Cardiac Magnetic Resonance Findings of COVID-19 Vaccine-Associated Myopericarditis at Intermediate Follow Up: A Comparison with Classic Myocarditis.

OBJECTIVE: To report intermediate cardiac magnetic resonance (CMR) findings of COVID-19 vaccine associated myopericarditis (C-VAM) and compare with classic myocarditis. STUDY DESIGN: Retrospective cohort study including children diagnosed with C-VAM from 5/2021 through 12/2021 with early and intermediate CMR. Patients with classic myocarditis from 1/2015 through 12/2021 and intermediate CMR were included for comparison. RESULTS: There were 8 patients with C-VAM and 20 with classic myocarditis. Among those with C-VAM, CMR performed at median 3 days (IQR 3, 7) revealed 2/8 patients with left ventricular ejection fraction (LVEF)<55%, 7/7 patients receiving contrast with late gadolinium enhancement (LGE), and 5/8 patients with elevated native T1 values. Borderline T2 values suggestive of myocardial edema were present in 6/8. Follow-up CMRs performed at median 107 days (IQR 97, 177) showed normal ventricular systolic function, T1, and T2 values; 3/7 patients had LGE. At intermediate follow-up, C-VAM patients had fewer myocardial segments with LGE than classic myocarditis patients (4/119 vs 42/340, p=0.004). C-VAM patients also had a lower frequency of LGE (42.9 vs 75.0%) and lower percentage of LVEF<55% compared with classic myocarditis (0.0 vs 30.0%), although these differences were not statistically significant. Five classic myocarditis patients did not receive an early CMR, leading to some selection bias in study design. CONCLUSION: Patients with C-VAM had no evidence of active inflammation or ventricular dysfunction on intermediate CMR, although a minority had persistent LGE. Intermediate findings in C-VAM revealed less LGE burden compared with classic myocarditis.

Cardiac Magnetic Resonance Findings after Multisystem Inflammatory Syndrome in Children.

OBJECTIVE: To describe the cardiac magnetic resonance (MR) findings of children recovered from multisystem inflammatory syndrome in children (MIS-C) longer than 3 months after acute illness. STUDY DESIGN: We performed a retrospective cohort study of children hospitalized with MIS-C at a single institution receiving cardiac MR imaging between July 2020 and May 2021. Patient demographics, echocardiogram data from diagnosis through follow-up, and cardiac MR data obtained at approximately 3 months after hospitalization were recorded. RESULTS: In total, 51 children with a median age of 11.3 years were included; 80% of patients had left ventricular ejection fraction <55%, 65% of patients developed valvular regurgitation, and 20% of patients developed coronary artery dilation during acute illness. Cardiac MR was performed at a median time of 105 days after diagnosis; 8% of patients had left ventricular ejection fraction <55%; 1 patient had residual valvular regurgitation; and 2 patients had residual coronary artery dilation. Two of 51 patients were found to have late gadolinium enhancement, T1 mapping abnormalities, and abnormal or borderline extracellular volume calculations suggesting myocardial fibrosis. No patient had T2 mapping abnormalities corresponding with edema, and no patient met the modified Lake Louise criteria for acute myocarditis; 10 of 51 patients had isolated elevated T1 values. CONCLUSIONS: At 3-5 months following diagnosis, cardiac MR reveals no evidence of acute myocarditis as described by the modified Lake Louise criteria in patients with MIS-C. Two patients were observed to have myocardial fibrosis without regional wall motion abnormalities, and 10 had isolated imaging changes (elevated T1 values) in the absence of macroscopic fibrosis.

Multisystem Inflammatory Syndrome in Children: Survey of Protocols for Early Hospital Evaluation and Management.

OBJECTIVE: To describe the similarities and differences in the evaluation and treatment of multisystem inflammatory syndrome in children (MIS-C) at hospitals in the US. STUDY DESIGN: We conducted a cross-sectional survey from June 16 to July 16, 2020, of US children's hospitals regarding protocols for management of patients with MIS-C. Elements included characteristics of the hospital, clinical definition of MIS-C, evaluation, treatment, and follow-up. We summarized key findings and compared results from centers in which >5 patients had been treated vs those in which ≤5 patients had been treated. RESULTS: In all, 40 centers of varying size and experience with MIS-C participated in this protocol survey. Overall, 21 of 40 centers required only 1 day of fever for MIS-C to be considered. In the evaluation of patients, there was often a tiered approach. Intravenous immunoglobulin was the most widely recommended medication to treat MIS-C (98% of centers). Corticosteroids were listed in 93% of protocols primarily for moderate or severe cases. Aspirin was commonly recommended for mild cases, whereas heparin or low molecular weight heparin were to be used primarily in severe cases. In severe cases, anakinra and vasopressors frequently were recommended; 39 of 40 centers recommended follow-up with cardiology. There were similar findings between centers in which >5 patients vs ≤5 patients had been managed. Supplemental materials containing hospital protocols are provided. CONCLUSIONS: There are many similarities yet key differences between hospital protocols for MIS-C. These findings can help healthcare providers learn from others regarding options for managing MIS-C.