Five early warning indicators at emergency department presentation — gastrointestinal symptoms, elevated lactate, elevated cardiac troponin I, third-degree atrioventricular block, and decreased serum sodium — may help identify children at high risk of fulminant myocarditis.
Key Findings
Results
Gastrointestinal symptoms were the most common clinical manifestation in children with fulminant myocarditis, present in 88.9% of FM cases.
FM group n=54, ANFM group n=86, total cohort n=140 children with acute myocarditis admitted through the ED between 01/01/2015 and 31/12/2024
Gastrointestinal symptoms were identified as an early warning indicator with OR = 11.468 (95% CI: 2.495–52.713)
Early clinical manifestations of FM are often nonspecific, making gastrointestinal presentation a potentially important distinguishing feature
Third-degree atrioventricular block was the strongest individual early warning indicator of fulminant myocarditis, with an odds ratio of 32.211.
OR = 32.211 (95% CI: 2.943–352.484) for third-degree atrioventricular block
The very wide confidence interval (2.943–352.484) suggests this finding was based on a relatively small number of cases with this arrhythmia
This variable was identified through LASSO regression followed by multivariable logistic regression
Third-degree AV block was measured at ED presentation
Results
Elevated serum lactate at ED presentation was independently associated with fulminant myocarditis in children.
OR = 1.887 (95% CI: 1.155–3.082) per unit increase in lactate
Children with FM had higher lactate levels compared with the ANFM group (P < 0.05)
Lactate was one of five variables selected via LASSO regression and confirmed by multivariable logistic regression
Elevated lactate likely reflects hemodynamic compromise and reduced tissue perfusion in FM
Results
Elevated cardiac troponin I (cTnI) at ED presentation was independently associated with fulminant myocarditis in children.
OR = 1.188 (95% CI: 1.055–1.337) per unit increase in cTnI
Children with FM had higher myocardial injury marker levels compared with ANFM group (P < 0.05)
cTnI was one of five early warning indicators identified through LASSO and multivariable logistic regression
cTnI is a routinely available biomarker in the emergency department setting
Results
Lower serum sodium levels at ED presentation were independently associated with fulminant myocarditis in children.
OR = 0.785 (95% CI: 0.652–0.944), indicating that lower serum sodium was associated with higher odds of FM
Children with FM had lower serum sodium levels compared with the ANFM group (P < 0.05)
Serum sodium was one of five early warning indicators identified through the combined LASSO and multivariable logistic regression approach
Hyponatremia may reflect neurohormonal activation or hemodynamic instability in the context of FM
Methods
LASSO regression followed by multivariable logistic regression was used to identify and optimize selection of early warning indicators from ED presentation data.
Study population: 140 children with acute myocarditis, classified as FM (n=54) or ANFM (n=86)
Data collected from ED admissions over a 10-year period (01/01/2015 to 31/12/2024)
Least absolute shrinkage and selection operator (LASSO) regression was used to reduce variable selection bias before multivariable logistic regression
Retrospective, single-center design; authors call for prospective multicenter studies to validate findings
What This Means
This research suggests that certain measurements and symptoms available at the time a child arrives in the emergency department can help doctors identify which children with heart inflammation (myocarditis) are most likely to have the dangerous, rapidly progressing form called fulminant myocarditis (FM). The study analyzed records from 140 children seen over 10 years, comparing those with FM to those with a less severe form. Five warning signs stood out: stomach or intestinal symptoms (like nausea or vomiting), high blood lactate levels, high levels of a heart damage protein called troponin I, a serious heart rhythm problem called third-degree atrioventricular block, and low blood sodium levels. Notably, nearly 9 out of 10 children with FM had gastrointestinal symptoms, which could mislead clinicians into considering a digestive illness rather than a heart condition.
The practical importance of these findings is that all five warning indicators can be measured or observed during a standard emergency department visit using routine blood tests and an electrocardiogram. Early recognition of FM is critical because it can rapidly lead to life-threatening heart failure, and children who are identified early may benefit from more aggressive monitoring or treatment. The combination of seemingly unrelated symptoms — like stomach upset alongside abnormal heart rhythm and low sodium — could serve as a red flag prompting faster cardiac evaluation.
This research is limited by its retrospective, single-center design, meaning the findings were drawn from records at one hospital and were not tested prospectively. The authors acknowledge that multicenter prospective studies are needed to confirm whether these five indicators reliably predict FM across different patient populations and settings. Until then, these results provide a useful framework for clinicians to consider when evaluating children presenting to the emergency department with possible myocarditis.
Huang L, Jiang J, Qi Y, Deng X, Ma W, Chen X, et al.. (2026). Clinical characteristics and emergency department-based warning indicators of fulminant myocarditis in children.. PloS one. https://doi.org/10.1371/journal.pone.0358335