AUTHOR AND EDITOR INFORMATION

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INTRODUCTION

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Background

The term endocardial fibroelastosis (EFE) was introduced by Weinberg and Himmelfarb in 1943.¹ EFE refers to a pronounced, diffuse thickening of the ventricular endocardium and presents as unexplained heart failure in infants and children. The disease can be primary or secondary to various congenital heart diseases, most notably hypoplastic left heart syndrome, aortic stenosis, or atresia. The 2 pathologic forms of primary EFE include dilated, which is most common, and contracted. Primary EFE is not associated with any significant structural anomaly of the heart. Secondary EFE is associated with other congenital heart diseases. Once regarded as a common cause of unexplained heart failure, EFE is now considered rare.

Pathophysiology

EFE is characterized by diffuse endocardial thickening and myocardial dysfunction. The endocardial thickening is believed to be caused by persistent and increased wall tension in the ventricles, possibly secondary to damaged myocardium, mitral regurgitation, or both. However, EFE changes are progressive with age. The disease is usually sporadic, but familial cases have been reported (10%). Observations that favor a viral etiology include a clinical presentation similar to that of chronic myocarditis, findings of myocarditis or myocardial fibrosis in affected patients, a higher incidence following epidemics of coxsackievirus B infection, demonstration of persistent viral infection with molecular studies, and experimental production of the disease in animal models by viral infections of the myocardium. A phenotypic resemblance to dilated cardiomyopathy has been noted.

Dilated EFE is characterized by a markedly enlarged globular heart, mainly involving the left ventricle (LV) and left atrium (LA). The LV endocardium is opaque, glistening, milky white, and diffusely thickened to about 1-2 mm. The thickening is most marked in the outflow tract.

Papillary muscles arise more superiorly on the ventricular wall with thickened and shortened chordae tendineae, the characteristic rolled-free edge of mitral leaflets. Papillary muscles and trabeculae carneae are flattened and partially incorporated in the fibrotic process, giving a smooth appearance to the lining of the cavity; thus, the papillary muscles exert an undesirable lateral traction on the chordae tendineae and mitral cusps, leading to faulty leaflet opposition.

Although the endocardium is thickened, the ventricular wall (myocardium) thickness is within the reference range. Endocardial thickening extends to the LA, right ventricle, and right atrium. Microthrombi may adhere to the endocardium. The right ventricle is anteriorly displaced to the right, and its cavity is usually flattened. The pulmonary artery may be enlarged, but the aorta and coronary arteries appear normal in caliber. In approximately 50% of patients, the mitral and aortic valves are involved, often producing marked deformity and either valvar regurgitation or stenosis.

The less common contracted type of primary EFE is associated with a relatively hypoplastic or normal LV size. The right and left atria and the right ventricle are markedly enlarged and hypertrophied, with minimal or no endocardial sclerosis. An early event in fetal life is believed to result in dilated EFE, which later morphoses into a contracted type. This suggests that the dilated type could appear as 2 different diseases while remaining a single disease. Secondary EFE, associated with cardiac malformations, is attributed to the cardiac hypertrophy and consequent imbalance in the myocardial oxygen supply-demand relationship. Resultant fibroelastotic thickening is often focal and less severe.

Acute congestive heart failure (CHF) becomes progressive CHF that results in death within weeks, usually within the first 6 months of life. In a subgroup of individuals who survive from a few months to several years, a more chronic course is common. Such patients respond to medications used to treat CHF. A variable cyclical clinical course ensues, with CHF recurrences related to respiratory or other intercurrent infections or to progression of disease. Remissions can occur with intensification of medical therapy.

Frequency

United States

A 1964 study demonstrated an incidence rate of 1 per 5,000 live births.² The incidence over subsequent years has been markedly reduced for unknown reasons, with almost no new cases in the current era. The disappearance of this condition is believed to be related to the declining prevalence of mumps.

International

A 1978 study reported that EFE comprised 1-2% of all congenital heart diseases.³ Currently, the number of EFE cases has dramatically fallen to almost zero. The idiopathic form of the disease is sporadic, but familial cases are also reported (10%).

