Clinical Performance of a Novel Point-of-Care High-Sensitivity Cardiac Troponin I Assay

Background: High-sensitivity cardiac troponin (hs-cTn) assays performed in the central laboratory have long turnaround times. This study evaluates the clinical performance of a novel bedside point-of-care (POC) hs-cTnI assay (i-STAT^® hs-TnI) to aid in the diagnosis of myocardial infarction (MI). Methods: A prospective multisite cohort study involving emergency department (ED) patients with symptoms suggestive of acute coronary syndrome was conducted at 28 sites across the United States. Serial whole blood samples were collected at 0–1 h and >1–3 h from ED presentation. Primary outcome was MI or non-MI. Sensitivity, specificity, and negative predictive value (NPV) for MI were calculated with 97.5% lower confidence limits (LCL) using the female, male, and overall 99th percentile upper reference limit (URL, 13, 28, and 21 ng/L, respectively). Post hoc analysis was also conducted for initial measurements below the limit of quantification (LoQ, 2.9 ng/L) and <5.0 ng/L. Results: The cohort included 3582 patients, median age 59 y, 64% female. MI incidence was 8.6%. Sensitivity and specificity at >1–3 h were 96.6% (LCL 91.7%) and 82.1% (80.2%) using the female URL; 90.7% (LCL 84.1%) and 83.9% (LCL 81.4%) using the male URL; and 92.4% (LCL 88.3%) and 85.6% (LCL 84.2%) using the overall URL. NPVs for MI of initial hs-cTnI measurements <LoQ and <5.0 ng/L were 99.8% (LCL 99.2%) and 99.8% (LCL 99.4%) respectively. Conclusions: The whole blood POC i-STAT hs-TnI assay demonstrated performance characteristics similar to other hs-cTn assays and achieved high sensitivity and NPV for initial measurements <LoQ and <5.0 ng/L.