Analytical Performance of the Sixth Generation High-Sensitivity Cardiac Troponin T Assay

BACKGROUND: High-sensitivity cardiac troponin assays are integral to diagnosing myocardial infarction. The current Roche Elecsys® Troponin T high-sensitivity Gen 5 assay (Gen 5) received FDA clearance in 2017. A sixth-generation assay was recently developed with improved analytical characteristics, including sensitivity and resistance to interferences. Reference ranges for this assay were reported, but analytical performance in the clinical laboratory has yet to be evaluated. METHODS: The Elecsys® Troponin T high-sensitivity Gen 6 (Gen 6) assay was evaluated on the Roche cobas e 801 analyzers. Measurement limits of the assay were determined in lithium-heparin plasma specimens per CLSI EP17-A2. Repeatability and intermediate precision of QC materials and plasma specimens were determined according to CLSI EP05-A2 and EP15-A2, respectively. RESULTS: 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 concentration-dependent crossover. The limit of blank and limit of detection were 0.4 ng/L and 1.2 ng/L, respectively. The limit of quantitation was 2.2 ng/L with a 10% CV. No cross-reactivity was observed on Gen 6 for skeletal muscle troponin T, cardiac troponin I, skeletal muscle troponin I, or troponin C at concentrations up to 10 000 ng/L. Interference from hemolysis was not observed up to 5000 mg/dL of hemoglobin. CONCLUSIONS: The Gen 6 assay demonstrates resistance to interference and greater analytical sensitivity, with a lower limit of detection and limit of quantitation relative to Gen 5, enabling broader coverage of healthy individuals.