Clinical characteristics and emergency department-based warning indicators of fulminant myocarditis in children

Fulminant myocarditis (FM) in children is associated with a high mortality rate, while its early clinical manifestations are often nonspecific. This study aimed to identify early warning indicators available at emergency department (ED) presentations to facilitate early recognition of children at high risk of FM.

A retrospective analysis was conducted on 140 children with acute myocarditis admitted through the ED between 01/01/2015 and 31/12/2024. Patients were classified into acute non-fulminant myocarditis (ANFM) (n = 86) and FM (n = 54) groups. The least absolute shrinkage and selection operator (LASSO) regression was utilized to optimize variable selection, followed by multivariable logistic regression analysis to identify early warning indicators of FM.

Gastrointestinal symptoms were the most common clinical manifestation in children with FM (88.9%). Compared with the ANFM group, children with FM had lower serum sodium levels and higher lactate and myocardial injury marker levels (all P < 0.05). Multivariable logistic regression identified five early warning indicators of FM: gastrointestinal symptoms (OR = 11.468, 95% CI: 2.495-52.713), lactate (OR = 1.887, 95% CI: 1.155-3.082), cardiac troponin I (cTnI) (OR = 1.188, 95% CI: 1.055-1.337), third-degree atrioventricular block (OR = 32.211, 95% CI: 2.943-352.484), and serum sodium (OR = 0.785, 95% CI: 0.652-0.944).

Elevated lactate and cTnI, decreased serum sodium, gastrointestinal symptoms, and third-degree atrioventricular block at ED presentation may help identify children at high risk of FM. Prospective multicenter studies are needed to validate these findings.