Access hsTnI

The Access hsTnI is a chemiluminescent immunoassay that quantitatively measures cardiac troponin I (cTnI) levels in human serum and plasma samples using automated Unicel DxI immunoassay instruments. It is intended to aid in the diagnosis of myocardial infarction (MI) by detecting and measuring cTnI concentrations across a range of 2.3 to 27,027 pg/mL.

The device uses a two-site sandwich immunoassay with chemiluminescent detection, identical assay principle and technology to the predicate. It processes the same sample types (serum and lithium heparin plasma) in 55 µL volumes, maintains the same precision specifications (≤10% CV for concentrations ≥11.5 pg/mL), uses identical monoclonal antibodies, and has comparable reference intervals and reagent stability (64 days at 2-10°C).

CLSI EP05-A3 (precision evaluation), CLSI EP06-2nd Edition (linearity evaluation), CLSI EP17-A2 (detection capability), CLSI EP09c (method comparison using patient samples), and CLSI EP34 1st Edition (extended measuring interval through dilution and spiking).

The candidate device demonstrates substantial equivalence because it maintains identical assay principles, technology, reagent materials, and sample types as the predicate Access hsTnI. Performance data from 239 clinical samples across three instruments showed method comparison results meeting acceptance criteria (slope 1.00 ±0.10), imprecision within predicate specifications (3-4% CV), linearity across the measuring range (≤10% bias), and comparable reference intervals. The only modification is a software upgrade to improve washing efficiency, which did not alter clinical performance or safety characteristics.