Acute chest pain evaluation: Is there too much stress on the system?

Abstract

See related article, pp. 1002-1012Those who have followed the literature regarding the evaluation of patients with acute chest pain over the last two decades are aware of these commonly repeated facts: Over 100 million patients present to the emergency department (ED) each year, of whom approximately 6%-8% are related to chest pain or other symptoms suggestive of myocardial infarction (MI). 1The missed acute coronary syndrome (ACS) rate is estimated at 2%-4% 2,3 (although recent studies are lacking), with substantially worse outcomes than those who are recognized.2 The cost related to chest pain evaluation is significant, estimated to be in the tens of billions of dollars, 4 which has likely increased since these estimates. This high cost is in part related to the low threshold for evaluation, owing to a conservative practice to avoid litigation related to missed MI, 5 one of the largest sources of ED malpractice awards. 6In response, a variety of strategies have been developed for rapid assessment to exclude MI, 7-10 followed by provocative testing to exclude ischemia, and more recently imaging to identify significant coronary artery disease (CAD).11,12 The goal of this ''secondary'' evaluation is to identify the few remaining high risk patients among the many low risk patients (at times analogous to finding a needle in a haystack). Multiple studies have demonstrated that using a standardized protocol that included serial biomarkers and subsequent testing could reduce overall costs with similar or improved outcomes compared to standard care for evaluating low risk chest pain patients [13][14][15] As a result, this approach has become the standard of care and is often carried out in the ED or Observation Unit.Secondary testing can take numerous forms. Although exercise stress testing alone has been shown to be effective, 8,16 the use of imaging, either myocardial perfusion imaging (MPI), 17 echocardiography, 18,19 or more advanced protocols using cardiac MRI 20 is frequently used as an alternative. Recently, evaluation with cardiac computed tomographic angiography (CTA) has emerged, in which coronary anatomy can be defined with high accuracy in a rapid fashion. 11,12This frequent use of imaging may in part be related to the proportion of patients who cannot exercise, have uninterpretable ECGs, or possibly the perception that the increased sensitivity added by imaging is important. 21All of these tests have the goal of excluding myocardial ischemia as a potential cause for the patient's symptoms, although the optimal test for evaluation remains unclear.Only a few randomized studies have been performed that compare different types of testing, and most have included relatively small numbers of patients, 12,18,19 with a few notable exceptions. 11,13 In this regard, the current study by Lim et al 22 is timely. The authors compare stress MPI to a standard evaluation process of ED patients presenting with possible myocardial ischemia. Patients underwent clinical assessment with subsequent exclusion of MI using both CKM...