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Troponin T Percentiles From a Random Population Sample, Emergency Room Patients and Patients With Myocardial Infarction
Study Questions:
What is the variation in the 99th percentile and serial changes in high-sensitivity cardiac troponin T (hs-cTnT) in hospitalized patients?
Methods:
High-sensitivity cardiac troponin T (cTnT) assays may yield higher rates of false-positive results as a result of its ability to be detected in some patients without myocardial infarction (MI). To better understand the factors influencing the 99th percentile of hs-cTnT concentrations, the authors determined cTnT percentiles using the Elecsys® hs-cTnT immunoassay in a random population sample, in emergency department (ED) patients, and in patients with non–ST-elevation MI (NSTEMI). Changes in cTnT concentrations were determined in hospitalized patients without MI.
Results:
The 99th cTnT percentile in a random population sample (median age, 65 years) was 24 ng/L. In ED patients <65 years old without obvious conditions that increase hs-cTnT, the 99th cTnT percentile was 12 ng/L with little age dependence. In contrast in those >65 years old, it was 82 ng/L and highly age dependent. In hospitalized patients without MI, the 97.5th percentile for change in the hs-cTnT concentration was 51-67%. Hs-cTnT remained below the 99th percentile (12 ng/L) in 1% of patients with NSTEMI until 8.5 hours after symptom onset and 6 hours after ED arrival.
Conclusions:
The authors concluded that age >65 years was the dominant factor associated with increased hs-cTnT in ED patients. This age association was more prominent in ED patients than in a random population sample. Changes in serial hs-cTnT concentrations >20% were common in hospitalized patients without MI.
Perspective:
This is an extremely comprehensive evaluation of the hs-cTnT assay in community populations and in the coronary care unit. The data are similar to prior data in showing marked increases (likely related to comorbidities) in the baseline values in those >65 years old and the expected differences between men (higher) and women. Fourteen percent of patients diagnosed with non-STEMI had changes in hs-cTnT <20% of the baseline value, but the 97.5% change in this group was 51-67%. Furthermore, 1% of patients did not manifest elevations above the 99th percentile upper reference limit until 8.5 hours after symptom onset (6 hours after ED arrival). More of this type of analysis will substantially assist clinicians who are using the hs-cTnT assay in understanding how to use this assay appropriately.
Keywords: Immunoassay, Myocardial Infarction, Tegafur, Cytoskeletal Proteins, Biomarkers, Troponin I, Coronary Care Units, Comorbidity, Cardiovascular Diseases, Troponin T, Fluorouracil
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