BackgroundCoronavirus disease 2019 (COVID-19) in children is rarely severe. However, severe courses occur, especially in the presence of risk factors. A minority of children develop pediatric inflammatory multisystem syndrome (PIMS) with substantial morbidity. While the importance of cardiac involvement after PIMS is well established, its role after severe acute COVID-19 remains unclear. We aim to compare cardiac sequelae of children after severe acute COVID-19 using cardiac MRI and compare them with patients after PIMS.MethodsFor this prospective cohort study, we recruited patients with acute COVID or PIMS in a single center. Clinical follow-up, lab work, ECG, and echocardiography were done within 2 days after disease onset and 3–6 months after discharge. At the last visit 3–6 months later, cardiac MRI (CMR) with late gadolinium enhancement (LGE) was performed to evaluate cardiac sequelae and compare both groups.ResultsData were obtained from n = 14 patients with PIMS and n = 7 patients with severe acute COVID-19. At the start of the respective disease, left ventricular (LV) ejection fraction was reduced in seven patients with PIMS but none in the acute COVID-19 group. Transient mitral valve insufficiency was present in 38% of patients, of whom PIMS accounted for 7/8 cases. Eight patients (38%) with PIMS presented coronary artery abnormalities, with normalization in 7/8 patients. A significant decrease in LV mass index 3–6 months after disease onset was observed in both groups. MRI follow-up revealed non-ischemic myocardial pattern of LGE in 12/21 patients- in all (6/6) after severe acute COVID-19 and in less than half (6/14) after PIMS. Normal body weight-adjusted stroke volumes and end-diastolic volumes were found in 20/21 patients.ConclusionsWe show that children suffering from severe acute COVID-19 have a similar, or worse, cardiac risk profile as patients with PIMS. Both patient groups should therefore receive close pediatric cardiac follow-up examinations. Cardiac MRI is the technique of choice, as most patients presented with delayed LGE as a sign of persistent cardiac injury despite normalization of laboratory and echocardiographic findings.