Multisystem inflammatory syndrome in children: Salient echocardiogram findings in the acute phase and longitudinal follow-up

Background: Coronary artery (CA) abnormalities and left ventricular (LV) systolic dysfunction have been reported in multisystem inflammatory syndrome in children (MIS-C); however, a thorough review of all findings on transthoracic echocardiogram (TTE) with long term follow-up is lacking. Objectives: Comprehensively describe the findings on TTE during the acute phase of MIS-C and how those findings change on serial follow-up 6 months after diagnosis. Methods: Pediatric patients meeting CDC criteria for MIS-C were included, with data collected from acute phase (T0), outpatient follow-up at 2 weeks (T1), 6–8 weeks (T2), and 6 months (T3), including TTE findings of descending aorta Doppler profile, CA abnormalities, valvar regurgitation, LV systolic function, and pericardial effusion. Results: Fifty patients (52% male) were included; 45 (90%) were SARS-CoV-2 IgG antibody positive, 13 (26%) PCR positive, and 8 (16%) positive for both. Mean age was 8.3 years (range 9 months - 17 years). Holodiastolic flow reversal in descending aorta was seen in 72% at T0, in 6% at T1, with complete resolution in all by T2. CA abnormalities were seen in 52% at T0, 31% at T1, 13% at T2, and none at T3. Mitral regurgitation was present in 84% at T0, 40% at T1, 36% at T2, and 24% by T3. LV systolic dysfunction (ejection fraction <55%) occurred in 52% at T0, with resolution by discharge in 69%, and complete resolution by T2. Trivial to small pericardial effusion was present in 48% at T0, 13% at T1, 3% at T2 and 4% by T3. Conclusion: In addition to CA abnormalities and LV systolic dysfunction, holodiastolic flow reversal in the descending aorta, valvar regurgitation, and pericardial effusion are prominent findings in MIS-C. Longitudinal follow-up shows improvement in all.