Coronary heart disease is the leading cause of death for both men and women in the United States. One of the most characteristic and troubling features of coronary disease is the sudden and unexpected onset of symptoms in clinically stable patients and sometimes in even previously healthy individuals.

The development of symptoms is associated with an increased risk of sudden death, acute myocardial infarction, and other life-threatening complications. The development of symptoms suggestive of coronary disease therefore mandates prompt and accurate diagnosis and treatment.

The cardinal symptom of coronary artery disease (CAD) is angina, which classically presents as a squeezing or strangulating deep chest discomfort that may radiate to the arm or jaw. Angina that is brought on by exercise stress and is relieved promptly after cessation of exertion is termed "typical angina." Stable angina is a pattern of symptoms that has been unchanged for 6 or more weeks. Unstable angina is a pattern of symptoms that is new in onset, changing in severity or frequency, occurring at rest, or lasting longer than 20 minutes.

The evaluation of suspected coronary disease is complicated by the fact that chest discomfort has many causes, and bona fide coronary disease may present in an atypical fashion. Thus, a population of patients with symptoms suggestive of coronary disease includes some patients with acute, life-threatening medical problems, some patients with other medical problems mimicking CAD, and even some "worried well" in need only of reassurance.

The evaluation and treatment of this highly heterogeneous population is the difficult task for clinicians in emergency departments (ED) and in office practice. The key goal of these clinicians must be to identify the patient's short-term risk. The high-risk patient may develop life-threatening complications and require hospitalization and immediate therapy. The low-risk patient may need further evaluation, but in a less urgent and less costly setting. Because identification of patient risk is central to all further patient management in unstable angina, this evidence report focuses on clinical and laboratory markers of patient risk, such as results of diagnostic tests (troponin values, stress testing, echocardiography, and nuclear scintigraphy).

Because chest pain units attempt to "risk stratify" (group patients according to their degree of risk) based on readily available data, an assessment of the efficacy of chest pain units is significant to this report. Our in-depth review focused on information that would be readily available to all providers caring for patients with suspected unstable angina. Information in this report applies to adult men and women.