30  Endomyocardial Fibrosis

Author

Dr Samuel Blay Nguah

30.1 Definition

Endomyocardial fibrosis (EMF) is a progressive, restrictive cardiomyopathy characterized by fibrotic thickening of the endocardium, predominantly affecting the inflow tracts of the right and/or left ventricles. This leads to impaired diastolic filling, atrioventricular valve regurgitation, and ultimately heart failure. EMF is most commonly seen in tropical and subtropical regions, and it remains an important cause of pediatric heart failure in these areas.

30.2 Incidence/Prevalence

  • EMF is primarily seen in tropical and subtropical regions, particularly in sub-Saharan Africa, India, and parts of South America.
  • It is estimated to affect 10 million people worldwide, with the highest burden in children and young adults.
  • The prevalence in endemic areas ranges from 10% to 20% of all heart diseases.
  • The condition is more common in socioeconomically disadvantaged populations and is associated with malnutrition and infections.
  • While rare in developed countries, cases have been reported in immigrants from endemic regions.

30.3 Aetiology

The exact cause of endomyocardial fibrosis remains unknown, but several contributing factors have been proposed, including:

  1. Infectious Causes:
    • Parasitic infections such as Plasmodium falciparum (malaria) and Schistosoma species have been implicated in the pathogenesis.
    • Viral infections, including Epstein-Barr virus and Coxsackie virus, have also been suggested.
  2. Autoimmune Mechanisms
    • Immune system dysregulation leading to chronic inflammation and fibrosis.
    • Presence of eosinophilia in many patients suggests an allergic or immune-mediated response.
  3. Nutritional Deficiencies:
    • Chronic malnutrition, specifically deficiencies in magnesium, selenium, and protein, may predispose individuals to EMF.
    • Exposure to toxic dietary substances such as cassava, which contains cyanogenic glycosides, is considered a potential factor
  4. Genetic Predisposition:
    • Familial clustering has been noted in some endemic areas, suggesting a genetic susceptibility to the disease.
  5. Environmental Factors:
    • Living in rural, low-income areas with high exposure to infections and dietary toxins.

Pathophysiology

  • EMF predominantly affects the ventricular endocardium, leading to fibrosis that extends from the apex toward the atrioventricular valves.
  • Right ventricular involvement is more common than left, but both can be affected (biventricular disease).
  • Fibrosis results in:
    1. Diastolic dysfunction: The stiff ventricle cannot fill adequately, leading to elevated atrial pressures.
    2. Atrioventricular valve regurgitation: Fibrosis and restriction of valve movement lead to tricuspid or mitral regurgitation.
    3. Thrombus formation: The fibrotic endocardium is prone to thrombus development, which can embolize systemically or to the lungs.
    4. Myocardial dysfunction: Though the myocardium is often spared early in the disease, late-stage fibrosis can affect contractility and lead to heart failure.

Signs and Symptoms

The clinical presentation of EMF in children varies depending on the extent of cardiac involvement and which ventricle is affected.

Right Ventricular EMF (Most Common Presentation):

  • Signs of right heart failure:

    • Hepatomegaly

    • Ascites

    • Peripheral edema

    • Elevated jugular venous pressure

  • Fatigue and exercise intolerance
  • Right upper quadrant pain due to liver congestion

Left Ventricular EMF:

  • Signs of left heart failure:
    • Pulmonary congestion (dyspnea, orthopnea)
    • Cough, hemoptysis (in advanced cases)
    • Fatigue and poor growth in children
  • Systemic embolization (e.g., stroke) from left-sided thrombus formation

Biventricular Disease:

  • Severe heart failure with a combination of right- and left-sided symptoms
  • Anasarca (generalized edema)
  • Reduced cardiac output leading to shock in advanced case

General Symptoms:

  • Failure to thrive
  • Recurrent respiratory infections
  • Cyanosis (in severe cases)

Investigations

1. Blood Tests:

  • Eosinophilia: Found in a subset of patients.
  • Elevated inflammatory markers (CRP, ESR).
  • Liver function tests: Abnormal in cases with severe right heart failure.
  • Pro-BNP: Elevated in cases of heart failure.

2. Electrocardiogram (ECG):

  • Low voltage QRS complexes.
  • Right or left atrial enlargement.
  • Conduction abnormalities (e.g., atrioventricular block)

3. Echocardiography (Key Diagnostic Tool):

  • Thickened endocardium, especially in the apical region.
  • Atrioventricular valve regurgitation.
  • Restricted ventricular filling pattern.
  • Intracardiac thrombus formation.
  • Diastolic dysfunction with preserved systolic function in early stages.

4. Cardiac MRI:

  • Provides detailed imaging of fibrotic areas.
  • Helps differentiate EMF from other restrictive cardiomyopathies.

5. Cardiac Catheterization:

  • Confirms restrictive physiology with elevated end-diastolic pressure

6. Endomyocardial Biopsy:

  • Rarely performed but can confirm fibrosis histologically.

Treatment

Treatment of endomyocardial fibrosis in children is primarily supportive and aimed at symptom relief.

1. Medical Management:

  • Diuretics: Reduce fluid overload and symptoms of heart failure.
  • Anticoagulation: Indicated for patients with atrial fibrillation or intracardiac thrombi.
  • ACE inhibitors/ARBs: Help reduce afterload and improve heart function.
  • Nutritional support: Address malnutrition with appropriate supplementation.

2. Surgical Management:

  • Endocardial resection and valve repair or replacement in selected cases.
  • High surgical risk with variable outcomes in children.

3. Symptomatic Care:

  • Management of complications such as arrhythmias and infections.
  • Regular follow-up for disease progression and heart failure management.

Complications

  • Heart Failure: Progressive and refractory to medical therapy.
  • Thromboembolism: Stroke, mesenteric ischemia, or pulmonary embolism.
  • Arrhythmias: Atrial fibrillation or heart block leading to sudden cardiac death.
  • Growth retardation: Due to chronic illness and malnutrition.
  • Infective endocarditis: Due to damaged endocardial surfaces.

Prognosis

  • EMF is a chronic, progressive condition with a poor long-term prognosis.
  • Early diagnosis and medical management can improve quality of life.
  • In children, the prognosis is worse if diagnosed late or if biventricular involvement is present.
  • Surgical intervention provides limited benefit and carries high perioperative risks.

Differential Diagnosis

  • Restrictive Cardiomyopathy: Similar presentation but without endocardial fibrosis on imaging.
  • Constrictive Pericarditis: Presents with similar right heart failure symptoms but is distinguished by pericardial thickening on imaging.
  • Rheumatic Heart Disease: Can cause valvular regurgitation and heart failure but lacks endocardial thickening.
  • Hypereosinophilic Syndrome: Can mimic EMF but includes systemic involvement (e.g., skin, lungs).
Figure 30.1: Endomyocardial Fibrosis showing classical Egg-on-Stick appearance