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.¹

The 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, possibly secondary to better antenatal scanning.
• 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 feint 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 varying degree of mitral regurgitation is common
• Fetal echocardiography¹⁰
  • Valuable tool for early identification, particularly of the secondary type
  • One of the congenital malformations e.g. aortic stenosis often demonstrated at the initial study
  • EFE becomes obvious in repeat studies
• Electron beam computed tomography can demonstrate calcification and fibrosis of the ventricles (particularly at apex¹¹)
• Cardiac MRI¹²

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.¹³
• 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.¹⁴
• 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.