Results of a Cluster Randomized Trial Implementing a Rapid High-Sensitivity Troponin I Protocol

Objectives: To compare 30‐day major adverse cardiac events (MACE) and resource utilization between a traditional protocol and a new 0/1‐hour, high sensitivity cardiac troponin I (hs‐cTnI) rapid protocol for exclusion of acute myocardial infarction (AMI). Background: Data on the impact of new, rapid rule‐out protocols using hs‐cTnI in the US healthcare system are lacking. While validated in European cohorts, the impact of such protocols on US emergency care is unclear. Methods: We performed a stepped wedge, cluster randomized trial of patients evaluated for possible AMI in 9 EDs (urban and suburban) in an integrated health system from 7/2020‐3/2021. The trial arms included a new 0/1‐hour rapid protocol and standard care. Randomization occurred by ED site. We included all adult ED patients for whom 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. In the rapid protocol, MI was excluded, and ED discharge advised if hs‐cTnI <4 ng/L at time 0, or =4 ng/L at time 0 with 1 hour <8 ng/L. In standard care, troponin was measured at 0 and 3 hours, clinicians were blinded to values =18 ng/L, and =18 ng/L was used to exclude AMI and guide ED discharge. Outcomes included MACE at 30‐days (death or AMI), ED discharge rates, length of stay, and cardiac testing. 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 13,505 were in the standard care and 19,104 in the rapid protocol arms. At 30‐days, MACE occurred in 32 (0.25%) patients in the rapid protocol vs. 18 (0.19%) patients in the standard care arm (aOR 0.82, 95% CI 0.30 – 2.26). The ED discharge rates were lower under the rapid protocol (58.0%) vs. standard care (59.8%). The proportion of patients receiving cardiac stress testing (4.0% vs. 3.4%) and coronary catheterization (1.3% vs. 1.0%) fell under the rapid protocol. In adjusted analysis, there was no statistically significant difference in rates of ED discharge (aOR 1.03, 95% CI 0.94‐1.13) with the rapid protocol. There was a reduction in the odds of observation placement (aOR 0.90, 95% CI 0.82‐0.99) as well as a reduced overall length of stay for patients discharged from the ED or observation unit (aOR 0.95, 95% CI 0.91–0.99) under the rapid protocol. The difference in the odds of coronary catheterization was not statistically significant (aOR 0.83, 95% CI 0.36 – 1.86), but there was reduced odds of cardiac stress testing under the rapid protocol (aOR 0.71, 95% CI 0.53 – 0.95). Conclusion: Implementation of a rapid 0/1‐hour protocol to evaluate for AMI in the ED was safe and associated with modest reductions in healthcare resource utilization.