What Is Endocardial Fibroelastosis

Endocardial Fibroelastosis (EFE) is a rare disease in which increased amounts of connective tissue and elastic fibres cause the walls of the heart to thicken.¹ EFE is commonly associated with heart failure in infants and children but can also occur in adulthood.²

The heart can be divided into four chambers: the left and right atria, separated by the atrial septum, and the left and right ventricles. The heart chambers are lined by a thin layer of endothelial cells termed the endocardium.³ During EFE, excess fibrous and elastic tissue buildup causes the usually thin layers of the endocardium to thicken and the heart to enlarge (cardiac hypertrophy). This overgrowth of fibrous tissue reduces the overall size of the ventricles and, as such, their capacity to pump blood around the body. Cardiac hypertrophy is particularly common in the left ventricle. Over time, the heart’s reduced ability to pump blood leads to congenital heart failure, which is often fatal.³

Symptoms of endocardial fibroelastosis

Symptoms of EFE often begin between the ages of 4 to 12 months; however, EFE onset in later life is also possible.¹ Symptoms include:

• Breathlessness 
• Pale facial appearance (pallor)
• Coughing
• Wheezing
• Fever
• Bluish discolouration of the fingers and toes (peripheral cyanosis)

What causes endocardial fibroelastosis?

Whilst EFE can both be inherited or sporadic, the exact cause of onset is not always known. EFE can be classified as primary (not associated with any other disease) or secondary (developed as a result or complication of a previous disease). Primary EFE is commonly associated with abnormal development of the heart during development due to inherited gene mutations in both X-linked EFE2 and autosomal recessive EFE1 genes.¹ A range of factors can contribute to secondary EFE, including:

• Cardiomyopathies - diseases that cause the heart to stiffen, thicken or weaken
• Congenital heart defects - including aortic stenosis, a heart valve disease affecting the major artery (aorta) that supplies blood to the body and brain
• Viral infection - including mumps disease
• Autoimmune diseases - in which the body accidentally attacks its own healthy cells²

Diagnosis

Diagnosis of EFE typically involves taking an ultrasound of the heart muscle (echocardiography). Typical features seen in echocardiograms of EFE patients include misshapen, spherical left ventricles, thickened ventricle walls and enlarged ventricles(4). CT and MRI scans may also be used to assess any structural changes to the heart in greater detail. Physical examination of an EFE patient typically reveals bubbling sounds heard through a stethoscope (respiratory distress) due to fluid buildup in the airways and abnormal heart rhythms (murmurs).² 

Treatment and management

Treatment for EFE can be divided into medical and surgical approaches. Treatment approaches vary depending on the severity of the disease. Whilst there is no cure for EFE, successful treatment can reduce several symptoms of the disease.

1. Medical⁵
   • Diuretics, angiotensin-converting enzyme (ACE) inhibitors and beta blockers are heart failure medications commonly prescribed to patients with EFE. 
   • Anti-arrhythmia drugs, such as beta-blockers, may also be prescribed to patients with irregular heartbeats.

2. Surgical²
   • In severe cases of EFE where medical interventions are not sufficient, heart replacement from a healthy donor may be performed.
   • Ventricular assist devices help the heart to pump blood around the body and may help relieve symptoms of EFE whilst avoiding a full heart transplant.

Summary

Endocardial fibroelastosis is a rare heart disease that mostly affects infants and children. EFE is characterised by the thickening of the inner layer of the heart chambers, reducing the heart’s ability to pump blood effectively. EFE can be a primary disease or secondary to other common congenital heart diseases. The cause of EFE may be unclear and is often due to a range of factors, including viral infections, autoimmune disorders and accompanying heart diseases. EFE can also be inherited genetically via X-linked (EFE2) and autosomal recessive (EFE1) mutations. Diagnosis typically involves a physical examination and an ultrasound of the heart muscle (echocardiography), which reveals several structural changes to the heart indicative of EFE. Treatment of EFE varies depending on the stage and severity of the disease, from the prescription of heart failure medications such as diuretics to surgical interventions such as fitting ventricular assist devices and heart transplants from a healthy donor.