Alterações cardíacas em crianças e adolescentes diagnosticados com síndrome inflamatória multissistêmica pediátrica relacionada à COVID-19

Abstract

Introduction: Pediatric multisystem inflammatory syndrome (MIS-C), associated with SARS-CoV-2 infection, is widely recognized for its potential cardiovascular involvement, highlighting the need for comprehensive cardiac assessment in the acute phase and prolonged follow-up to better understand its progression, cardiovascular impact, and possible future complications. Objectives: To describe the epidemiological data, clinical manifestations, laboratory abnormalities, treatment provided, and electrocardiographic and echocardiographic findings in children and adolescents diagnosed with multisystem inflammatory syndrome in children (MIS-C). Additionally, to report echocardiographic findings during the first 12 months of follow-up and Left Ventricular Global Longitudinal Strain (LV-GLS) measurements on echocardiography three years after the initial diagnosis. Materials and Methods: A retrospective and prospective, observational, longitudinal, and descriptive with exploratory analysis cohort study was conducted, including children and adolescents aged 0 to 18 years diagnosed with MIS-C according to WHO criteria, treated at a specialized university center between March 2020 and December 2024. Demographic data, clinical manifestations, laboratory and microbiological tests, electrocardiograms, and echocardiograms were analyzed. Transthoracic echocardiograms were performed at admission and at 12 months after diagnosis. Echocardiographic assessments with LV-GLS were performed three years after diagnosis. Statistical analysis was descriptive, using absolute and relative frequencies for categorical variables, and means with standard deviations or medians with interquartile ranges for continuous variables. Patients with and without cardiovascular abnormalities were compared. Differences in proportions between the two groups were assessed using Fisher's exact test, Chi-squared test, or Wilcoxon rank-sum test. A p-value < 0.05 was considered statistically significant. The T-test was used to compare left ventricular ejection fraction (LVEF) and coronary artery Z-scores. To assess measurement standardization and accuracy, the intraclass correlation coefficient (ICC) was calculated using a two-way random-effects model to evaluate intra- and interobserver agreement for coronary artery diameter measurements (20% of the total sample). Results: Thirty-six patients were included, with a median age at diagnosis of 2.15 years (IQR 3.3), and a predominance of males (69.4%). At admission, 41.7% of patients presented cardiovascular abnormalities detected clinically or by echocardiography, including 10 of clinical origin, 2 imaging, and 3 combining both. At the 1-year follow-up, 22 patients were reassessed clinically and by echocardiography, with no abnormalities observed; however, among them, 5 had shown clinical alterations at admission, 2 imaging alterations, and 3 both clinical and imaging alterations. In the third phase, conducted three years after diagnosis, 11 patients underwent echocardiography with analysis of LV-GLS, of whom 4 had previously presented clinical alterations and 1 an imaging alteration at admission. In 10 of the 11 patients evaluated, LV-GLS demonstrated subclinical dysfunction not identified by electrocardiography or conventional echocardiography. Conclusion: Clinical and echocardiographic cardiovascular abnormalities are common findings in the acute phase of MIS-C. In the studied cohort, no patients showed alterations in cardiac function at the 1-year echocardiographic follow-up when assessed by conventional methods. In this context, LV-GLS analysis using speckle-tracking echocardiography has proven to be a sensitive and promising tool for identifying subclinical myocardial dysfunction that would not be detected by parameters such as LVEF. Therefore, long-term follow-up of these patients is essential, as some subclinical alterations may persist or progress over time, allowing for early detection of residual cardiac dysfunction, prevention of late complications, and implementation of appropriate therapeutic interventions to reduce future cardiovascular risk.