Multisystem inflammatory syndrome in children (MIS-C): A nationwide collaborative study in the Greek population.

Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe hyperinflammatory condition that may occur following SARS-CoV-2 infection. This retrospective, descriptive study of children hospitalized with multisystem inflammatory syndrome in children (MIS-C) in 12 tertiary care centers from 3/11/2020 to 12/31/2021. Demographics, clinical and laboratory characteristics, treatment and outcomes are described. Among 145 patients (95 males, median age 8.2 years) included, 123 met the WHO criteria for MIS-C, while 112 (77%) had serological evidence of SARS-CoV-2 infection. Fever was present in 99%, gastrointestinal symptoms in 77%, mucocutaneous involvement in 68% and respiratory symptoms in 28%. Fifty-five patients (38%) developed myocarditis, 29 (20%) pericarditis and 19 (13%) coronary aneurysms. Among the above cases 11/55 (20%), 1/29 (3.4%) and 5/19 (26.3%), respectively, cardiac complications had not fully resolved at discharge. Underlying comorbidities were reported in 18%. Median CRP value was 155 mg/l, ferritin 535 ng/ml, PCT 1.6 ng/ml and WBC 14.2 × 109/mm3. Most patients had elevated troponin (41.3%) and/or NT-pro-BNP (49.6%). Intravenous immunoglobulin plus corticosteroids were used in 117/145 (80.6%), monotherapy with IVIG alone in 13/145 (8.9%) and with corticosteroids alone in 2/145 (1.3%). Anti-IL1 treatment was added in 15 patients (10.3%). Thirty-three patients (23%) were admitted to the PICU, 14% developed shock and 1 required ECMO. Mortality rate was 0.68%. The incidence of MIS-C was estimated at 0.69/1000 SARS-CoV-2 infections. Patients who presented with shock had higher levels of NT-pro-BNP compared to those who did not (p < 0.001). Acute kidney injury and/or myocarditis were associated with higher risk of developing shock. CONCLUSION: MIS-C is a novel, infrequent but serious disease entity. Cardiac manifestations included myocarditis and pericarditis, which resolved in most patients before discharge. Timely initiation of immunomodulatory therapy was shown to be effective. NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. Further research is required to elucidate the pathogenesis, risk factors and optimal management, and long-term outcomes of this clinical entity. WHAT IS KNOWN: • MIS-C is an infrequent but serious disease entity. • Patients with MIS-C present with multi-organ dysfunction, primarily involving the gastrointestinal and cardiovascular systems. WHAT IS NEW: • NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. • Acute kidney injury and/or myocarditis were associated with higher risk of developing shock.

The importance of heart and brain imaging in children and adolescents with Multisystem Inflammatory Syndrome in Children (MIS-C).

Multisystem Inflammatory Syndrome in Children (MIS-C) recently reported in a minority of children affected by SARS-CoV-2, mimics Kawasaki disease (KD), a medium vessel vasculitis of unknown cause. In contrast to acute COVID-19 infection, which is usually mild in children, 68% of patients with MIS-C will need intensive care unit. Myocarditis and coronary artery ectasia/aneurysm are included between the main cardiovascular complications in MIS-C. Therefore, close clinical assessment is need it both at diagnosis and during follow-up. Echocardiography is the cornerstone modality for myocardial function and coronary artery evaluation in the acute phase. Cardiovascular magnetic resonance (CMR) detects diffuse myocardial inflammation including oedema/fibrosis, myocardial perfusion and coronary arteries anatomy during the convalescence and in adolescents, where echocardiography may provide inadequate images. Brain involvement in MIS-C is less frequent compared to cardiovascular disease. However, it is not unusual and should be monitored by clinical evaluation and brain magnetic resonance (MRI), as we still do not know its effect in brain development. Brain MRI in MIS-C shows T2-hyperintense lesions associated with restricted diffusion and bilateral thalamic lesions. To conclude, MIS-C is a multisystem disease affecting many vital organs, such as heart and brain. Clinical awareness, application of innovative, high technology imaging modalities and advanced treatment protocols including supportive and anti-inflammatory medication will help physicians to prevent the dreadful complications of MIS-C.