Early echocardiographic and cardiac MRI findings in multisystem inflammatory syndrome in children (MIS-C)

ABSTRACT

Introduction: Multisystem Inflammatory Syndrome in Children (MISC) is a known severe condition affecting children previously exposed to SARS-CoV-2. Cardiovascular manifestations in MIS-C are quite common and include myocardial dysfunction, coronary artery dilation or aneurysms, arrhythmias, conduction abnormalities, pericarditis and valvulitis. Severe cases can present even with cardiogenic shock. To date, little is known about the very early myocardial abnormalities in pediatric patients with MIS-C. The Speckle Tracking Echocardiography (STE) and cardiac MRI (cMRI) have shown to be potential candidate for identifying regional ventricular dysfunctions in early stages of inflammatory COVID-related conditions [1,2]. Objectives: To describe the early cardiac findings in patients with MIS-C, evaluated by two advanced cardiovascular imaging, STE and cMRI. Methods: Consecutive patients with MIS-C underwent standard transthoracic echocardiography (TTE), speckle-tracking echocardiography (STE) with analysis of left ventricle (LV) global longitudinal strain (GLS) and cardiac MRI (cMRI). Clinical and laboratory data, including markers of systemic inflammation, Troponin I (TnI) and Brain Natriuretic Peptide (BNP) were also collected at onset and during follow up. All patients received intravenous immunoglobulins (IVIGs), intravenous corticosteroids (methylprednisolone) and antiplatelet therapy (aspirin). The use of biological agents (Anakinra) was reserved to patients with severe or critical illness. The need for Intensive Care Unit (ICU) was based on clinical and hemodynamic status at presentation. Results: Twenty-three patients (13M, 10F), mean age 8.1±4years (range 5.4-15.7), all with positive clinical and/or serological evidence of previous SARS-COV2 infection, entered the study. The majority (78.2%) was caucasian. All presented high degree fever, gastrointestinal symptoms and rash. Conjunctivitis and cardiovascular symptoms, as hypotension, thoracic pain or dysrhythmia, were present in 10 (43.5%). Nine children (39.1%) shared Kawasaki Disease-like symptoms. Four patients (17.4%) needed ICU admission and 3 required inotropic support. Short-term survival was 100%. All patients showed an hyperinflammatory state with elevated CRP, ESR, and D-Dimer. Tn- I was abnormal (>34 ng/L) in 15 patients (65.2%), BNP was significantly elevated in 20 (86.9%). Median time to STE evaluation was 8 days and to cMRI was 18 days since fever onset. Mean LVEF and RVEF were respectively 59±10% and 45±7%. Coronary dilation was observed in 6 (26.1%) patients. STE showed reduced mean LVGLS (-17±4.3%). LVEF on cMR was 60±13%, LGE with non-ischemic pattern was evident in 6/16 patients (37.5%) and pericardial effusion in 2 (12.5%). Conclusion: MIS-C can occur in a small but not negligible proportion of children previously affected by COVID-19 and affects the heart in a significant proportion of them. STE and cMRI were shown to be very sensitive tools to evaluate and monitor the early cardiac dysfunctions in patients with MIS-C. The elevation of myocardial necrosis markers, the myocardial injury confirmed by reduced LVGLS and presence of LGE on cMR in about a quarter of the patients support the pathogenetic hypothesis of a post-viral immuno-mediated myocarditis.