Since May 2020, there has been some attention in the general public and the news media to a specific constellation of symptoms seen in children with COVID-19 or who have been exposed to COVID-19. For a time, headlines even called it a “Kawasaki-like” disease. At first glance, both the symptoms and the effective treatments are remarkably similar. However, a new review published in Trends in Cardiovascular Medicine finds that under closer scrutiny, the two conditions have some interesting differences as well.

“At the beginning of this journey, we thought we might be missing actual cases of Kawasaki disease because we identified a few patients who presented late and developed coronary artery abnormalities,” says Ashraf Harahsheh, M.D., senior author of the review article, “Multisystem inflammatory syndrome in children: Is there a linkage to Kawasaki disease?” and a cardiologist at Children’s National Hospital. “But as time passed, children exposed to COVID-19 started to present with a particular constellation of symptoms that actually had some important similarities and distinctions from Kawasaki.”

Similarities between Kawasaki disease and MIS-C

Both disease patterns seem to have a common trigger that provokes the inflammatory cascade reaction in genetically susceptible children, the authors write. However, there is also early evidence that children with each disease have different genetic markers, meaning different populations are genetically susceptible to each disease.

Additionally, the authors found that the massive activation of pro-inflammatory cytokines seen in MIS-C, also known as a “cytokine storm,” overlaps with a similar occurrence seen in Kawasaki disease, adult COVID-19 patients, toxic shock syndrome and some other viral infections.

Primary differences between Kawasaki disease and MIS-C

Overall, when compared to Kawasaki disease, children with MIS-C tend to:

• Present at an older age
• Have a more profound form of inflammation
• Have more gastrointestinal manifestation
• Show different laboratory findings
• Have greater risk of left ventricle dysfunction and shock

Further study of both Kawasaki and MIS-C needed

Despite noted differences, the authors are also careful to credit the documented similarities between Kawasaki disease and MIS-C as a key to the quick identification of the new syndrome in children. The study of Kawasaki disease also gave clinicians a valid basis to begin developing diagnostic recommendations and treatment protocols.

The review’s first author Yue-Hin Loke, M.D., who is also a cardiologist at Children’s National, says, “The quick recognition of MIS-C is only possible because of meticulous research conducted by Dr. Tomisaku Kawasaki, who recently passed away on June 5^th, 2020. Even though some aspects of both are still shrouded in mystery, the previous research and clinical advancements made in Kawasaki disease set the stage for our immediate response to MIS-C.”

“Previous research provided key information for cardiologists facing this new syndrome, including the necessity of routine echocardiograms to watch for coronary artery abnormalities (CAAs) and for use of  intravenous immunoglobulin (IVIG) to mitigate  the development of CAAs,” says Charles Berul, M.D., chief of Cardiology at Children’s National and a co-author. “Both of these factors have played a key role in reducing the mortality of MIS-C to almost zero.”

The authors note that more research is needed to understand both Kawasaki disease and the specifics of MIS-C, but that what is learned about the mechanisms of one can and should inform study and treatment of the other. And in the meantime, caution and continued surveillance of these patients, especially with respect to coronary artery and myocardial function, will continue to improve the long-term outcomes for both syndromes.