Mortality/Morbidity

• Progressive CHF causes deteriorating conditions that lead to death in one third of patients. One third of the patients survive and may experience persistent symptoms or have residual ECG abnormalities or evidence of cardiomegaly. Although some authorities are skeptical, some believe that approximately one third of the patients completely recover. Early diagnosis and prompt persistent administration of digitalis may result in clinical improvement and reversion of the cardiac enlargement (CE) to normal.
• Morbidity varies depending on presentation. Infants who present with acute failure almost always die from the acute episode unless they receive a transplant.
• Patients with a chronic presentation have a 30-40% mortality rate due to resistant heart failure.
• Contracted EFE has a grave prognosis and is generally fatal.

Sex

EFE affects both sexes equally.

Age

EFE presents during the first 3-6 months of life in 80% of cases. The typical age at diagnosis is 2-12 months. EFE is rarely reported in adolescents and adults and is an important cause of nonimmune hydrops fetalis.

CLINICAL

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History

• Symptoms include feeding difficulty, excessive sweating, breathlessness, failure to thrive, and wheezing.
• Onset may acute enough to produce cardiogenic shock or sudden death; it is a recognized cause of sudden death in infancy.
• Approximately 20% of patients have a history of frequent or recent respiratory tract infections.
• Episodes of severe sudden abdominal pain may indicate coronary insufficiency.
• The contracted form of endocardial fibroelastosis (EFE) presents with features of left-sided obstructive disease and acute LV failure.
• EFE is one of the recognized causes of nonimmune hydrops fetalis.

Physical

• EFE manifests as the classic features of heart failure.
• Tachypnea during feeding and grunting respirations with subcostal or intercostal retractions have been reported. Fine expiratory wheezes or rales in the lung bases are common.
• The following may be present upon admission:
• • Pallor
• • Peripheral cyanosis
• • Fever
• • Leukocytosis
• • Anemia
• • Rash
• Thromboembolic episodes may lead to sudden death, myocardial infarction, cerebrovascular events, or even pulmonary embolism.
• The usual physical findings are as follows:
• • Cardiomegaly with normal-to-faint first and second heart sounds, a gallop rhythm with an audible third heart sound, apical pansystolic murmur of mitral regurgitation, and hepatosplenomegaly
• • Clinically detectable pleural or pericardial effusions (rare)

Causes

• Possible causative factors include intrauterine viral infection (mumps, coxsackievirus B), subendocardial ischemia, impaired lymphatic drainage of the heart, and systemic carnitine deficiency. Using polymerase chain reaction (PCR) analysis, Ni et al reported that the mumps viral genome persisted in the myocardium of children with EFE; however, this requires further study.⁴ The authors suggested cause and effect and speculated that the disease disappeared after the initiation of the measles-mumps-rubella (MMR) vaccination.
• Nine patients with familial EFE were reported in 4 families, and inheritance patterns included X-linked recessive, autosomal dominant, and autosomal recessive.⁵ Recently, mutation of the gene G4.5 (tafazzin) has been associated with familial X-linked EFE and Barth syndrome and has been reported to result in morphologic changes in the fetal heart as early as 18 weeks' gestation.
• Dilated (primary) EFE occurs when the heart is otherwise normal and no other cause of unexplained heart failure, including systemic carnitine deficiency, is demonstrable. Dilated EFE (secondary) is associated with aortic stenosis or atresia and includes coarctation of the aorta, ventricular septal defect, anomalous origin of left coronary artery from the pulmonary artery, myocardial injury from any cause, and metabolic or carnitine deficiency. Contracted EFE (secondary) is associated with hypoplastic left heart syndrome.

DIFFERENTIALS

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Other Problems to be Considered

Congenital heart diseases (especially LV outflow tract obstruction)
Other causes of nonimmune hydrops fetalis
Neonatal lupus erythematosus
Left ventricular noncompaction
Centronuclear myopathy

WORKUP

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Lab Studies

Blood tests include the following:

• Serum electrolyte levels
• BUN and creatinine levels
• CBC count
• Blood culture tests indicated for management of acute episodes
• Autoantibody profile including anti-Ro and anti-La

