Cardiac Presentation of Multisystem Infammatory Syndrome in Children (MIS-C)

ABSTRACT

Coronavirus disease 2019 (COVID-19) is usually mild in children. Rarely, children are severely afected. Multisystem infammatory syndrome in children (MIS-C) is an uncommon complication of COVID-19 often involving previously healthy older children and adolescents. It is thought to be the result of an abnormal immune response to the infection. Most afected children have negative polymerase chain reaction (PCR) and positive serology for SARS-CoV-2. Clinical presentation may include persistent fever, gastrointestinal symptoms and features like Kawasaki disease (KD) followed by shock or multisystem involvement. Infammatory markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], D-dimer and procalcitonin) and cardiac biomarkers (Troponin, brain natriuretic peptide [BNP] or N-terminal proBNP [NT-proBNP]) are often elevated. Evidence of infection (PCR, antigen test or positive serology) or likely contact with COVID-19 patients should accompany. Myocardial injury, identifed by the presence of cardiac troponin above the 99th percentile upper reference limit, is common. Possible causes include viral myocarditis, infammation, hypoxia, stress cardiomyopathy and ischemia. Combinations of these mechanisms could be responsible for cardiac dysfunction. A minority of patients present cardiac symptoms or nonspecifc symptoms. ST-segment and T-wave changes, arrhythmia or heart block may occur on electrocardiography (ECG) although most patients have non-specifc ECG. Depressed left ventricular (LV) function, Coronary artery (CA) dilation or aneurysm, mitral valve regurgitation or pericardial efusion may occur on echocardiographic evaluation. Management depends on the clinical presentation and severity. All patients should receive empiric antibiotic and also antiviral therapy if evidence of active infection exists. Patients presenting shock are treated with intravenous fuid and vasoactive agents. Signifcant LV dysfunction necessitates supportive care to maintain hemodynamics, intravenous immune globulin (IVIG), diuretics and inotropes and rarely mechanical hemodynamic support. For patients with KD features, standard therapies are applied. Glucocorticoid therapy is recommended for severe or refractory shock, KD-like features with risk of IVIG resistance risk and persistent fever. Systemic anticoagulation is used for moderate to severe LV dysfunction and also older children and adolescents with moderate to severe MIS-C. The mortality rate is approximately 1 to 2 percent for MIS-C patients. Most children with cardiac involvement have recovery of ventricular function and resolution of arrhythmias at the time of hospital discharge, although mildly diastolic ventricular dysfunction usually persists in 20%.