When cardiac muscle damage occurs, cardiac troponins are released to blood and their detection is used as a marker in clinical setting. The prognostic value of the quantitative levels of blood troponin I in cases of myocarditis and myopericarditis is unclear. The aim of this study was to analyse whether troponin quantitative blood levels can be correlated with the course of hospitalisation and prognosis.

Retrospective data was collected from all consecutive patients aged ≤30 hospitalised with a diagnosis of acute myocarditis or acute myopericarditis in our health Care Campus between the years 2010–2016.

Ninety-three patients with myocarditis and myopericarditis were identified. Higher peak troponin levels correlated with longer hospitalisation times in the cardiac or paediatric wards (p = 0.03, Pearson correlation: r −0.23), and median troponin level at admission correlated with longer overall hospitalisation (p = 0.026, Pearson correlation: r = 0.23). Patients admitted to ICU, received oral cardiac supportive therapy or that were discharged with cardiac drugs had higher median troponin compared to patients who were not but this was not statistically significant. A small group of patients that needed intravenous cardiac support had significantly lower median peak troponin levels (n = 4, 0.375ng/ml, p = 0.048). Only two patients needed extracorporeal membrane oxygenation support, and one died. The small number of patients precludes statistical analysis.

Higher troponin levels correlated significantly with longer hospitalisation, lower troponin values correlated with intravenous cardiac support, while other variables related to the severity of disease could not be significantly related to higher troponin levels.

When encountering adolescents with chest pain and a high troponin level but with no underlying coronary artery illness, it is advisable to consider myopericarditis. Though myopericarditis is a self-limiting, benign condition, it nevertheless causes anxiety in the patient and the family.

Thirty-nine patients diagnosed with myopericarditis were included. We retrospectively analysed the demographic and clinical features, laboratory tests, echocardiography, electrocardiograms, MRI findings, coronary CT angiography, and conventional angiography findings in these patients.

Of the 39 patients (female/male = 4/35) aged 7–17 years, 66.6% had viral infection in the 2 weeks preceding presentation. Eleven patients were tested for high-sensitivity cardiac troponin I, 28 for high-sensitivity cardiac troponin T, and 10 patients were tested for both biomarkers. The median hs-TnI and hs-TnT values were 6.3 (0.05–29.9) ng/mL and 586 (51–9398) ng/L, respectively. Twenty-three patients showed ST changes on electrocardiography, of whom 11 had ST-elevation in the leads supporting left ventricular involvement. Coronary CT angiography and catheter angiography evaluations performed for differential diagnosis of coronary anomaly and acute coronary syndrome were normal. Cardiac MRI was conducted on 28 patients, and the results in 10 (35.7%) were suggestive of myopericarditis.

Myopericarditis is common in the adolescent age group and is generally benign but should be carefully monitored for differential diagnosis and possible complications. Cardiac MRI, which has been used more frequently in recent years, has an important role in differential diagnosis and the follow-up of patients.

In March 2018, the US Department of Defense (DOD) added the smallpox vaccination, using ACAM2000, to its routine immunizations, increasing the number of persons receiving the vaccine. The following month, Fort Hood reported a cluster of 5 myopericarditis cases. The Centers for Disease Control and Prevention and the DOD launched an investigation.

The investigation consisted of a review of medical records, establishment of case definitions, causality assessment, patient interviews, and active surveillance. A 2-sided exact rate ratio test was used to compare myopericarditis incidence rates.

This investigation identified 4 cases of probable myopericarditis and 1 case of suspected myopericarditis. No alternative etiology was identified as a cause. No additional cases were identified. There was no statistically significant difference in incidence rates between the observed cluster (5.23 per 1000 vaccinated individuals, 95% CI: 1.7–12.2) and the ACAM2000 clinical trial outcomes for symptomatic persons, which was 2.29 per 1000 vaccinated individuals (95% CI: 0.3–8.3).

Vaccination with ACAM2000 is the presumptive cause of this cluster. Caution should be exercised before considering vaccination campaigns for smallpox given the clinical morbidity and costs incurred by a case of myopericarditis. Risk of myopericarditis should be carefully weighed with risk of exposure to smallpox.