Abstract 9776: Association of Early Stress Testing With Outcomes for Emergency Department Evaluation of Suspected Acute Coronary Syndrome

Abstract

Introduction: The emergency department (ED) evaluation of suspected acute coronary syndrome (ACS) is a common, challenging, and costly task with high clinical stakes. Professional society guidelines recommend early stress testing (within 72 hours of ED visit); however, there are no data to demonstrate improved outcomes with this approach. Hypotheses: 1.) Early stress testing improves outcomes, and 2.) The association between early stress testing and outcomes is modified by pre-test ACS risk. Methods: We analyzed prospectively collected registry data from 9 emergency departments on patients with suspected ACS. The primary outcome was 30-day major adverse cardiovascular events (MACE), including all-cause death, acute myocardial infarction, and urgent revascularization. The exposure variable of interest was early stress testing. We used the HEART score to determine pre-test ACS risk (low, intermediate, high). To mitigate potential confounding by indication, patients with and without early stress testing were matched in a 1:2 ratio using propensity score methods. The propensity score model included over 40 demographic, clinical, biomarker, and ECG covariates. Results: The analytic cohort included 946 patients with early stress testing and 1,892 without early stress testing. There were no significant baseline imbalances after propensity score matching (p>0.1 for all covariates). There was no association between early stress testing and 30-day MACE in the overall cohort (OR 1.3; 95%CI 0.8-2.1). There was evidence of effect modification by pre-test ACS risk strata (low: OR 1.2, 95%CI 0.2-5.3; intermediate: 2.1, 95%CI 1.1-4.1; high: 0.4, 95%CI 0.1-1.4). In intermediate risk patients, early stress testing is associated with increased rates of revascularization (OR 2.8, 95%CI 1.3-6.0), but not with death/ acute myocardial infarction (OR 0.9, 95%CI 0.1-4.6). Conclusions: Early stress testing does not reduce 30-day MACE in the ED evaluation of suspected ACS. In intermediate-risk patients, early stress testing may result in increased revascularization rates without reduction in the objective outcomes of death or myocardial infarction. These findings challenge existing care guidelines and require confirmation by randomized trials.