Heart function recovered quickly in children with COVID-19-related MIS-C condition

MIS-C is a new illness identified during the COVID-19 pandemic that affects children about four to six weeks after exposure to COVID-19. The new condition has some overlapping symptoms with Kawasaki disease, however, MIS-C is associated with more profound inflammation. MIS-C can cause inflammation in different parts of the body, including the heart, lungs, kidneys and gastrointestinal organs. About 80%-85% of MIS-C cases across the U.S. and Europe have involved the heart's left ventricle.

This study details the cardiovascular complications or damage found during a three-month follow-up period to assess the short-term impact of MIS-C. It also employs newer cardiac measurements, known as "strains," to assess heart function related to MIS-C. Strain testing is a more sensitive tool that can detect whether an area of the heart is deformed or if there are any subtle changes in heart function during cardiac contraction and relaxation.

"There is limited data at this time about how frequently and how long we should monitor heart function during the recovery state of MIS-C after the child leaves the hospital," said the study's senior author Anirban Banerjee, M.D., a professor of clinical pediatrics at the University of Pennsylvania Perelman School of Medicine and an attending cardiologist with the Cardiac Center at the Children's Hospital of Philadelphia, both in Philadelphia.

"Given that MIS-C was identified as a result of the COVID-19 pandemic, treatment protocols have not yet been standardized and follow-up care varies greatly, which may lead to confusion and anxiety among families of patients and their care team. Our research team hoped to provide some guidance and reduce the ambiguity on optimal care approaches, especially as it relates to sports participation," Banerjee added.

Researchers retroactively reviewed data on 60 children hospitalized with MIS-C due to COVID-19 exposure who were treated at two Philadelphia hospitals between April 2020 and January 2021. None of the children were initially diagnosed with COVID-19 before the onset of MIS-C symptoms. This group of children were 60% male, with an average age of 10 years. About 48% were Black children, 27% were white children, 15% were Hispanic children, 4% were Asian children and the race/ethnicity of 23% of the children was unknown. The participants were treated with intravenous immunoglobulin and/or systemic steroids. Researchers reviewed echocardiographic and clinical data from medical records, including demographic factors, testing, treatment and hospital outcomes.

Data on another 60 children who had structurally normal hearts and did not have MIS-C or COVID-19 exposure served as control subjects. Their average age was 11.5 years, and 55% were male; 62% white children, 27% Black children, 7% Hispanic children, 3% Asian and 8% unknown. The control participants were divided into two groups: 60% had echocardiograms on file that were done prior to the COVID-19 pandemic, and 40% had echocardiograms under rigid COVID-19 protocols after October 2020.

For the children with MIS-C, researchers analyzed images of the heart taken at the initial hospitalization (acute phase) and examined additional imaging for a portion of the children who also had scans up to three additional times – one week after the first scan (subacute phase); at the one-month follow-up; and at a three or four-month follow-up. The children were screened using conventional echocardiography, speckle tracking echocardiography – an imaging technique that analyzes the motion of the heart tissue - and cardiac magnetic resonance imaging (MRI) for images of the heart.