Examination of troponin testing following implementation of the IMProved Assessment of Chest pain Trial (IMPACT) Protocol, an accelerated chest pain assessment strategy

Field: Medicine (Health Sciences)

BackgroundThe 2006 National Heart Foundation and Cardiac Society of Australia and New Zealand (NHFA/CSANZ) guidelines on the management of acute coronary syndrome (ACS) recommended stratifying patients with possible ACS into low-, intermediate- and high-risk cohorts. Low- and intermediate-risk patients were assessed with serial cardiac biomarkers and electrocardiography (ECG). If negative results were obtained, further objective testing for intermediate-risk patients was required while low-risk patients may be discharged. High-risk patients required admission, which often included early invasive interventions as part of management. Biomarker testing was recommended on presentation (zero hours) and then six to eight hours later when using sensitive (contemporary) troponin assays. Such practice was resource-intensive and time-consuming. Local ProblemThe Emergency Department (ED) at the Royal Brisbane and Women’s Hospital (RBWH), a large tertiary hospital in Australia, had recently implemented the IMProved Assessment of Chest pain Trial (IMPACT) protocol, an accelerated diagnostic protocol for assessing patients presenting to the ED with possible ACS. The IMPACT protocol was evaluated in the IMPACT study, an intervention trial between February 2011 and March 2014. The IMPACT protocol was then immediately translated into clinical practice as the standard protocol for use at all hours (during and out of working hours) at the RBWH from April 2014. The IMPACT protocol utilised zero- and two-hour troponin testing for low- and intermediate-risk patients. Troponin ordering for high-risk patients was unchanged at zero and six hours.This study sought to investigate whether the troponin ordering practices detailed by the IMPACT protocol were translated into clinical care in the post-implementation period. MethodologyThis was an observational study of adult patients presenting to the RBWH ED with chest pain between April 2014 and June 2016. The study included patients who had at least two troponins ordered, with the first being within four hours of presentation to the ED. Troponin data was obtained from the hospital pathology database. The proportion of patients in the overall cohort who had zero- and two-hour troponin testing was calculated along with median ED and short stay unit (SSU) length of stay, and proportion of patients admitted into hospital. ResultsThe proportion of patients that had zero- and two-hour troponin testing, which was considered the accelerated cohort, increased rapidly over the first six months. The overall proportion of patients who underwent accelerated assessment during this study period was 49.2%. It reached a predicted 53.7% of the overall cohort by the end of this study, a figure less than that of the 75.6% reported by the IMPACT study.The overall cohort was older than that recruited into the IMPACT study. After adjustment for age and sex (to the average age of the IMPACT cohort), the predicted proportion of accelerated patients was 66.7% for males and 72.7% for females by the end of the study period. The median ED and SSU length of stay was 7.2 hours for accelerated patients. The median hospital length of stay was 9.8 hours for accelerated patients and 23.9 hours for all patients. The proportion of patients admitted into hospital was 23.3% for accelerated patients, and 53.5% for the overall cohort. ConclusionsThis study demonstrated that the IMPACT protocol was rapidly being adopted and utilised in a clinical setting following conclusion of the original trial. The initial increase in proportion of patients being accelerated, followed by a plateau before the end of the study period, indicated acceptability, adoption and sustainability of the IMPACT protocol. The secondary outcomes of ED and SSU length of stay and admission rates remained unchanged for accelerated patients across the post-implementation period, demonstrating sustainability and consistency in the use of the IMPACT protocol at the RBWH ED.