Tni ultra assay

The trial protocol included measurement of troponin I prior to discharge at the time of study randomization (i.e. baseline/Visit 2), which occurred at a median of 5 days after hospital admission and after patients had been haemodynamically stabilized. The protocol also included measurement of troponin I at 1 month post-randomization. All troponin samples in ASTRONAUT were measured at a central core laboratory blinded to clinical data (Quest Diagnostics, Valencia, CA, USA). Serum concentrations were measured using the TnI-Ultra assay (Siemens Healthcare Diagnostics, Tarrytown, NY, USA) with a 99th percentile upper reference limit of 0.04 ng/mL and an imprecision at this level of 0.004 ng/mL. In the trial database, the lowest observed value was 0.02 ng/mL and lesser values were imputed as 0.01 ng/mL.

HEART Pathway risk assessments were calculated at the point-of-care by the treating provider using a clinical decision support tool integrated into the electronic health record (EHR) [2 (link),3 (link)]. Data extracted included patient demographics (age, sex, race, ethnicity), HEART Pathway assessments, troponin results, stress testing results, ICA findings, and outcomes data (incidence of death, MI, or revascularization at 30 days). Race and ethnicity, as reported by the patient and collected in the EHR, were collapsed into a two-level variable (white and non-white) for the purpose of regression modeling. Troponin assays used during the study period included the AccutTnI+3 assay (Beckman Coulter, CA) with a 0.025 ng/mL upper reference limit (URL) and the TnI-Ultra assay (Siemens, Munich, Germany) with a 0.040 ng/mL URL.