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Myocarditis

Last updated: November 8, 2020

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Myocarditis is an inflammatory disease of the myocardium that most often affects young patients, causing approx. 10% of sudden deaths in young adults. The disease is commonly caused by viral infections (e.g., parvovirus B19, coxsackievirus) or acute rheumatic fever, but may also manifest in patients with systemic conditions such as systemic lupus erythematosus or vasculitic syndromes. Adult patients are commonly asymptomatic or present with nonspecific symptoms, including fever, fatigue, and weakness. Some patients also experience cardiac signs that vary in severity from chest pain and arrhythmias to heart failure or sudden cardiac death. Infants and children typically have a more severe presentation. Inflammation may also spread and lead to concurrent pericarditis. Myocarditis should be suspected in patients with a history of flulike symptoms and new evidence of ECG abnormalities, such as sinus tachycardia or concave ST-segment elevations. Further diagnostic tests may show elevated cardiac enzymes and cardiac enlargement in chest x-rays. If the diagnosis is uncertain, an additional myocardial biopsy may also be indicated. Initial management of myocarditis involves supportive measures and treatment of any underlying diseases (e.g., antibiotic therapy). Cardiac symptoms usually require additional medication, including amiodarone for arrhythmias or beta-blockers for congestive heart failure. Whereas most adults with viral myocarditis make a full recovery, there is a small risk of the condition progressing to dilated cardiomyopathy. The prognosis is especially poor for infants and small children.

The exact incidence is unknown.

  • 1–5% of viral infections are estimated to have cardiac involvement.
  • Often occurs in young patients (average age ∼ 40 years)
  • In ∼ 10% of sudden deaths in young adults, myocarditis is diagnosed in the post-mortem examination. [1]

Epidemiological data refers to the US, unless otherwise specified.

Infectious [2]

Noninfectious [3]

The clinical manifestation of myocarditis is heterogeneous and nonspecific, ranging from asymptomatic courses to fulminant cardiac decompensation.
References:[3][5]

Patients suspected of myocarditis should have an ECG and laboratory tests conducted to support the diagnosis. Ultimately, if the diagnosis is unclear, a biopsy may be indicated to help determine treatment.

ECG/24-hour Holter monitoring

Although ECG abnormalities due to myocardial inflammation are very nonspecific and may only manifest temporarily, myocarditis should be suspected if the following findings are observed:

Laboratory findings

Imaging

Myocardial biopsy

References:[1][5][6]

The differential diagnoses listed here are not exhaustive.

References:[5][6][7]

References:[5]

We list the most important complications. The selection is not exhaustive.

  1. Kindermann, Barth, Mahfoud, et al.. Update on Myocarditis. Journal of the American College of Cardiology. 2012; 59 (9). doi: 10.1016/j.jacc.2011.09.074 . | Open in Read by QxMD
  2. Cooper LT. Etiology and pathogenesis of myocarditis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/etiology-and-pathogenesis-of-myocarditis?source=search_result&search=myocarditis&selectedTitle=4~150.Last updated: March 21, 2016. Accessed: December 21, 2016.
  3. Cooper LT. Myocarditis. N Engl J Med. 2009; 360 (15): p.1526-1538. doi: 10.1056/nejmra0800028 . | Open in Read by QxMD
  4. Kang M, An J. Viral Myocarditis. StatPearls. 2020 .
  5. Cooper LT. Clinical manifestations and diagnosis of myocarditis in adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-myocarditis-in-adults?source=search_result&search=myocarditis&selectedTitle=1~150.Last updated: May 20, 2016. Accessed: December 22, 2016.
  6. Tang WHW. Myocarditis. In: Ooi HH, Myocarditis. New York, NY: WebMD. http://emedicine.medscape.com/article/156330-overview#a6. Updated: December 19, 2016. Accessed: December 21, 2016.
  7. Cooper LT. Treatment and prognosis of myocarditis in adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-and-prognosis-of-myocarditis-in-adults?source=search_result&search=myocarditis&selectedTitle=2~150#H550303768.Last updated: August 28, 2015. Accessed: December 21, 2016.
  8. Dancea AB. Myocarditis in infants and children: A review for the paediatrician. Paediatr Child Health. 2001; 6 (8): p.543-545.
  9. Blauwet LA, Cooper LT. Myocarditis. Prog Cardiovasc Dis. 2010; 52 (4): p.274-288. doi: 10.1016/j.pcad.2009.11.006 . | Open in Read by QxMD
  10. Herold G. Internal Medicine. Herold G ; 2014