Comparison of 0/3-Hour Rapid Rule-Out Strategies Using High-Sensitivity Cardiac Troponin I in a US Emergency Department

igh-sensitivity (hs) cTn (cardiac troponin) assays have been used clinically for years outside the United States.Compared with contemporary cTn assays, hs-cTn assays have higher analytical sensitivity and improved imprecision that allows for more precise quantification of cTn at lower concentrations. 13][4][5] Following recent 510 (k) clearance by the Food and Drug Administration of 1 hs-cTnT (Roche Gen 5) assay in 2018 and 3 hs-cTnI assays (Siemens Healthineers, Beckman Coulter, and Abbott Diagnostics) in 2019, US clinicians and laboratorians require comparative data that facilitates selection and clinical implementation of one of the available rule-out strategies.The goal of the present study was to compare the diagnostic and prognostic performance of 0-and 3-hour hs-cTnI testing strategies to rule out MI. METHODS AND RESULTSThe data that support the findings of this study are available from the corresponding author upon reasonable request.Following institutional review board approval, we prospectively included consecutive, unselected, emergency department patients (Hennepin County Medical Center, Minneapolis, MN) in whom initial preset serial contemporary cTn measurements were obtained on clinical indication, for which hs-cTnI (Abbott, investigational for study purposes; Food and Drug Administration-cleared September 2019) was also measured (use of Abbott high-sensitivity troponin I assay in acute coronary syndromes, [UTROPIA], NCT02060760).The methods and primary results have been published. 6,7For inclusion, patients needed a baseline cTnI measurement at presentation and at least 1 additional cTnI within 24 hours of presentation before discharge and at least one 12-lead ECG performed.The current study-a secondary analysis of UTROPIA-evaluated three 0/3-hour rule-out pathways in a patient subset (n=582) with established symptom onset in whom both 0-and 3-hour samples were available, as follows: the classic approach based on serial hs-cTnI concentrations ≤99th percentile (Figure [A]), the 0/3-hour European Society of Cardiology pathway (Figure [B]), 8 and the High-STEACS (High-sensitivity troponin in the evaluation of patients with acute coronary syndrome) pathway (Figure [C]). 3Each pathway was examined using both serial hs-cTnI results alone and in combination with a normal 12-lead ECG, with our normal ECG criteria described previously. 7Briefly, a normal 12-lead ECG was defined as entirely normal ECG or where there were nondiagnostic ST/T-wave abnormalities.Of note, the initial High-STEACS pathway publication 3 focused on results addressing an hs-cTnI algorithm without ECG findings, with sensitivity analysis evaluating the performance in patients without ischemic findings on the presenting ECG.The High-STEACS pathway (highsteacs.com) and HiSTORIC trial (NCT03005158) have since mandated the absence of diagnostic