficient, by themselves, to account for the entire clinical picture. The term includes conditions that differ markedly in etiology, age at onset, natural history and prognosis, but share the fact that the primary target is the cardiomyocyte, the extracellular matrix, the conduction system, the intramyocardial microcirculation or the functional architecture of the ventricle.
Modern classification no longer considers cardiomyopathy as a simple description of the shape of the heart. The dilated, hypertrophic, restrictive, arrhythmogenic, noncompacted, metabolic, toxic or inflammatory phenotype represents only the first level of assessment. To reach a clinically useful diagnosis, it is necessary to integrate ventricular morphology, systolic and diastolic function, rhythm, family history, genetics, myocardial tissue, exposures, extracardiac diseases and longitudinal response. Two patients with the same degree of ventricular dysfunction may have completely different causes, arrhythmic risk, therapeutic indications and prognosis.
Cardiomyopathies have major clinical relevance because they may present with heart failure, arrhythmias, sudden death, thromboembolism, chest pain, syncope, reduced functional capacity or incidental findings. Some forms remain silent for years, whereas others present with acute events. Early diagnosis is essential because many conditions have specific treatments, family prevention strategies, indications for implantable devices or interventions on lifestyle and exposures. The central concept is that a cardiomyopathy should not be defined as “idiopathic” until signs pointing to a genetic, inflammatory, toxic, metabolic, neuromuscular, autoimmune, infiltrative or endomyocardial cause have been reasonably sought.
The definition of cardiomyopathy requires a balance between anatomical description and etiological diagnosis. From a morphofunctional standpoint, the heart may be dilated, hypertrophic, stiff, arrhythmogenic, hypertrabeculated, inflamed, fibrotic or apparently normal in the early stages. From a biological standpoint, the cause may be genetic, familial, acquired, toxic, autoimmune, metabolic, neuromuscular, eosinophilic, endocrine, infectious or still unidentified. The same anatomical form may derive from different causes, while the same cause may produce different phenotypes in different patients or in the same patient at later stages.
The main phenotypic categories remain essential because they guide the initial diagnostic approach. Dilated cardiomyopathy is dominated by ventricular dilatation and systolic dysfunction not explained by loading conditions or proportionate ischemia. Hypertrophic cardiomyopathy is characterized by increased wall thickness not justified exclusively by pressure overload or other secondary causes. Restrictive cardiomyopathy is defined by impaired ventricular filling and increased diastolic pressures, often with nondilated ventricles. Arrhythmogenic right ventricular cardiomyopathy concentrates clinical risk on fibrofatty replacement, electrical vulnerability and ventricular arrhythmias.
Alongside the major phenotypes, there are forms that do not fit stably into a single category. Unclassified cardiomyopathies include conditions in which the causal mechanism, reversibility, endomyocardial involvement, toxic origin or multisystem nature are more relevant than simple ventricular shape. This group includes Takotsubo cardiomyopathy, left ventricular noncompaction cardiomyopathy, mitochondrial cardiomyopathies, hypereosinophilic cardiomyopathy and toxic cardiomyopathies.
Classification must also distinguish familial and nonfamilial forms. A familial cardiomyopathy may be autosomal dominant, autosomal recessive, X-linked, mitochondrial or oligogenic. An apparently sporadic form may become familial when relatives are screened or when a pathogenic variant is identified. Conversely, a genetic variant of uncertain significance must not automatically become a causal diagnosis. Clinical genetics is useful only when interpreted together with the phenotype, family segregation and pre-test probability.
A modern classification model must describe at least five dimensions: the morphofunctional phenotype, the organs involved, the familial pattern, the etiology and the functional status. This logic is particularly useful because it avoids weak labels such as “idiopathic cardiomyopathy” when specific signals exist. A patient with a dilated ventricle, atrioventricular block, muscle weakness and a family history of pacemaker implantation is not comparable to a patient with a dilated ventricle after years of alcohol consumption, nor to a patient with ventricular dysfunction after chemotherapy. The phenotype may be similar, but the true diagnosis is different.
Classification is not merely descriptive. It determines which investigations to perform, which relatives to assess, which therapies to start, which exposures to discontinue, which arrhythmic risk to estimate and which follow-up to plan. The diagnosis “dilated cardiomyopathy” may be correct as an initial description, but remains incomplete if it does not clarify whether the cause is genetic, inflammatory, toxic, unrecognized ischemic, tachyarrhythmic, metabolic, neuromuscular or autoimmune. Diagnostic precision is part of treatment.
