The value of chosen diagnostic tools in evaluating myocarditis in children and adolescents

Introduction
Myocarditis is an inflammatory disease of the myocardium. Paediatric myocarditis is frequently overlooked due a misleading presentation when characteristic symptoms are lacking.

Aim of the study
The aim of our study was to assess the clinical presentation of myocarditis in children, and the sensitivity and usefulness of chosen tests for diagnosing this disease.

Material and methods
A retrospective chart review of paediatric patients with myocarditis was performed, where electrocardiography (ECG) and biomarker test results (leucocytes number, creatine kinase – CK, creatine kinase myocardial band – CKMB, troponin I, C-reactive protein – CRP, N-terminal precursor of natriuretic peptide type B – NT-proBNP) at admission and discharge were analysed along with echocardiography and cardiac magnetic resonance (CMR).

Results
Thirty-one cases were gathered, of which the majority presented with cardiac (90.3%) or respiratory (61.3%) symptoms. In most cases, normal or only slightly lowered ejection fraction (EF) was observed (mean 62.9%, 95% CI 60.6–65.1%). ECG changes, cardiac troponin I, and CMR proved the most sensitive tests with respective sensitivities of 96.8% (95% CI 83.3–99.9%), 96.7% (95% CI 82.78–99.9%), and 100% (95% CI 83.2–100%). At discharge, levels of inflammatory and myocardial necrosis marker concentrations were significantly lower, and ejection fraction was significantly improved compared to ejection fraction at admission. CMR changes (i.e. signs of inflammation, delayed enhancement) were usually located in the inferolateral basal and mid-ventricular segments of the left ventricle. CRP, CK, and CKMB at admission correlated with the length of hospital stay.

Conclusions
Cardiac troponin, ECG changes, and cardiac magnetic resonance are highly sensitive tests for myocarditis in children. The initial values of biomarkers (concentration of CRP and activities of CK and CKMB) correlate with the length of hospital stay. Myocarditis in children is most commonly located in the inferolateral wall of the left ventricle.