49 Comparing the Safety and Efficacy of a Rapid High-Sensitivity Cardiac Troponin I Protocol Between Hospital-Based and Free-Standing Emergency Department

Document Type

Conference Proceeding

Publication Date


Publication Title

Ann Emerg Med


Study Objectives: Significant variability exists in patient population and diagnostic capabilities of large academic tertiary, community-based hospital, and free-standing emergency departments (ED). Current high sensitivity cardiac troponin I (hs-cTnI) research has been conducted almost exclusively in hospital-based ED (HBED) settings and the translation of these protocols into the free-standing EDs (FSED) has yet to be explored. This study compared the safety, efficacy, and ED throughput of applying a 0/1-hour, rapid-rule out protocol using hs-cTnI for exclusion of acute myocardial infarction (AMI) in HBEDs and FSEDs.

Methods: This was a pre-planned, secondary analysis of a stepped wedge cluster randomized trial of patients evaluated for possible AMI in 9 EDs in an integrated health system from July 2020 through March of 2021. Five of the EDs were HBEDs and four were FSEDs. The trial arms included a new 0/1-hour rapid protocol using hs-cTnI versus standard care, which used a 0/3-hour protocol without reporting hs-cTnI values below the 99th percentile. All adult ED patients were eligible if the treating clinician ordered an ECG and cardiac troponin. We excluded patients with STEMI, a hs-cTnI >18 ng/L in the ED, or a traumatic cause of symptoms. The primary outcome was safe ED discharge, defined as discharge with no death or AMI within 30-days. Analysis included a mixed effect model adjusting for ED site, time, sex, age, and race. We report adjusted odds ratios (aOR).

Results: The trial included 32,609 patients, of whom 26,957 were seen in HBEDs and 5,652 were seen in FSEDs. Safe discharge from HBED occurred 53% (5947/11,062) of the time in the standard care arm and 50.4% (8,005/15894) under the rapid rule-out protocol (aOR 1.04, 95% CI 0.94 – 1.15, p = 0.5). Safe discharge from a FSED occurred 86.2% (2106/2443) of the time in the standard care arm and increased to 95.1% (3052/3209) under the rapid protocol (aOr 1.48, 95% CI 1.03 – 2.13, p=.033). Initiation of a rapid rule-out protocol had no significant impact on overall ED length of stay (aOR 1.00, 95% CI 0.98-1.03, p = 0.8). There was a statistically significant reduction in FSED length of stay with application of a rapid rule-out protocol (3.43 hours (2.55, 4.58) vs. 3.97 hours (2.88, 4.77) using standard care, aOR 0.91, 95% CI 0.87- 0.95, p <0.001). The percentage of patients who rule-out with their initial hs-cTnI (<4 ng/L) at FSEDs (74%) was significantly larger when compared to hospital based EDs (54%), p<.001. Safe discharge data for all 9 ED sites is detailed in table 1.

Conclusion: Implementation of a hs-cTnI rapid 0/1-hour protocol to evaluate for AMI in FSEDs is feasible and had greater impact on safe ED discharge and length of stay compared to HBEDs.





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