Learn About Myocarditis

What is the definition of Myocarditis?

Myocarditis is inflammation of the heart muscle.

The condition is called pediatric myocarditis when it occurs in children.

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What are the alternative names for Myocarditis?

Inflammation - heart muscle

What are the causes of Myocarditis?

Myocarditis is an uncommon disorder. Most of the time, it is caused by an infection that reaches the heart.

When you have an infection, your immune system produces special cells to fight off disease. If the infection affects your heart, the disease-fighting cells enter the heart. However, the chemicals made by these cells can also damage the heart muscle. As a result, the heart can become thick, swollen, and weak.

Many cases are caused by a virus that reaches the heart. These can include the SARS-CoV-2 virus (the virus that causes COVID-19), influenza (flu) virus, coxsackievirus, parvovirus, cytomegalovirus, adenovirus, and others.

It may also be caused by bacterial infections such as Lyme disease, streptococcus, mycoplasma, and chlamydia.


Other causes of myocarditis include:

  • Reactions to certain medicines, such as certain chemotherapy drugs
  • Exposure to chemicals in the environment, such as heavy metals
  • Infections due to fungus or parasites
  • Radiation
  • Autoimmune disorders that cause inflammation throughout the body
  • Myocarditis following COVID-19 vaccination has been reported, but is very rare

Sometimes the exact cause may not be discovered.

What are the symptoms of Myocarditis?

There may be no symptoms. Symptoms may be similar to the flu. If symptoms occur, they may include:

  • Chest pain that may resemble a heart attack
  • Fatigue or listlessness
  • Fever and other signs of infection including headache, muscle aches, sore throat, diarrhea, or rashes
  • Joint pain or swelling
  • Leg swelling
  • Pale, cool hands and feet (a sign of poor circulation)
  • Rapid breathing
  • Rapid heart rate
  • Shortness of breath

Other symptoms that may occur with this disease:

  • Fainting, often related to irregular heart rhythms
  • Low urine output
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What are the current treatments for Myocarditis?

Treatment is aimed at the cause of the problem, and may involve:

  • Antibiotics to fight bacterial infection
  • Medicines called steroids to reduce swelling
  • Intravenous immunoglobulin (IVIG), a medicine made of substances (called antibodies) that the body produces to fight infection, to control the inflammatory process
  • Diuretics to remove excess water from the body
  • Low-salt diet
  • Reduced activity

If the heart muscle is weak, your provider will prescribe medicines to treat heart failure. Abnormal heart rhythms may require the use of other medicines. You may also need a device such as a pacemaker, or implantable cardioverter-defibrillator to correct a dangerous abnormal heartbeat. If a blood clot is in the heart chamber, you will also receive blood thinning medicine.

Rarely, a heart transplant may be needed if the heart muscle has become too weak to function.

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What is the outlook (prognosis) for Myocarditis?

The outcome can vary, depending on the cause of the problem and a person’s overall health. Some people may recover completely. Others may have lasting heart failure.

What are the possible complications of Myocarditis?

Complications may include:

  • Cardiomyopathy
  • Heart failure
  • Heart rhythm problems
  • Pericarditis
When should I contact a medical professional for Myocarditis?

Contact your provider if you have symptoms of myocarditis, especially after a recent infection.

Seek medical help right away if:

  • Your symptoms are severe.
  • You have been diagnosed with myocarditis, and you have increased chest pain, swelling, or breathing problems.
How do I prevent Myocarditis?

Treat conditions that cause myocarditis promptly to reduce the risk.

Heart - section through the middle
Heart - front view
What are the latest Myocarditis Clinical Trials?
IMPRoving Cardiovascular RiSk Stratification Using T1 Mapping in General populatION

Summary: Magnetic properties of myocardial tissue change in the presence of disease. This is detectable in the change of rate of magnetic relaxation, and measurable by T1 and T2 mapping using cardiovascular magnetic resonance (CMR). These markers provide novel quantifiable imaging measures for myocardial tissue characterisation. Despite similar principles, the measurements differ considerably between diffe...

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Randomised Placebo Controlled Clinical Trial of Efficacy of MYOcardial Protection in Patients With Postacute inFLAMmatory Cardiac involvEment Due to COVID-19

Summary: Postacute sequelae of COVID-19 infection (PASC) are increasingly recognised complications and are defined by lingering symptoms, not present prior to the infection, typically persisting for more than 4 weeks. Cardiac symptoms due to post-acute inflammatory cardiac involvement affect a broad segment of people, who were previously well and may have had only mild acute illness (PASC-cardiovascular sy...

What are the Latest Advances for Myocarditis?
Early identification of Lyme disease complications.
Influence of extracorporeal membrane oxygenation on in-hospital survival and prognosis of adult patients with fulminant myocarditis.
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Neonatal MIS-C: Managing the Cytokine Storm.
Who are the sources who wrote this article ?

Published Date: January 09, 2022
Published By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 08/24/2022.

What are the references for this article ?

Centers for Disease Control and Prevention. Safety of COVID-19 vaccines. www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/safety-of-vaccines.html. Updated August 22, 2022. Accessed August 24, 2022.

Cooper LT, Knowlton KU. Myocarditis. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 55.

Knowlton KU, Anderson JL, Savoia MC, Oxman MN. Myocarditis and pericarditis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 84.

McKenna WJ, Elliott PM. Diseases of the myocardium and endocardium. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 54.

What are some Advocacy Organizations?

Simon’s Heart is a nonprofit organization dedicated to raising awareness about, and preventing deaths from, conditions that cause sudden cardiac arrest in children.