Cardiologists share the latest details on COVID-related MIS-C

MIS-C is a rare condition associated with the SARS-CoV-2 virus that usually occurs two to six weeks after a child becomes infected with COVID-19. Most children have very mild or asymptomatic cases of COVID-19, but children with MIS-C are even more affected by a massive inflammatory response as the body’s immune system overreacts to the virus. This can cause damage to the patient’s organs. MIS-C causes inflammation of internal and external parts of the body, including the heart, lungs, kidneys, brain, skin, eyes and gastrointestinal tract. The US Centers for Disease Control and Prevention (CDC) has said that MIS-C can be a serious and even deadly condition. However, most children diagnosed with the disease recover fully with medical care.

MIS-C is very similar to Kawasaki disease, which some patients were initially diagnosed with. However, the number of pediatric patients seen in pediatric hospitals skyrocketed from the normal number and was quickly identified as a new type of COVID-related inflammatory response disease. This greatly alarmed public health officials around the world, who quickly moved to educate clinicians to identify cases of MIS-C and collate data to better understand how to treat it.

Thacker said the CDC’s initial definition of the disease and its symptoms created in 2020 has withstood the test of the pandemic and hasn’t really changed. This stability helped identify these patients and treat them.

Since the beginning of the COVID pandemic, the CDC has reported 9,333 cases of MIS-C as of January 2, 2023. The CDC has also reported a total of 76 infant deaths from MIS-C since 2020.

Thankfully, Thacker said the number of cases actually declined starting in mid-2022. She said they went from one or two patients a week showing up with MIS-C, to no cases for two months before November 2022, when she spoke with Cardiovascular Business.

“We believe that the current variant of the COVID Omicron variant does not produce the same types of COVID effects on the heart that it used to in the past, and vaccination definitely played a role as well,” explained Thacker. “The severity of the MIS-C cases we saw in 2022 also decreased significantly. So these children are less likely to be intubated, less likely to have kidney failure, and less likely to need ICU treatment.”

How to Diagnose and Treat for MIS-C

For patients with suspected MIS-C, she said, they usually order blood tests, including troponin, echocardiogram, ECG and X-ray to assess the heart. Treatment includes efforts to suppress the hyperimmune response using steroids and intravenous immunoglobulin, which is commonly used to treat patients with antibody deficiencies. Biological agents such as infliximab and anakinra are also used. She said supportive care is given for other issues the condition causes.

“When and how echocardiograms are performed is crucial because there is a subset of children who have severe myocardial involvement and a subset who may have coronary artery involvement,” explained Srivastava. “That’s why it’s very important that the echocardiogram be done when the child is admitted or is treated at the emergency room. A certain protocol must be followed so that the coronary arteries are not missed.”

Echo examination includes ejection fraction, assessment of valvular and coronary involvement, and an assessment of myocardial strain. If there appears to be a high level of cardiac involvement, a cardiac MRI is performed for a more detailed evaluation to look for scarring or involvement with the myocardium. MRI scans are also done if there are elevated troponin levels, indicating that there may be heart muscle damage or severe inflammation.

“In just under half of the children we’ve seen, we find that troponin is elevated,” explained Thacker. “Early on, we noticed that these children had a lot of myocardial muscle dysfunction. Fortunately, coronary involvement is usually mild and doesn’t persist.”

Thrombosis is a common problem found in COVID patients due to the way the virus damages vascular beds.

“We see clotting, but the number of children showing clotting is much lower than we thought we would see,” Thacker said. Overall, she said, adults have a much higher incidence of clotting than children. “Usually in children, we don’t see this, but we usually put them on aspirin and low-molecular-weight heparin to prevent clotting.”

Since most pediatric patients have asymptomatic COVID cases, parents are often unaware that their child may be at risk for MIS-C until the onset of symptoms such as high fever and rash, often combined with other issues.

The COVID antibody test was used early on to test children with MIS-C to confirm their prior exposure to COVID. Thacker said this is a little harder to do today because most people have already been exposed to COVID, and vaccines will show up as COVID exposure in the spike protein antibody test. Today they moved on to the nucleocapsid (N) protein of the SARS-CoV-2 antibody test. She said a negative N-antibody test can help rule out MIS-C when trying to diagnose patients.

In a small number of adults infected with COVID, there are cases of MIS-A (A for adult), Thacker said. This is the same Kawasaki disease-like condition that causes an adult’s immune system to switch to an exaggerated immune response. She said that MIS-A is very rare and MIS-C is much more commonly seen in children.

Find up-to-date information on the diagnosis and treatment of MIS-C.

What are the long term health issues of MIS-C?

While there were serious concerns about the long-term consequences of MIS-C, the data collected on these patients to date has shown that most will fully recover. Nemours is involved in several long-term MIS-C studies to assess long-term damage and other issues. This includes involvement in the National Institutes of Health (NIH) COVID MUSIC, RECOVER, and National COVID Cohort Collaborative (N3C) studies.

“The data so far has been very reassuring, very few of them have long-term symptoms,” Thacker said.

Of the patients who have long-term problems, most of them are “brain fog” and confusion issues, similar to a common complaint in patients with COVID-19.

While major heart problems are not seen, Srivastava said the N3C data shows that there may be problems later in some of these patients, similar to what is being seen in some adult patients with COVID-19. In adults who had cardiac involvement during the acute phase of the disease, COVID appears to damage the cardiac muscle substrate, which can cause the onset of cardiac arrhythmias. This includes the onset of atrial fibrillation, including in young patients.

“There’s some indication of ongoing heart involvement in terms of electrical disturbances or arrhythmias, so we’ve added Holter monitoring and screening questions for patients. We’ve also provided patients with a checklist of things they should look out for and get back to us if they come up. problems, because we continue to learn from this patient population,” explained Srivastava.

When can children with MIS-C return to school and sports?

Initially, myocarditis guidelines were followed for patients with MIS-C. These guidelines recommended keeping children away from sports and other intense activities for three to six months. This has changed in some centers that have become more familiar with the condition.

“I think now that we have more experience with MIS-C, we realize that even though there is cardiac involvement, many of these children recover quickly. So if there is no cardiac involvement, we say they can get back to engaging in sports and other activities. With patients who have cardiac involvement, we’ve reduced the time we’re asking them not to participate in sports activities from three to six months, to about one to three months, depending on how severe they were,” Thacker explained.

She said they do a stress test on these kids and sometimes an MRI to assess inflammation. But overall, she said they’ve become a lot more lenient about letting kids get back into sports.

Cardiologists share the latest details on COVID-related MIS-C

Leave a Reply

Your email address will not be published.

Scroll to top