Diagnostic Accuracy of a Novel 0/1-H Algorithm Using Point-of-Care High-Sensitivity Troponin in the Emergency Department

High-sensitivity cardiac troponin (hs-cTn) assays in combination with clinical assessment and electrocardiogram are central to accelerated diagnostic protocols for rapid assessment of patients presenting with suspected acute coronary syndrome (1). Point-of-care (POC) testing can reduce the total turnaround time and improve accessibility. To our knowledge, there are 3 commercially available high-sensitivity POC assays: PATHFAST (LSI Medience), TriageTrue (Quidel), and Atellica VTLi® (Siemens Healthineers) (2); only the first has 0/1-h cutoffs endorsed by the European Society of Cardiology (1). A novel 0/1-h accelerated diagnostic protocol using the Atellica VTLi assay was recently used in the WESTCOR-POC randomized controlled trial (NCT05354804). In this trial of 1494 patients, emergency department length-of-stay was compared between the novel POC-based protocol, in which nonlaboratory staff performed the analysis, and a standard protocol using hs-cTnT measured on a central laboratory platform (3). The VTLi assay has a limit of detection of 1.6 ng/L and sex-specific 99th percentile upper reference limits of 18 ng/L for women and 27 ng/L for men (2). A previously proposed single-sample rule-out threshold of 4 ng/L (4), together with correlations with other central laboratory assays, informed a suggested 0-h cutoff of <6 ng/L with a 1-h delta <3 ng/L applied for rule-out used in this study. Cullen et al. provided supporting evidence for similar baseline and delta values in a 0/2-h accelerated diagnostic protocol (5). In the absence of validated rule-in criteria, values above the 99th percentile (>23 ng/L) were conservatively interpreted as “rule-in.” Cullen et al. proposed rule-in thresholds of ≥60 ng/L with a 2 h delta of ≥15 ng/L. The Roche Elecsys hs-cTnT assay was used in the control arm with 0/1 cutoffs endorsed by the European Society of Cardiology guidelines (1) (Table 1). The index diagnosis of non-ST-elevation myocardial infarction (NSTEMI) was adjudicated by 2 independent cardiologists using central hs-cTnT results and all available clinical data. During the inclusion periods, we did weekly (first year) to monthly (last year) quality control at 3 different concentrations (n = 41 quality control measurements/concentration). Quality control material was provided by the manufacturer. The long-term analytical variability (CV) including multiple different lots of cartridges and QC material per the 3 instruments ranged from 14.7% to 19.1% at a target of 17.8 ng/L (corresponding to the female 99th percentile), being slightly higher than the recommended 10% CV. At higher concentrations, CV ranged from 6.6% to 8.2% at 30.2 ng/L and 8.6% to 10.0% at 299.5 ng/L.