Cardiac Troponin T and Intravenous Immunoglobulin in the Diagnosis and Follow-up of Childhood Myocarditis

Objective: Our aim was to investigate the therapeutic efficacy of intravenous immunoglobulin (IVIG) in pediatric patients with elevated cardiac troponin T (cTnT) levels and diagnosed with myocarditis confirmed by cardiac magnetic resonance imaging or clinically assessed as probable myocarditis (PM). Method:We retrospectively reviewed 105 children (mean age 13.43.1 years; 81% male) hospitalized with PM between January 2013 and April 2025.Patients were classified as those whose diagnosis of myocarditis was confirmed using cardiovascular magnetic resonance (CMR-confirmed) or PM based on Lake Louise diagnostic criteria.Data concerning demographic features, electrocardiography (ECG), echocardiography, CMR, baseline and follow-up cTnT (Roche high-sensitivity assay; 99 th -percentile 0.014 ng/dL), time to normalization of cTnT levels, and IVIG therapy (400 mg/kg/day up to 5 days) were analyzed.Results: CMR abnormalities were found in 44 (41.9%) patients.Median baseline cTnT level was 0.135 ng/dL (range 0.016-9.057)and median normalization of cTnT levels was achieved within median period of 5 days (range: 2-42 days).IVIG was administered to 38 (36.2%) patients and more often patients with confirmed myocarditis (CM) received IVIG therapy rather than cases with PM (50% vs. 24.5%).Pathologic ECG findings were detected in 32% of all study participants and more frequently in IVIG-treated patients.Troponin normalization rate was slower in IVIG-treated patients (median: 10 vs 6 days), especially in patients with CM.Echocardiographic outcomes and recovery of left-ventricular systolic function had not shown any significant differences between IVIG-treated and untreated groups. Conclusion:Serum cTnT is a useful adjunct for diagnosis and follow-up of patients with pediatric myocarditis.IVIG was more often used in clinically severe cases but showed no significant effect on recovery of ventricular function or on fluctuations in troponin levels.Larger multicenter studies should be conducted to clarify therapeutic benefit of IVIG.