Cardiac manifestations in children and adolescents diagnosed with pediatric multisystem inflammatory syndrome related to COVID-19.

OBJECTIVES: To describe clinical and cardiologic findings in patients with multisystem inflammatory syndrome in children (MIS-C) in a follow-up of up to 3 years. MATERIALS AND METHODS: A retrospective-prospective, observational, longitudinal study was conducted, including children and adolescents up to 18 years diagnosed with MIS-C (WHO criteria), at a university center between March 2020 and December 2024. Demographic, clinical, and laboratory data, electrocardiograms, and transthoracic echocardiograms were analyzed at admission and at 12 months and left ventricular global longitudinal strain (LV-GLS) three years after diagnosis. Statistical analysis used frequencies for categorical variables, and means with standard deviations or medians with interquartile ranges for continuous variables. Differences in proportions between patients with and without cardiovascular abnormalities were assessed using Fisher's exact test, Chi-squared, or Wilcoxon rank-sum test (significant p-value < 0.05). T-test was used to compare left ventricular ejection fraction (LVEF) and coronary artery Z scores. RESULTS: Thirty-six patients were included (males 69.4%), with a median age at diagnosis of 2.15 years (IQR 3.3). At admission, 41.7% presented with clinical or echocardiographic abnormalities, which were absent at 1-year follow-up. However, three years after diagnosis, among the 11 patients evaluated with LV-GLS, 10 showed changes indicating subclinical dysfunction not detected by conventional electrocardiogram or echocardiography. CONCLUSION: Clinical and echocardiographic cardiovascular abnormalities are common in the acute phase of MIS-C. Although most patients showed clinical and echocardiographic resolution, LV-GLS proved valuable for detecting subclinical myocardial dysfunction not identified by conventional evaluation, highlighting its potential as a screening tool in short- and long-term follow-up.