Imaging Studies

• Chest radiography
• • Cardiomegaly and cardiothoracic ratios exceed 0.65 in 50% of patients.
  • CE is present in some patients at birth. In others, the heart size is normal during the first few weeks to the first few months of life, but CE subsequently develops.
  • The shape of the cardiac silhouette varies, although it is often globular.
  • Pulmonary venous congestion is common.
  • Left lower lobe atelectasis secondary to dilated LA is found in 25% of patients.
• Echocardiography
• • LA and LV dimensions are increased.
• • LV, septal, and posterior wall (PW) excursions are reduced.
• • The ejection fraction (EF) is reduced.
• • Mitral valve (MV) motion is abnormal.
• • Echogenicity along the endocardium of the LV (diagnostic clue) is dense.
• • Suggestive indicators include increased endocardial echo brightness and globular shape of the LV.
• • The echocardiograph may depict a normalization of the shortening fraction and the LV dimensions when the clinical condition improves following medical therapy.
• • A varying degree of mitral regurgitation is common.
• Fetal echocardiography
• • This is a valuable tool for early identification, particularly of the secondary type.
• • One of the congenital malformations (eg, aortic stenosis) is often demonstrated at the initial study. The EFE becomes obvious in repeat studies.
• Recently, electron beam CT has been reported to be useful in the early diagnosis of EFE because of its demonstration of calcification and fibrosis of the ventricles, especially at the apex.
• Myocardial delayed-enhancement MRI has been reported to assist in delineation of the extent of endocardial fibroelastosis.

Other Tests

• The 24-hour Holter ECG is useful in documenting ambient arrhythmias.
• Electrocardiography
  
  
  • Tall R waves, deep Q waves, and T-wave inversion or flattening in the left precordial or inferior lead have been reported. 
  • Findings depict LV hypertrophy in more than 75% of patients.
  • In the first few weeks of life, right axis deviation and isolated right ventricular hypertrophy are more common.
  • Pulmonary hypertension may develop in patients who survive for a long period and appears as biventricular hypertrophy on electrocardiography.
  • Patterns of left, right, or biatrial enlargement are evident in 50% of patients.
  • Conduction or rhythm abnormalities include Wolff-Parkinson-White syndrome, left bundle branch block, supraventricular and ventricular arrhythmias, and varying degrees of atrioventricular block.
  • Low-voltage tracings in the initial stage of heart failure and in the terminal phase are noted in 5% of patients.
  • Occasionally, an infarct pattern appears, pointing to extensive myocardial fibrosis and necrosis.

Procedures

• Cardiac catheterization
• • Cardiac chambers and pulmonary arteries contain elevated pressures consistent with heart failure. Generally, systolic pulmonary artery pressure is not more than 50% of systemic pressure. Marked pulmonary hypertension may be seen in older children.
  • The constrictive type of EFE is rare and is associated with a left-sided atrioventricular obstructive pattern, with very high LA pressures from an early age. A diastolic gradient can be detected across the MV. Pulmonary artery pressure is elevated and often reaches systemic levels in this type of EFE.
  • Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction due to thrombosis or spasm.
  • Complications may include blood vessel rupture, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.
• Angiocardiographic findings
• • Marked dilation of the LV cavity
• • Reduced EF with little or no LV wall thickening
• • Dyskinetic LV contraction
• • Mitral regurgitation (common)
• • In the contracted type, dilated right ventricle, right atrium, and pulmonary artery  with slow clearance of the contrast from the left side of the heart
• Digital subtraction angiography may demonstrate an avascular rim between the opacified LV cavity and the ventricular walls perfused by the coronary arteries. The contrast void rim can be identified even in ordinary cineangiographic films.
• In cases in which the diagnosis is unclear, myocardial biopsy can be helpful.

Histologic Findings

Endomyocardial biopsy shows an invasion of the endocardium and subendocardium by fibroelastic tissue. Abnormalities are largely confined to the endocardium, with marked hyperplasia of its constituents, especially collagen and elastic fibers; hence, the basic abnormality in EFE appears to involve the synthesis of abnormally large amounts of collagen and elastin rather than a qualitative change in the structure of elastic fibers. Surface deposits of fibrin have also been detected using electron microscopy. The underlying myocardium generally appears normal.

TREATMENT

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Medical Care

• The treatment of endocardial fibroelastosis (EFE) is essentially the same as that of chronic cardiac failure; its acute exacerbations are often precipitated by respiratory infections.
• Early and prolonged treatment with digoxin is suggested. Continue therapy for several years after the symptoms disappear; cessation of drug administration may result in acute cardiac failure, even when heart size has returned to normal.
• Other measures for acute failure and exacerbations of failure may be required, and precipitating factors, such as infection and anemia, require attention.
• Anticoagulation may be required in the presence of thromboembolic complications.
• Case reports in the literature cite resolution of antenatally diagnosed EFE associated with positive anti-Ro and anti-La antibodies with corticosteroid therapy.

