John W Pickering PhD, Scott Kelland MBChB, Otis Williams BMedSci(Hons), Jamin Kim MBChB, Sally Aldous MD, Laura R Joyce MBChB, Martin P Than MBBS
Abstract 
Objective
Changing cardiac troponin (cTn) assays may affect a hospital’s admission and myocardial infarction rates. The effect of changing from a contemporary to high-sensitivity (hs) cTnI assay has been well described, but the real-life impact on disposition and diagnosis of changing from one hs-cTnI assay to another has not.
Methods
All patients who received a troponin measurement in the ED during 16 weeks were adjudicated to identify those the attending physician investigated for possible acute coronary syndrome (ACS) and for clinical outcomes. The Abbott ARCHITECT hs-cTnI assay was in use for the first 8 weeks, followed by the Beckman Coulter hs-cTnI assay for the second 8 weeks.
Results
Fewer patients were investigated with the Abbott assay (2213), than the Beckman assay (2683). A larger proportion were investigated for ACS in the Abbott (64.8%) than the Beckman (60.3%) arm. Among those investigated for ACS the rate of myocardial infarction decreased on changing from Abbott (12.8%) to Beckman (8.8%). Adjusted odds of a myocardial infarction were lower for the Beckman arm, Odds Ratio 0.69 (95% CI 0.55 to 0.88). A lower proportion of Abbott than Beckman had myocardial injury (at least one ED cTnI ≥ upper reference limit) 26.4% compared with 29.8%. The proportion admitted to hospital decreased from the Abbott arm (42.5%) to the Beckman arm (36.8%).
Conclusions
A change in cTnI assay resulted in a decreased rate of myocardial infarction and admission despite an increase in rate of myocardial injury among patients investigated for ACS.
Key findings
- Changing from one high-sensitivity troponin I assay (Abbott) to another (Beckman) decreased the rate of diagnosis of myocardial infarction.
- Changing Abbott to Beckman reduced the overall proportion of patients admitted to a hospital ward.
- Changing from the Abbott to Beckman increased the proportion of patients with troponin results in the ED above the upper reference limit.