The etiology of cardiomyopathies is broad and includes genetic, acquired and multifactorial causes. Genetic causes involve proteins of the sarcomere, cytoskeleton, desmosome, nuclear lamina, ion channels, mitochondria, lysosomes, energy metabolism and extracellular matrix. Acquired causes include myocarditis, autoimmunity, toxicity, pharmacological exposures, alcohol, stimulant substances, endocrine diseases, nutritional deficiencies, persistent tachyarrhythmias, hemodynamic overload, infiltrative diseases and systemic inflammatory states. In many patients, the disease arises from the interaction between genetic predisposition and environmental factors.
Sarcomeric abnormalities modify contractile force generation, calcium sensitivity and energy consumption. In hypertrophic cardiomyopathy, variants in genes such as MYH7 and MYBPC3 may produce hypertrophy, myocyte disarray, fibrosis and arrhythmic risk. In dilated cardiomyopathy, variants in TTN, LMNA, FLNC, RBM20, DSP and other genes may reduce structural stability, force transmission, nuclear integrity or electrical conduction. In arrhythmogenic cardiomyopathy, desmosomal variants impair mechanical adhesion between cardiomyocytes and promote cell death, fibrosis and electrical instability.
Energy impairment is a cross-cutting mechanism. The cardiomyocyte depends on continuous production of adenosine triphosphate (ATP) for contraction, relaxation, calcium homeostasis and maintenance of ionic gradients. Mitochondrial defects, anthracycline toxicity, alcohol, methamphetamine, antimalarials, metals, lysosomal diseases and metabolic conditions may reduce energy reserve and increase oxidative stress. From this perspective, mitochondrial cardiomyopathies represent the most direct model of bioenergetic cardiomyopathy, but the same principle also recurs in many toxic and genetic forms.
Inflammation may produce cardiomyopathy through cellular infiltration, immune-mediated damage, necrosis, edema, microvasculopathy and fibrosis. Viral myocarditis, autoimmune diseases, vasculitides, oncological immunotherapies and eosinophilic syndromes may have similar phenotypes, but require different treatments. In hypereosinophilic cardiomyopathy, damage evolves from eosinophilic degranulation to endocardial thrombosis and restrictive fibrosis; in cardiomyopathies associated with autoimmune disorders, the heart may be affected by myocarditis, vasculopathy, thrombosis, fibrosis or damage secondary to systemic inflammation.
Toxic injury may act directly on the cardiomyocyte or indirectly through ischemia, hypertension, arrhythmias, endothelial dysfunction, intracellular accumulation or autonomic alteration. Toxic cardiomyopathies include oncological toxicity, alcoholic cardiomyopathy, injury from cocaine and methamphetamine, anabolic androgenic steroids, antimalarials, metals and other exposures. The central pathogenetic point is that the heart may improve if the toxic agent is recognized and removed early, whereas it may evolve toward fibrosis and heart failure if exposure persists.
Endomyocardial abnormalities show that damage does not necessarily have to begin in the deep myocardium. In endomyocardial fibrotic cardiomyopathy, thrombosis, fibrous organization and endocardial retraction may produce restriction, cavity obliteration and valvular regurgitation. In idiopathic restrictive cardiomyopathy, ventricular stiffness remains the main functional finding when no infiltrative, endomyocardial or systemic cause sufficient to explain the picture is recognized.
Neuromuscular and lysosomal diseases link the heart to skeletal muscle and the conduction system. Cardiomyopathies associated with neuromuscular disorders may present with dilatation, fibrosis, conduction block, arrhythmias and associated respiratory insufficiency. Danon disease is a genetic cardiomyopathy caused by an X-linked lysosomal defect involving LAMP2, with often severe hypertrophy, pre-excitation, arrhythmias, rapid progression and variable extracardiac manifestations. In these forms, cardiac treatment must be integrated with neurology, genetics, pulmonology, metabolism and family counseling.
