Acute and late echocardiographic and cardiac MRI findings in multisystem inflammatory syndrome in children

ABSTRACT

Aims Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe condition affecting children previously exposed to SARS-CoV-2. The aim of our study was to describe the acute and late cardiac abnormalities in patients with MIS-C, evaluated by speckle-tracking echocardiography (STE) and cardiac MRI (CMR). Methods and results Twenty-three (13 M, 10 F) patients with confirmed MIS-C diagnosis were recruited. All children underwent standard TTE, STE with analysis of LV global longitudinal strain (GLS). Seventeen (75%) were evaluated with CMR. All children received standard therapy. During follow-up echocardiography and CMR were repeated. Mean age was 8.1 ± 4 years. The majority (78.2%) was Caucasian. Cardiovascular symptoms were present in 10 (43.5%). Nine children (39.1%) shared Kawasaki Disease-like symptoms. Four patients (17.4%) needed ICU admission and three required inotropic support. Short-term survival was 100%. All patients showed a hyperinflammatory state. Tn-I was abnormal (>34 ng/l) in 15 patients (65.2%), BNP was elevated in 20 (86.9%). Median time to STE evaluation was 8 days and to CMR 18 days since fever onset. Mean LVEF and RVEF were, respectively, 59 ± 10% and 45 ± 7%. Coronary dilation was observed in six (26.1%) patients. STE showed reduced mean LVGLS (−17 ± 4.3%). LVEF on CMR was 60 ± 13%, LGE with non-ischaemic pattern was evident in 6/17 patients (35.2%). Median time to follow-up was 49 days for echocardiography and 200 days for CMR since disease onset. STE showed improvement of LVGLS (−18.8 ± 2.2%), while CMR displayed persistence of LGE in two patients and reduction or absence in two of the six patients previously diagnosed. Conclusions The elevation of myocardial necrosis markers, the myocardial injury testified by reduced LVGLS and the presence of LGE on CMR in about a quarter of the patients support the hypothesis of a post-viral immune-mediated myocarditis-like pathogenesis of MIS-C. Early follow-up shows improvement of STE and CMR findings corroborating the evidence of excellent short-term survival.