What to Know About Myocarditis in Children

The wall of your heart has three layers: the epicardium, myocardium, and endocardium. The myocardium is the middle layer and is the heart’s muscle layer. It is responsible for the heart’s contraction.

Sometimes, the myocardium can become inflamed or swollen. This is known as myocarditis.

Myocarditis affects your heart’s ability to function, making it more difficult to pump blood and putting you at risk of abnormal heart rhythms. Most people recover, but in its most severe cases, it can be life-threatening.

The condition can affect people of any age, but it may be especially concerning for children.

What Is Myocarditis in Children?

Myocarditis is a general term for inflammation of the heart. It usually happens as a result of an infection, but other factors also can cause inflammation.

Myocarditis is typically a rare disease among children. According to the American Heart Association, it affects 1 to 2 children per 100,000 in the United States. Children are more likely to have acute, or sudden-onset, myocarditis.

“Just like any other organ, (the heart) can get inflamed. You can have hepatitis or encephalitis or myocarditis,” says Tyler Harris, MD, pediatric cardiologist, UPMC Children’s Hospital of Pittsburgh.

“The reason myocarditis is such a concern and why we get concerned about life-threatening illnesses with myocarditis is when the heart muscle gets inflamed and you stress that heart muscle, it can become angry and typically can cause abnormal heart rhythms that then lead to death.”

Myocarditis is one of the leading causes of sudden, exercise-related death among children and young adults.

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What Causes Myocarditis?

Myocarditis most often happens after a viral infection, such as influenza or the common cold.

When your body fights off the infection, it releases cells that can cause inflammation in various organs. When that happens in your myocardium, it leads to myocarditis.

The American Heart Association says children are more likely than adults to have viral-related myocarditis.

Other causes of myocarditis include:

  • Bacterial infections.
  • Reactions to medicines/vaccines.
  • Eating or drinking toxins.
  • Autoimmune conditions.

What Are the Symptoms of Myocarditis in Children?

The symptoms of myocarditis in children can range from mild to severe. Some children may not have symptoms at all.

The most common symptoms include:

  • Fatigue.
  • Shortness of breath.
  • Abdominal pain and vomiting.
  • Fever.
  • Chest pain.
  • Heart palpitations.
  • Fast or irregular breathing, or trouble breathing.
  • Dizziness or lightheadedness.
  • Fainting.

If your child is showing any of these symptoms, call their pediatrician. Doctors may use a variety of tests to help diagnose myocarditis. Those may include an echocardiogram or electrocardiogram, blood tests, and/or imaging tests such as MRIs or CT scans.

Treatment of Myocarditis in Children

Some myocarditis cases can go away on their own, while others will require treatment. Because of the risks of myocarditis, it’s important to talk to your child’s doctor as soon as possible if they are having symptoms.

Your child should see a pediatric cardiologist for treatment. Depending on the severity of the symptoms, some children will need hospital care — potentially in the cardiac or pediatric intensive care unit.

Myocarditis puts you at risk of sudden cardiac arrest and death during exercise. Doctors typically will recommend a restriction of activity until the heart inflammation goes away.

“I try to explain to families that exercise restriction after myocarditis is a brace and some ice for your heart,” Dr. Harris says. “Basically, relax your heart for a little bit, let it recover, let the inflammation go away, so that you’re not straining it to then reinjure it. So we typically recommend for kids who have myocarditis from all causes to rest for a period of time until we know that the inflammation is recovered.”

Your child’s doctor also may prescribe medication to reduce inflammation, treat symptoms, and prevent arrhythmias.

In more severe cases, ventricular assist devices (VADs), extracorporeal membrane oxygenation (ECMO), or a heart transplant may be necessary if the heart is severely damaged.

Can Myocarditis Be Cured?

Most cases of myocarditis do eventually heal, whether on their own or with treatment. But some children may develop chronic heart failure or cardiomyopathy. The most severe possible complication is sudden cardiac arrest during activity and heart failure.

Those risks make it important to seek care for myocarditis as soon as possible. Your child can get the treatment necessary to help them have the best chance at success. Follow-up care with a pediatric cardiologist may be necessary depending on your child’s case.

