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

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.

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 an hs-cTnI to an 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 1 year, and all-cause death at 1 year. Patients were stratified as low-risk at presentation using established thresholds. Higher proportions of patients were identified as low-risk (57.3% vs. 17.6%) and discharged following a single troponin measurement (47% vs. 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 [inter-quartile range 40–62] vs. 41 [32–51] years) with fewer comorbidities, and had lower rates for the composite outcome (0.8% vs. 0.2%) and all-cause death (2.0% vs. 0.3%) (P < 0.001 for both) at 1 year.

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.