Fibrotic endomyocardial cardiomyopathy, more correctly defined as endomyocardial fibrosis, is a restrictive cardiomyopathy characterized by fibrous thickening of the endocardium and subendocardium, predominantly located at the ventricular apices and in the ventricular inflow regions. The scarring process may involve the right ventricle, the left ventricle or both, causing apical obliteration, reduction of the functional cavity, diastolic dysfunction, atrioventricular valve regurgitation and progressive systemic or pulmonary congestion. The disease must not be confused with generic interstitial myocardial fibrosis: its distinguishing feature is endocardial-subendocardial involvement, often associated with mural thrombosis, retraction of the valvular apparatus and restrictive physiology.
Historically, endomyocardial fibrosis has been described as a tropical heart disease, particularly frequent in areas of sub-Saharan Africa, southern India, some regions of Asia and Latin America. It more often affects children, adolescents and young adults living in poor rural settings, but it may also be observed in adults and, in non-endemic countries, in people from tropical areas or in patients with eosinophilic diseases. Its true prevalence is uncertain, because many affected areas have limited diagnostic resources, but population-based echocardiographic studies have shown that early, paucisymptomatic or asymptomatic forms may exist and may not be recognized by clinical assessment alone.
The pathogenesis has not been fully clarified. The disease is considered a multifactorial condition in which individual predisposition, environment, poverty, malnutrition, infections, parasitic diseases, dietary or toxic exposures, chronic inflammation, eosinophilia and endocardial injury may converge toward a fibrotic reparative response. In some patients, the condition conceptually overlaps with eosinophilic heart disease and Loeffler endocarditis; in others, especially in classic tropical forms, eosinophilia may be absent at the time of diagnosis, because the initial inflammatory phase may already have resolved by the time the patient is evaluated. For this reason, endomyocardial fibrosis should be interpreted as an anatomopathological and restrictive phenotype rather than as a disease with a single etiology.
Endomyocardial fibrosis is one of the classic causes of acquired restrictive cardiomyopathy. Unlike idiopathic restrictive cardiomyopathy, in which the main problem is the intrinsic stiffness of the myocardium without a demonstrable specific endocardial lesion, here the anatomical damage has a recognizable location: endocardium, subendocardium, ventricular apices and atrioventricular valvular apparatus. The fibrosis forms a sort of internal shell that reduces ventricular compliance, deforms intracavitary geometry and shortens or incorporates chordae tendineae, papillary muscles and inflow regions. The functional result is restriction of filling, often accompanied by mitral regurgitation, tricuspid regurgitation or both.
Geographical distribution is one of its most distinctive features. The historically most affected areas include Uganda, Mozambique, Nigeria, Ivory Coast, Brazil, Colombia, Venezuela, Kerala and other tropical or subtropical regions. The disease has been described mainly in rural populations with low socioeconomic status, poor diet, exposure to recurrent infections and limited healthcare access. This association with poverty does not by itself prove a cause, but suggests that environment, nutrition, infectious burden and living conditions may modify endocardial vulnerability or the immune-inflammatory response.
Echocardiographic studies have changed the epidemiological understanding of the disease. In the past, endomyocardial fibrosis was recognized mainly in advanced stages, when the patient had massive ascites, edema, cardiomegaly, right or left heart failure and severe functional limitation. Screening echocardiography has instead shown that mild and moderate forms exist, sometimes asymptomatic, with initial endocardial thickening, partial apical reduction, valvular abnormalities or atrial dilatation. This finding is important because late diagnosis selects the worst cases and makes the disease appear even more lethal than it would seem if it were detected at an early stage.
The age group most affected in endemic areas is childhood and youth, but the disease may remain clinically silent and manifest later. In children, the right-sided phenotype may present with ascites disproportionate to peripheral edema, hepatomegaly, growth delay, fatigue and reduced exercise tolerance. In adults, the diagnosis may emerge after years of congestion, atrial arrhythmias, thromboembolism, valvular regurgitation or suspected constrictive pericarditis. In non-endemic countries, recognition requires an accurate geographical history, because a migrant patient or a patient from tropical areas may be incorrectly classified as having heart failure with preserved ejection fraction, degenerative valvular heart disease or idiopathic restrictive cardiomyopathy.
