JUL 12, 2021 12:31 PM PDT

Myocarditis in Children is Usually Due to a Virus

WRITTEN BY: Carmen Leitch

The heart is a muscle, and the wall of the heart has several layers. In a condition called myocarditis, the middle layer becomes inflamed; it may cause the heart to be weakened temporarily or permanently. About 15 out of 100,000 people are diagnosed with the condition every year. Children don't get the disorder as often; only about one in 100,000 are impacted. Viral infections including COVID-19 and hepatitis B and C can cause myocarditis. While the condition may resolve on its own, it may also be difficult to treat. Severe cases of myocarditis can cause shortness of breathe, chest pains, and heart palpitations; the heart may beat abnormally, and the heart may fail to pump enough blood to the body to fulfill its needs.

A photomicrograph of a section of myocardial tissue, specifically in an area of myocarditis / Credit: CDC/ Dr. Flynt

"Myocarditis has distinct characteristics in children and a potential impact on their lifelong health," noted Yuk M. Law, M.D., FAHA, director of Cardiac Transplant and Heart Failure Service at Seattle Children's Hospital. Law and other researchers have gathered the latest information about myocarditis in kids.

"We hope that this statement serves as an educational update as well as a unifying call for much needed research to better understand and treat this important pediatric condition. And, in light of the recently recognized occurrence of myocarditis after COVID-19 infection, as well as the emergence of cases of suspected myocarditis after COVID-19 vaccination, this statement is a resource for clinicians and health care professionals in caring for these patients," said Law.

Myocarditis could once only be diagnosed after a biopsy was done, which can also show whether a virus is infecting the tissue. Biopsies are no longer necessary though since less invasive options are now available. There are also biomarkers of myocarditis that can be detected in blood tests, and imaging tools like MRIs can look for heart damage. Electrocardiography (ECG) screening also reveals signs of heart injury and dysfunction.

The researchers noted that when kids have active cases of myocarditis, they should not participate in competitive sports. Stress tests should also be given to athletes between three and six months after a myocarditis diagnosis, and prior to their returning to playing sports.They study noted that in children, viral infections are the most common cause of myocarditis, which is usually sudden-onset and not chronic myocarditis that tends to impact adults.

Kids may exhibit a range of symptoms. Typically, shortness of breath, fever, abdominal pain and fatigue happens, and it may lead to arrhythmias and cardiogenic shock. Patients with acute myocarditis may suddenly experience life-threatening problems, and the study authors noted that these patients may have to be monitored in a clinical setting.

A few cases of myocarditis have arisen in people that have gotten a COVID-19 vaccine; of millions of doses administered, about 1,000 myocarditis cases have happened. Clinicians and scientists say the risk of myocarditis should not stop anyone from getting the vaccine. COVID-19 infections can also cause serious heart problems, and it seems to do so at a far higher rate than the vaccine.

If viral infections are detected in these cases, antiviral therapy should be considered, and immunotherapy like corticosteroids might be administered. More research is needed to understand what doses kids should get, however. The COVID-19 pandemic is also linked to multisystem inflammatory syndrome in children (MIS-C), which may affect the coronary arteries or myocardium.

"While our work on this scientific statement preceded the COVID-19 pandemic and the cases of suspected myocarditis after COVID-19 vaccination and after COVID-19 infection being reported in adolescents and young adults, the guidance detailed in this scientific statement can help to advise treatment for these patients as well," Law said.

Sources: AAAS/Eurekalert! via American Heart Association, Circulation

About the Author
Bachelor's (BA/BS/Other)
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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