Getting it right the first time: Stress-only MPI in the ER

Journal of Nuclear Cardiology, Feb 2017

David G. Wolinsky MD, FACC, MASNC

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Getting it right the first time: Stress-only MPI in the ER

Received Feb Getting it right the first time: Stress-only MPI in the ER David G. Wolinsky 0 FACC 0 MASNC 0 1 0 Reprint requests: David G. Wolinsky, MD, FACC, MASNC , Heart and Vascular Institute, Cleveland Clinic Florida , Weston , USA 1 Heart and Vascular Institute, Cleveland Clinic Florida , Weston Determining the optimal pathway for evaluating patients presenting to the emergency with chest pain remains an ongoing challenge. The 2011 National Hospital Ambulatory Medical Care Survey reported over seven million emergency room (ER) visits for evaluation of chest pain.1 Only a very small percentage of these patients actually have acute coronary syndrome (ACS)2 or severe coronary artery disease. Presenting symptoms, electrocardiogram changes, and initial biomarkers can usually identify the small group of patients with acute myocardial infarction (MI) or acute coronary syndromes (ACS). These patients are rapidly admitted and undergo coronary angiography if indicated. The larger portion of remaining patients is left to undergo diagnostic and prognostic evaluation. These evaluations are usually done in an observation unit or a dedicated chest pain unit with the goal to identify all patients who are at increased short-term risk (48 to 72 hours) of a cardiac event and refer them promptly for care. Additionally, these patients may be at risk for further downstream testing, recurrent hospitalization, or late cardiovascular event. The workup of these patients should minimize these long-term risks. In the present issue of the Journal of Nuclear Cardiology, Amirian et al analyze the utility of both exercise treadmill testing (ETT) and stress-only myocardial perfusion imaging (MPI) in assessing short- and long-term events in a lowrisk population.3 Their analysis sheds new light on better options to manage these patients under the pressure of - new health care delivery models. Incorporating stressonly imaging would assign specific decision-making responsibility to the groups involved in the care of these patients— ER physicians, hospitalists, and cardiologists. By eliminating resting studies in the majority of patients, the evaluation can be completed more quickly and radiation exposure is reduced. Historically, patients inappropriately discharged from the emergency room with ACS have risk-adjusted mortalities twice that of similar patients who are hospitalized and treated.4 In fact, the overall risk in this population is low, but few patients presenting to ER with chest pain are discharged because of medical-legal concerns. As a consequence, these patients undergo exhaustive workups within a 24-48 hour span while hospitalized. From 1999-2000 to 2007-2008, utilization of advanced imaging for evaluation of chest pain increased by 376%.2 Multiple clinical pathways have been developed incorporating biomarkers, functional testing, and noninvasive angiography, all of which have high success rates.5 Although patients are no longer admitted, direct costs remain high ($2226-$3168) regardless of modality, driven to a great degree by length of stay in the hospital.3 In order to reduce the cost, the focus should be on three critical factors—reduce the number of people requiring chest pain pathways, reduce utilization of advanced imaging, or decrease length of hospital stay. There is a preponderance of data demonstrating that patients with chest pain who do not have a myocardial infarction are at low risk during short- and longer-term follow-up. Foy et al demonstrated in a national sample of over 650,000 patients that the incidence of MI was very low—only 0.11% at 7 days and 0.33% at 190 days of follow-up. The incidence of myocardial infarction was not impacted by decision to pursue noninvasive testing prior to discharge nor was the choice of testing a factor.6 This analysis was based on insurance claims data; therefore, there was a paucity of clinical data available such as pre-test likelihood of disease. Conclusions regarding the true value of testing such as MPI are therefore limited. Other authors have similar data demonstrating low risk in this population. The Cleveland Clinic has demonstrated that patients who ‘‘rule out’’ for an MI have a low thirty-day event rate. In patients with TIMI scores of 2 or less, stress MPI before discharge adds little prognostic value. In patients with higher TIMI scores, MPI was more likely to be ischemic and coronary angiography was more likely to be carried out; however, revascularization did not significantly improve prognosis. Patients with normal MPI had low cardiac event rates consistent with multiple studies demonstrating excellent prognosis associated with a normal MPI. A Singapore study incorporating SPECT MPI in the ER showed that patients with normal or probably normal (with return for resting images) stress-only MPI were associated with a low 30-day event rate. Incorporating MPI reduced the incidence of coronary angiography significantly and patients with positive MPI were more (...truncated)


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David G. Wolinsky MD, FACC, MASNC. Getting it right the first time: Stress-only MPI in the ER, Journal of Nuclear Cardiology, 2017, pp. 1-3, DOI: 10.1007/s12350-017-0825-z