Ventricular involvement is not uniform. The right-sided form produces obliteration of the right ventricular apex, reduction of the inflow chamber, right atrial dilatation, tricuspid regurgitation, systemic venous congestion, ascites and possible pericardial effusion. The left-sided form causes obliteration of the left ventricular apex, diastolic restriction, left atrial dilatation, pulmonary venous hypertension, dyspnea and mitral regurgitation. The biventricular form combines the two patterns and tends to have a more severe course. This distribution has clinical value because it explains why some patients are dominated by ascites and others by dyspnea, despite having the same anatomopathological disease.
The term “endomyocardial” indicates that the damage does not remain confined to an inert surface. The fibrotic endocardium adheres to the subendocardium, alters perfusion of the innermost layers, modifies segmental mechanics and may involve the junction between myocardium and valvular apparatus. In active stages, inflammation, thrombosis and subendocardial necrosis may coexist; in chronic stages, dense fibrosis, calcification, thrombotic organization and scar retraction predominate. For this reason, the disease is restrictive, valvular, thrombotic and electrical at the same time.
In the context of the modern classification of cardiomyopathies, endomyocardial fibrosis should be considered a specific cause of restrictive phenotype. It is therefore not correct to include it among idiopathic restrictive cardiomyopathies when endocardial morphological characteristics are present. The distinction is substantial: the diagnosis directs the search for eosinophilia, parasitic diseases, inflammatory diseases, intracavitary thrombi, endocardial calcifications, secondary valvular regurgitation and possible surgical indication. It also requires a strict differential diagnosis with Loeffler endocarditis, heart disease due to hypereosinophilic syndrome, constrictive pericarditis, rheumatic heart disease, primary restrictive cardiomyopathy, amyloidosis and congenital abnormalities of the ventricular apex.
The etiology of endomyocardial fibrosis has not been defined unequivocally. The classic tropical form is considered a multifactorial disease, in which no single agent is sufficient to explain all cases. Nutritional, environmental, infectious, parasitic, immunological, genetic and toxic factors have been proposed. The association with poor rural regions, malnutrition, parasitic infestations, exposure to recurrent infections and young age suggests that endocardial injury may arise from the interaction between biological vulnerability and environment. However, many epidemiological associations have not demonstrated a direct and reproducible causal relationship; for this reason, it is more correct to distinguish between definite causes of fibrotic endomyocardial damage and factors that increase the probability of developing the phenotype.
Among the causes most clearly linked to endomyocardial fibrosis are eosinophilic diseases. Hypereosinophilic syndrome, some myeloproliferative neoplasms with eosinophilia, immunological reactions, parasitic diseases, eosinophilic vasculitides and persistent allergic or inflammatory conditions may cause cardiac damage through eosinophilic infiltration, degranulation and endocardial toxicity. Loeffler endocarditis is the prototypical form of eosinophilic heart disease: initially, endocardial necrosis and inflammation are observed, followed by mural thrombosis and finally fibrotic organization. Tropical endomyocardial fibrosis shares some final aspects with this model, but does not always show persistent or documentable eosinophilia.
The role of eosinophils is biologically plausible. Activated eosinophils release major basic protein, eosinophil cationic protein, eosinophil peroxidase, eosinophil-derived neurotoxin, oxidant radicals, cytokines and lipid mediators. These molecules may damage endocardial endothelium, subendocardial cells and extracellular matrix; they increase platelet adhesiveness, promote mural thrombosis and amplify the inflammatory response. The injured endocardial surface becomes thrombogenic; the adherent thrombus organizes; fibroblasts, myofibroblasts and inflammatory cells deposit collagen; the active lesion progressively turns into a fibrotic scar. The sequence of endocardial injury, thrombosis, organization and fibrosis is one of the most coherent models of the disease.
Parasitic diseases have been studied mainly in tropical areas. Filariasis, schistosomiasis, soil-transmitted helminthiases and other infestations may induce eosinophilia, chronic immune activation, anemia, malnutrition and persistent inflammation. However, the presence of parasites in endemic areas does not automatically prove causality, because many infested individuals do not develop endomyocardial fibrosis and some patients with advanced disease do not have significant eosinophilia. Parasitic diseases probably act as promoting factors in subgroups of patients rather than as a single universal cause.
Malnutrition has also been implicated. Diets poor in protein, micronutrient deficiencies, high consumption of inadequately processed cassava, exposure to cyanogenic glycosides, low magnesium intake or other nutritional imbalances have been proposed as elements capable of facilitating endocardial injury, oxidative stress or fibrotic response. None of these hypotheses, however, has reached the status of a definite cause. The most prudent interpretation is that malnutrition and poverty may reduce the biological resilience of the myocardium, increase susceptibility to infections and modify tissue repair, indirectly contributing to fibrosis.
