Background High-sensitivity cardiac troponin I (hs-cTnI) assays promise high diagnostic accuracy for myocardial infarction (MI). In an ED where conventional cTnI was in use, we evaluated an assessment pathway using the new Access hsTnI assay.
Methods This retrospective analysis recruited ED patients with suspected MI between June and September 2019. All patients received routine care with a conventional cTnI assay (AccuTnI +3: limit of detection (LoD) 10 ng/L, 99th centile upper reference limit (URL) 40 ng/L, abnormal elevation cut-point 80 ng/L). Arrival, then 90-minute or 360-minute cTnI levels for low and non-low risk patients, respectively (ED Assessment of Chest pain score) guided diagnosis and disposition which was at treating physician discretion. The same patients had arrival and 90-minute or 180-minute samples drawn for hs-cTnI levels (Access hsTnI: LoD 2 ng/L, 99th centile URL 10 ng/L (females) and 20 ng/L (males); abnormal elevation above the URL and delta >30%). Treating physicians were blinded to the hs-cTnI results. Using the hs-cTnI values, investigators retrospectively assigned likely diagnosis, disposition and likelihood of a 30-day major adverse cardiac event (MACE). Admission was recommended for significantly rising hs-cTnI elevations. The primary objective was to demonstrate an acceptable unexpected 30-day post-discharge MACE rate of <1%. cTnI elevation rates, diagnostic outcomes and ED disposition were also compared between pathways.
Results For the 935 patients, unexpected 30-day post-discharge MACE rates were 0/935 (0%, 95% CI 0% to 0.4%) with the conventional or novel pathway. For the high-sensitivity and conventional assays, respectively, abnormal elevation rates were 29% (95% CI 26% to 32%) and 19% (95% CI 17% to 22%), for MI were 9% (95% CI 8% to 11%) and 8% (95% CI 6% to 10%), and for hospital admission were 42% (95% CI 39% to 45%) and 43% (95% CI 40% to 47%).
Conclusion The novel pathway using the Access hsTnI assay has an acceptably low 30-day MACE rate.
- emergency department
- cardiac care
- care systems
- acute myocardial infarct
- cardiac care
Data availability statement
Data are available upon reasonable request.
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Handling editor Richard Body
Contributors RM and ZXL originally conceived the study with contributions from LC, AN and LK. ZXL, RM and LS were responsible for data acquisition and entry. RM and AN were responsible for clinical outcome allocations. RM and LS performed the data analysis. RM and LC drafted the manuscript with ongoing contributions from ZXL, LK, AN and LS. RM takes responsibility for the manuscript as a whole.
Funding Beckman Coulter, Inc, Chaska, MN, USA, provided (1) an unrestricted grant of AUD$10,000.00 for employment of a research assistant to aid data collection, data entry, analysis and report preparation (LS); (2) five Access hsTnI calibrators and Access hsTnI reagent for conduct of 3000 assays (sufficient for approximately 1000 patients). The study was investigator-led and designed. Beckman Coulter, Inc, had no role in study design, conduct, analysis or final report preparation.
Disclaimer The study was investigator-led and designed. Beckman Coulter, Inc, had no role in study design, conduct, analysis or final report preparation.
Competing interests LC has received research funding, consulting fees and/or honorarium from Beckman Coulter, Siemens Healthineers and Abbott Diagnostics.
Provenance and peer review Not commissioned; externally peer reviewed.
Author note If the current final sentence is not sufficient it may be changed as required. Perhaps "RM as guarantor accepts full responsibility for the manuscipt, study conduct, access to data and the decision to publish."
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