Single high-sensitivity troponin-I for ruling out acute coronary syndrome: a detection limit approach.

Aims: The aim of this study was determine the incidence of major adverse cardiac events within 30 and 365-days among patients discharged from emergency departments (EDs), following a single high-sensitivity cardiac troponin I test result below or close to the limits of detection (LoD).

Methods and results: Patients ≥20 years old who presented to four EDs from mid-2014 to end-2015, underwent a single high-sensitivity troponin test and were discharged were included. Data from ED presentations, hospital admissions, mortality records, and pathology laboratories were linked and harmonized. High-sensitivity troponin levels were categorized as below (<2 ng/L) or close to (<5 ng/L) the LoD. The primary outcome was cardiovascular death and myocardial infarction (MI), identified using ICD-10-AM codes. In a cohort of 6633 patients, 49% had high-sensitivity troponin levels below the LoD (<2 ng/L), and 79% had levels <5 ng/L. There were no primary outcome events at 30-day follow-up among patients with high-sensitivity troponin results below 2 or 5 ng/L. At 365-days, there were 5 (0.15%) and 11 (0.21%) primary outcome events for patients with high-sensitivity troponin results below 2 and 5 ng/L, indicating negative predictive values of 99.85% and 99.79%.

Conclusion: These findings confirm that patients with a single very low level of high-sensitivity troponin on presentation to EDs are at low risk of MI and cardiovascular death at 30 and 365 days, supporting the safety of a triage strategy incorporating a single high-sensitivity troponin result below the LoD to identify patients at low-risk, who may be suitable for expedited discharge.