Intravenous Immunoglobulin Efficacy and Safety in Paediatric Patients Diagnosed with Acute Myocarditis

<b>Background:</b> Acute myocarditis is defined as an inflammatory process consisting of multiple complex physiopathological processes. Due to its variability, the management of this condition has been a topic of debate. Our study aimed to evaluate the efficacy and safety of intravenous immunoglobulin (IVIg). <b>Methods:</b> We retrospectively collected data from patients admitted to a paediatric cardiology department from 2015 to 2020. Following the inclusion and exclusion criteria, a total of 68 patients diagnosed with acute myocarditis were selected and divided into two groups: treated with IVIg and untreated. We determined clinical and paraclinical parameters, such as symptom remission, normalisation of the ejection fraction at discharge, and cardiac marker evolution. Mixed-design analysis of variance and McNemar tests were performed to determine the statistical differences between groups. <b>Results:</b> In the treated group, 88.2% of the patients developed symptom remission at discharge vs. 50% in the untreated group, and 61.8% of the treated patients presented normalisation of the ejection fraction (EF) vs. 8.8% in the untreated group (<i>p</i> < 0.05). The evolution of cardiac markers did not statistically differ between the treated and untreated groups. Regarding safety, three treated patients presented mild, temporary side effects. <b>Conclusions:</b> Having found a statistically significant improvement in symptomatology and left ventricular EF, our study suggests the efficacy of IVIg in the treatment of acute myocarditis. Treatment with immunoglobulins was relatively safe, with only mild adverse reactions (fever and mild chest pain).