The final pathophysiology converges on several common events: cardiomyocyte death or dysfunction, fibrosis, ventricular remodeling, increased filling pressures, arrhythmias, functional valvular insufficiency, thrombosis and reduced cardiac reserve. The initial cause may differ, but the heart responds with a limited number of adaptations: hypertrophy to reduce wall stress, dilatation to maintain output, fibrosis to repair damage, neurohormonal activation to sustain pressure and perfusion, and electrical instability when tissue becomes heterogeneous. The clinical problem arises when these adaptations become maladaptive.
The clinical manifestations of cardiomyopathies are variable and depend on phenotype, age, rate of progression, arrhythmias, extracardiac disease and functional reserve. History taking must begin with cardiac symptoms, but must include family history, sudden death, heart failure at a young age, pacemaker or defibrillator implantation in relatives, heart transplantation, congenital heart disease, neuromuscular diseases, deafness, juvenile diabetes, toxic exposures, oncological therapies, alcohol, stimulant substances, autoimmune diseases, eosinophilia, infections, pregnancy and athletic activity. The clinical history often provides stronger diagnostic orientation than the first instrumental examination.
Exertional dyspnea is one of the most frequent symptoms. It may result from systolic dysfunction, impaired diastolic relaxation, functional mitral or tricuspid regurgitation, pulmonary hypertension, arrhythmias, microvascular ischemia or respiratory muscle weakness associated with neuromuscular diseases. In the dilated form, dyspnea tends to reflect reduced output and congestion; in the hypertrophic form, it may derive from diastolic dysfunction, dynamic obstruction or microvascular ischemia; in the restrictive form, it is often linked to increased filling pressures; in mitochondrial or neuromuscular forms, it may be confused with muscle fatigability or hypoventilation.
Palpitations may express atrial fibrillation, premature beats, nonsustained ventricular tachycardia, sustained ventricular tachycardia, pre-excitation, sinus tachycardia or rhythm disturbances secondary to medications and electrolytes. Syncope requires particular attention because it may result from ventricular arrhythmias, atrioventricular block, dynamic obstruction, hypotension, ischemia or pulmonary embolism. In a patient with cardiomyopathy, unexplained syncope must not be trivialized, especially when there is a family history of sudden death, fibrosis on cardiac magnetic resonance imaging (CMR), reduced left ventricular ejection fraction (LVEF), severe hypertrophy, desmosomal disease, laminopathy, Danon disease or conduction disturbances.
Chest pain may occur even in the absence of obstructive coronary artery disease. In hypertrophic cardiomyopathy, it may depend on microvascular ischemia and increased myocardial demand; in Takotsubo syndrome, it mimics an acute coronary syndrome; in myocarditis and eosinophilic forms, it reflects inflammatory injury; in toxic forms caused by cocaine, methamphetamine or fluoropyrimidines, it may be ischemic due to vasospasm or thrombosis. The presence of a known cardiomyopathy does not exclude acute myocardial infarction, aortic dissection, pulmonary embolism or acute myocarditis.
Embolic events may be an initial manifestation or a complication. Atrial fibrillation, atrial dilatation, ventricular thrombi, noncompaction with dysfunction, extensive apical Takotsubo syndrome, hypereosinophilia and severe dilated cardiomyopathies may promote cerebral or systemic embolism. A cryptogenic ischemic stroke in a young patient or in a patient with abnormal cardiac imaging should prompt investigation for thrombi, occult arrhythmias, familial cardiomyopathies and endomyocardial conditions.
The physical examination may be normal in the early stages. In symptomatic stages, it may show tachycardia, irregular rhythm, murmurs, a third heart sound, crackles, jugular venous distension, dependent edema, hepatomegaly, ascites, signs of hypoperfusion or pulmonary hypertension. In obstructive phenotypes, dynamic murmurs may be detected and modified by maneuvers that change preload and afterload. In restrictive forms, jugular venous distension, systemic congestion and dilated atria dominate. In multisystem forms, it is necessary to look for muscle weakness, ptosis, ophthalmoplegia, neuropathy, rash, nasal polyposis, liver disease, endocrine signs, skeletal abnormalities or cutaneous manifestations.
Presentation may be incidental. An abnormal electrocardiogram (ECG), a murmur, a family history, an echocardiogram performed for another reason, a sports evaluation or oncological monitoring may lead to diagnosis before symptoms occur. This does not make the disease less relevant. Some cardiomyopathies carry arrhythmic risk before overt heart failure, others require family screening, and others still must be monitored because they may progress slowly. The asymptomatic patient must therefore be stratified, not simply reassured or alarmed.
