ABSTRACT
Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a rare complication of SARS-CoV-2 infection, with an incidence of about 1:100'000 children. According to published case series, between 10% and 40% of MIS-C develop coronary artery modifications, mainly hyperechogenicity, with a lower incidence of aneurysm. Evolution and outcome of coronary artery aneurysm post MIS-C is unknown. Methods: We report the case of a 10-year old male with medium left anterior descending coronary artery (LAD) aneurysm (diameter of 6.2 mm, z-score +7.9) and small right coronary artery (RCA) aneurysm (z-score +2.9) detected one week after his hospital admission for hypotensif shock in the context of MIS-C and positive serologies for SARS-CoV-2. He didn't meet diagnosis criteria for Kawasaki disease. He was treated with 2 g/kg immunoglobulin (administered after coronary artery dilatation was observed, as the recognition and definition of MIS-C was contemporary with our case), corticosteroids and anakinra. He rapidly normalized his initial mild LV dysfunction and cardiac enzymes elevation. Results: Since discharge, the patient was treated with antiplatelet therapy (100 mg aspirin daily) and carefully followed up in outpatient cardiology. On echocardiography, coronary artery dimensions progressively regressed, prompting a control computed tomography (CT) 6 months after MIS-C episode. CT confirmed LAD and RCA dimension near-normalization, compared to the fusiform dilatations 6 months ago : LAD maximal diameter of 3.7 mm (z-score +2.3), RAD maximal diameter of 4 mm (zscore +1.8). Moreover, no coronary stenosis was observed. Conclusions: Coronary artery aneurysm in the context of MIS-C probably represents a post-infectious vasculitis. This case illustrates a regression of coronary artery dilatation after a few months. Further research is needed to assess if this finding reflects a generalisable outcome and to study the effect of medical treatment on the evolution of coronary artery dilatation post MIS-C.