What Is the Most Common Type of Cardiomyopathy?

Patient Presentation
A 15-week-old male came to clinic to establish care in the general pediatric clinic at an academic children’s hospital. The past medical history showed he had been born full-term to a 19 year old G1P1 female with little prenatal care. After delivery he was noted to have respiratory distress that did not improve. A chest radiograph showed an enlarged cardiothoracic ratio and initially he was thought to have either a congenital infection causing myocarditis or neonatal thyrotoxicosis. Eventually he was diagnosed with dilated cardiomyopathy because of Barth syndrome. The social history revealed that he had been discharged from a children’s hospital in another city, and his mother moved to the new city to be with her parents. The infant had already seen the pediatric cardiologist in the new city.

The pertinent physical exam showed a small infant with weight at the 15% but he had gained appropriate weight. His head circumference and length were 25%. His heart rate was 138 beats/minute, and respiratory rate was 44 per minute with a saturation of 95% on room air. He had prominent cheeks and relatively large ears. His heart showed S1 and S2 with a low-pitched S3. He seems slightly hypotonic, but the rest of his examination was normal.

The diagnosis of Barth syndrome was made. The pediatrician worked with the clinic social worker to help set up transportation for medical appointments, supplemental food programs, and appropriate maternal medical care, in addition to a followup appointment in 1 month.

Barth syndrome is characterized by a dilated cardiomyopathy, proximal skeletal muscle weakness, neutropenia and short stature that usually presents at birth or soon after. It is a rare X-linked recessive disease process caused by mutations in the TAZ gene. The TAZ gene codes for tafazzin which alters cardiolipin in mitochondria. Characteristic facies can be seen especially in infancy including a tall and broad forehead, prominent chin and full cheeks, larger ears, and deep-set eyes. Most patients present at birth or soon afterwards but some may not until later in life. Life expectancy is reduced with many children dying in infancy and young childhood because of cardiomyopathy.

Myocarditis is inflammation of the myocardium that causes cardiac dysfunction. It is usually caused by infectious diseases particularly viruses, but also drugs, toxins and systemic diseases.

Causes include:

  • Infectious diseases
    • Virus
      • Adenovirus**
      • Coxsackie virus**
      • Cytomegalovirus
      • Epstein-Barr virus
      • Hepatitis C**
      • Human immunodeficiency virus
      • Human herpes virus 6**
      • Influenza
      • Parvovirus B-19**
    • Other infections
      • Streptococcus
      • Trypanosomiasis

  • Non-infectious causes
    • Idiopathic
    • Drug-induced hypersensitivity
    • Eosinophilic myocarditis
    • Giant cell myocarditis
    • Sarcoidosis
    • Systemic lupus erythematosus

** = most common viruses identified

Myocarditis is divided into 3 phases: acute (where muscle fibers can be lysed), subacute (where viral cell damage occurs including apoptosis, and inflammatory processes), and chronic (where antibody production and cross-reactivity can cause myocyte damage). Myocarditis can be difficult to detect as patients may be asymptomatic but can also present with fulminant heart failure. Patient often have a preceding viral illness and then present with respiratory distress, dyspnea, edema or weakness especially around 7-14 days (subacute phase). Common physical examination findings are abnormal respiratory examination, cyanosis/hypoxia, tachycardia, new murmur, hypotension, fever, hepatomegaly, lethargy, and/or pallor. Evaluation includes looking for various causes of myocarditis including viral infections, cardiac enzymes, chest radiographs and potentially cardiac magnetic resonance imaging, electrocardiogram and/or echocardiogram. Treatment is supportive with treatment for dysrhythmias, and heart failure along with any treatment for the specific cause. Prognosis is usually good for most patients but it depends on the particular circumstances.

Learning Point

Cardiomyopathy (CM) is a disease of the myocardium where the heart is abnormally enlarged, thickened, and/or stiffened. The heart then is ineffective in pumping blood and may lead to heart failure.
CM caused by some of the following:

  • Genetic factors
    • Dilated cardiomyopathy
    • Hypertrophic CM
    • Conduction defects
    • Glycogen storage diseases
    • Ion channel defects
    • Left ventricular noncompaction
    • Mitochondrial myopathies
    • Neuromuscular syndrome
  • Mixed
    • Dilated CM
    • Restricted CM
  • Acquired
    • Myocarditis
    • Infants of diabetic mothers
    • Peripartum
    • Tachycardia or arrhythmia induced

Dilated cardiomyopathy (DCM) is the most common type of CM; up to 60% of cases. The differential diagnosis is extremely broad especially for acquired cases with viruses felt to be the most common cause and are the most common cause identified. Although for many patients no identifiable cause is found. A history of first degree relative with DCM or sudden death under age 30-35 increases the risk of DCM by a genetic cause. Presentation is similar to myocarditis but heart failure is more common along with respiratory problems, tachycardia, tachypnea, and feeding difficulties. Physical examination can show abnormal apical pulse, distant heart sounds, murmurs, and third heart sounds on cardiac examination. Pulmonary congestion on auscultation can be heart. Hepatomegaly and peripheral edema can occur but are less common in infants. Findings from specific causes can be seen such as hypotonia, muscle weakness or dysmorphic features.

Questions for Further Discussion
1. What are causes of sudden cardiac death in young patients? A review can be found here
2. What causes restrictive cardiomyopathy?
3. What causes hypertrophic cardiomyopathy?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for these topics: Cardiomyopathy and Congenital Heart Defects.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Soares P, Rocha G, Pissarra S, Soares H, Flor-de-Lima F, Costa S, Moura C, Doria S, Guimaraes H. Neonatal dilated cardiomyopathy. Rev Port Cardiol. 2017 Mar;36(3):201-214.

Ware SM, Genetics of paediatric cardiomyopathies. Curr Opin Pediatr. 2017 Oct;29(5):534-540.

Pettit MA, Koyfman A, Foran M. Myocarditis. Pediatr Emerg Care. 2014 Nov;30(11):832-5.

Buggey J, ElAmm CA. Myocarditis and cardiomyopathy. Curr Opin Cardiol. 2018 May;33(3):341-346.

Barth Syndrome. Genetics Home Reference
Available from the Internet at https://ghr.nlm.nih.gov/condition/barth-syndrome (rev. 11/27/18, cited 11/28/18).

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa