Longitudinal Assessment of Cardiac Outcomes of Multisystem Inflammatory Syndrome in Children Associated With COVID-19 Infections.

Background In multisystem inflammatory syndrome in children, there is paucity of longitudinal data on cardiac outcomes. We analyzed cardiac outcomes 3 to 4 months after initial presentation using echocardiography and cardiac magnetic resonance imaging. Methods and Results We included 60 controls and 60 cases of multisystem inflammatory syndrome in children. Conventional echocardiograms and deformation parameters were analyzed at 4 time points: (1) acute phase (n=60), (2) subacute phase (n=50; median, 3 days after initial echocardiography), (3) 1-month follow-up (n=39; median, 22 days), and (4) 3- to 4-month follow-up (n=25; median, 91 days). Fourteen consecutive cardiac magnetic resonance imaging studies were reviewed for myocardial edema or fibrosis during subacute (n=5) and follow-up (n=9) stages. In acute phase, myocardial injury was defined as troponin-I level ≥0.09 ng/mL (>3 times normal) or brain-type natriuretic peptide >800 pg/mL. All deformation parameters, including left ventricular global longitudinal strain, peak left atrial strain, longitudinal early diastolic strain rate, and right ventricular free wall strain, recovered quickly within the first week, followed by continued improvement and complete normalization by 3 months. Median time to normalization of both global longitudinal strain and left atrial strain was 6 days (95% CI, 3-9 days). Myocardial injury at presentation (70% of multisystem inflammatory syndrome in children cases) did not affect short-term outcomes. Four patients (7%) had small coronary aneurysms at presentation, all of which resolved. Only 1 of 9 patients had residual edema but no fibrosis by cardiac magnetic resonance imaging. Conclusions Our short-term study suggests that functional recovery and coronary outcomes are good in multisystem inflammatory syndrome in children. Use of sensitive deformation parameters provides further reassurance that there is no persistent subclinical dysfunction after 3 months.