Outpatient Myocardial Perfusion Imaging Scan for a Low-Risk Chest Pain Cohort From the Emergency Department: A Retrospective Analysis

Abstract

Chest pain accounts for a significant attendances at emergency departments (ED). We examined the utility of early stress myocardial perfusion imaging (SMPI) for stratification of low-risk patients post-ED discharge. A retrospective audit was conducted of patients with chest pain and normal troponin-T (<30Ng/L), who were discharged with outpatient SMPI (median = 3 days post-ED discharge) between January 2018 to January 2020. 880 patients were included and followed up for 12 months. Outcomes measured were: 1) Cardiac events (CE) within 1 year of visit or 2) Significant coronary artery disease (CAD) - coronary angiography demonstrating ≥70% stenosis of epicardial vessels or coronary revascularization procedures performed. In the SMPI negative group, 2 of 802 patients (0.25%) had significant CEs and 11 patients (1.37%) were diagnosed with significant CAD. Of the 78 SMPI positive patients, 1 (1.28%) had a significant CE, while 24 had significant CAD. SMPI had a sensitivity of 65.8%, specificity of 93.7%, positive predictive value of 32.1% and a negative predictive value of 98.4% for predicting adverse CE. Early SMPI post-ED discharge demonstrated high negative predictive value in predicting CEs or significant CAD diagnosis at up to 1 year, suggesting that low-risk patients discharge from ED with early outpatient SMPI is a safe management option.