AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Background

Endomyocardial fibrosis (EMF) is an idiopathic disorder of the tropical and subtropical regions of the world that is characterized by the development of restrictive cardiomyopathy.

The nosology of EMF coincides with some related disorders. EMF is sometimes considered part of a spectrum of a single disease process that includes Löffler endocarditis (nontropical eosinophilic endomyocardial fibrosis or fibroplastic parietal endocarditis with eosinophilia).

Tropical EMF and Löffler endocarditis should be distinguished from endocardial fibroelastosis, which is characterized by cartilaginous thickening of the mural endocardium, chiefly of the left ventricle. This disease is most common in the first 2 years of life and, in some patients, appears to be an inherited disorder that is associated with congenital cardiac malformations.

Pathophysiology

In EMF, the underlying process produces patchy fibrosis of the endocardial surface of the heart, leading to reduced compliance and, ultimately, restrictive physiology as the endomyocardial surface becomes more generally involved. Endocardial fibrosis principally involves the inflow tracts of the right and left ventricles and may affect the atrioventricular valves, leading to tricuspid and mitral regurgitation.

The earliest changes of EMF are not well described because most patients do not present with symptoms until relatively late in the clinical course. Olsen described 3 phases of EMF. The first phase involves eosinophilic infiltration of the myocardium with necrosis of the subendocardium and a pathologic picture consistent with acute myocarditis. This is reportedly present in the first 5 weeks of the illness. The second stage, typically observed after 10 months, is associated with thrombus formation over the initial lesions, with a decrement in the amount of inflammatory activity present. Ultimately, after several years of disease activity, the fibrotic phase is reached, when the endocardium is replaced by collagenous fibrosis. Extensive calcification is rarely associated with fibrosis. This pathomorphologic schema is not observed uniformly and has not been consistently supported by other investigators.

The etiopathogenesis of EMF remains unclear. Hypotheses include infectious, inflammatory, and nutritional processes. EMF is frequently associated with concomitant parasitic infections (eg, helminths) and their attendant eosinophilia, although the role of parasitic infections and/or the eosinophil remains speculative. The development of EMF as a sequela to toxoplasma-related myocarditis has also been described, as has a relationship of malarial infection to development of EMF. However, no specific organism has been consistently associated with EMF.

The role of the eosinophil in the pathogenesis of EMF is controversial. Whether the eosinophil actually induces myocardial necrosis and subsequent fibrosis or is attracted to the endocardial surface as a result of the initial insult is unknown. The eosinophil is not present as frequently in cases of tropical EMF as in Löffler endocarditis; thus, the role of the eosinophil in the tropical disease is likely less significant.

EMF is most frequently observed in the socially disadvantaged and in children and young women. These groups frequently have malnutrition, and in regions of sub-Saharan Africa where the disease is most prevalent, the typical diet is high in a tuber called cassava, which contains relatively high concentrations of the rare earth element cerium (Ce). The combination of high Ce levels and hypomagnesemia has been shown to produce EMF-like lesions in laboratory animals.

A familial tendency has rarely been noted in Uganda and Zambia.

Frequency

United States

EMF is rarely encountered in patients who have not traveled from the subtropical regions of Africa and tropical and subtropical regions elsewhere in the world, including areas in India and South America that are within 15° of the equator. Löffler endocarditis (also called nontropical eosinophilic endocarditis) is a related condition that is observed in the United States and is considered by some authors to be a different stage of a similar process related to eosinophilia.

International

EMF occurs primarily in the subtropical regions of Africa but is also encountered in tropical and subtropical regions elsewhere in the world, including areas in India and South America that are within 15° of the equator.

More than 90% of reported cases of EMF have occurred in geographic locations that are within 15° of the equator. In equatorial African nations, such as Nigeria, EMF is the fourth most common cause of cardiac disease in adults, and EMF accounts for 22% of cases of heart failure in Nigerian children. EMF is the most common type of restrictive cardiomyopathy in tropical countries.

Mortality/Morbidity

• The overall prognosis of patients with EMF is poor and depends on the extent and distribution of disease within the various chambers and valves of the heart.
• Most patients have extensive disease at the time of presentation; therefore, survival after diagnosis is relatively brief. In one study, 95% of a group of patients had died at 2 years. In a second study, 44% of patients died within 1 year after the onset of symptoms, and another 40% of patients died 1-3 years after onset.

Race

EMF is most commonly reported in individuals living in Nigeria and Uganda.

Sex

Women of reproductive age and children are more commonly affected than men.

