Prognostic Performance of High-Sensitivity Cardiac Troponin Assay Evaluated

Scientists at Brigham and Women's Hospital (Boston, MA, USA) evaluated the prognostic performance of a new high-sensitivity cardiac troponin I (hs-cTnI) assay compared with a fourth-generation commercial cardiac-specific isoforms of troponin T (cTnT) assay in 4,695 patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) from the Early Glycoprotein IIb/IIIa Inhibition in NSTE-ACS (EARLY-ACS) and the Otamixaban for the Treatment of Patients with NSTE-ACS (SEPIA-ACS1-TIMI) trials. Baseline cardiac troponin was categorized at the 99th percentile reference limit (26 ng/L for hs-cTnI; 10 ng/L for cTnT) and at sex-specific 99th percentiles for hs-cTnI.

The ARCHITECT STAT High Sensitive Troponin-I assay (hs-cTnI, Abbott; Abbott Park, IL, USA) is a two-step, sandwich chemiluminescent magnetic-microparticle immunoassay that uses two mouse monoclonal antibodies recognizing amino acids 41–49 (capture) and 24–40 (detection) on human cTnI, and a limit of detection of 1.5 ng/L. Troponin T was also measured, using the cTnT, fourth generation assay (Roche Diagnostics; Indianapolis, IN, USA), in 4,221 of the 4,695 study participants with hs-cTnI data; and this assay has a limit of detection of 10 ng/L.

All patients at baseline had detectable hs-cTnI compared with 94.5% with detectable cTnT. At 30 days, patients with a baseline hs-cTnI equal to or greater than 26 ng/L had a significantly higher rate of cardiovascular death or MI compared with those with a baseline measurement below the reference limit. The authors concluded that the assay performed well prognostically, identifying patients at significantly higher 30-day risk of cardiovascular death or new MI using the guideline-based 99th percentile decision limit. The results of the study demonstrate a gradient of risk at very low ranges of concentrations, and performs better with respect to prognosis than a current commercial assay. The study was published in the January 2014 issue of the journal Clinical Chemistry.

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