Myocarditis and COVID-19

During the COVID-19 pandemic, reports emerged showing myocarditis as a complication. According to the Centers for Disease Control and Prevention (CDC), myocarditis inpatient encounters rose by more than 42% in 2020, the first year of the pandemic.

Dr. Harris says COVID-19 can lead to myocarditis among children in three major ways:

  • After a COVID-19 illness.
  • As a complication of multisystem inflammatory syndrome in children (MIS-C).
  • After COVID-19 vaccination.

Myocarditis after COVID-19 illness

The CDC says the overall risk of myocarditis after COVID-19 illness is low. However, people with COVID-19 are at higher risk of myocarditis than people without. The risk varies by age group and severity of illness. Patients who are very sick from COVID-19 and require hospitalization and breathing support are more likely to have myocarditis.

Myocarditis and MIS-C

MIS-C is a rare complication of COVID-19 among children that develops as a result of your immune system’s response to infection. It can cause inflammation in many different organs, including the heart. If that inflammation happens in the myocardium, it can cause myocarditis.

COVID-19 vaccine and myocarditis

Reports began to emerge in spring 2021 of increased cases of myocarditis after COVID-19 vaccination. The mRNA vaccines developed by Pfizer-BioNTech and Moderna were associated with this complication as well as the non-mRNA vaccine from Janssen.

According to the CDC, the risk of myocarditis after COVID-19 vaccination is very low. Most cases happened in male adolescents and young adults 16 years old and up. Most people responded well to medications and recovered quickly. It is very uncommon in children less than 11 years old.

“What we’ve seen is kids after their second dose of the vaccine, three to four days later, have chest pain and fevers and trouble breathing,” Dr. Harris says. “And we see inflammation of their heart muscle. The good news is it’s been very mild. Most kids come to the hospital and we observe them briefly, but they are not here very long and typically respond to Ibuprofen and recover very quickly with minimal long-term side effects.

“And it’s also much, much less common to get myocarditis from the vaccine than either of the other two ways that COVID can affect the heart. If you want to decrease your chance of myocarditis, get vaccinated.”

Does the COVID-19 vaccine cause myocarditis?

Myocarditis is possible after COVID-19 vaccination. But it is extremely rare. Most cases also are mild and respond well to medication. Overall, vaccination reduces your risk of myocarditis due to COVID-19.

Children 6 months old and up are eligible for COVID-19 vaccination, and the CDC continues to recommend vaccination. The risks of COVID-19 are much higher than any risks of vaccination.

Heart Care at UPMC Children’s Hospital of Pittsburgh

If your child has a heart condition, including myocarditis, the experts at the Heart Institute at UPMC Children’s Hospital of Pittsburgh can help. UPMC Children’s is nationally ranked in heart care. Our experts can provide diagnosis, treatment, and long-term care for heart conditions, from newborns to adults.

For more information, visit our website.

Editor's Note: This article was originally published on , and was last reviewed on .

American Heart Association, Diagnosis and Management of Myocarditis in Children. Link

American Heart Association, Viruses Are the Most Common Cause of Myocarditis in Children, Experts Offer Guidance. Link

Centers for Disease Control and Prevention, Association Between COVID-19 and Myocarditis Using Hospital-Based Administrative Data — United States, March 2020–January 2021. Link

Centers for Disease Control and Prevention, Clinical Considerations: Myocarditis and Pericarditis after Receipt of mRNA COVID-19 Vaccines Among Adolescents and Young Adults. Link

Nitai Levy, MD, Jordanna H. Koppel, MD, Or Kaplan, MD, et al, Journal of the American Medical Association, Severity and Incidence of Multisystem Inflammatory Syndrome in Children During 3 SARS-CoV-2 Pandemic Waves in Israel. Link

Fares Najari, Alimohammad Alimohammadi, and Parisa Ghodrati, Emergency (Tehran), Sudden Death Following Exercise: A Case Series. Link

National Cancer Institute, Structure of the Heart. Link

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Severity and Incidence of Multisystem Inflammatory Syndrome in Children During 3 SARS-CoV-2 Pandemic Waves in Israel. Link

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