The transition from the initial lesion to restrictive cardiomyopathy depends on the location of the fibrosis. Scar deposition is concentrated at the apices and ventricular inflow tracts, not uniformly throughout the wall. When the apex is filled by fibrotic tissue and organized thrombus, the effective ventricular cavity shortens; the ventricle may appear relatively normal in size, but the volume available for filling is reduced. During diastole, the fibrotic wall does not distend; the atrium must generate high pressures to push blood into a rigid chamber; retrograde venous pressure rises; the patient develops congestion. This explains why the ejection fraction may be preserved in the early stages despite severe heart failure.
Involvement of the atrioventricular valves results from several mechanisms. Fibrosis may incorporate papillary muscles, chordae tendineae and the subvalvular region; scar retraction prevents proper leaflet coaptation; atrial and annular dilatation amplifies regurgitation; high ventricular and atrial pressure worsens the regurgitant flow. In the left-sided form, functional or restrictive mitral regurgitation predominates; in the right-sided form, tricuspid regurgitation, often massive, predominates. Valvular regurgitation is not a separate disease: it is an anatomical consequence of endomyocardial fibrosis and in turn contributes to atrial dilatation and congestion.
Intracavitary thrombosis is an integral part of the pathogenesis. The injured endocardium loses antithrombotic properties, flow in the obliterated apices becomes slow, dilated atria promote stasis and atrial arrhythmias amplify risk. Thrombi may remain adherent and organize inside the fibrotic plaque, contributing to apical obliteration, or they may embolize. In the left ventricle, the risk is systemic embolism; in the right heart, venous thrombosis, pulmonary embolism or further hemodynamic compromise may coexist. The distinction between recent thrombus and organized fibrotic tissue has implications for anticoagulation, surgery and embolic risk.
The final pathophysiology is that of diastolic restriction with relatively fixed output. If the ventricle cannot increase end-diastolic volume, the increase in output during exercise is limited; the patient experiences dyspnea, asthenia and exercise intolerance. Chronically elevated atrial pressures dilate the atria, promote atrial fibrillation and increase thromboembolic risk. The pulmonary circulation may develop post-capillary hypertension in the left-sided form; the liver and abdominal venous system undergo congestion in the right-sided form. In advanced stages, cardiac cachexia, renal failure due to congestion and low output, congestive hepatopathy and refractoriness to diuretic therapy appear.
The clinical presentation depends on the site of ventricular involvement, the phase of the disease and the presence of thrombi, arrhythmias or valvular regurgitation. The medical history should begin with a geographical and temporal reconstruction: place of birth, stay in tropical areas, housing conditions, history of parasitic diseases, known eosinophilia, allergic or inflammatory episodes, recurrent fevers, weight loss, malnutrition, dietary exposures, family history, previous thromboembolic events and duration of symptoms. In non-endemic countries, these details are decisive because the disease may be far from the usual diagnostic horizon.
The patient with the right-sided form often reports progressive abdominal enlargement, hepatic heaviness, early satiety, leg swelling, fatigue, weight loss, reduced work or school capacity and dyspnea that is less marked than would be expected from the severity of the heart failure. Ascites may be massive and dominate the clinical picture, initially leading toward hepatological or abdominal diagnoses. Chronic venous congestion may cause right upper quadrant pain, nausea, anorexia and malabsorption. In children, growth delay, poor appetite, a distended abdomen and progressive reduction in physical activity may be observed.
The left-sided form more often produces exertional dyspnea, orthopnea, nocturnal cough, reduced exercise tolerance, palpitations, episodes of pulmonary edema and symptoms of pulmonary venous hypertension. When mitral regurgitation is significant, dyspnea may become the main symptom. The patient may report fatigability disproportionate to the ejection fraction, because the limitation is diastolic and not necessarily systolic. If ventricular or atrial thrombi are present, the onset may be a stroke, a transient ischemic attack, a peripheral embolism or a visceral ischemic event.
The biventricular form combines systemic and pulmonary congestion. The patient may have dyspnea, ascites, edema, hepatomegaly, palpitations, weight loss, relative hypotension and severe reduction in quality of life. The condition may be confused with constrictive pericarditis, liver cirrhosis, multivalvular rheumatic heart disease, primary restrictive cardiomyopathy or advanced heart failure of another origin. The presence of obliterated apices, enormously dilated atria, atrioventricular regurgitation and endocardial calcifications points toward endomyocardial fibrosis.
