Impact of switching high-sensitivity cardiac troponin assays on risk stratification in suspected acute coronary syndrome

BACKGROUND: Cardiac troponin is central to risk stratification in patients with suspected acute coronary syndrome. High-sensitivity assays measuring cardiac troponin (hs-cTn) I or T are recommended by international guidelines. However, diagnostic thresholds for these assays are derived from different populations. We aimed to evaluate whether the change in assay influenced risk stratification.

METHODS: This is a secondary analysis of the TWITCH-ED study enrolling 25,849 patients with suspected acute coronary syndrome between October 2020 and October 2022. In October 2021, sites changed from a hs-cTnI to a hs-cTnT assay. Study outcomes included discharge from the Emergency Department following a single cardiac troponin measurement, a composite outcome of subsequent myocardial infarction, heart failure hospitalization, or cardiovascular death at one year, and all-cause death at one year. Patients were stratified as low-risk at presentation using established thresholds.

RESULTS: Higher proportions of patients were identified as low-risk (57.3% versus 17.6%) and discharged following a single troponin measurement (47% versus 30%) using the hs-cTnI assay, compared to the hs-cTnT assay (P<0.001 for both). Those identified as low-risk with the hs-cTnT assay were younger (median 52 [IQR 40-62] versus 41 [32-51] years) with fewer comorbidities, and had lower rates for the composite outcome (0.8% versus 0.2%) and all-cause death (2.0% versus 0.3%) (P<0.001 for both) at one year.

CONCLUSIONS: Risk stratification thresholds for hs-cTnI and hs-cTnT assays do not provide equivalent performance. The hs-cTnT assay and threshold identified fewer low-risk patients suitable for discharge, with fewer subsequent cardiovascular events at 1 year.