In the early stages of multisystem inflammatory syndrome in children (MIS-C) with COVID-19, the coronary arteries are not frequently involved, unlike in Kawasaki disease (KD), however, cardiac and diastolic dysfunction are more common, likely resulting from a myocarditis-like state, according to results of a study published Sept. 2 in the Journal of the American College of Cardiology.

The retrospective study at The Children's Hospital in Philadelphia, led by Daisuke Matsubara, MD, and colleagues, compared echocardiographic findings in 28 patients with MIS-C and positive for COVID-19, 20 patients with classic KD and 20 healthy controls. Echocardiographic parameters were examined for the acute phase in patients with MIS-C and KD and during the subacute phase in the MIS-C patients (interval, 5.2 days).

Five of the patients with MIS-C (18%) had symptoms similar with KD and 23 (82%) similar with toxic shock. The patients with MIS-C, compared with KD, were significantly older (median age, 11.4 vs. 3.1 years) and were larger in stature (median body mass index, 22.5 vs. 16.0 kg/m2). Based on the WHO definition, 50% of MIS-C patients were considered obese. Researchers found among the patients with MIS-C, only one patient (4%) had coronary artery dilatation (z score=3.15) during the acute phase, which had resolved during early follow up.

In addition, patients with MIS-C, compared with KD, had worse left ventricular (LV) systolic and diastolic function as measured by deformation parameters, which are used to detect subtle changes in myocardial function and, according to the authors, have not been used in MIS-C to date. All functional parameters were more affected in the MIS-C patients who had myocardial injury compared with those who did not. Global longitudinal strain (GLS) was the strongest parameter to predict myocardial injury in MIS-C (odds ratio [OR, 1.45]), followed by right ventricular strain and left atrial strain. Researchers noted that while there was good recovery of systolic function in the subacute phase, without the development of coronary aneurysms, the diastolic dysfunction persisted.

The authors conclude longer follow up is needed of a larger number of patients with MIS-C to better understand the mechanisms leading to cardiac injury and determine the late impact on coronary and myocardial structure and function.

Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, COVID-19 Hub, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Stable Ischemic Heart Disease, Atrial Fibrillation/Supraventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, Chronic Angina

Keywords: Mucocutaneous Lymph Node Syndrome, Body Mass Index, Coronary Aneurysm, Coronary Vessels, Myocarditis, Shock, Septic, COVID-19, severe acute respiratory syndrome coronavirus 2, Atrial Fibrillation, Dilatation, Systole

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