What is Endocardial Fibroelastosis?
Endocardial fibroelastosis (EFE) is mainly seen in infants and children, but very rarely, it can also affect adults. The term ‘endocardial fibroelastosis’ was first used in 1943 by Weinberg and his team to describe children who had unexplained heart failure, previously known as ‘fetal endocarditis.’ To put it simply, EFE is a condition where the inner lining of the heart chambers, also known as the endocardium, becomes thick due to the overgrowth of fibrous and elastic tissue.
Usually, the endocardium is a thin layer of cells that line the inner side of the heart chambers. The signs and symptoms of EFE can vary greatly, and often, they may overlap with other heart-related abnormalities. It is commonly associated with other birth defects of the heart like hypoplastic left heart syndrome. There have even been instances where a condition where the left coronary artery abnormally originates from the lung artery, known as ALCAPA, was mistakenly identified as EFE due to similar findings on a heart ultrasound.
Therefore, it is essential to be aware of conditions that may appear similar to EFE, which we will discuss in the portion talking about diagnosing different conditions.
What Causes Endocardial Fibroelastosis?
The exact cause of Endomyocardial Fibroelastosis (EFE), a heart disease, is still not completely understood. Even though the primary type is usually considered as occurring without a known reason, some research suggests there might be a genetic factor involved. Specifically, EFE has been linked to changes in a gene known as TAZ, which is found on the X chromosome and codes for a protein called Tafazzin. Alterations in this gene are believed to play a role in causing EFE.
Other research, using animal models, suggests another gene called NEX, which makes a protein called nexilin, may also be involved in developing EFE. Further, some research indicates that a process where cells lining the blood vessels turn into a different type of cell could be a possible mechanism behind the EFE.
Additionally, infection or viral causes, and even an immune system response, have been proposed as potential factors. For example, the presence of specific antibodies, called anti-Ro and anti-La, have been documented in EFE cases. There has been a reported case of EFE disappearing in a fetus after mother was treated with medications called corticosteroids, supporting this idea.
While EFE can occur on its own, in about 25% to 50% of cases, it has been seen in conjunction with other genetic heart conditions such as hypoplastic left heart syndrome, aortic stenosis, and atresia.
Risk Factors and Frequency for Endocardial Fibroelastosis
Endocardial fibroelastosis (EFE) is a rare condition, and because of its rarity, there’s not much data on how often it occurs. This condition typically starts showing symptoms in the first year of a child’s life. EFE is a type of pediatric cardiomyopathy, which is a term for heart muscle diseases in children. About 1 in every 100,000 children are affected by pediatric cardiomyopathies. Boys and girls are equally likely to be affected, which challenges the common belief that the condition only passes down through an X-linked recessive pattern. Some research suggests an autosomal recessive pattern might be involved as well.
Signs and Symptoms of Endocardial Fibroelastosis
Endocardial fibroelastosis commonly presents as difficulty in feeding, excessive sweating, shortness of breath, slow growth, respiratory distress, coughing, blueness of the skin, and swelling of the lower limbs. Patients often show these signs after a recent respiratory infection.
Additionally, patients may exhibit symptoms of cardiogenic shock, an irregular pulse, a specific type of heart rhythm called a gallop rhythm, heart murmurs, lung crackling sounds, elevated jugular venous pressure, an enlarged liver or spleen, and swelling of the feet or ankles. Increased heart rate and a condition where the strength of the heartbeat varies with each beat, known as pulsus alternans, are also possible. Other less common presentations include fetal water accumulation, congestive heart failure, heart wall clots, heart attack, congenital heart block, blockage in the lungs’ blood vessels and sudden cardiac death.
Due to the broad range of ways this condition can present, medical professionals have a specific set of criteria to help diagnose endocardial fibroelastosis. These include:
- No other birth defects present
- No underlying vascular, metabolic, or inflammatory disorders
- A spherical or dilated left ventricle (LV)
- Diffuse thickening of LV endocardium
- LV papillary muscles displaced upward towards the left atrium
- Thickened edges of the mitral valve leaflets
- Excessive straight elastic fibers in the endocardium visible under a microscope
Testing for Endocardial Fibroelastosis
As part of diagnosing your condition, your doctor may wish to run several routine tests. These could include tests to determine serum electrolyte levels, kidney functionality, a complete metabolic profile, and a specific heart hormone called brain natriuretic peptide. In addition, a kind of test might be conducted to detect the presence of certain antibodies, namely anti-Ro and anti-La, this is done as these antibodies affect the type of treatment you may receive.
A chest X-ray is a common and quick method to check for certain heart and lung conditions. Results from it may show heart enlargement (cardiomegaly), fluid in the lungs (pulmonary edema), fluid around the heart (pleural effusion) or lung infection (pneumonia).
Your doctor might also want to perform an electrocardiogram (ECG). This is used to detect abnormalities in the heart’s rhythm and structure, as well as any sign of a heart attack.
Another imaging method is echocardiography, which is used to view the heart’s structure and check its function. This can show various signs of primary endocardial fibroelastosis, a type of heart disease, such as a balloon-shaped left ventricle (the main pump of the heart), decreased heart movement, increased thickness of the heart walls, enlargement of the heart chambers and different kinds of irregularities related to heart valves and blood flow. Indeed, an expert can see increased brightness of the heart’s inner lining – a sign of the disease at hand.
Another technique is CT scanning which is a quite effective, non-invasive test that can detect hardened areas in blood vessels and the heart, and exclude other conditions like inflammation of the heart lining (pericarditis). A variant of the CT scan, called electron beam CT scan, is particularly good at spotting calcification (hardening) at the lower tip of the heart.
