Age-specific 99th percentile cutoff of high-sensitivity cardiac troponin T for early prediction of non-ST-segment elevation myocardial infarction (NSTEMI) in middle-aged patients.

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) assay is used in the diagnosis and risk assessment of patients with symptoms of myocardial infarction. This study was undertaken to establish an age-specific 99th percentile cutoff value for hs-cTnT in Chinese population, and to evaluate its potential for early prediction of non-ST-segment elevation myocardial infarction (NSTEMI) in middle-aged patients.

METHODS

Troponin T levels in blood obtained from healthy Chinese adults were assayed using hs-cTnT. The distribution was plotted and 99th percentiles were determined by nonparametric statistics. Prediction performance at the conventional cutoff (14 ng/L) recommended by the Roche company was compared with the age-specific cutoff for NSTEMI in 100 middle-aged patients (40-60 years of age) with acute chest pain.

RESULTS

The 99th percentile for hs-cTnT was 14 ng/L for patients ≥60 years of age and 11 ng/L for those <60. Fifty of the 100 patients were finally diagnosed with NSTEMI. The age-specific 99th percentile cutoff value of 11 ng/L identified a higher number of patients with NSTEMI than the conventional 14 ng/L cutoff (46 vs. 40 patients), although the difference was not statistically significant (P = 0.084). In addition, the sensitivity of hs-cTnT increased from 80 to 92% and the negative predictive values increased from 82.4 to 91.8%.

CONCLUSION

Using 11 ng/L as a decision-making cutoff point for hs-cTnT facilitated earlier prediction of NSTEMI in middle-aged patients than the conventional 14 ng/L cutoff. Further studies are needed to confirm this finding in larger group of patients.