BACKGROUND In spring 2020, a novel hyperinflammatory process associated with severe acute respiratory syndrome coronavirus 2 multisystem inflammatory syndrome in children (MIS-C) was described. The long-term impact remains unknown. We report longitudinal outcomes from a New York interdisciplinary follow-up program. METHODS All children <21 years of age, admitted to NewYork-Presbyterian with MIS-C in 2020, were included. Children were followed at 1 to 4 weeks, 1 to 4 months, and 4 to 9 months postdischarge. RESULTS In total, 45 children were admitted with MIS-C. The median time to last follow-up was 5.8 months (interquartile range 1.3–6.7). Of those admitted, 76% required intensive care and 64% required vasopressors and/or inotropes. On admission, patients exhibited significant nonspecific inflammation, generalized lymphopenia, and thrombocytopenia. Soluble interleukin (IL) IL-2R, IL-6, IL-10, IL-17, IL-18, and C-X-C Motif Chemokine Ligand 9 were elevated. A total of 80% (n = 36) had at least mild and 44% (n = 20) had moderate-severe echocardiographic abnormalities including coronary abnormalities (9% had a z score of 2–2.5; 7% had a z score > 2.5). Whereas most inflammatory markers normalized by 1 to 4 weeks, 32% (n = 11 of 34) exhibited persistent lymphocytosis, with increased double-negative T cells in 96% of assessed patients (n = 23 of 24). By 1 to 4 weeks, only 18% (n = 7 of 39) had mild echocardiographic findings; all had normal coronaries. At 1 to 4 months, the proportion of double-negative T cells remained elevated in 92% (median 9%). At 4 to 9 months, only 1 child had persistent mild dysfunction. One had mild mitral and/or tricuspid regurgitation. CONCLUSIONS Although the majority of children with MIS-C present critically ill, most inflammatory and cardiac manifestations in our cohort resolved rapidly.

Background We sought to assess the impact and predictors of Coronavirus Disease 2019 (COVID‐19) infection and severity in a cohort of congenital heart disease (CHD) patients at a large CHD center in New York City. Methods and Results We performed a retrospective review of all individuals with CHD followed at Columbia University Irving Medical Center who were diagnosed with COVID‐19 between 3/1/2020 and 7/1/2020. The primary endpoint was moderate/severe response to COVID‐19 infection defined as a) death during COVID‐19 infection; or 2) need for hospitalization and/or respiratory support secondary to COVID‐19 infection. Among 53 COVID‐19 positive patients with CHD, 10 (19%) were <18 years old (median age 34 years). 31 (58%) had complex congenital anatomy including 10 (19%) with a Fontan repair. Eight (15%) had a genetic syndrome, six (11%) had pulmonary hypertension (PH), and nine (17%) were obese. Among adults, 18 (41%) were physiologic class C or D. For the entire cohort, nine (17%) had a moderate/severe infection, including three deaths (6%). After correcting for multiple comparisons, the presence of a genetic syndrome (OR=35.82: p=0.0002), and in adults, physiological Stage C or D (OR=19.38: p=0.002) were significantly associated with moderate/severe infection. Conclusions At our CHD center, the number of symptomatic COVID‐19 patients was relatively low. CHD patients with a genetic syndrome and adults at advanced physiological stage were at highest risk for moderate/severe infection.

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OBJECTIVES: Multisystem inflammatory syndrome in children (MIS-C) has spread through the pediatric population during the coronavirus disease 2019 pandemic. Our objective for the study was to report the prevalence of conduction anomalies in MIS-C and identify predictive factors for the conduction abnormalities. METHODS: We performed a single-center retrospective cohort study of pediatric patients &lt;21 years of age presenting with MIS-C over a 1-month period. We collected clinical outcomes, laboratory findings, and diagnostic studies, including serial electrocardiograms, in all patients with MIS-C to identify those with first-degree atrioventricular block (AVB) during the acute phase and assess for predictive factors. RESULTS: Thirty-two patients met inclusion criteria. Median age at admission was 9 years. Six of 32 patients (19%) were found to have first-degree AVB, with a median longest PR interval of 225 milliseconds (interquartile range 200–302), compared with 140 milliseconds (interquartile range 80–178) in patients without first-degree AVB. The onset of AVB occurred at a median of 8 days after the initial symptoms and returned to normal 3 days thereafter. No patients developed advanced AVB, although 1 patient developed a PR interval &gt;300 milliseconds. Another patient developed new-onset right bundle branch block, which resolved during hospitalization. Cardiac enzymes, inflammatory markers, and cardiac function were not associated with AVB development. CONCLUSIONS: In our population, there is a 19% prevalence of first-degree AVB in patients with MIS-C. All patients with a prolonged PR interval recovered without progression to high-degree AVB. Patients admitted with MIS-C require close electrocardiogram monitoring during the acute phase.

SARS-CoV-2 infection for most children results in mild or minimal symptoms, though in rare cases severe disease can develop, including a multisystem inflammatory syndrome (MIS-C) with myocarditis. Here, we present longitudinal profiling of immune responses during acute disease and following recovery in children who developed MIS-C, relative to children who experienced more typical symptoms of COVID-19. T cells in acute MIS-C exhibited transient signatures of activation, inflammation, and tissue residency which correlated with cardiac disease severity, while T cells in acute COVID-19 upregulated markers of follicular helper T cells for promoting antibody production. The resultant memory immune response in recovery showed increased frequencies of virus-specific memory T cells with pro-inflammatory functions in children with prior MIS-C compared to COVID-19 while both cohorts generated comparable antibody responses. Together our results reveal distinct effector and memory T cell responses in pediatric SARS-CoV-2 infection delineated by clinical syndrome, and a potential role for tissue-derived T cells in the immune pathology of systemic disease.