Characterisation of a highly sensitive troponin I assay and its application to a cardio-healthy population.

BACKGROUND: Abbott Diagnostics have developed a new highly sensitive troponin I (hs-TnI) assay. We have assessed its analytical characteristics and applied the assay to a population of apparently cardio-healthy persons.
METHODS: We assessed imprecision, bias compared to the previous generation assay, matrix effects, and interferences and applied the assay to an apparently healthy population, deriving the 99th percentile limit of the distribution of values in reference populations for men and women separately.
RESULTS: The dynamic range of the assay was ranged from 0.5-50,000 ng/L (pg/mL). The 10% CV was at a concentration of 3.9 ng/L, and the 20% CV was at a concentration of 1.8 ng/L. The new and current version of the TnI assay were highly correlated [slope: 0.98 (95%CI:0.88-1.07), y-intercept:1.20 (95%CI:-2.35-4.75) r²=0.99]. The 99th percentile limit of the distribution of values in a reference population was different for males and females: for males 14.0 ng/L and for females 11.1 ng/L and at these concentrations the assay CV was 5.0%. TnI was detectable in nearly all patient samples from the healthy reference population (98.6%).
CONCLUSIONS: This new hs-TnI assay is able to measure to an order of magnitude lower than the current generation TnI assay from the same manufacturer. With TnI being detectable in nearly all apparently healthy subject samples this suggests that TnI presence does not always indicate cardiomyocyte necrosis.