A-011 Analytical performance of the sixth generation high-sensitivity cardiac troponin T assay

Abstract

High-sensitivity cardiac troponin assays are integral to diagnosing myocardial infarction. The current high-sensitivity cardiac troponin T assay (Elecsys® Troponin T hs 5th generation; Gen 5) received FDA clearance in 2017, with a limit of detection (LoD) and limit of quantitation (LoQ) of 3 ng/L and 6 ng/L, respectively. A 6th generation assay (Elecsys® Troponin T hs Gen 6; Gen 6) was recently developed with improved analytical characteristics, including sensitivity and resistance to interferences. Reference intervals for this assay have been reported, but analytical performance in the clinical laboratory has yet to be evaluated. The Gen 6 and Gen 5 assays were evaluated on the Roche cobas e 801 and e 601/602 analyzers, respectively. Analytical accuracy and linearity were determined using recombinant human cardiac troponin T (Hytest, 8RTT5) serially diluted in blank material (Mass Spect Gold Human Serum, Golden West Diagnostics). Measurement limits were determined in blank material and lithium-heparin plasma specimens per CLSI EP17-A2. A non-linear regression fitting model (R version 4.5.0) was used to estimate the relationship between variation and analyte concentration, and the LoQ estimate was determined at a coefficient of variation (%CV) of 10%. Repeatability and intermediate precision of plasma specimens were evaluated according to CLSI EP15-A2. To evaluate cross-reactivity, other troponin isoforms (e.g. skeletal muscle troponin T, cardiac troponin I, skeletal muscle troponin I, or troponin C) were spiked into lithium-heparin plasma pools. Interference from hemolysis was assessed by adding hemolyzed erythrocytes and evaluating the change in cardiac troponin T concentration. Serial dilutions of cardiac troponin T revealed that Gen 6 exhibits a positive bias relative to Gen 5 at concentrations >10 ng/L. Below this point, the bias reverses, indicating a concentration-dependent crossover. The limit of blank (LoB), LoD, and LoQ were 0.4 ng/L, 1.2 ng/L, and 2.2 ng/L, respectively. %CV for repeatability and intermediate precision were <3%. No cross-reactivity was observed on Gen 6 for skeletal muscle troponin T, or troponin C at concentrations up to 10,000 ng/L. Interference from hemolysis was not observed up to 5,000 mg/dL of hemoglobin. The Gen 6 assay demonstrates resistance to interference and greater analytical sensitivity, with a lower LoD and LoQ relative to Gen 5, enabling broader coverage of healthy individuals.