High-Sensitivity Troponin T in Pediatric Myocarditis

Source: Degen M, Leviter J, Bradley A, et al. Association between high-sensitivity troponin (hs-cTnT) and diagnosis of myocarditis in previously healthy pediatric patients. Pediatr Cardiol. Published online ahead of print August 10, 2024; doi: 10.1007/s00246-024-03621-7.Investigators from Yale University, New Haven, CT, conducted a retrospective study to assess the association between elevated high-sensitivity cardiac troponin T (hs-cTnT) levels and myocarditis in children, and to identify the optimal threshold hs-cTnT level that maximizes the sensitivity and specificity of this test in predicting myocarditis. For the study, they reviewed the medical records of pediatric patients, seen at Yale New Haven Health York Street Campus between February 2022 and February 2023, in whom an hs-cTnT level was obtained. Children with a previously known cardiac diagnosis were excluded. Data abstracted from the medical records of study patients included demographics, hs-cTnT levels, echocardiogram and electrocardiogram (EKG) results, and final diagnoses. Diagnoses were categorized as non-cardiac, cardiac, and specific cardiac diagnoses, such as myocarditis. The primary study outcome was a diagnosis of myocarditis. The peak hs-cTnT levels in those with and without myocarditis were compared. In addition, the sensitivity and specificity of different threshold values for defining an elevated hs-cTnT were determined to identify the level that maximized the utility of the test in identifying a child with myocarditis. Peak hs-cTnT levels were compared in those with and without a cardiac diagnosis, in those with abnormal vs normal left ventricular function (based on echocardiogram results), and normal or abnormal EKG findings.Data were analyzed on 308 children, with a mean age of 10.6 ±5.8 years. There were 45 (14.6%) study patients with a new cardiac diagnosis, including arrhythmia, ventricular dysfunction, Kawasaki disease, and pericarditis; 8 children, ranging in age from 5–16 years, were diagnosed with myocarditis. Median peak hs-cTnT levels were significantly higher in patients with a cardiac diagnosis than in those with a non-cardiac diagnosis (29.0 ng/L vs <6 ng/dL, P <.001). Similarly, the median peak hs-cTnT level among children with myocarditis was 506.5 ng/dL, compared to 6.0 ng/dL for those with all other diagnoses (P <0.001). A threshold hs-cTnT level of 90 ng/dL provided a sensitivity of 100% and specificity of 95% in identifying a patient with myocarditis. Among 89 study children in whom an echocardiogram was obtained, peak hs-cTnT levels were significantly higher in the 12 patients with left ventricular dysfunction than in those with normal function (median values, 119.0 ng/dL and 19.0 ng/dL, respectively; P <0.001). However, there was not a significant difference in hs-cTnT levels between children with abnormal or normal EKG results (median values, 7.0 ng/dL and <6.0 ng/dL, respectively; P = 0.14).The authors conclude that obtaining hs-cTnT levels may be useful in the diagnosis of pediatric myocarditis.Dr Philip has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Advances in cardiac magnetic resonance (CMR) imaging have aided the clinician in diagnosing myocarditis by detecting myocardial injury and inflammatory changes. This has led to a paradigm shift in the diagnostic approach to myocarditis. It has changed from a more invasive yet less sensitive endomyocardial biopsy-driven, histopathology-based diagnosis to a less invasive clinical diagnosis with CMR.1 Despite the minimally invasive advantage of CMR, it requires sedation in children, is more expensive, and may not be as easily available. Hence, CMR is reserved as a confirmatory test when there is a clinical suspicion.2 Screening tools such as cardiac biomarkers (including hs-cTnT), EKG, and transthoracic echocardiogram (TTE) have been used to help triage those who need may need CMR. A missed diagnosis of myocarditis can be detrimental and demands good screening tools. (See AAP Grand Rounds. 2008;19[3]:26-27.)3In the current single-center study, researchers found that a hs-cTnT cutoff value of 90ng/dL provided the highest sensitivity and specificity for the diagnosis of myocarditis. Though troponin levels were shown to be elevated in non-cardiac diagnoses, the levels were significantly higher with a cardiac diagnosis. All patients with evidence of cardiac dysfunction on TTE had an elevated hs-cTnT level. However, more than 50% of those with CMR-diagnosed myocarditis had normal function by TTE despite having elevated hs-cTnT. This further attests to the sensitivity of this biomarker. Among the patients with a normal hs-cTnT level, no one was diagnosed with myocarditis.The main limitation of the current study is that it is retrospective. Albeit impractical, since CMR imaging was not performed in all patients, it cannot be assumed that patients with a normal hs-cTnT level did not have myocarditis. Despite having a relatively large sample size, the cohort of diagnosed myocarditis was too small to allow subgroup analysis of troponin levels for severity of disease and progression.High-sensitivity cardiac troponin T is a useful screening test to aid the clinician diagnosis of pediatric myocarditis, especially in non-tertiary centers that may not have access to advanced imaging.