Endocardial Fibroelastosis (EFE)

A rare condition characterised by pronounced, diffuse, thickening of the ventricular endocardium. It appears as unexplained heart failure in infants and children.¹The disease can be primary or secondary to a variety of congenital heart diseases, most notably hypoplastic left heart syndrome, aortic stenosis, or atresia. The 2 pathological forms of primary endocardial fibroelastosis (EFE) are dilated, which is most common, and contracted.² It has been suggested that one form may progress to the other.³

• It is rare, representing 1-2% of all congenital heart diseases. The number of cases has fallen dramatically in recent years.
• It may be familial (10%) with a predominantly x-linked pattern.²
• It affects both sexes equally, usually presenting during the first 3-6 months of life in 80% of cases.
• Typical age of diagnosis is 2-12 months. It rarely is reported in adolescents and adults.
• It is an important cause of non-immune hydrops fetalis.

Primary dilated EFE occurs when the heart is otherwise normal and there is no other cause of unexplained heart failure.
Secondary dilated EFE is associated with aortic stenosis or atresia.
Secondary contracted EFE is associated with hypoplastic left heart syndrome.
Possible causative factors include:

• Intrauterine viral infection (mumps,⁴ Coxsackie B virus)
• Subendocardial ischaemia
• Impaired lymphatic drainage of the heart
• Systemic carnitine deficiency
• Familial

Severe congestive heart failure (CHF) in previously healthy infants, less than 6 months old. It may follow respiratory infection. ⁵

Symptoms

• Breathlessness
• Cough
• Wheezing
• Feeding difficulty
• Excessive sweating
• Failure to thrive
• Recurrent chest infections (20%)⁵

Severe sudden abdominal pain may be indicative of coronary insufficiency.

Signs

Onset may be so acute that it produces cardiogenic shock or sudden death.⁶

• Tachypnoea during feeding, grunting respiration with subcostal or intercostal recession
• Pallor
• Peripheral cyanosis
• Fever
• Cardiomegaly - normal or faint first and second heart sounds, a gallop rhythm with an audible third heart sound
• Apical pansystolic murmur of mitral regurgitation
• Hepatomegaly
• Oedema
• Rash
• Leukocytosis
• Anaemia

It is one of the recognised causes of non-immune hydrops fetalis.
Thromboembolic episodes may cause pulmonary embolism, myocardial infarction, cerebrovascular events or sudden death.

• Blood tests:
  • Blood urea and creatinine
  • Blood count
  • Autoantibody profile including anti-Ro and anti-La^7,8
  • Blood culture tests indicated for management of acute episodes
• Chest X-ray:
  • Cardiothoracic (CT) ratio exceeds 0.65 in 50% of patients⁵
  • Left lower lobe atelectasis is seen in 25% of patients
  • The cardiac silhouette is often globular
  • Pulmonary venous congestion is common
• ECG:
  • Tall R waves
  • Deep Q waves
  • T-wave inversion or flattening in the left precordial or inferior lead
  • Findings depict LV hypertrophy
  • Right axis deviation and isolated right ventricular hypertrophy (more common in the first few weeks of life)
  • Left, right (or both) atrial enlargement
  • Wolff-Parkinson-White syndrome, left bundle branch block, supraventricular and ventricular arrhythmias, and varying degrees of atrioventricular block.
  • The early and terminal stages of heart failure show low-voltage tracings
• Echocardiography⁹:
  • Increase in left atrium and LV dimensions
  • Reduced ejection fraction
  • Abnormal mitral valve motion
  • Dense echogenicity along the endocardium of the LV; a diagnostic clue
  • A varying degree of mitral regurgitation is common
• Fetal echocardiography¹⁰
  • This is a valuable tool for early identification, particularly of the secondary type
  • One of the congenital malformations e.g. aortic stenosis is often demonstrated at the initial study
  • The EFE becomes obvious in repeat studies
• Electron beam computed tomography has been shown to diagnose EFE. It can demonstrate calcification and fibrosis of the ventricles particularly at the apex.¹¹
• Cardiac MRI

The principles are the same as treatment of chronic cardiac failure.

• Any acute exacerbations are often precipitated by respiratory infections.
• Early and prolonged treatment with digoxin is suggested.
• Therapy should be continued for several years after the symptoms disappear, as cessation of the drug may result in acute cardiac failure.⁵
• Steroid therapy (dexamethasone) has been shown to cure fetal EFE and AV conduction delays associated with maternal anti-Ro and anti-La antibodies.¹²
• Supportive measures for acute failure and exacerbations may be required e.g. treatment of infection and anaemia.
• Thromboembolic complications may require anticoagulation.

Surgical

Cardiac transplantation may be recommended for those with end-stage disease.

• Primary EFE prognosis is relatively poor, although the condition is not universally fatal; 4 years survival of 77%.⁵
• Infants presenting with acute failure almost always die from the acute episode, unless they receive a transplant.¹³
• Those with a chronic presentation have a 30-40% mortality rate from resistant heart failure.
• Acute CHF becomes progressive CHF. It terminates in death within weeks, usually in the first 6 months of life.
• Progressive CHF causes one third of patients' conditions to deteriorate leading to death.
• One third of the patients survive, and they can experience persistent symptoms, show residual ECG abnormalities, or show evidence of cardiomegaly.
• Early diagnosis and prompt persistent administration of digitalis may result in clinical improvement and reversion of the cardiac enlargement (CE) to normal.
• Episodes of CHF recurring more than 6 months after initial onset of symptoms also indicates a poor prognosis.