COVID-linked MIS-C outcomes reassuring at 6 months

Children and young adults with multisystem inflammatory syndrome in children (MIS-C) related to COVID-19 infection show good cardiovascular and noncardiovascular outcomes at 6 months, according to data from the long-term MUSIC study.

MIS-C is a life-threatening complication of COVID-19 infection. However, data on outcomes are limited, said study author Dr Dongngan Truong from the Children’s Healthcare of Atlanta Cardiology, Emory University School of Medicine in Atlanta, Georgia, US.

In this study sponsored by the US National Heart, Lung, and Blood Institute, 99 percent of the patients had normalization of left ventricular systolic function and 92.3 percent had normalization of coronary artery dimension by 6 months following hospital discharge. More than 95 percent reported being >90 percent back to their baseline health. [JAMA Pediatr 2025;doi:10.1001/jamapediatrics.2024.5466]

PROMIS* Global Health parent/guardian proxy median T scores for fatigue, global health, and pain interference improved significantly from 2 weeks to 6 months (fatigue 56.1 vs 48.9; global health 48.8 vs 51.3; pain interference 53 vs 43.3; p<0.001) and were at least equivalent to pre-pandemic normative values by the 6-week visit. Sleep, appetite, cognition, and mood also normalized.

Looking into MUSIC

The researchers sought to characterize the frequency and time course of cardiac dysfunction, coronary artery aneurysms, and noncardiac involvement through 6 months after MIS-C in 1,204 children and young adults from the MUSIC study.

Enrolment was between March 2020 and January 2022, with a follow-up of 2 years. Participants were recruited from 32 North American paediatric hospitals. All met the 2020 Centers for Disease Control and Prevention case definition of MIS-C.

The cohort's median age was 9 years; 60 percent were male. They identified themselves as either American Indian or Alaska Native (0.1 percent), Asian (3.3 percent), Black (27 percent), Hawaiian Native or Other Pacific Islander (0.2 percent), Hispanic or Latino (26.9 percent), multiracial (2.7 percent), White (31.2 percent), other (1 percent), or unknown (7.6 percent).

Most common symptoms

At 2 weeks, the most common symptoms reported were fatigue (15.9 percent) and low stamina/energy (9.2 percent), which decreased to 3.4 percent and 3.3 percent, respectively, by 6 months. Palpitation (1.5 percent) was the most common cardiovascular symptom, which decreased to 0.6 percent by 6 months.

However, chest pain increased over time, with 1.3 percent reporting it while at rest at 2 weeks and 2.2 percent at 6 months. Although gastrointestinal symptoms were common during the acute phase of MIS-C, only 5.3 percent reported experiencing those at 2 weeks.

A moment of collective exhale

In an accompanying editorial, Dr David Goldberg from the Cardiac Center, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, US, and colleagues said MIS-C has features resembling toxic shock and Kawasaki disease, which require a rapid response to manage and treat the symptoms and understand the medium- and long-term sequelae. [JAMA Pediatr 2025;doi:10.1001/jamapediatrics.2024.5474]

“The decreased frequency of the disease, along with the reassuring reports on midterm outcomes, can allow the paediatric community a moment of collective exhale,” said Goldberg. “The results add to the emerging midterm outcomes data suggesting a near-complete cardiovascular recovery in the overwhelming majority of patients who develop MIS-C.”

Despite the severity of acute presentation at diagnosis, Goldberg said the data suggest an encouraging outlook for the long-term health of these children.

He added that despite the protective value of vaccination, children with MIS-C continue to require intensive care in the acute phase of their illness.