Diagnosis begins with identification of the cardiac phenotype and continues with the search for the cause. The first level includes personal and family history, physical examination, 12-lead ECG, transthoracic echocardiography, blood tests, cardiac biomarkers when indicated, rhythm monitoring and assessment of common causes. The aim is not to accumulate investigations, but to build a coherent diagnostic probability. A dilated ventricle, a hypertrophic ventricle, a stiff ventricle and an arrhythmogenic ventricle require different initial pathways, although they share some tools.
The ECG provides information on hypertrophy, pathological or pseudoinfarction Q waves, bundle branch block, atrioventricular block, pre-excitation, repolarization abnormalities, corrected QT interval (QTc), atrial fibrillation, premature beats and signs of arrhythmogenic disease. A normal ECG does not exclude cardiomyopathy, but an abnormal ECG may provide strong diagnostic orientation. Pre-excitation and hypertrophy may suggest storage diseases or Danon disease; progressive conduction block may point toward laminopathies, mitochondrial diseases, neuromuscular disorders or antimalarial toxicity; T-wave inversion in specific leads may support suspicion of arrhythmogenic or hypertrophic cardiomyopathy.
Echocardiography is the baseline examination for measuring cardiac chambers, wall thickness, LVEF, diastolic function, right ventricular function, atria, valves, pulmonary pressures, dynamic obstruction, trabeculation, thrombi and pericardial effusion. Analysis of global longitudinal strain (GLS) may detect subclinical dysfunction, especially in oncological toxicity, infiltrative diseases, hypertrophic cardiomyopathy and early stages of dysfunction. The echocardiogram must be interpreted in context: the same wall thickness does not have the same meaning in hypertension, hypertrophic cardiomyopathy, Fabry disease, amyloidosis, Danon disease, mitochondrial disease or athletic adaptation.
CMR is central when echocardiography is not sufficient or when tissue characterization is needed. It allows assessment of volumes, mass, function, the right ventricle, edema, fibrosis, late gadolinium enhancement (LGE), thrombi, noncompaction, infiltration, accumulation, and ischemic and nonischemic patterns. The presence, location and extent of LGE have diagnostic and prognostic value. Mid-wall septal fibrosis may support nonischemic dilated cardiomyopathy; a subendocardial pattern points toward ischemia or endocardial injury; a diffuse pattern may suggest infiltration or accumulation; active edema may point toward myocarditis. CMR does not replace genetics, histology or history taking, but it reduces the margin of error.
Laboratory tests should be selected according to clinical suspicion. Complete blood count, renal function, electrolytes, liver function, glucose, glycated hemoglobin, lipid profile, thyroid function, ferritin, transferrin saturation, creatine kinase, autoantibodies, inflammatory markers, eosinophils, serology, B-type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP), and troponin may point toward specific causes. Eosinophilia opens a hematological, infectious disease and immunological pathway; elevated creatine kinase points toward myopathy; elevated ferritin and transferrin saturation toward iron overload; thyroid abnormalities toward an endocrine cause; persistent troponin elevation toward inflammation or active injury.
Coronary assessment is necessary when age, symptoms, risk factors, troponin, ECG or imaging make ischemic heart disease plausible. Nonischemic cardiomyopathy cannot be diagnosed while ignoring significant coronary artery disease. Coronary computed tomography angiography, invasive coronary angiography, functional testing or perfusion imaging must be selected according to pre-test probability and clinical urgency. Coexistence of coronary artery disease and cardiomyopathy is possible, so the question is not only whether stenoses exist, but whether they are sufficient to explain the phenotype.
Rhythm monitoring is indicated in the presence of palpitations, syncope, family history of sudden death, reduced LVEF, fibrosis, severe hypertrophy, arrhythmogenic disease, conduction disturbances, neuromuscular disease, mitochondrial disease, Danon disease or proarrhythmic toxicity. Holter ECG, prolonged monitoring or loop recorders may document intermittent arrhythmias not visible on baseline ECG. Arrhythmic stratification is decisive because some cardiomyopathies cause death through electrical instability before producing terminal heart failure.