Physical examination should follow the hemodynamic logic. In the right-sided form, jugular venous distension, prominent venous waves, hepatojugular reflux, congestive hepatomegaly, ascites, dependent edema, possible mild jaundice due to hepatic congestion and right pleural effusion are observed. The murmur of tricuspid regurgitation may increase with inspiration and may coexist with a parasternal impulse if the right ventricle is overloaded. Blood pressure may be normal in the early stages and decrease in advanced stages, when output becomes insufficient.
In the left-sided form, examination may show pulmonary crackles, a third heart sound, an apical holosystolic murmur due to mitral regurgitation, signs of pulmonary hypertension and, if the right ventricle becomes secondarily involved, systemic congestion. The dilated left atrium promotes atrial fibrillation, which on auscultation manifests as an irregular rhythm. Loss of atrial contraction is particularly harmful because the fibrotic and poorly distensible ventricle depends on atrial pressure to fill; for this reason, an atrial arrhythmia may abruptly precipitate heart failure.
Some extracardiac findings help identify the etiological context. Persistent eosinophilia, asthma, sinusitis, neuropathy, purpura, fever or systemic signs point toward an eosinophilic or vasculitic disease. Splenomegaly, hematological abnormalities and recurrent thrombosis may suggest myeloproliferative neoplasms. History of parasitic infestations, pruritus, chronic diarrhea, anemia or malnutrition supports suspicion of tropical and infectious factors. However, absence of eosinophilia at the time of the visit does not exclude endomyocardial fibrosis, especially if the patient is in an advanced scar stage.
Clinical severity depends not only on the extent of fibrosis, but also on the rate of progression, valvular regurgitation, pulmonary hypertension, right ventricular function, the presence of arrhythmias and the patient’s ability to access specialist care. In many endemic areas, diagnosis occurs when the disease is already advanced, with massive ascites, extreme atrial dilatation and secondary malnutrition. In these cases, the clinical picture may appear dominated by abdominal congestion rather than by the classic cardiological symptom, and this contributes to diagnostic delay.
Suspicion of endomyocardial fibrosis arises from the association between restrictive heart failure, dilated atria, ventricles that are not primarily dilated, apical obliteration, atrioventricular regurgitation and a compatible epidemiological or biological context. The diagnostic pathway must demonstrate the endomyocardial lesion, define the involved ventricle, estimate hemodynamic severity, recognize thrombi and calcifications, assess the valves, distinguish the disease from constrictive pericarditis and search for treatable eosinophilic, parasitic, hematological or inflammatory causes. The diagnosis cannot be based on a single isolated finding.
First-level tests include electrocardiogram, chest radiography when useful, blood tests, B-type natriuretic peptide or N-terminal pro-B-type natriuretic peptide, complete blood count with differential, renal and liver function, electrolytes, coagulation, inflammatory markers, high-sensitivity troponin and assessment of eosinophilia. The electrocardiogram may show atrial fibrillation, atrial flutter, signs of atrial enlargement, bundle branch blocks, nonspecific repolarization abnormalities or low voltages. Radiography may show cardiomegaly due to atrial dilatation, pleural effusion or calcifications, but it is not sufficient to characterize the disease.
Transthoracic echocardiography is the central examination. It allows visualization of apical obliteration, endocardial thickening, organized thrombi, reduction of the ventricular cavity, atrial dilatation, mitral or tricuspid regurgitation, abnormalities of the subvalvular apparatus, pericardial effusion and restrictive filling pattern. In the right-sided form, obliterated right apex, markedly dilated right atrium, narrowed inflow tract, tricuspid regurgitation and sometimes an “amputated” right ventricular appearance are observed. In the left-sided form, left apical obliteration, possible apical thrombus, dilated left atrium, mitral regurgitation and increased filling pressures are observed.
The echocardiographic criteria proposed by Mocumbi and colleagues were developed for epidemiological studies and to standardize recognition of the disease, especially in endemic areas. They should not be presented as universal guideline diagnostic criteria, but they represent a scheme widely used in the literature to increase diagnostic consistency. In this approach, echocardiographic diagnosis is supported by the presence of two major criteria or one major criterion associated with two minor criteria. The logic of the scheme is to recognize the most specific structural signs and integrate them with supportive findings.
