Figure

Figure. Treatment algorithm for children with multisystem inflammatory syndrome associated with COVID-19, Chile, May–August 2020. †Prophylactic anticoagulation was considered if D-dimer was >1,000 ng/dL or progressively increasing: treatment was 1 mg/kg/d...

We analyzed patients with MIS-C treated in the PICU of Roberto del Río Hospital (Santiago, Chile) during May 11–August 30, 2020 (Figure). We used the case definition of MIS-C proposed by the Ministry of Public Health of Chile (13).

We collected demographic data, medical history, clinical symptoms, and physical examination findings, as well as results of imaging, cardiac, and laboratory tests conducted during the patient’s stay in the emergency room and PICU. We also analyzed data on treatment, complications, outcome, and length of PICU and total hospital stay. The institutional ethics committee of Roberto del Rio Hospital approved the study protocol. We described categorical variables with absolute frequencies and percentages; we described continuous variables with medians and IQRs.

Of the 33 patients with SARS-COV-2 who were hospitalized in the PICU during the study period, 26 met the definition for MIS-C. In total, 16 (61.5%) of these 26 patients met the criteria for Kawasaki disease. The median age was 6.5 years (IQR 2–10.5 years); 15 (57.7%) patients were male. Only 1 patient had a chronic underlying condition (Table 1) (14).

In total, 22 (84.6%) patients tested positive for SARS-CoV-2 infection, 7 (26.9%) by reverse transcription PCR and 15 (57.6%) by serologic assay. The other 4 (15.3%) patients tested negative for SARS-CoV-2 but had a COVID-19 exposure. The most frequent symptoms were fever (26, 100%), shock (24, 92.3%), abdominal pain (17, 65.4%), diarrhea (16, 61.5%), vomiting (12, 46.2%), rash (16, 61.5%), and conjunctivitis (15, 57.7%) (Table 1).

We also collected data on laboratory test values (Table 2), critical care interventions, treatments, and outcomes (Table 1). Ten (38.5%) patients required mechanical ventilation for a median duration of 4 days (IQR 2.5–5 days). Only 1 (3.8%) patient met the criteria for acute respiratory distress syndrome; that patient had an oxygenation index of 25. Half (13, 50.0%) of the patients required vasoactive drugs. We used high-flow hemofiltration as salvage therapy for refractory shock in 1 patient. No patients required extracorporeal membrane oxygenation (ECMO). In total, 20 (76.9%) patients received intravenous immunoglobulin; 2 (9.1%) received a second dose. We treated 23 (88.5%) patients with corticosteroids; 1 (3.8%) required a larger dose (Figure). We prescribed immunomodulatory agents for 4 (15.4%) patients: tocilizumab for 3 patients and infliximab for 1.

In total, 18 (69.2%) patients had echocardiographic abnormalities (Table 1), including 5 (19.2%) patients who met the criteria for Kawasaki disease with coronary artery abnormalities. The median duration of PICU stay was 5 days (IQR 2–7 days). None of the patients died.

We describe 26 MIS-C patients in the PICU of Roberto del Río Hospital in Chile. In this hospital, the maximum incidence of MIS-C occurred ≈4 weeks after the peak of COVID-19 cases in adults, as described in the literature (5–9).

The median age of the cohort in our study was 6.5 years, lower than usually reported for patients with MIS-C (8–9 years) (5); 2 patients were neonates. Slightly more than half (61.5%) of patients met criteria for typical or atypical Kawasaki disease.

Nearly all (84.6%) patients had laboratory-confirmed SARS-CoV-2 infection. However, whereas many (57.6%) had antibodies against SARS-CoV-2, only 7 (26.9%) tested positive by PCR. These findings suggest that MIS-C might be caused by a hyperinflammatory response after asymptomatic SARS-CoV-2 infection, rather than direct cell injury from active viral replication. Although the syndrome’s pathophysiology has been correlated with the cytokine storm described in adults with severe COVID-19 (13), the mechanisms of MIS-C remain unclear.

We observed clinical manifestations similar to those described internationally (5–9). In this cohort, the most frequent manifestation was fever with gastrointestinal symptoms (65.4%), in agreement with findings described in the literature (8).

Similar to previous reports (5–9), our results showed almost all patients had cardiovascular involvement: 92% had shock and 50% required vasoactive support. Although Roberto del Río Hospital is a national reference center for ECMO, none of the patients in this cohort required extracorporeal supportive treatment; in contrast, Radia et al. (15) found that 4% of patients with MIS-C needed ECMO. This difference might be attributable to early immunotherapy.

Approximately two thirds (69.2%) of patients had echocardiographic abnormalities. The most frequent (26.9%) anomaly was left ventricular dysfunction with or without pericardial effusion. In all affected patients, cardiac function recovered before discharge from the PICU. Only 5 (19.2%) of our patients had coronary abnormalities: 4 had a coronary dilatation (Z-score of ≈2.5–2.8) and 1 had a medium coronary aneurysm (Z-score of 6). The frequency of coronary involvement is also consistent with previous reports (5–9).

We treated nearly all children with intravenous immunoglobulin (76.9%) or corticosteroids (88.5%). Treatment seemed to improve symptoms and decrease inflammatory responses, similar to findings in Europe and the United States (5–9). According to our treatment protocol, we administered tocilizumab to 3 (11.7%) children; we administered infliximab to 1 (3.8%) child with a medium coronary aneurysm. The main limitations of this study are small sample size and descriptive, nonrandomized design.

In conclusion, we described 26 children with MIS-C in Chile. Our findings were similar to those reported in other countries. Most patients had echocardiographic abnormalities, and half required vasoactive drug support. We administered immunomodulatory therapy to most patients. Clinical trials and long-term follow-up are needed to elucidate the mechanisms of various treatments and potential sequelae of this condition.