Concordance between i-STAT Contemporary Troponin I and Beckman High Sensitivity Troponin I Only when Both Tests Were...

Often in the Emergency Department (ED) of our hospital, troponin I is measured by the i-STAT (contemporary troponin I) followed by analysis of high sensitivity troponin I (hs-TnI) using the Beckman analyzer in the clinical laboratory. In this study, contemporary troponin I concentrations obtained by the i-STAT were compared with the Beckman hs-TnI concentrations in patients with myocardial infarction.

Troponin I concentrations were determined by both methods in 56 specimens collected from 56 patients admitted to the ED (time between both measurements; <1 h to up to 16 h).

When troponin I concentrations determined by the iSTAT-1 were repeated in the laboratory within 2 h, there was concordance between both values using standard regression analysis (y=1.14 x-0.56, n=18, r=0.98; hs-TnI values converted into ng/mL) as well as Passing-Bablock regression analysis (y=0.89 x-0.006). However, overall correlation when all 56 data points were considered was very poor. In addition, we also observed very poor correlation in another 38 specimens when laboratory determinations of hs-TnI were conducted >2 h up to 16 h.

We concluded that the iSTAT-1 contemporary troponin I concentrations were concordant with hs-TnI values only if measured within 2 h.