EM@3AM: Myocarditis

Author: Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

Welcome to EM@3AM, an emDocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 18-year-old male presents with chest pain and shortness of breath for several days. Approximately one week prior he was suffering from myalgias, congestion, sore throat, and fever and was diagnosed with an upper respiratory infection. Today his vital signs are HR 132, RR 28, BP 92/48, T 37.8 C, and Sats 95% on RA. Chest X-ray is consistent with pulmonary edema.

What should you consider, and what are your next steps?

Answer: Myocarditis


  • Myocarditis is an inflammatory cardiomyopathy due to lymphocytic/fibroblast infiltration and necrosis of myocytes.
  • It is often caused by viral infection (enterovirus, influenza, or adenovirus) but can be due to a variety of causes: hypersensitivity, giant cell myocarditis, autoimmune (lupus, scleroderma), bacterial infection (Streptococcus, mycoplasma), parasitic infection, drug reaction (cocaine, chemo agents).
  • Disease phases include acute (myocardial cytotoxicity and focal necrosis), subacute (host response leads to further injury), and chronic (diffuse fibrosis and cardiac dysfunction).
  • True incidence is difficult to determine, as many cases are mild.
  • Initial diagnosis is often delayed due to wide range of non-specific symptoms. Misdiagnosis is common and often includes asthma, pneumonia, URI, or gastroenteritis in pediatric patients.



  • Patients are typically young and may present with chest pain, fatigue, dyspnea, and/or palpitations.
  • Flu-like syndrome including fever, fatigue, myalgia, vomiting, tachycardia out of proportion to fever, new CHF, and tachypnea may be present.
  • Exam may demonstrate fever, S3/S4, pericardial rub, cardiogenic shock. Tachycardia is common, but its absence does not rule out myocarditis.
  • In previously normal pediatric patients, myocarditis is the most common cause of heart failure.
  • Grunting, retractions, respiratory distress may occur in pediatric patients. Younger children may present with fulminant disease with respiratory distress, fever, cardiac failure, and ventricular dysrhythmias. However, younger children typically do not have cardiac symptoms such as chest pain.
  • Pediatric patients may present with dyspnea, hepatomegaly, vomiting, abdominal pain, decreased oral intake, and hypoperfusion.
  • Patients who are treated for sepsis but worsen with fluid resuscitation warrant consideration of myocarditis.



  • ECG is typically abnormal with tachycardia (up to 58%), low voltage, AV block, long QTc, or acute ST changes (MI).
  • Chest Xray may reveal signs consistent with CHF (interstitial edema, cardiomegaly, effusions, etc.).
  • Normal ECG and Xray decrease the likelihood of myocarditis.
  • Labs including troponin are recommended, along with CRP, ESR, viral studies, electrolytes, CBC, Cr, and LFTs.
  • Labs often demonstrate leukocytosis, eosinophilia, elevated LFTs and inflammatory markers, elevated troponin.
  • Echocardiography may demonstrate global hypokinesis with decreased EF. Regional wall abnormalities can occur.
  • Gold standard is biopsy, but MR or nuclear study can be diagnostic.



  • Treatment depends on hemodynamic status of patient and phase of disease. All patients with diagnosed or suspected myocarditis should be admitted to a monitored setting.
  • Management of idiopathic or viral myocarditis is generally supportive. If due to bacterial etiology, antibiotics are needed.
  • Acute phase may be treated with antivirals; subacute with immunosuppressives (IVIG), and chronic with medications targeting heart failure.
  • Immunosuppressive agents can be used (primarily in subacute phase), but trials do not consistently show benefit. These agents are typically reserved for severe cases.
  • Patients with chronic phase may benefit from heart failure treatment: beta blockers, ACE-I, inotropes.
  • Patients may return to normal cardiac function. Mortality is 20% at one year, 50% at 5 years.
  • Fulminant myocarditis paradoxically has the best prognosis compared to those who present with less severe symptoms.
  • ECMO or VAD may be needed for patients in fulminant disease.


References/Further Reading:

  1. Cooper LT. Myocarditis. N Engl J Med. 2009;360:1526.
  2. Schultz JC, Hilliard AA, Cooper LT, et al. Diagnosis and treatment of viral myocarditis. Mayo Clin Proc. 2009;84:1001.
  3. Monney PA, Sekhri N, Burchell T, et al. Acute myocarditis presenting as acute coronary syndrome: role of early cardiac magnetic resonance in its diagnosis. Heart. 2011;97:1312.
  4. Durani Y, Egan M, Baffa J, et al. Pediatric myocarditis: presenting clinical characteristics. Am J Emerg Med. 2009 Oct;27(8):942-7.
  5. Freedman SB, Haladyn JK, Floh A, et al. Pediatric myocarditis: emergency department clinical findings and diagnostic evaluation. Pediatrics. 2007 Dec;120(6):1278-85.

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