High-sensitivity troponin safely reduces admissions and duration of stay in the emergency department

Reference

Anand A, Lee KK, Chapman AR, et al, for the HiSTORIC Investigators. High-sensitivity cardiac troponin on presentation to rule out myocardial infarction: a stepped-wedge cluster randomized controlled trial. Circulation 2021;143(23):2214-2224.

Synopsis

New high-sensitivity troponin tests are able to detect very low levels of troponin, and protocols have been proposed with the potential to rule-out acute coronary syndrome in patients more quickly, therefore being able to discharge them more quickly. This is the largest study to date of one of these early rule-out protocols. These researchers identified 7 Scottish hospitals and included 31,492 patients presenting with clinically suspected acute coronary syndrome and an initially normal high-sensitivity troponin I (hsTrop) test, defined as less than the upper limit of the 99th percentile of the reference limit. Patients were excluded if they presented following out-of-hospital cardiac arrest, with ST-elevation myocardial infarction, or were not Scottish. Patients were enrolled consecutively using a screening tool built into the electronic health record to reduce the impact of selection bias by physicians. The study began with a validation phase in which all hospitals used their standard rule-out protocol, followed by a cluster randomization phase in which they rolled out the early rule-out protocol incrementally at different hospitals. This allows the comparison between hospitals randomized to usual care versus early rule-out protocol. The study concluded with an implementation phase in which all hospitals used the new protocol. The protocol itself placed patients in a low-risk group (outpatient care) if the hsTrop level was less than 5 ng/L and in a high-risk group if the hsTrop level was greater than a sex-specific 99th percentile. Patients presenting within 2 hours of the onset of symptoms or who had an initial hsTrop level between 5 ng/L and the 99th percentile were retested 3 hours later. If the second hsTrop result was less than 3 ng/L the patient was classified as low risk, and if the second hsTrop was 3 ng/mL or higher the patient was classified as high risk and admitted for a 6- to 12-hour test. The protocol was successful at significantly reducing the length of stay in the emergency department (from 10.4 hours to 6.8 hours) and at significantly increasing the percentage of patients who could be discharged home (from 50% to 71%). The likelihood of myocardial infarction or cardiac death within 30 days was 0.4% before and 0.3% after implementation of the protocol. At 1 year, the likelihood of myocardial infarction or cardiac death was 2.7% before and 1.8% after implementation of the protocol. There were also no differences between groups in readmission or all-cause mortality.