Cardiac Troponin T as a Screening Test for Myocarditis in Children

OBJECTIVE: The objective of this study was to define the test characteristics of cardiac troponin T (cTnT) in pediatric patients who presented with suspected myocarditis. METHODS: We performed a retrospective cohort study of all patients at a large urban children's hospital 21 years or younger who had a cTnT test sent for evaluation for myocarditis over a 13-month period. Patients were excluded if they had any history of heart disease or cardiac arrest before presentation, or the cTnT was sent for reasons other than concern for myocarditis. Positive cases of myocarditis were defined by characteristic pathology findings, magnetic resonance imaging results, or diagnosis of the attending cardiologist at time of discharge. RESULTS: Six hundred fifty-two patients had cTnT sent during the study period. Two hundred sixty were excluded because of prior history of heart disease, and 171 had the test sent for reasons other than concern for myocarditis. Of the 221 patients included in the study, 49 had an initial positive cTnT (≥0.01 ng/mL), whereas 172 had a negative test result. Eighteen cases of myocarditis were identified. All patients with myocarditis had an elevated cTnT at presentation. Using a cutoff value of 0.01 ng/mL or greater as a positive test, cTnT had a sensitivity of 100% (95% confidence interval [CI], 78%-100%), with a negative predictive value of 100% (CI, 97%-100%), and a specificity of 85% (CI, 79%-89%), with positive predictive value of 37% (CI, 24%-52%), in the diagnosis of myocarditis. CONCLUSIONS: In children without preexisting heart disease, a cTnT level of less than 0.01 ng/mL can be used to exclude myocarditis.