Evaluation of analytical performance of the Pathfast® cardiac troponin I

BACKGROUND: Cardiac troponins are considered the cornerstone for risk stratification and diagnosis of patients with acute coronary syndrome (ACS). Following Clinical Laboratory Standards Institute (CLSI) guidelines, we assessed the analytical performances of the Pathfast (Mitsubishi, Japan) cTnI method. METHODS: We evaluated different sample types. Control materials and lithium heparin plasma pools were used to determine: limit of blank (LoB), limit of detection (LoD), imprecision and linearity. The effects of potential endogenous interfering substances and the possibility of falsely increased cardiac troponin I (cTnI) concentrations attributable to the presence of heterophilic antibodies (HA), rheumatoid factor (RF) and human anti-mouse antibodies (HAMA) in high concentrations were evaluated. The 99th percentile limit of the cTnI value distribution was determined from 320 Caucasian reference individuals. RESULTS: No significant differences were found when cTnI concentrations of 40 lithium-heparin plasma samples were compared with the matched values of K(2)-EDTA plasma, whole blood and serum samples. The LoB and the LoD of the cTnI method were 0.0048 and 0.0066 microg/L, respectively. cTnI mean values from 0.66 to 6.0 microg/L showed a total CV% from 6.0 to 6.4. cTnI at a concentration of 0.02 microg/L was associated with a total CV of 9.6%. The method gave a linear response for cTnI concentrations within the measurement range. In six of 12 samples containing HA, a positive interference was demonstrated. The 99th percentile limit of the cTnI distribution in the reference population was 0.013 microg/L. CONCLUSIONS: The data indicate that the cTnI Pathfast method may be suitable for helping clinicians in the management of patients with ACS.