Genetic testing must be preceded by counseling and guided by the phenotype. It is particularly useful in familial cardiomyopathies, early onset, unexplained hypertrophy, nonischemic dilatation with family history, conduction disturbances, ventricular arrhythmias, sudden death, neuromuscular, mitochondrial or multisystem phenotypes. Identification of a pathogenic variant allows cascade screening of relatives, risk definition and, for some genes, changes in the threshold for implantable cardioverter-defibrillator (ICD) placement. Variants of uncertain significance must be handled cautiously and must not independently guide invasive decisions.
Endomyocardial biopsy has selected indications. It is useful when the result may rapidly change therapy: fulminant myocarditis, shock, severe arrhythmias, suspected eosinophilic myocarditis, giant cell myocarditis, cardiac sarcoidosis, immunotherapy-related toxicity, unclear infiltrative or storage diseases, rejection in transplant recipients or cases in which imaging and clinical findings remain inconclusive. The risk of false-negative sampling exists, but the value increases when the procedure is imaging-guided and interpreted in experienced centers.
In the absence of a single diagnostic criterion valid for all cardiomyopathies, according to European Society of Cardiology (ESC) guidelines, a clinically correct diagnosis requires integration of several levels:
essential elements of diagnostic assessment
The differential diagnosis must remain broad until the final definition is reached. Ischemic heart disease, hypertension, valvular heart disease, athlete’s heart, myocarditis, amyloidosis, sarcoidosis, hemochromatosis, Fabry disease, tachycardia-induced cardiomyopathy, toxicity, endocrinopathies, constrictive pericarditis, unrecognized congenital heart disease and systemic diseases may mimic or overlap with a primary cardiomyopathy. The most useful diagnosis is not the one that quickly provides a name, but the one that explains the whole patient.
Risk stratification in cardiomyopathies must consider heart failure, arrhythmias, sudden death, thromboembolism, structural progression and family involvement. LVEF is important, but not sufficient. Fibrosis on CMR, genotype, syncope, nonsustained ventricular tachycardia, family history of sudden death, wall thickness, obstruction, conduction disturbances, right ventricular function, dilated atria, biomarkers, arrhythmic burden and extracardiac disease may substantially modify risk. Prognostic stratification must be phenotype-specific.
In dilated forms, risk depends on LVEF, functional class, ventricular volumes, LGE, right ventricular function, response to therapy, arrhythmias and genotype. Variants in LMNA, FLNC, RBM20, PLN, DSP and other genes may increase arrhythmic risk compared with what would be suggested by LVEF alone. In hypertrophic forms, the risk of sudden death depends on family history, syncope, maximum wall thickness, nonsustained ventricular tachycardia, LGE, apical aneurysm, reduced ejection fraction and other markers. In arrhythmogenic forms, ventricular function, disease extent, arrhythmias, genotype and intense sports activity influence prognosis.
In restrictive forms, risk is linked to increased filling pressures, atrial fibrillation, pulmonary hypertension, right ventricular function, systemic congestion, thrombosis and the underlying cause. Restriction due to amyloidosis, idiopathic restriction and endomyocardial fibrosis do not have the same treatment or natural history. In unclassified forms, risk may be dominated by specific mechanisms: shock and thrombi in Takotsubo syndrome, recurrence and fibrosis in eosinophilic forms, conduction block in mitochondrial forms, persistent toxic exposure in toxic forms, and conduction and respiration in neuromuscular forms.
Family screening is indicated when cardiomyopathy is familial, genetic, suspicious for inheritance or diagnosed at a young age without a convincing acquired cause. First-degree relatives are assessed with history, ECG, echocardiography and, when necessary, CMR, Holter monitoring or genetic testing. If a pathogenic variant is identified, cascade genetic screening makes it possible to distinguish carrier and noncarrier relatives. If genetics does not identify a variant, clinical screening may remain indicated when family history is strong.
Genetic counseling must explain inheritance patterns, incomplete penetrance, variable expressivity, test limitations, variants of uncertain significance, reproductive implications and the need for follow-up. Not all carriers will develop clinical disease; not all patients without an identified variant are free from familial risk. In mitochondrial diseases, maternal transmission and heteroplasmy make counseling more complex; in X-linked diseases, such as Danon disease, men and women may have different severity and timing of expression.