Magnetic resonance imaging (MRI) is another tool that can be used to detect the heart disease, especially as taking a tissue sample from the heart lining (biopsy) – which is the best way to diagnose – comes with some risks and invasiveness. Certain features in the MRI can indicate the presence of this disease.
Treatment Options for Endocardial Fibroelastosis
Endocardial fibroelastosis doesn’t have a specific cure. Treatment is usually focused on controlling the symptoms of the condition. The common strategy is to manage the resulting chronic heart failure with particular medications. These include diuretics, which help your body get rid of extra fluid; digoxin, which helps regulate your heart’s rhythm and pumping capacity; angiotensin-converting enzyme (ACE) inhibitors, which relax blood vessels and lower blood pressure; and beta-blockers, which reduce your heart’s workload. It has been suggested that early and ongoing treatment with digoxin can help improve the condition, but we’re still not sure if it can increase life expectancy in these situations.
Corticosteroids, drugs that reduce inflammation, have shown some success in reversing fetal endocardial fibroelastosis in cases where it’s associated with certain maternal antibodies (anti-Ro and anti-La). However, in cases where these antibodies are not present, steroids are not typically recommended, as they haven’t shown to be particularly helpful. If a person experiences blood clots because of the condition, they may need anticoagulation therapy, which involves medicine to prevent more clots from forming.
Surgery for endocardial fibroelastosis is typically only considered in severe cases that don’t respond well to medication attempts. Some of these procedures have included trying to remove the fibrotic (thickened) layer of heart tissue to try to improve the heart’s ability to contract, but these experimental attempts have shown limited success. In late stages of the disease, when the heart function severely deteriorates, a heart transplant may be suggested.
What else can Endocardial Fibroelastosis be?
Several diseases can be misidentified as endocardial fibroelastosis, so a thorough check-up and knowledgeable doctor are needed for the right diagnosis. Since this condition is rare and lacks precise diagnostic tools, endocardial fibroelastosis is often confirmed by excluding other conditions. The reported conditions that should be cleared out if endocardial fibroelastosis are suspected include:
- Different types of heart muscle diseases: Dilated or hypertrophic (linked to Noonan syndrome), restrictive, Barth syndrome
- Born-with heart defects: Narrow aortic valve, narrowed aorta, mismatched coronary arteries, underdeveloped left heart
- Heart infections caused by viruses: mumps, coxsackie, adenovirus
- Rare genetic disorders that affect cell function: Pompe, Hurler, Niemann-Pick disease
- Other conditions: Systemic carnitine deficiency (a type of protein deficiency), heart attack
Also, rare conditions like fibroplastic parietal endocarditis (inflammation of inner heart layer), cardiovascular collagenosis (collagen disease of the cardiovascular system), and endomyocardial fibrosis (thickening of the heart wall) are to be considered in differentiating diagnoses.
What to expect with Endocardial Fibroelastosis
The condition in question isn’t always a death sentence, but it does have a generally poor outcome. After four years, only about 77% of patients are still alive. Infants who have severe, sudden heart failure are particularly at risk, and often, they can only survive if they get a heart transplant. Even those who do survive frequently continue having symptoms. If a child with this disease has a specific pattern on their ECG (a test that checks how your heart is functioning), known as the ‘infarct’ pattern, it usually means they’re more likely to pass away, which is a bad sign for their survival rate.
Some interesting observations were made by a team of researchers led by someone named Manning. They found that:
- If the symptoms were already present for a while or are recurring over time at the time of diagnosis, the outlook tends to be better.
- If a patient reacts positively to the first treatment received, that also tends to be a good sign.
- If, after two years of treatment, the size ratio of the heart to the chest (cardiothoracic ratio) is below 55%, that’s a good sign for their outlook.
- If, between two to five years after starting treatment, the ECG returns to what’s considered normal, that also bodes well for the patient’s outlook.
Possible Complications When Diagnosed with Endocardial Fibroelastosis
Endocardial fibroelastosis, a heart condition, can lead to several complications. These can range from clots forming inside the heart due to reduced heart function and irregular heartbeat patterns, to difficulties with heart valves marked by severe mitral valve leakage. This valve leakage could be a direct result of valve involvement or ongoing poor heart performance.
Other complications that can occur include:
- Clots being sent to the brain (causing strokes), lungs (causing pulmonary embolism), or other areas of the body
- Blockage of blood supply to the heart, leading to heart attacks, either from a shortage of blood supply or from these travelling clots
- Irregular heartbeats due to issues with the heart’s electrical system
- Heart failure leading to fluid build-up in the body and a sudden drop in the heart’s ability to pump blood (cardiogenic shock)
Additionally, if the right side of the heart is involved, this can lead to high blood pressure in the lungs. During the fetal stage, the condition can also cause Hydrops fetalis, which is abnormal accumulation of fluid in the fetus and is generally due to in-utero heart failure. In the most serious cases, the condition can lead to sudden cardiac death.
Preventing Endocardial Fibroelastosis
If you have a child who suffered from endocardial fibroelastosis in the past, it’s important to have tests during future pregnancies to check for this condition. For mothers having Sjögren syndrome, a condition that can cause dry eyes and mouth, extra care is recommended due to the potential risk for endocardial fibroelastosis in their child. Tests for anti-Ro and anti-La antibodies, which are associated with autoimmune diseases, should be conducted.
It is crucial for parents to understand the severity of endocardial fibroelastosis, a heart muscle disease that can make the heart less efficient, because it has high rates of sickness and death. Additionally, they should be provided with genetic counseling. This guidance can help parents understand the genetic risks and consequences related to endocardial fibroelastosis, which might be beneficial for family planning.