The major and minor echocardiographic elements are useful especially when read in the clinical context and not as a mechanical list. In summary, the scheme evaluates the most representative signs of the disease:
Cardiac magnetic resonance imaging is the most useful second-level examination for anatomical and tissue characterization. It allows distinction between thrombus, fibrosis, viable myocardium, indirect evidence of calcifications, apical involvement and valvular abnormalities. Cine sequences show ventricular geometry, cavity reduction and valve motion; late gadolinium enhancement highlights subendocardial or endocardial enhancement in fibrotic areas; mapping may help define extracellular expansion; morphological assessment distinguishes endomyocardial fibrosis from apical hypertrophic cardiomyopathy, ventricular noncompaction, post-ischemic apical thrombus, intracavitary tumors and constrictive pericarditis. When magnetic resonance imaging is unavailable or contraindicated, computed tomography may be particularly useful for documenting endocardial calcifications and anatomical relationships.
Differential diagnosis with constrictive pericarditis is mandatory. Both may cause ascites, jugular venous distension, edema, hepatomegaly, dilated atria and restrictive symptoms. In constrictive pericarditis, the problem is a rigid pericardium that limits filling from the outside, with marked ventricular interdependence and characteristic respiratory variations; in endomyocardial fibrosis, the limitation is internal, located in the endocardium and subendocardium, with apical obliteration and intracavitary lesions. Doppler echocardiography, tissue Doppler, cardiac magnetic resonance imaging, computed tomography and cardiac catheterization may be necessary to separate the two conditions. Diagnostic error is serious because pericardiectomy does not correct restriction produced by intracavitary fibrosis.
Cardiac catheterization may be useful when filling pressures, pulmonary arterial pressure, pulmonary vascular resistance and cardiac output must be measured, or when the differential diagnosis remains uncertain. It may show elevated diastolic pressures, a dip-and-plateau waveform, increased right atrial or pulmonary capillary wedge pressure and signs of restriction. In patients eligible for surgery or transplantation, hemodynamic assessment is essential to estimate risk, especially if pulmonary hypertension is present. Coronary angiography or coronary computed tomography is requested according to age, risk factors and surgical planning, not because the disease is coronary in origin.
Etiological tests must be guided by the context. The complete blood count with differential should be repeated if intermittent eosinophilia is suspected. In the presence of persistent eosinophilia, hematological evaluation, search for secondary causes, investigations for hypereosinophilic syndrome, possible molecular tests for myeloproliferative neoplasms, and parasitological and serological tests appropriate to the geographical origin are required. Investigations may include testing for Strongyloides stercoralis, Schistosoma, filariae and other parasites according to the area of exposure. When systemic signs are present, vasculitides, connective tissue diseases, immunoglobulins, inflammatory markers and target organs are evaluated.
Endomyocardial biopsy is not necessary in every patient if imaging and clinical context are typical, but it may be useful in unclear cases, in non-endemic forms, when tumors, myocarditis, amyloidosis, sarcoidosis or active eosinophilic heart disease must be distinguished, and when the result may change therapy. Histology shows endocardial fibrosis, subendocardial thickening, organized thrombus, possible inflammatory infiltrate, eosinophils in active stages, calcifications and involvement of the valvular apparatus. A negative biopsy does not always exclude the disease if the sample does not capture the lesion, so the choice of site must be guided by imaging.
The final diagnosis integrates anatomy, function and cause. Advanced right ventricular endomyocardial fibrosis with ascites, huge right atrium, obliterated right apex, tricuspid regurgitation and tropical context differs from left-sided eosinophilic heart disease with recent apical thrombus and marked eosinophilia. Both may fall within the spectrum of restrictive endomyocardial diseases, but therapy, prognosis and follow-up differ. The diagnostic report should therefore specify the involved ventricle, severity, presence of thrombi, valvular regurgitation, pulmonary hypertension, arrhythmias, eosinophilic activity and excluded differential diagnoses.
The most useful classification of endomyocardial fibrosis combines anatomical site, evolutionary phase and hemodynamic severity. From an anatomical perspective, right-sided, left-sided and biventricular forms are distinguished. This distinction is not purely descriptive: it predicts the type of congestion, prevailing complications, surgical strategy and hemodynamic risk. The right-sided form tends to manifest with ascites, hepatomegaly, edema, tricuspid regurgitation and marked right atrial dilatation; the left-sided form with dyspnea, pulmonary venous hypertension, mitral regurgitation and systemic embolic risk; the biventricular form with more complex heart failure and a generally worse prognosis.
