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

Area of Science:

• Cardiology
• Emergency Medicine
• Biomarkers

Background:

• Major adverse cardiac events (MACE) are a concern for patients presenting to emergency departments (EDs).
• High-sensitivity cardiac troponin I (hs-cTnI) is a key biomarker for diagnosing acute myocardial infarction (MI).
• Current ED protocols often require serial troponin testing, potentially delaying discharge.

Purpose of the Study:

• To determine the incidence of MACE within 30 and 365 days in patients discharged from EDs.
• To evaluate the safety of using a single hs-cTnI test result below or near the limit of detection (LoD) for risk stratification.
• To assess the potential for expedited discharge in low-risk patients identified by a single hs-cTnI test.

Main Methods:

• A cohort study included 6633 patients aged ≥20 years discharged from four EDs between mid-2014 and end-2015.
• Data were linked from ED presentations, hospital admissions, mortality records, and pathology laboratories.
• hs-cTnI levels were categorized as <2 ng/L (below LoD) or <5 ng/L (near LoD). The primary outcome was cardiovascular death and MI.

Main Results:

• 49% of patients had hs-cTnI <2 ng/L, and 79% had hs-cTnI <5 ng/L.
• No MACE occurred within 30 days for patients with hs-cTnI <2 ng/L or <5 ng/L.
• At 365 days, MACE occurred in 0.15% (<2 ng/L) and 0.21% (<5 ng/L), yielding negative predictive values of 99.85% and 99.79% respectively.

Conclusions:

• A single very low hs-cTnI level (<2 ng/L or <5 ng/L) in ED patients indicates a low risk of MI and cardiovascular death at 30 and 365 days.
• This supports the safety and efficacy of a triage strategy using a single hs-cTnI result below the LoD.
• Such a strategy can identify low-risk patients suitable for expedited discharge, optimizing ED resource utilization.