ENDOMYOCARDIAL FIBROSIS – Dr. Akif Baig

Description

Endomyocardial Fibrosis (EMF) is a progressive form of restrictive cardiomyopathy that primarily affects the endocardium and the inner layer of the myocardium, leading to fibrosis. It predominantly occurs in tropical and subtropical regions, often referred to as “tropical endomyocardial fibrosis.” The condition results in impaired diastolic filling of the heart, ultimately leading to heart failure.

Endomyocardial Fibrosis (EMF) is a progressive form of restrictive cardiomyopathy that primarily affects the endocardium and the inner layer of the myocardium, leading to fibrosis. It predominantly occurs in tropical and subtropical regions, often referred to as “tropical endomyocardial fibrosis.” The condition results in impaired diastolic filling of the heart, ultimately leading to heart failure.

Pathophysiology

EMF involves the deposition of fibrotic tissue in the endocardium of one or both ventricles, leading to restrictive filling and reduced cardiac output. Over time, the fibrotic process may involve the atrioventricular valves, leading to valve dysfunction, and the chordae tendineae, causing them to shorten or rupture. The precise etiology of EMF remains unclear, but multiple factors have been proposed:

1. Parasitic Infections: Chronic exposure to parasitic infections, particularly schistosomiasis and filarial infections, has been implicated.
2. Nutritional Deficiencies: Chronic malnutrition, particularly deficiencies in magnesium or eosinophil-lowering factors.
3. Autoimmune Factors: Some theories suggest that EMF may have an autoimmune component, with eosinophilia playing a central role.
4. Genetic Susceptibility: Familial clustering in certain populations points to a potential genetic component.

Clinical Features

EMF generally presents with symptoms of heart failure, often related to the involvement of the right or left ventricle, or both.

1. Right Ventricular EMF:
   • Right-sided heart failure signs: jugular venous distension, hepatomegaly, ascites, peripheral edema.
   • Reduced cardiac output and signs of systemic congestion.
2. Left Ventricular EMF:
   • Left-sided heart failure signs: dyspnea, orthopnea, pulmonary edema.
   • Reduced cardiac output and pulmonary congestion.
3. Bi-Ventricular EMF:
   • Involvement of both ventricles leads to a combination of systemic and pulmonary congestion.

Key Signs and Symptoms

• Dyspnea on exertion or at rest.
• Fatigue and exercise intolerance due to reduced cardiac output.
• Ascites, leg swelling, and other signs of fluid overload (right-sided heart failure).
• Murmurs due to valve dysfunction (mitral or tricuspid regurgitation).
• Thromboembolic events due to atrial thrombus formation in dilated atria.
• Arrhythmias: Atrial fibrillation and other arrhythmias are common due to atrial dilation.

Diagnosis

1. Echocardiography:
   • The most important diagnostic tool for EMF.
   • Shows endocardial thickening and fibrosis, typically involving the apex of the ventricles.
   • Restricted ventricular filling with dilated atria.
   • May show thrombus formation in the ventricular apices.
   • Valve involvement: thickening of the mitral or tricuspid valves with regurgitation.
2. Cardiac MRI or CT:
   • Useful in visualizing the extent of fibrosis.
   • May show calcifications in the advanced stages of the disease.
3. Cardiac Catheterization:
   • Hemodynamic studies may show increased filling pressures and reduced ventricular compliance.
   • Confirms the restrictive physiology of the heart.
4. Endomyocardial Biopsy:
   • May be required for a definitive diagnosis, though it is often avoided due to risks associated with biopsy in fibrotic tissue.

Differential Diagnosis

• Restrictive Cardiomyopathy (RCM): Can be caused by other conditions like amyloidosis, hemochromatosis, or sarcoidosis.
• Constrictive Pericarditis: Often confused with EMF, but imaging studies and hemodynamics help distinguish between the two.

Feature	Endomyocardial Fibrosis (EMF)	Restrictive Cardiomyopathy (RCM)
Pathology	Endocardial fibrosis	Myocardial stiffness
Involvement	Predominantly ventricular apices	Diffuse myocardial involvement
Atrial Dilatation	Common	Common
Valve Dysfunction	Mitral and tricuspid regurgitation	Possible but less common
Calcifications	Seen in advanced cases	Rare

Treatment

1. Medical Therapy:
   • Diuretics: To manage fluid overload and reduce systemic congestion.
   • Anticoagulation: Indicated in patients with atrial fibrillation or evidence of atrial thrombus.
   • Afterload Reduction: Agents like ACE inhibitors may help reduce ventricular load.
2. Surgical Treatment:
   • Endocardiectomy: Surgical resection of fibrotic tissue is an option for advanced cases, although it is technically challenging and associated with significant risk.
   • Valve Replacement or Repair: Mitral or tricuspid valve replacement may be necessary in patients with severe regurgitation.
3. Thromboembolism Prevention:
   • Long-term anticoagulation is often necessary due to the high risk of thrombus formation, particularly in the atria.
4. Heart Transplantation:
   • In severe cases where medical therapy fails and surgical resection is not feasible, heart transplantation may be considered.

Prognosis

The prognosis for patients with EMF depends on the stage of the disease at diagnosis and the extent of the fibrosis. Early diagnosis and appropriate management can help improve symptoms and prolong survival, but advanced disease has a poor prognosis due to the irreversible nature of the fibrosis and complications like thromboembolism and heart failure.