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Endomyocardial Fibrosis

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NORD is very grateful to Leslie T. Cooper, MD, Professor of Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, for assistance in the preparation of this report.

Synonyms of Endomyocardial Fibrosis

Disorder Subdivisions

General Discussion

Endomyocardial fibrosis (EMF) is a progressive disease of unknown origin (idiopathic) that may seriously affect the heart. Its most obvious feature is a gross change in the makeup of the lining of the heart cavities (the endocardium) of one or both of the lower chambers of the heart (the ventricles) leading to the replacement of normal cells with fibrous tissue (fibrosis). This process is progressive and leads to the narrowing (constriction) of the right or left ventricular cavities. It may involve the valves between the chambers of the heart as well as the tendon-like cords that fix the valves to the ventricles (chordae tendineae).

Loeffler's disease is a disease of the heart much like endomyocardial fibrosis. Some clinicians regard it as an early stage of EMF, although this idea remains controversial. Loeffler's disease is a rare disorder of unknown origin, characterized by abnormal increases in the number of particular white blood cells (eosinophilia), and like EMF, gross fibrosis of the endocardium, and inflammation of small blood vessels (arteritis).


The main microscopic feature of endomyocardial fibrosis (as well as of Loeffler's disease) is fibrosis of the inner lining of the heart cavities (the endocardium). This means that the normal endocardium is replaced by a thick, inelastic tissue. The fibrotic lesions may be over 1 cm thick and may extend finger-like projections into the heart muscle (the myocardium).

Fibrosis frequently affects the heart asymmetrically. It may specifically involve one or more of the following areas: the top (apex) of the left ventricle, the back (posterior) wall of the left ventricle including the fibrous cords that connect the valves to the ventricles (the chordae tendineae), and the top (apex) of the right ventricle, extending backwards to encase the muscle and cords (chordae tendineae) attaching the heart valve (tricuspid).

If fibrosis of the left ventricle is predominant, then blood flow from the right side of the heart is reduced often with mitral valve failure causing back-flow (regurgitation) of blood. The results may include pulmonary venous hypertension and left ventricular enlargement. Abnormal heartbeat patterns (atrial fibrillation or atrial arrhythmia) are common. Difficulty in breathing (dyspnea) especially, but not exclusively, on physical exertion is the major physical sign.

If fibrosis of the right ventricle is predominant, then circulation is restricted often with tricuspid valve failure, causing backflow (tricuspid regurgitation). Enlargement of the heart (cardiomyopathy) because of right atrial dilatation is often seen. Facial swelling (edema), swelling of the legs, enlargement of the spleen and liver (hepatosplenomegaly), and an accumulation of fluid in the abdominal cavity (ascites) are to be expected.

Biventricular fibrosis with circulation features is a mixture of the two forms listed above. That is, the symptoms are a combination of left and right ventricular fibrosis.

The extracardiac manifestations of Loeffler's disease include emboli to the brain (stroke), spotty (petechial) hemorrhages, and an enlarged liver (hepatomegaly).


At this time, clinicians believe that an as yet unknown immunological process is the preferred explanation for the cause of most cases of endomyocardial fibrosis and Loeffler's disease. In the past, the cause of both conditions was attributed to the presence of the filaria worm in patients or to poor nutrition. Widespread infection with such worms and poor diets are typical in the tropical regions in which these disorders are more common. Eosinophils have been observed in some cases of endomyocardial fibrosis, suggesting a form of hypersensitivity may play a role in select cases. In children, endomyocardial fibrosis has been associated with the mumps virus.

Affected Populations

Endomyocardial fibrosis is principally an endemic disease of the equatorial tropics. It is exceedingly rare in Europe and North America. It affects all races, mostly children and young adults. The disease has been described in a few patients over 60 years of age and, rarely, in patients younger than 5 years of age.

Related Disorders

Amyloidosis is the term applied to a group of metabolic disorders characterized by the abnormal accumulation of a fibrous protein (amyloid) in various tissues of the body. This can lead to impaired function of the affected organs. When amyloidosis affects the gastrointestinal system, symptoms may include ulceration, bleeding, weak stomach activity, protein loss, diarrhea, and/or vomiting. Amyloid accumulation may also cause a lack of movement in the esophagus and intestines. (For more information on this disorder, choose "Amyloidosis" as your search term in the Rare Disease Database.)

Hemochromatosis is a hereditary disorder of iron metabolism characterized by excess deposits of iron in the tissues, especially in the liver, pancreas, and heart, and by bronze-colored pigmentation of the skin. Cirrhosis of the liver, diabetes mellitus, and associated bone and joint changes may also occur.

Sarcoidosis is a rare disorder that affects many systems of the body. It is characterized by small round lesions (tubercles) of granular material. Symptoms vary depending on the severity of the disease. They may be absent, slight, or severe. Organ function may be impaired by active granulomatous disease or by fibrous changes that are associated with acute inflammation. The initial symptoms may include fever, weight loss, and/or joint pain. Persistent fever is especially common with liver (hepatic) involvement. Enlargement of lymph glands is also common and usually without symptoms. The lungs and the lymph glands between the lungs are frequently affected, and symptoms may include coughing and difficulty breathing. (For more information on this disorder, choose "Sarcoidosis" as your search term in the Rare Disease Database.)

Standard Therapies

A combination of X-ray, echocardiography, and investigation of the state of the ventricles (ventriculography) is used to diagnose suspected cases of endomyocardial fibrosis or Loeffler's disease.

Responses to medical treatment are generally poor and unproven. For patients with severe symptoms, surgical treatment may be applied when other treatments have not been successful. These procedures, however, are not without risk. Mortality as a consequence of surgery may run as high as 20%. Successful surgery reduces symptoms and increases survival times and rates.

Surgery is usually designed (1) to take out the fibrous endomyocardium so that the ventricles can be filled once more; (2) to repair or replace the mitral or tricuspid valve (or both), if one or another is involved; and (3) to leave a portion of fibrous endocardium in place to prevent postoperative heart block.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

Endomyocardial Fibrosis Resources

NORD Member Organizations:

(To become a member of NORD, an organization must meet established criteria and be approved by the NORD Board of Directors. If you're interested in becoming a member, please contact Susan Olivo, Membership Manager, at solivo@rarediseases.org.)

Other Organizations:


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Report last updated: 2012/01/31 00:00:00 GMT+0