Fastidious adherence to 0/1-hour high-sensitivity troponin T testing reduces emergency department length of stay in patients presenting with suspected acute coronary syndromes
Authors: Vimalaratnam G , Alazrag W A , Idris H I , Juergens C P , Ferguson I M C , Middleton P M , French J K 
Published: October 2024

Abstract

Background
High-sensitivity cardiac troponins (hs-cTn) are key clinical biomarkers in patients presenting with suspected acute coronary syndromes (ACS) to Emergency Departments (EDs). They have facilitated rapid 0h/1h troponin testing protocols, leading to safe, effective, and efficient triage of patients. However, early distinction of myocardial infarction (MI), which has a reported frequency of less than 10% in most cohorts, from the apparently stable hs-cTn elevations of chronic myocardial injury (CMI) remains a challenge. Often CMI patients require confirmation by further testing and observation, prolonging patient length of stay. Further, reliably obtaining serial hs-cTn samples at 60-minutes in a busy ED setting may be difficult. A potential explanation for only 5-6% of Australian sites adopting 0h/1h hs-cTn testing.

Methods and Results
We undertook a case-control study between March and August 2023 among patients with suspected ACS presenting to Liverpool Hospital ED (Sydney, Australia). 185 patients (cases) underwent hs-cTnT sampling at 30- and 60-minutes (± 5 minutes) after baseline. Diagnosis of MI was made in 8.6%, 35.7% were placed into a further observation group and MI ruled-out in 55.7%. The latter two groups were matched to 169 patients (controls) who received ‘usual’ care, which was a 0h/1h hs-cTnT testing protocol. The case and control arms were matched by age, gender, time from symptom onset and main presenting symptom. Control patients had a median sampling interval of 118 [85 to 174] minutes, rather 60 minutes as the protocol directs. When comparing the paired differences between the case and control arms, there was a mean reduction in length of stay of 104 (95% CI: 41 to 186, P = 0.01) and 47 (95% CI: 11 to 84, P = 0.01) minutes, for the observation and rule-out MI groups respectively. The figure shows the distribution of lengths of stay by group. Among the rule-out group, Wilcoxon signed rank test indicated the control arm had a longer median length of stay of 6.3 [5.1 to 8.4] hours, compared to 5.0 [4.5 to 7.1] hours in the case arm (P=0.005). Similarly, in the further observation group, control patients also had a longer median length of stay of 9.2 [6.9 to 10.4] hours compared to case patients of 8.1 [5.1 to 10.3] hours (P = 0.009). At 30-days, ED representation rates were 10.7% in controls and 8.3% in cases, rehospitalisation 3.6% in controls and 5.3% in cases, cardiac death 0% in both arms and non-cardiac death 1% in both arms. There were no differences in event rates between each arm (P &gt; 0.05).

Conclusion
Accurate 0h/1h hs-cTnT testing reduces patient length of stay in ED and offers more personalised prediction of MI risk. The importance of adherence to protocol-directed sampling times is clear, where further studies are required regarding routine implementation in a busy ED setting.Exact 60 min TnT and LOSOutcomes at 30 days