MONITORING OF CHILDREN WITH KAWASAKI-LIKE (MULTISYSTEM INFLAMMATORY) SYNDROME IN THE EAST SIBERIAN AREA OF RUSSIA

The pathogenetic basis for Pediatric Multisystem Inflammatory Syndrome (PMIS) associated with SARS-CoV-2 is systemic vasculitis resulting from hyperproduction of pro-inflammatory cytokines associated with dysregulation of the immune response. Clinical manifestations of PMIS include fever with features of Kawasaki Syndrome (KS) and multi-organ dysfunction coupled with frequent unusual heart involvement, ranging from mild with minimal ECG changes or elevated troponin to fulminant myocarditis or Takotsubo syndrome (TTS). The purpose of the research was to study the characteristics of cardiovascular disorders in Kawasaki-like multisystem inflammatory syndrome associated with COVID-19 in children observed in the East Siberian area of Russia. A single-center retrospective cohort study was carried out on the basis of the Irkutsk Oblast Regional Children's Clinical Hospital (Irkutsk, Russia): 36 patients with PMIS associated with COVID-19 in Nov. 18, 2020 - Dec. 31, 2021, including 21 boys (M/F ratio 1.4:1) at the average age of 7.5 years old (1.5 months to 17 years old). The diagnostic signs of KS were observed in 34 (94%) children, including the complete set of diagnostic signs in 21 (58%). Refractory fever and a sharp increase in inflammatory biomarkers were detected in all 36 (100%) children; multiorgan dysfunction in 31 (86%); thrombocytopenia in 24 (67%); gastrointestinal syndrome in 25 (69%); cerebral dysfunction in 24 (66)%; various cardiovascular disorders in 30 (83%), including: dilatation of the left ventricle (LV) and a decrease in myocardial contractility in 3 (8%); moderate coronary dilatation in 5 (14%); thickening of the posterior LV walls in diastole in 5 (13%); thickening of the interventricular septum in diastole in 6 (16%). According to the MRI results performed in 15 children the signs of myocardial damage were found in 6 (40%). LV dilatation and decreased myocardial contractility were noted in 3 (8%) children, clinically apparent thrombotic complications in 3 (8%) children as well, and severe neurological deficit in one patient (3%). An increase in the level of D-dimer was observed in 26 (72%) patients, thrombocytopenia in 24 (67%), a statistically significant correlation between thrombocytopenia and myocardial damage was found (R=-0.506, p=0.001). The treatment measures were given as follows: inotropic support (dobutrex/dobutamine) was received by 8 (22%), artificial lung ventilation - by 8 (22%), intravenous human immunoglobulin 1.5-2.0 g/kg/course - by 28 (77%), dexamethasone - by 24 (67%), tocilizumab - by 2 (5%) patients. All 36 (100%) patients have survived. Conclusion: the Kawasaki-like multisystem inflammatory syndrome associated with COVID-19 was accompanied by the cardiovascular disorders (pericarditis, arrhythmias, abnormal ECG changes, elevated troponin and/or natriuretic peptide, LV thickening on echocardiography, coronary dilatation) in most patients, although LV dilatation and decreased myocardial contractility were observed in a few cases only. A negative correlation between thrombocytopenia and myocardial damage was found, which may indicate the involvement of thrombotic microvascular inflammation in the genesis of myocardial disorders.