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SymPOSIUm ON CArdIOVASCULAr dISEASES EVALUATION OF CHEST PAIN

Emergency Department and Office-Based Evaluation of Patients With Chest Pain
Michael C. Kontos, MD; Deborah B. Diercks, MD; and J. Douglas Kirk, MD
On completion of this article, you should be able to (1) recognize common causes of troponin elevations not related to acute coronary syndrome, (2) identify characteristics associatedwith high and low risk of ischemic complications in patients with possible myocardial infarction, and (3) describe the advantages and disadvantages of imaging tests (rest myocardial perfusion imaging, computed tomographic coronary angiography, and cardiac magnetic resonance imaging) for the early diagnosis and risk stratification of low-risk patients with chest pain.
The management of patientswith chest pain is a common and challenging clinical problem. Although most of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent management of a serious problem such as acute coronary syndrome (ACS) and those with more benign entities who do not require admission. Although clinical judgment continues to be paramount in meetingthis challenge, new diagnostic modalities have been developed to assist in risk stratification. These include markers of cardiac injury, risk scores, early stress testing, and noninvasive imaging of the heart. The basic clinical tools of history, physical examination, and electrocardiography are currently widely acknowledged to allow early identification of low-risk patients who have less than 5%probability of ACS. These patients are usually initially managed in the emergency department and transitioned to further outpatient evaluation or chest pain units. Multiple imaging strategies have been investigated to accelerate diagnosis and to provide further risk stratification of patients with no initial evidence of ACS. These include rest myocardial perfusion imaging, rest echocardiography,computed tomographic coronary angiography, and cardiac magnetic resonance imaging. All have very high negative predictive values for excluding ACS and have been successful in reducing unnecessary admissions for patients at low to intermediate risk of ACS. As patients with acute chest pain transition from the evaluation in the emergency department to other outpatient settings, it is important that allclinicians involved in the care of these patients understand the tools used for assessment and risk stratification. Mayo Clin Proc. 2010;85(3):284-299
ACC = American College of Cardiology; ACS = acute coronary syndrome; ADP = accelerated diagnostic protocol; AHA = American Heart Association; CAD = coronary artery disease; CHF = chronic heart failure; CMRI = cardiac magnetic resonance imaging;CPU = chest pain unit; CT = computed tomography; CTCA = computed tomographic coronary angiography; ECG = electrocardiography; ED = emergency department; ETT = exercise treadmill testing; MI = myocardial infarction; MPI = myocardial perfusion imaging; TIMI = Thrombolysis in Myocardial Infarction

of patients with acute coronary syndrome (ACS) has been associated with a short-term mortality of 2%,as well as major risk of liability.2 Identifying patients with chest pain who are at risk of adverse events is important not only to ED physicians but also to all physicians who evaluate such patients. In one insurance industry–based study, the physician group most likely to be sued for missed myocardial infarction (MI) was family practitioners (32%), followed by general internists (22%) and EDphysicians (15%).3 Myocardial infarction can be misdiagnosed for a number of reasons. Misinterpretation of findings on electrocardiography (ECG) occurs in 23% to 40% of misdiagnosed MIs.4-7 Younger age,4,6,7 physician inexperience,8 and atypical presentations4,6,7 are more common in these patients. An insurance claims–based study found that in 28% of cases no diagnostic study, not even ECG, was...