Risk must be reassessed over time. An initially normal LVEF may decrease, fibrosis may appear, an arrhythmia may emerge, family history may become evident, a genetic variant may be reclassified, a toxic exposure may resume or an autoimmune disease may reactivate. Cardiomyopathies are not static diagnoses. Follow-up does not only serve to confirm stability, but also to intercept the moment when prognosis and therapy change.
The treatment of cardiomyopathies is based on four objectives: treating the cardiac phenotype, acting on the cause when identifiable, preventing sudden death and thromboembolism, and preserving quality of life and function over time. Heart failure therapy, arrhythmia management, anticoagulation, implantable devices, rehabilitation and follow-up must be integrated with specific etiological interventions. Correct heart failure therapy is incomplete if a toxic exposure continues, if eosinophilia remains active, if an autoimmune disease is not controlled or if at-risk relatives are not assessed.
In forms with reduced LVEF, validated therapies for heart failure are applied when tolerated: angiotensin receptor neprilysin inhibitor (ARNI), angiotensin-converting enzyme inhibitor (ACE inhibitor) or angiotensin receptor blocker, beta-blocker, mineralocorticoid receptor antagonist (MRA), sodium-glucose cotransporter 2 inhibitor (SGLT2 inhibitor), diuretics for congestion, correction of iron deficiency and control of comorbidities. Therapy must be individualized according to blood pressure, renal function, potassium, heart rate, arrhythmias, age, frailty and cause.
Etiological therapies vary according to the disease. In toxic forms, removal of the cardiotoxic agent is decisive. In eosinophilic forms, corticosteroids, hematological, immunological, antiparasitic or biological therapy are required according to the cause. In autoimmune forms, the immunological activity responsible for the damage is treated. In mitochondrial and neuromuscular forms, metabolism, respiration, neurology, conduction and systemic crises are managed. In Danon disease and other genetic forms, early diagnosis guides devices, transplantation, counseling and family screening. In restrictive and endomyocardial forms, congestion, arrhythmias, thrombi and valvular disease are managed, with selected procedures in expert centers.
Prevention of sudden death requires specific assessment. ICD implantation is indicated for secondary prevention after cardiac arrest or nonreversible sustained ventricular tachycardia. In primary prevention, the decision depends on LVEF, genotype, LGE, syncope, nonsustained ventricular tachycardia, family history and phenotype. Cardiac resynchronization therapy (CRT) is indicated in patients with heart failure, reduced LVEF and electrical dyssynchrony according to established criteria. Pacemakers, ICDs and CRT are not substitutes for etiological diagnosis, but preventive tools when electrical or mechanical risk requires them.
Anticoagulation is indicated in atrial fibrillation according to thromboembolic risk, intracardiac thrombus, some high-risk phenotypes and specific clinical conditions. It must not be automatic in all cardiomyopathies, but must be considered carefully when severely reduced LVEF, apical aneurysm, noncompaction with dysfunction, extensive apical Takotsubo syndrome, thrombotic hypereosinophilia or a previous embolic event are present. The search for thrombi must be active in at-risk patients, using contrast echocardiography or CMR if standard imaging is insufficient.
Follow-up must be individualized. ECG, echocardiography, Holter monitoring, CMR, biomarkers, functional testing, genetic assessment, evaluation of relatives and surveillance of exposures are adjusted according to diagnosis and risk. A stable patient with a mild phenotype may require spaced controls; a patient with a high-risk genotype, fibrosis, arrhythmias, oncological therapy, eosinophilia, neuromuscular disease or recent toxicity requires closer monitoring. The frequency of controls must increase after changes in symptoms, pregnancy, new cardiotoxic therapy, severe infection, syncope, arrhythmia, biomarker increase or worsening imaging.
Physical activity must not be prohibited or allowed generically. Prescription depends on phenotype, arrhythmic risk, LVEF, obstruction, symptoms, therapy, genotype, LGE and history of syncope. Moderate exercise may be useful in many patients with stable heart failure, whereas competitive sports or intense exertion may be contraindicated in specific arrhythmogenic, hypertrophic or high-risk dilated forms, or in the presence of uncontrolled arrhythmias. Cardiac rehabilitation helps transform an indistinct prohibition into a safe and measurable prescription.
