131 - MULTISYSTEM INFLAMMATORY SYNDROME IN CHILDREN BEFORE THE SARS-COV2 PANDEMIC

Background. The SARS-CoV2 pandemic highlighted the ability of this virus to trigger the Multisystem Inflammatory Syndrome in Children (MIS-C), overlapping with KD shock syndrome (KDSS). Similarities between MIS-C and KDSS raise the questions of whether these conditions could be related or identical, and whether other viruses could induce MIS-C.
Methods. To address these questions, we reanalyzed our pre-pandemic cohort of KD patients hospitalized in intensive care unit (ICU) to get an idea of how much of them could be similar to MIS-C. The KD-ICU cohort retrospectively included children < 18yo, retrieved through a case-call of French/German ICU, with complete/incomplete KD (AHA criteria), requiring ICU hospitalization, from 2001 to 2018. To the exception of SARS-CoV2 exposure, all these KD-ICU patients responded to WHO criteria of MIS-C. As myocardial failure is a hallmark of MIS-C, we studied the particularities of KD-ICU patients with confirmed myocarditis (MyoKD-ICU), defined as: hypotension/shock + echocardiography myocardial abnormalities +/- elevated troponin.
Results. We compared the 9 MyoKD-ICU patients to the 39 other KD-ICU patients (Table). MyoKD-ICU patients tended to be older and presented systematically digestive signs, both hallmarks of MIS-C. MyoKD-ICU patients had longer duration of hospitalization, more frequent requirement of inotropic drugs. They presented higher level of first/maximal C-reactive protein, lower level of initial natremia and had no CA. Regarding immunomodulatory treatments, MyoKD-ICU patients were more resistant to IVIG, despite earlier treatment and comparable use of additional corticosteroids.
Conclusion. In our non-SARS-CoV2 KD-ICU cohort, those with myocarditis shared all phenotypic features with MIS-C, which was thus not a new disease at the time of the pandemic. All MIS-C occurring before, after or during the pandemic might share common pathophysiology, related to both individual factors and triggering agents ability to induce hyper-inflammation. The experience acquired in the management of MIS-C should contribute to the improvement of the management of MyoKD-ICU.