A risk assessment score and initial high-sensitivity troponin combine to identify low-risk of acute myocardial infarction in the emergency department

Abstract

Objectives

Early discharge of patients with presentations triggering assessment for possible acute coronary syndrome is safe when clinical assessment indicates low-risk, biomarkers are negative, and electrocardiograms (ECGs) are non-ischemic. We hypothesized that the Emergency Department Assessment of Chest Pain Score (EDACS) combined with a single measurement of high-sensitivity cardiac troponin (hs-cTn) could allow early discharge of a clinically meaningful proportion of patients.

Methods

We pooled data from 4 patient cohorts from New Zealand and Australia presenting to an ED with symptoms suggestive of ACS. The primary outcome was major adverse cardiac events (MACE) within 30 days of presentation. In patients with a non-ischemic ECG we evaluated the sensitivity for MACE and percentage low-risk of every combination of hs-cTnT concentration and hs-cTnI concentration with EDACS. We used a standard smoothing technique on the probability density function for hs-cTn and EDACS and applied bootstrapping to determine the optimal threshold combinations, namely the combination that maximized the percentage low-risk with ≥98.5% sensitivity for MACE.

Results

From 2536 patients, 2258 presented without an ischemic ECG of whom 272 (12.1%) had a MACE within 30 days. The optimal threshold for hs-cTnI was 7 ng/L combined with an EDACS threshold of 16 (36.8% patients low-risk). The optimal thresholds for hs-cTnT were 8 ng/L combined with an EDACS threshold of 15 (30.2% patients low-risk).

Conclusion

Single measurements of both hs-cTnI and hs-cTnT at presentation combined with EDACS to identify over 30% of patients as low-risk and therefore eligible for safe early discharge after only one blood-draw.

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