Age

• EMF is not generally observed in children younger than 4 years, although the typical pathology for EMF has recently been described in a 4-month-old infant with left ventricular inflow tract obstruction.
• The people most commonly affected are older children (aged 5-15 y) and young adults, but cases have been reported in individuals aged 70 years.

CLINICAL

Section 3 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

History

Typically, endomyocardial fibrosis (EMF) has an insidious onset, and symptoms relate to the specific chambers and valves where the disease is most extensive.

• When right ventricular involvement or tricuspid regurgitation predominates, lower extremity swelling, increasing abdominal girth, and nausea may be expected.
• With left ventricular involvement, dyspnea is the predominant symptom, especially exertional dyspnea. Additionally, fatigue, paroxysmal nocturnal dyspnea, and orthopnea may be present.
• Thromboembolic complications may occur in EMF.
• Rarely, patients may present early in the course of the disease with an acute febrile illness with symptoms of cardiac insufficiency mimicking myocarditis.
• Recently, anginalike chest pain and syncope were reported in a patient with EMF involving the left ventricle.

Physical

Physical findings are also dependent on the extent and distribution of disease.

• In those with right ventricular involvement, jugular venous pressure elevation, ascites, and edema may be present.
• • The presence of ascites may appear out of proportion to the amount of peripheral edema. This may occur because of the concomitant presence of a protein-losing enteropathy and subsequent hypoalbuminemia.
  • Patients with tricuspid regurgitation may have giant V waves observed in the jugular venous pulsations.
  • A third or fourth heart sound and tachycardia may be present.
• Signs of pulmonary congestion are present in patients with left-sided disease.

Causes

A specific single etiology of EMF has not been established. Suggested potential causes include the following:

• Infectious causes
• • Parasites (eg, helminths)
  • Protozoans (eg, toxoplasmosis, malaria)
• Inflammatory causes - Eosinophilia
• Nutritional causes
• • General malnutrition
  • High-tuber diet
  • Ce toxicity
  • Hypomagnesemia

DIFFERENTIALS

Section 4 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Anthracycline toxicity
Carcinoid heart disease
Drug-induced cardiotoxicity (eg, serotonin, methysergide, ergotamine, mercurial agents, busulfan)
Fabry disease
Fatty infiltration
Gaucher disease
Glycogen storage disease
Hurler disease
Idiopathic cardiomyopathy
Metastatic cancers
Radiation
Rheumatic heart disease
Occasionally, a masslike lesion seen in endomyocardial fibrosis masquerades as an intracardiac tumor.

WORKUP

Section 5 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Lab Studies

• Complete blood cell count may show anemia and eosinophilia.

Imaging Studies

• Chest radiography
• • The cardiac silhouette in endomyocardial fibrosis (EMF) may be normal in size, and generalized cardiomegaly is unusual because the ventricles are not typically dilated.
  • The roentgenographic image may exhibit significant enlargement of the atria, and significant right atrial enlargement creates a cardiac silhouette in the shape of the African continent, which is a specific heart shadow sign that has been termed the heart of Africa.
• Echocardiography
• • Echocardiography is a useful tool when making the diagnosis of EMF and has been demonstrated to successfully differentiate EMF and other processes such as rheumatic heart disease and congenital heart disease.
  • The presence and location of fibrosis as determined by echocardiography correlates well with autopsy findings.
  • Findings include thickening of the inferior and basal left ventricular wall, apical obliteration, thrombi adherent to endocardial surface, mitral regurgitation, and tricuspid regurgitation.
  • A pericardial effusion is frequently present and may be large.
  • While parameters of diastolic function by Doppler echocardiography tend to correlate with the functional status of the patient, because most patients present with later stages of EMF, a restrictive filling pattern in the left ventricular outflow tract is most common.
  • Recently, decreased flow propagation velocity (Vp) has been demonstrated in a large percentage of patients with EMF.
  • Color-flow imaging frequently exhibits tricuspid and mitral regurgitation. Spectral Doppler analysis of tricuspid regurgitation frequently reflects an increased pulmonary artery systolic pressure.
• Angiography
• • Traditionally, angiography has been considered the criterion standard when making the diagnosis of EMF.
  • Left and right ventriculography exhibits distortion of chamber morphology by fibrosis and obliteration and variable degrees of mitral and tricuspid regurgitation.
  • The mushroom sign has been used to describe the shape of the affected ventricle when the apex is obliterated completely by fibrosis.
• Electron beam computed tomography scanning
• • Features of EMF observed with this modality were described in the mid 1990s.
  • The fibrotic process is delineated as a band of low attenuation within the endocardium.
  • Obliteration of the apex and inflow tract, when present, is also demonstrated.
  • This method reportedly assists in distinguishing EMF from constrictive pericarditis.
• Cardiovascular magnetic resonance imaging: Recently, the use of cardiovascular magnetic resonance imaging has been shown to demonstrate obliterative changes in the ventricles, atrial dilation, and regurgitant atrioventricular valve lesions in patients with EMF. However, the use of contrast-enhanced imaging was not able to demonstrate fibrosis within the ventricles of these patients.

