What are the 99th percentiles and serial changes of high-sensitivity cardiac troponin T across different clinical and community populations?
Age >65 years significantly increases the 99th percentile of high-sensitivity troponin T in ER patients, and serial changes >20% are common even without MI, which may complicate the diagnosis of acute myocardial infarction.
BACKGROUND: High-sensitivity cardiac troponin T (cTnT) assays detect small clinically important myocardial infarctions (MI) but also yield higher rates of false-positive results owing to increased concentrations sometimes present in patients without MI. Better understanding is needed of factors influencing the 99th percentile of cTnT concentrations across populations and the frequency of changes in cTnT concentrations >20% often used in combination with increased cTnT concentrations for diagnosis of MI. METHODS: cTnT percentiles were determined by use of the Elecsys® hscTnT immunoassay (Modular® Analytics E170) in a random population sample, in emergency room (ER) 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 ER patients 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 cTnT concentration was 51%-67%. cTnT remained below the 99th percentile (12 ng/L) in 1% of patients with NSTEMI until 8.5 h after symptom onset and 6 h after ER arrival. CONCLUSIONS: Age >65 years was the dominant factor associated with increased cTnT in ER patients. This age association was more prominent in ER patients than in a random population sample. Changes in serial cTnT concentrations >20% were common in hospitalized patients without MI.
Hammarsten et al. (Wed,) studied this question.