Surgical Care

• Both pericardial poudrage and MV replacement have had disappointing results.
• Cardiac transplantation may be recommended for patients with end-stage disease.

Consultations

• Pediatric cardiologist
• Radiologist
• Nuclear medicine specialist
• Family physician
• Occupational therapist
• Physiotherapist
• Psychologist
• School teacher
• Specialist nurse
• Pharmacist
• Dietitian

Diet

• Diet is dictated by the underlying heart disease and degree of malnutrition.

Activity

• Limitations to activity are dictated by the symptomatology.

MEDICATION

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If the patient is asymptomatic and his or her heart size is normal, provide early, adequate, and prolonged therapy with digitalis and diuretics for at least 2-3 years, with gradual discontinuation. 

Early and prolonged treatment with digoxin is suggested. Anticoagulants may be required in the presence of thromboembolic complications.

Antibiotics for endocarditis prophylaxis are administered to patients with certain cardiac conditions, such as endocardial fibroelastosis, before procedures that may cause bacteremia are performed. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.

Drug Category: Diuretics

These agents are used to eliminate retained fluid and to lower preload.

Drug Category: ACE inhibitors

These agents reduce afterload and decrease myocardial remodeling, which worsens chronic heart failure.

Drug Category: Cardiac glycosides

These agents provide symptomatic improvement.

Drug Category: Oral anticoagulants

These agents prevent recurrence of thromboembolic episodes of cardiac origin.

FOLLOW-UP

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Further Inpatient Care

• Further inpatient care may be required for exacerbations of heart failure and for invasive procedures.

Further Outpatient Care

• Schedule regular follow-up care until symptoms subside and cardiac size and function are normal.

Deterrence/Prevention

• Withdrawal of therapy may lead to reappearance of symptoms.

Complications

• Resistant cardiac failure
• Recurrent chest infections
• Severe failure to thrive
• Cardiac cirrhosis
• Cerebral, coronary, and pulmonary thromboembolism
• Persistent collapse of left lower lobe or entire left lung

Prognosis

• Primary endocardial fibroelastosis (EFE) prognosis is relatively poor, although the condition is not universally fatal.
• The prognosis is worse if onset of heart failure occurs earlier.
• Congestive heart failure
  
  
  • Acute CHF becomes progressive CHF and terminates in death within weeks, usually within the first 6 months of life.
  • In patients who survive from a few months to several years, a more chronic course is common. Such patients respond to medications for CHF. A variable cyclical clinical course ensues, with CHF recurrence related to respiratory or other intercurrent infections or to progression of disease. Remissions can occur through intensification of medical therapy.
  • Progressive CHF causes deteriorating conditions that lead to death in one third of patients. One third of the patients survive and may experience persistent symptoms or show residual ECG abnormalities or evidence of cardiomegaly. Some believe that approximately one third of patients completely recover, although others are skeptical.
  • Early diagnosis and prompt persistent administration of digitalis may result in clinical improvement and reversion of the ECG and CE to normal.
  • Poor prognostic signs of CHF include (1) presentation in the newborn period and (2) recurrent episodes of CHF despite adequate therapy, especially if episodes recur more than 6 months after initial onset of symptoms.

Patient Education

• Withdrawal of therapy may lead to reappearance of symptoms.
• Permit activity to the limit of tolerance.

MISCELLANEOUS

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Medical/Legal Pitfalls

• Failure to identify the disease or to rule out specifically treatable diseases in the differential diagnosis (eg, carnitine deficiency)
• Failure to recognize an associated congenital heart disease
• Failure to counsel the parents and caregivers on prognosis
• Premature discontinuation of medication

Special Concerns

• Make all possible efforts to detect any treatable cause, such as congenital heart disease or systemic carnitine deficiency.
• Risk of endocardial fibroelastosis (EFE) in subsequent pregnancies is 3-5% and warrants fetal echocardiography for early diagnosis.

MULTIMEDIA

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Media file 1:  Chest radiograph, anteroposterior view, showing cardiomegaly and pulmonary venous congestion in a 6-month-old infant with endocardial fibroelastosis (EFE).
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Media type:  Radiograph

Media file 2:  Chest radiograph, left lateral view, showing enlarged heart in 6-month-old infant.
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Media type:  Radiograph

REFERENCES

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Article Last Updated: Dec 7, 2007