From an evolutionary perspective, the most coherent model includes a necrotic-inflammatory phase, a thrombotic phase and a fibrotic phase. The initial phase may be clinically silent or present with fever, chest pain, eosinophilia, myocardial injury, systemic symptoms and endocardial inflammation. The thrombotic phase follows endocardial injury: the damaged surfaces promote mural thrombi, particularly at the apices and along the inflow regions. The chronic phase is dominated by dense fibrosis, retraction, calcification, cavity obliteration, valvular deformation and restrictive physiology. In practice, many patients are observed only in the chronic phase, when the initial event can no longer be reconstructed.
Echocardiographic severity may be graded using scoring systems derived from population studies. These systems consider the extent of fibrosis, apical obliteration, valvular involvement, atrial dilatation, thrombi, restrictive pattern, pericardial effusion and other supportive elements. Mild forms may show localized thickening and minimal abnormalities; moderate forms show more evident lesions with impact on filling; severe forms have marked obliteration, significant valvular disease, enormously dilated atria and overt heart failure. Severity classification is useful for comparing patients and planning follow-up, but it does not replace clinical judgment.
Etiological classification distinguishes tropical forms of undefined etiology, forms associated with eosinophilia, forms secondary to hypereosinophilic syndromes, forms related to hematological diseases, forms associated with parasitic diseases or immune activation and isolated non-endemic forms. This distinction has decisive therapeutic implications. A form with active eosinophilia requires treatment of the eosinophilic cause and prevention of progressive damage; a scar-stage form without inflammatory activity primarily requires heart failure management, thromboembolic prevention and surgical evaluation; a form with suspected hematological neoplasm requires a specialist hematological pathway.
Hemodynamic classification evaluates right atrial pressure, pulmonary capillary wedge pressure, pulmonary arterial pressure, pulmonary vascular resistance, cardiac output, degree of mitral or tricuspid regurgitation and right ventricular function. It is particularly important in advanced patients, because the surgical decision depends not only on anatomy but also on reversibility of pulmonary hypertension, ventricular reserve, nutritional status, liver and renal function and severity of congestion. A patient with massive ascites, hypoproteinemia, renal failure and severe pulmonary hypertension has a very different operative risk from a patient with localized disease and good organ reserve.
The classification must finally separate endomyocardial fibrosis from mimicking conditions. Apical hypertrophic cardiomyopathy may simulate left apical obliteration, but the apical tissue is hypertrophic myocardium, not an endocardial fibrotic plaque. Ventricular noncompaction shows prominent trabeculation and deep recesses, not retracting endocardial fibrosis. A post-infarction apical thrombus derives from ischemic akinesia and coronary necrosis, not from diffuse endomyocardial disease. Constrictive pericarditis produces restriction without apical obliteration. These distinctions are necessary because they change treatment and prognosis.
The treatment of endomyocardial fibrosis depends on the phase of the disease. In advanced chronic stages, medical therapy is mainly symptomatic, because organized endocardial fibrosis does not regress with medications. The objectives are to control congestion, prevent thromboembolism, manage arrhythmias, treat any eosinophilia or underlying cause, correct valvular complications when possible and refer early to centers experienced in restrictive cardiomyopathies and surgery for endomyocardial diseases. Management must be individualized, because a patient with right-sided ascitic disease requires different priorities than a patient with left-sided thrombotic and embolic disease.
Diuretics are the basis of congestion control. Loop diuretics, sometimes combined with mineralocorticoid receptor antagonists, may reduce ascites, edema, effusions and dyspnea. Titration must be cautious because the rigid ventricle depends on adequate preload; excessive depletion may reduce output, worsen renal function and cause hypotension. In the right-sided form with major ascites, selected therapeutic paracenteses, correction of hyponatremia, nutritional management and monitoring of liver function may be necessary. Diuretic therapy improves symptoms, but does not remove the fibrotic plaque or correct ventricular obliteration.
Anticoagulation should be considered when intracavitary thrombi, atrial fibrillation, embolic history or marked atrial dilatation with stasis are present. The decision must balance embolic risk and bleeding risk, especially in patients with congestive hepatopathy, malnutrition, varices or thrombocytopenia. In the left ventricle, apical thrombus exposes the patient to systemic embolism; in dilated atria, atrial fibrillation further increases the risk. The mere presence of fibrosis without visible thrombus does not automatically imply anticoagulation in all patients, but requires careful echocardiographic surveillance.
