Validation of the i-STAT Point-of-Care High-Sensitivity Troponin 0/2-Hour Algorithm

An accelerated diagnostic protocol for the 0- and 2-hour measurement of i-STAT point-of-care (POC) high sensitivity troponin I (hs-cTnI) was recently derived in Australia. However, it has yet to be externally validated and its performance in U.S. patients is unknown. The objective of this study was to assess the performance of the 0/2-hour algorithm in a multisite U.S. Emergency Department (ED) cohort.

A prospective cohort study was conducted across three U.S. EDs. Adult patients with chest pain or other symptoms suggestive of acute coronary syndrome, at least one hs-cTnI ordered, and without STEMI were accrued for 8 months in 2025. Blood samples for POC hs-cTnI measurement were collected at arrival (0-hour) and within 2-hours for measurement by trained research staff on an i-STAT 1 analyzer (Abbott Laboratories). The primary outcome was index myocardial infarction (MI), which was adjudicated by experts using the routine clinical hs-cTnI measures completed in the hospital central laboratories (Beckman Coulter). The diagnostic performance of the 0/2-hour algorithm was assessed by calculating its negative and positive predictive values and likelihood ratios (NPV, PPV, -LR, and +LR) with associated 95% confidence intervals. The efficacy of the algorithm was calculated, defined as the proportion of patient classified into the rule-out zone.

During the study period, 578 patients with complete 0/2-hour algorithm assessments were accrued. These patients were 48% (279/578) female, 40% (233/578) non-White, and had a median age of 60 years (IQR: 50-70). Index MI occurred in 7.4% (43/578). The efficacy of the algorithm was 54.8% (317/578) and 8.8% (51/578) were classified to the rule-in zone. Among patients ruled-out, the NPV was 99.4% (95%CI: 97.7-99.9%) with a -LR of 0.08 (95%CI: 0.02-0.31). The rule-in zone was associated with a PPV of 62.7% (95%CI: 48.1-75.9%) and +LR of 21.0 (95%CI 13.0-33.7). Among 36.3% (210/578) patients classified to the observation zone, 4.3% (9/210) had an adjudicated MI.

The 0/2-hour algorithm for i-STAT POC hs-cTnI measurement was safe and efficacious in a multisite U.S. cohort of ED patients with acute chest pain.