Abstract 73
Use of an ED- Based Observation Unit Followed by Outpatient Stress Testing in Chest Pain Patients with Prior Coronary Artery Disease History Evaluation of Safety and Prognostic Utility
- Khalil, Yasser
- Pandey, Prasant
- Schwartz, Mel
- Abdul-Latif, Maida
- Matsumura, Martin E
Objective: Chest pain (CP) observation units are increasingly being used to efficiently triage patients with CP but without high-risk features such as positive biomarkers or pathologic ECG changes. However, little data is available regarding the use of a CP observation strategy in patients presenting with low-risk CP but with history of prior CAD events. The aim of the present study was to determine the outcomes of patients with CP and established CAD managed with observation followed by outpatient stress myocardial perfusion imaging (MPI) and to determine the prognostic value of this strategy.
Methods: Retrospective analysis of patients with CP managed with observation followed by outpatient stress MPI at a single community teaching hospital and followed up for 3 years for CV events (defined as death, MI, or need for urgent revascularization). Follow-up event rates were stratified by CAD history at the time of initial CP evaluation.
Results: A total of 375 patients were included: 111 with and 264 without a CAD history. All patients safely completed outpatient stress MPI within 72 hours of observation. Stress MPI effectively identified patients at risk for CV events regardless of CAD history, although patients with CAD history had a significantly higher rate of +MPI (35/111 (31.5%) vs. 28/264 (10.6%) for patients with +CAD vs. [[Unable to Display Character: –]]CAD history, respectively, p=<0.001).
Patients managed in an observation unit followed by a non-ischemic outpatient stress MPI and without a CAD history had, as expected, very low rates of short- and long-term CAD events (2/264 (0.8%), and 3/264 (1.1%) at 1 year and 3 years, respectively). In contrast, follow-up event rates of those patients with a non-ischemic test but a +CAD history were significantly higher (6/111 (5.4%) and 7/111 (6.3%) at 1 year and 3 years, respectively; p=0.044 and p=0.034 compared to CAD- patients).
To determine if stress MPI testing contributed independent prognostic information regarding CP patients with a history of CAD, we developed a multivariable logistic regression model using patient demographic and risk factor data as well as MPI results: in this model a positive MPI proved to be a strong independent predictor of long-term CV events (OR=4.75 for CV events at 3yr follow-up, 95% CI 1.35-16.70, p=0.015).
Conclusion: A strategy of observation followed by stress MPI can safely and effectively risk stratify CP patients with prior CAD for long-term CV events. However, our data suggests these patients are at increased risk of CV events even after a low-risk follow-up stress MPI study. Thus, patients presenting with CP and managed with a strategy of observation and a non-ischemic stress MPI still warrant close short and long term monitoring for recurrent events.