Acute and short-term cardiac profile of multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19: prospective surveillance from the paediatric active enhance disease surveillance (PAEDS) network, Australia 2020-2023.

Abstract

Background: The clinical syndrome of MIS-C can have myocardial dysfunction, coronary artery abnormalities and conduction defects. Further evidence is required to inform the application of archetypal Kawasaki disease (KD) management to MIS-C despite clinical similarities. We describe the acute and short-term cardiac sequelae of MIS-C in Australia during 2020-2023. Method(s): Prospective surveillance of MIS-C cases across 4 of 8 PAEDS network paediatric hospital sites between Feb 2020 - May 2023. A consensus panel classified MIS-C cases as 'confirmed' or 'possible' based on the PAEDS case definition. All included cases had acute and convalescent (6 week) echocardiograms. Result(s): 79 MIS-C cases were included (mean age 7.3 years, 59% male) out of a total of 175 cases identified nationally. There were no deaths. Inotropes were used in 8 (10.8%) patients, none required ECMO. At presentation, 19 (24.0%) had systolic dysfunction; 13 (16.5%) had at least one dilated coronary artery (z-score > 2), of which 2 (2.5%) had aneurysms. The left main and left anterior descending coronary arteries were most involved. Only 4 (4.4%) patients had both systolic dysfunction and coronary abnormality. Pericardial effusion was present in 22 (27.8%) subjects. Elevated troponin-I was associated with systolic dysfunction (OR 6.8, p<0.003) but lacked specificity (66%) and sensitivity (78%). Treatment included corticosteroids alone (15.1%), IVIG alone (6.0%) or both (77.3%). At 6-week follow-up, no patients had residual systolic dysfunction, pericardial effusion or coronary aneurysms. Mild coronary artery dilatation (z-score < 2.5) was present in 2 (2.5%) patients, both of whom had coronary abnormality in the acute phase. Conclusion(s): Most cardiac sequelae of MIS-C resolves after the acute illness. All coronary aneurysms regressed; only 2 of 79 patients had residual mild coronary ectasia. None had late coronary abnormality without acute coronary changes. This data will inform cardiac follow-up after MIS-C. Data collection is ongoing and will be updated.