High-sensitivity cardiac troponin (hs-cTn) is essential for risk stratifying patients with suspected acute coronary syndrome (ACS). The European Society of Cardiology (ESC) 2025 study evaluated the impact of switching from a high-sensitivity cardiac troponin I (hs-cTnI) assay to a hhs-cTnT assay on patient risk classification, hospital admissions, and clinical outcomes.

In this prospective interrupted time series, 25,849 consecutive patients presenting with suspected ACS across three acute care hospitals were included between October 2020 and October 2022. All sites transitioned from hs-cTnI to hs-cTnT in October 2021. Risk was categorized as low (<5 ng/L), intermediate, or high using sex-specific 99th percentile upper reference limits (URL).

After switching to hs-cTnT, the proportion of patients classified as low risk decreased from 62% to 26% in females and from 53% to 11% in males (P<0.001 for both). Intermediate-risk classifications increased from 18% to 35% in females and from 30% to 56% in males, while high-risk classifications rose from 20% to 40% in females and from 17% to 33% in males (P<0.001 for all). Hospital admission rates also increased (adjusted odds ratio 2.82; 95% confidence interval 2.21–3.60; P<0.001).

However, one-year outcomes remained unchanged. The adjusted odds ratio for myocardial infarction, heart failure hospitalization, or cardiovascular death was 0.73 (95% CI 0.41–1.31; P=0.2967), and for all-cause death was 0.89 (95% CI 0.56–1.39; P=0.6023). These results show that switching from hs-cTnI to hs-cTnT increased hospital admissions by reclassifying fewer patients as low risk, without improving long-term clinical outcomes.