Other Tests

• Electrocardiography
• • Atrial fibrillation
  • Low QRS voltage
  • First-degree atrioventricular block in up to 44% of patients
  • Incomplete right bundle-branch block in up to 30% of patients
• Left atrial enlargement

Procedures

• Cardiac catheterization likely exhibits hemodynamic findings consistent with restrictive cardiomyopathy.
• Findings from endomyocardial biopsy may be diagnostic, but this procedure is typically not needed.
• • Biopsy findings may be nondiagnostic when the disease is patchy and sampling sites do not correlate with areas of disease.
  • Because biopsy (especially from the left ventricle) carries some risk, reserve the use of this technique until other diagnostic approaches have been used.

Histologic Findings

The heart size is not usually enlarged in EMF. The ventricular cavities are frequently laden with thrombi and, in severe cases, may be nearly totally obliterated by endocardial thickening and thrombosis. The histologic findings of EMF are characterized by reactive fibrosis associated with a selective increase in type I collagen deposition, subendocardial infarction and fibrosis, and thrombus formation. Additionally, specific features of other diseases, such as those associated with hemochromatosis or glycogen storage disease, are notably absent.

TREATMENT

Section 6 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical Care

• In general, the response to medical therapy is poor and unproven.
• Because most patients with endomyocardial fibrosis (EMF) present long after any possible period of early active myocarditis may have existed, little, if any, role exists for immunosuppressive therapy as is used in some patients with Löffler disease.
• Symptomatic therapy with diuretics has been shown to be useful, but digoxin, afterload reducers, and beta-blockers have little role in EMF.
• For patients with severe symptoms, consider surgical therapy because the prognosis for these patients with continued medical therapy alone is dismal.
• Because the rate of thromboembolism is low among patients with EMF and the patient population affected is not typically compliant with anticoagulation regimens, most authors do not recommend anticoagulant therapy.

Surgical Care

• Surgical therapy by endocardial decortication seems to be beneficial for many patients with advanced disease who are in functional-therapeutic class III or IV. The operative mortality rate is high (15-20%), but successful surgery has a clear benefit on symptoms and seems to favorably affect survival as well.
• The most commonly used approach is endocardiectomy, combined with mitral and/or tricuspid repair or replacement (when indicated), using a midline thoracotomy and cardiopulmonary bypass.
• • Depending on the location of the disease (right or left ventricle, apex or inflow tract), a transapical or transventricular approach can be used.
  • Because a well-defined plane of cleavage usually exists between the endocardium and myocardium, endocardiectomy is most frequently feasible.
  • Because the myocardium is not usually affected, the severe hemodynamic derangement associated with EMF is relieved with successful resection of the endocardium.
  • Common postoperative complications include low cardiac output, heart block, and ventricular arrhythmias.

Diet

No specific diet is recommended for this condition.

Activity

No activity restrictions are recommended because activity restrictions have not been proven to alter the prognosis of this condition, and no specific activity has been shown to hasten the onset of fatal arrhythmias or sudden death.

FOLLOW-UP

Section 7 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Transfer

• Transfer suitable patients with severe symptoms for consideration of endomyocardial resection. Although the operative mortality rate is high (approximately 20%), prognosis is favorably altered in those that survive the surgery.
• Consider heart transplant in patients who are classified in function class III or IV.

Deterrence/Prevention

• No specific preventive measures have been proven effective.

Complications

• Common postoperative complications include low cardiac output, heart block, and ventricular arrhythmias.

Prognosis

• Prognosis for this condition is poor. Incidence of sudden cardiac death from fatal arrhythmias or from progressive cardiac failure is high.
• Most patients have extensive disease at the time of presentation; therefore, survival after diagnosis is relatively brief. In one study, 95% of a group of patients had died at 2 years. In a second study, 44% of patients died within 1 year after the onset of symptoms, and another 40% of patients died 1-3 years after onset.

Patient Education

• Inform patients about the poor prognosis and increased likelihood of fatal and nonfatal arrhythmias.

MISCELLANEOUS

Section 8 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• As with other forms of restrictive cardiomyopathy, distinguish endomyocardial fibrosis (EMF) from constrictive pericarditis.

REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

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Article Last Updated: Jan 17, 2006