Treatment of atrial arrhythmias is crucial. Atrial fibrillation worsens ventricular filling and may precipitate heart failure. Rate control must avoid both persistent tachycardia and excessive bradycardia; rhythm control may be attempted in selected cases, but enormously dilated atria reduce the chances of maintaining stable sinus rhythm. Antiarrhythmic medications and ablation must be evaluated cautiously, considering ventricular function, proarrhythmic risk, access to follow-up and need for anticoagulation. In patients with conduction blocks or symptomatic bradyarrhythmias, pacing may be necessary, but the indication must be based on the specific electrical phenotype.
When active eosinophilia or hypereosinophilic syndrome is present, etiological treatment becomes a priority. Corticosteroids, immunomodulatory therapies, antiparasitic treatment, targeted hematological therapy or tyrosine kinase inhibitors in appropriate molecular subtypes may prevent further endocardial damage if introduced during the active phase. The choice must not be empirical: it requires identification of the cause of eosinophilia, exclusion of infections that could worsen with immunosuppression, hematological evaluation and cardiac monitoring. In the purely fibrotic phase, instead, immunosuppression has a much more limited rationale if there is no persistent inflammatory activity.
Surgery is the most relevant option in selected patients with advanced disease and severe symptoms. The operation may include endocardiectomy, endocardial decortication, removal of organized thrombus, release of the subvalvular apparatus, and mitral and tricuspid repair or replacement. The objective is to increase the functional ventricular cavity, improve filling, reduce valvular regurgitation and relieve congestion. However, this surgery is complex, technically difficult and burdened by significant operative mortality, especially in malnourished or cachectic patients, and in those with liver or renal failure, advanced pulmonary hypertension or severe biventricular disease.
Surgical selection must be very accurate. The best candidates are symptomatic patients not controlled by medical therapy, with correctable anatomical lesions, significant but potentially treatable valvular disease, sufficient ventricular reserve and acceptable operative risk. Patients in advanced functional class may derive symptomatic benefit, but if the operation is performed too late the risk may exceed the benefit. Preoperative assessment must include detailed echocardiography, cardiac magnetic resonance imaging or computed tomography, catheterization when indicated, evaluation of liver and renal function, nutritional status, coagulation and presence of thrombi.
Heart transplantation is theoretically conceivable in terminal non-correctable cases, but in practice it is limited by availability, comorbidities, pulmonary hypertension, socioeconomic context and access to transplant programs. In countries where the disease is more frequent, access to transplantation is often very limited. In non-endemic countries, it may be evaluated in selected cases of refractory heart failure, after exclusion of treatable active causes and after definition of pulmonary vascular resistance. Ventricular assist devices are less straightforward than in dilated cardiomyopathies, because the ventricular cavities may be small, obliterated and anatomically deformed.
The prognosis is often unfavorable when diagnosis occurs in an advanced stage. Negative prognostic factors include biventricular form, high functional class, persistent ascites, severe tricuspid or mitral regurgitation, pulmonary hypertension, atrial fibrillation, intracavitary thrombi, embolic events, malnutrition, renal failure, congestive hepatopathy, extensive calcifications and inability to access expert surgery. Mild or early-detected forms may remain stable longer, but require surveillance because progression may be slow and then accelerate with arrhythmias, infections, pregnancy, anemia or worsening valvular regurgitation.
Follow-up must monitor symptoms, weight, ascites, edema, blood pressure, heart rate, rhythm, renal function, electrolytes, liver function, natriuretic peptide, complete blood count with differential, any eosinophilia, periodic echocardiography, thrombi, severity of valvular regurgitation and pulmonary pressure. In patients with an eosinophilic context, the activity of the underlying disease must also be monitored. In operated patients, follow-up must assess recurrence of fibrosis, function of repaired or replaced valves, arrhythmias, anticoagulation and residual congestion. Monitoring cannot be limited to prescribing a diuretic, because the disease involves the heart, venous system, liver, kidney, coagulation and nutritional status.
