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Long-term outcome data suggest optimism for MIS-C patients



Only 1 child from a cohort of 45 children hospitalized with multisystem inflammatory syndrome following COVID-19 infection had persistent mild cardiac dysfunction after 9 months, according to data from patients younger than 21 years seen at a single center in 2020.

In a study published in Pediatrics, Kanwal M. Farooqi, MD, of Columbia University, New York, and colleagues provided the first report on longitudinal cardiac and immunologic outcomes in North American children hospitalized with multisystem inflammatory syndrome (MIS-C). In response to the COVID-19 pandemic, clinicians at New York–Presbyterian Hospital consolidated pediatric admissions and developed an interdisciplinary inpatient and outpatient MIS-C follow-up program to monitor cardiac and immunologic outcomes in their patients.

The study included all children younger than 21 years admitted to Columbia University Irving Medical Center/New York–Presbyterian Morgan Stanley Children’s Hospital for MIS-C in 2020. The median age of the patients was 9 years, and the median length of hospital stay was 5 days. Follow-up visits occurred at 1-4 weeks (average 2 weeks), 1-4 months (average 2 months), and 4-9 months (average 6 months) after hospital discharge. Follow-up visits included echocardiograms and measures of inflammatory markers.

Most of the children (84%) had no underlying medical conditions, but 24% presented with some level of respiratory distress or oxygen requirement, and 64% had vasodilatory shock. In addition, 80% had at least mild cardiac abnormalities and 66% had significant lymphopenia on admission.

Inflammatory profiles on admission showed elevation of C-reactive protein, ferritin, and D-dimer in 87%-98% of the patients. Consistent with cardiac involvement, 64% of the patients also had elevated troponin levels, and 91% had elevated N-terminal pro-brain natriuretic peptide (NT-proBNP) levels.

“These parameters peaked at or shortly after admission and then gradually normalized,” the researchers said. “By the first follow-up, [C-reactive protein], troponin, and NT-proBNP had normalized in nearly all tested patients (97%-100%),” they noted.

By the first follow-up period at 1-4 weeks, all patients had normal coronary arteries, and 18% (seven patients) had mild echocardiographic findings. However, approximately one-third (32%) of the patients had persistent lymphocytosis at 1-4 weeks, and 23 of the 24 patients assessed had elevated double-negative T cells, which persisted in 96% of the patients at 1-4 months’ follow-up. However, during the last follow-up of 4-9 months, only one patient had persistent mild biventricular dysfunction and a second patient had mild mitral and tricuspid valve regurgitation.

All patients were treated with steroids and immunoglobulins (2 g/kg), as well as enoxaparin prophylaxis or low-dose aspirin and GI prophylaxis. Treatment with methylprednisolone varied based on disease severity; patients with mild presentation received 2 mg/kg per day; those with moderate presentation received a methylprednisolone pulse of 10 mg/kg per day, followed by 2 mg/kg per day; those with severe disease received methylprednisolone at 20-30 mg/kg per day for 1-3 days, followed by 2 mg/kg per day.

“Aggressive use of steroids may also explain the lower incidence of coronary artery abnormalities in our cohort,” the researchers noted.

The study findings were limited by the observational design and inability to make definitive conclusions about treatment and outcomes, as well as the evolving case definitions for MIS-C, the researchers said.

The persistence of double-negative T cells was surprising, and “likely represent a prolonged postinflammatory recovery cell population, but further study is ongoing to better define this observation,” they noted.

“Our study reveals generally encouraging medium-term outcomes, including rapid normalization of inflammatory markers and significant cardiac abnormalities in the majority of patients with MIS-C,” the researchers said. “The exact nature and potential for long-term cardiac fibrosis, exercise intolerance, or other changes remain unknown,” and long-term caution and follow-up are recommended, they concluded.

Cautious optimism, long-term monitoring

The study is important to provide guidance for clinicians on how to manage their patients who have been hospitalized with MIS-C, said Susan Boulter, MD, of the Geisel School of Medicine at Dartmouth, Hanover, N.H.

“It was both surprising and reassuring to see that so many of the patients had positive outcomes in terms of cardiac function and that during the acute stage there were no deaths,” said Dr. Boulter. “Hospitalizations were brief, averaging just 5 days. The patients had many symptoms, but unlike adults, there was not a preponderance of underlying risk factors in this cohort of patients,” she said.

The results suggest optimism for MIS-C patients in that they generally recover, but the take-home message for clinicians is that these patients will require careful monitoring for long-term issues, Dr. Boulter said.

“These patients should be followed for years to assess long-term effects on morbidity and mortality,” Dr. Boulter emphasized.

The study was funded by Genentech. The researchers had no financial conflicts to disclose. Dr. Boulter had no financial conflicts to disclose, but serves on the Pediatric News Editorial Advisory Board.

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