Advanced therapies, such as left ventricular assist device (LVAD) support and heart transplantation, are reserved for patients with advanced heart failure despite optimized therapy. Candidacy depends not only on the heart, but also on systemic disease, malignancy, infection, active dependence, renal function, liver function, neuromuscular disease, nutritional status and family support. In genetic and multisystem cardiomyopathies, transplantation may be effective in selected cases, but requires accurate extracardiac assessment.
Complications of cardiomyopathies include heart failure, arrhythmias, sudden death, thromboembolism, shock, functional valvular insufficiency, pulmonary hypertension, fibrotic progression, right ventricular involvement and reduced quality of life. Their frequency and severity depend on cause and phenotype. An acute inflammatory cardiomyopathy may be fulminant but reversible; a genetic form may progress slowly yet carry high arrhythmic risk; a toxic form may improve after discontinuation of exposure; a fibrotic restrictive form may have limited reversibility even with preserved LVEF.
Heart failure may occur due to systolic dysfunction, diastolic dysfunction, dynamic obstruction, valvular regurgitation, right ventricular involvement, arrhythmias or restriction. Not all forms of heart failure are the same. In the dilated phenotype, low output and congestion dominate; in the restrictive phenotype, elevated filling pressures and systemic congestion dominate; in hypertrophic cardiomyopathy, obstruction, microvascular ischemia and diastolic dysfunction may contribute; in Takotsubo syndrome, acute shock may occur with or without dynamic obstruction; in neuromuscular forms, respiration may amplify heart failure.
Arrhythmias are a major cause of morbidity and mortality. Atrial fibrillation, ventricular tachycardia, ventricular fibrillation, torsades de pointes, atrioventricular block, pre-excitation and sinus node disease may occur differently according to the disease. Sudden death may be the first event in patients with arrhythmogenic, genetic or infiltrative phenotypes. Electrical risk must be assessed even when LVEF is preserved, because fibrosis, genotype, conduction and family history may have independent value.
Thromboembolism derives from atrial fibrillation, atrial dilatation, ventricular stasis, intracavitary thrombus, apical aneurysm, noncompaction, Takotsubo syndrome, hypereosinophilia or severe systolic dysfunction. Stroke, systemic embolism and ventricular thrombi may profoundly modify prognosis. Prevention requires identification of at-risk patients, rhythm monitoring, adequate imaging and anticoagulation when indicated.
Fibrotic progression is one of the main reasons for irreversibility. Fibrosis replaces functioning myocardium, stiffens the ventricle, worsens conduction, promotes re-entry arrhythmias and reduces the likelihood of complete recovery. In toxic forms, it indicates prolonged exposure; in inflammatory forms, it indicates scar injury; in genetic forms, it may precede dysfunction; in endomyocardial forms, it produces restriction and obliteration. Fibrosis is therefore a prognostic marker and an indirect target of early diagnosis.
Prognosis is favorable when diagnosis is early, the cause is reversible or treatable, LVEF is preserved, significant fibrosis is absent, rhythm is stable, the right ventricle is preserved, thrombi are absent and extracardiac disease is controlled. Prognosis worsens with persistently reduced LVEF, extensive LGE, ventricular arrhythmias, syncope, family history of sudden death, high-risk genotype, recurrent heart failure, pulmonary hypertension, right ventricular dysfunction, severe systemic disease or persistent toxic exposure. Prognosis is therefore not determined by the name of the cardiomyopathy, but by the interaction between cause, phenotype and response to treatment.
The risk of underdiagnosis and overdiagnosis must be considered. Underdiagnosing a cardiomyopathy exposes the patient to sudden death, heart failure, missed family screening and loss of etiological therapies. Overdiagnosing a physiological variant or an isolated finding may produce anxiety, inappropriate sports restrictions, unnecessary controls and unneeded treatment. The medicine of cardiomyopathies therefore requires proportionate precision: recognizing real risk without turning every morphological abnormality into disease.
The most important complication remains incomplete diagnosis. Defining a patient as “dilated”, “hypertrophic” or “restrictive” without searching for cause, electrical risk, exposures, family history and systemic disease may prevent correct treatment. Cardiomyopathy is a dynamic diagnosis: it must be updated when new data emerge, when the phenotype changes, when a genetic variant is reclassified, when exposure stops or resumes, when arrhythmias appear or when follow-up shows recovery or progression.