The most frequent complication is restrictive heart failure. In the right-sided form, ascites, hepatomegaly, edema, jugular venous distension and tricuspid regurgitation predominate; in the left-sided form, dyspnea, pulmonary congestion, pulmonary venous hypertension and mitral regurgitation predominate; in the biventricular form, the two components add together. Heart failure results from the inability of the fibrotic ventricle to fill at low pressure and from the reduction of the functional cavity. Even when global systolic function appears preserved, effective output may be insufficient during exercise or in advanced stages.
Ascites is a particularly characteristic complication of the right-sided form. It may be massive, recurrent and disproportionate to peripheral edema. It develops due to increased systemic venous pressure, hepatic congestion, sinusoidal hypertension, hydrosaline retention, reduced renal perfusion and neurohormonal activation. Over time, it may contribute to malnutrition, sarcopenia, infections, reduced mobility and worsening quality of life. Its persistence is a sign of hemodynamically significant disease.
Atrioventricular valvular disease is part of the disease and not a simple association. Tricuspid regurgitation results from retraction of the subvalvular apparatus, annular dilatation and deformation of the right ventricle; mitral regurgitation arises from similar mechanisms in the left ventricle. Regurgitation increases atrial volume, promotes dilatation, arrhythmias, congestion and worsening heart failure. In advanced cases, valvular disease may become the main determinant of symptoms and one of the reasons to consider surgery.
Intracavitary thrombosis and embolic events are central complications. Thrombus may form on damaged endocardial surfaces, in obliterated apices or in dilated atria. In the left heart, it may cause ischemic stroke, peripheral embolism, renal, splenic or mesenteric ischemia. In the context of atrial fibrillation, the risk increases further. Organized thrombus may also become part of the fibrotic mass that obliterates the apex, making it difficult to distinguish scar lesion from recent thrombotic component. This distinction is relevant because recent thrombus may respond to anticoagulation, whereas organized fibrosis does not.
Atrial arrhythmias are promoted by atrial dilatation and fibrosis. Atrial fibrillation and atrial flutter reduce the atrial contribution to ventricular filling, increase embolic risk and worsen congestion. The fibrotic ventricle poorly tolerates both tachycardia, because it shortens diastole, and bradycardia, because stroke volume cannot increase enough to compensate. For this reason, rhythm and rate control have direct hemodynamic value. Ventricular arrhythmias are less typical, but may appear in the presence of extensive fibrosis, myocardial damage, hypoxia, electrolyte abnormalities or advanced stage.
Pulmonary hypertension may develop especially in left-sided or biventricular forms. Chronic elevation of left atrial pressure is transmitted to the pulmonary venous circulation; over time, vasoconstriction, vascular remodeling and increased pulmonary resistance may appear. This complication worsens right ventricular function, increases surgical risk and may limit eligibility for transplantation. Its assessment requires echocardiography and, in advanced cases or in patients eligible for intervention, cardiac catheterization.
Congestive hepatopathy results from chronic venous stasis. The liver may become enlarged, painful and functionally compromised; cholestasis, hyperbilirubinemia, coagulation abnormalities and, in prolonged cases, congestive fibrosis may appear. Hepatic impairment increases operative risk, modifies anticoagulation management and promotes persistent ascites. The kidney is also involved through reduced output, increased renal venous pressure, hypotension and diuretics, with development of cardiorenal syndrome.
Cardiac cachexia and malnutrition are frequent in advanced forms, especially in endemic settings. Intestinal congestion, anorexia, chronic inflammation, ascites, increased work of breathing, poverty and recurrent infections contribute to loss of muscle mass. Malnutrition reduces tolerance to surgery, increases infectious risk and worsens recovery capacity. In children, it may translate into growth delay and general frailty.
Surgical complications must be considered part of the pathway. Endocardiectomy and valvular surgery may improve symptoms and survival in selected patients, but they are burdened by the risk of bleeding, conduction blocks, ventricular failure, embolism, residual valvular dysfunction, arrhythmias, low output and perioperative mortality. The risk is higher when the operation is performed in a very advanced stage, with congested organs and a malnourished patient. The therapeutic choice therefore requires a balance between the natural progression of the disease and the risk of the intervention.
A relevant diagnostic complication is misclassification. Mistaking endomyocardial fibrosis for constrictive pericarditis may lead to inadequate surgical treatment; confusing it with idiopathic restrictive cardiomyopathy may cause missed opportunities to search for eosinophilia, parasitic diseases, thrombi and surgical indications; interpreting it solely as cirrhosis or hepatic ascites may delay the cardiological diagnosis for years. In a rare and geographically unequal disease, early recognition is already a form of complication prevention.