Echocardiographic Evaluation of Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19

ABSTRACT

Cardiac involvement is an observable issue in multisystem inflammatory syndrome in children (MIS-C) associ20 ated with COVID-19. The most common echocardiographic findings in MIS-C are abnormal coronary arteries, decreased left ventricular function, mitral regurgitation, and pericardial effusion. Abnormalities in the coronary arteries were seen in less than 20% of MIS-C patients. These abnormalities include dilatation or aneurysms in the coronary arteries;however, giant or large aneurysms are rare. On the other hand, transient coronary artery dilatation (which can occur secondary to viral myocarditis) may also mean that the coronary artery Z-scores never exceed 2.5. Reviewing large case series revealed that approximately 30 - 40% of MIS-C patients had decreased left ventricular function. In most cases, left ventricular function is mildly depressed, and severe left ventricular dysfunction was observed in only one-fifth of cases. Hypoxia, myocardial ischemia secondary to coronary involvement, stress-induced cardiomyopathy, injury caused by systemic inflammation, and viral myocarditis are the possible etiologies for the myocardial injury in MIS-C. It is now clear that myocardial strain imaging indices such as a global longitudinal strain (GLS), end-diastolic strain rate (EDSR), and peak left atrial strain (LAS) can demonstrate systolic or diastolic dysfunction in myocarditis patients with preserved left ventricular ejection fraction. Furthermore, right-sided ventricular deformation imaging abnormalities have been reported in adult patients with MIS-C. Less information is currently available on mitral regurgitation and pericardial effusion in pediatric patients with MIS-C;however, in an extensive study on 286 pediatric patients with MIS-C, 28% had pericardial effusion, and 42.7% had mitral regurgitation;both were mild in most patients.