Transitioning to high-sensitivity troponin: 1-year mortality outcomes in patients with suspected acute coronary syndrome presenting to emergency departments

Background: Switching from a conventional to a high-sensitivity cardiac troponin (hs-cTn) assay enables detection of smaller amounts of myocardial damage, but the clinical benefit is unclear. We investigated whether switching to a hs-cTnI assay with a sex-specific 99th centile diagnostic threshold was associated with lower 1-year death or new myocardial infarction (MI) in patients with suspected acute coronary syndrome (ACS). Methods: This pre-post study included nine tertiary hospitals in Australia. During the pre-hs-cTn period, all hospitals used conventional troponin assays, and during the postperiod, four switched to using hs-cTnI. Participants were ≥20 years old and presenting to emergency departments (EDs) with suspected ACS between March 2011 and November 2015. Outcomes were determined using linked administrative data and compared using Kaplan-Meier and Cox regression analyses. Results: We identified 179 681 consecutive patients (62 (SD 19) years, 47% women), 87 019 (48%) during the preperiod, and 92 662 (52%) during the postperiod. Following the switch to hs-TnI, the proportion of patients diagnosed with new MI was not significantly different (3.9% postperiod vs 4.2% preperiod; p=0.08) while diagnoses of unstable angina were lower (1.5% postperiod vs 2.5% preperiod; p<0.0001). In non-switching jurisdictions, rates of new MI remained stable, while diagnoses of unstable angina increased. Switching to hs-cTnI assay was associated with lower mortality at 30 days (adjusted HR 0.88 (0.82, 0.95)) and 1 year (aHR 0.90 (0.85, 0.94)). The corresponding aHRs for non-switching jurisdictions were not statistically different. Conclusion: The use of an hs-cTnI assay in an ED population with suspected ACS was associated with lower mortality at 1 year.