Persistent long-term subclinical myocardial changes in multisystem inflammatory syndrome in children revealed by cardiac magnetic resonance and galectin-3

BACKGROUND Multisystem inflammatory syndrome in children (MIS-C), a post-infectious complication of severe acute respiratory distress syndrome corona virus-2, commonly presents with acute myocardial dysfunction. Although early recovery is frequently observed, the long-term myocardial health, particularly subclinical changes detectable by cardiac magnetic resonance imaging (CMRI), remains unclear. Biomarkers such as Galectin-3 may offer insight into persistent inflammation or fibrosis. AIM To evaluate long-term myocardial structure and function in children following MIS-C using CMRI and two-dimensional echocardiography (2D-ECHO), and to assess serum galectin-3 levels and their correlation with imaging findings. METHODS Twelve children diagnosed with MIS-C were prospectively evaluated ≥ 6 months post-illness (mean follow-up: 23.6 months). All participants underwent the same-day 2D-ECHO and 3T CMRI, including cine imaging, T1/T2 mapping, and late gadolinium enhancement. Serum galectin-3 levels were measured by enzyme-linked immunosorbent assay and compared with those of age-matched controls. RESULTS 2D-ECHO demonstrated a normal ejection fraction (EF) (mean EF: 62.3%) and normal coronary artery Z-scores in all patients. However, CMRI revealed reduced EF (< 55%) in 4/12 (33.3%) patients and low stroke volume in 5/12 (41.7%). Elevated native T1 values, suggestive of diffuse myocardial fibrosis, were observed in 2/12 (16.7%) patients. No late gadolinium enhancement, regional wall motion abnormalities (RWMA), or coronary changes were detected. Serum galectin-3 levels were higher in MIS-C patients compared to controls (13.49 ± 7.63 ng/mL vs 7.48 ± 3.13 ng/mL); however, this difference was not statistically significant. CONCLUSION At a mean follow-up of 23.6 months, CMRI identified subclinical myocardial abnormalities in a subset of children with prior MIS-C, including reduced EF (33.3%), low stroke volume (41.7%), and elevated native T1 values (16.7%), despite normal findings on 2D-ECHO. These findings suggest greater CMRI sensitivity than 2D-ECHO for long-term myocardial assessment. Although serum galectin-3 levels were higher in patients compared to controls, the difference was not statistically significant, and its clinical relevance remains to be established. Given the small sample size, larger studies are required to confirm these observations.