Guidelines for the Management of Patients with Chronic Stable Angina: Diagnosis and Risk Stratification

This article is the first of two papers about the care of patients with chronic stable angina. The second paper, which deals with the treatment of patients with chronic stable angina, will be published in a future issue. Both articles have been adapted from materials created by the Committee on Guidelines for Chronic Stable Angina sponsored by the American College of Cardiology (ACC), the American Heart Association (AHA), and the American College of PhysiciansAmerican Society of Internal Medicine (ACPASIM) (1-3). The adaptations in these articles are intended to make the information more useful for clinicians who do not specialize in the care of patients with heart disease. The committee created the original materials after reviewing published reports identified in part through MEDLINE searches of the English literature from 1975 through 1998. The weight of the evidence was ranked high and given a grade of A if the data were derived from multiple randomized clinical trials involving many patients. The weight of the evidence was ranked intermediate and given a grade of B if the data were derived from a few randomized trials involving small numbers of patients, nonrandomized studies, or observational registries. A lower rank and a grade of C were given when an expert consensus was the primary basis for the recommendation. We used the following classification system for final recommendations. Class I referred to conditions for which there is evidence or general agreement that a given procedure or treatment is useful and effective; class II referred to conditions for which there is conflicting evidence or a divergence of opinion about the usefulness or efficacy of a procedure or treatment; class IIa referred to conditions for which the weight of evidence or opinion is in favor of usefulness or efficacy of a procedure or treatment; class IIb referred to conditions for which usefulness or efficacy of a procedure or treatment is less well established by evidence or opinion; and class III referred to conditions for which there is evidence or general agreement that the procedure or treatment is not useful or effective and in some cases may be harmful. For the sake of brevity, we have combined some original recommendations and omitted others, especially those that affect fewer patients, are based on weaker evidence, or recommend that interventions not be done. Scope of the Guidelines These recommendations are intended for adult patients with stable chest pain syndromes and known or suspected ischemic heart disease and patients who have ischemic equivalents, such as dyspnea or arm pain with exertion. Also, some recommendations about follow-up apply to patients who become asymptomatic during therapy. These guidelines are not intended for patients with acute ischemic syndromes, patients with chest pain after cardiac transplantation, patients with chest pain within 6 months of revascularization by percutaneous techniques or coronary artery bypass grafting (CABG), patients with coronary artery disease (CAD) detected without symptoms, patients with nonanginal chest pain, or pediatric patients. The Initial Evaluation The initial evaluation of patients presenting with chest pain includes a detailed history, a focused physical examination, and performance of a few tests and procedures that are useful for estimating the probability of significant CAD (Figure 1). Significant CAD is defined as an obstruction of at least one major epicardial artery that occupies at least 70% of the artery's cross-sectional diameter or an obstruction of the left main coronary artery that occupies at least 50% of its diameter. Figure 1. Diagnosis of chest pain. Comorbid conditions and patient preferences. The history should elicit specific information about chest pain because accurate characterization helps determine whether CAD is the cause of angina. Angina usually occurs in patients with CAD, but it can occur in patients with unobstructed coronary arteries who have myocardial ischemia related to an arterial spasm or endothelial dysfunction. It also can occur in patients with other cardiovascular problems, such as aortic stenosis, hypertrophic cardiomyopathy, or uncontrolled hypertension. Symptoms that mimic angina can also occur in patients with noncardiac conditions involving the chest wall, esophagus, or lung. The following characteristics of chest pain should be determined: quality, location, duration, and the presence of factors that provoke and relieve the pain. Angina is characterized by a substernal pain or discomfort, although it may radiate to the neck, jaw, epigastrium, or arms. Patients often describe the quality of angina with characteristic terms, such as squeezing, grip-like, pressure-like, suffocating, or heavy. Angina usually lasts for minutes. Exertion or emotional stress provokes it, and rest or nitroglycerin relieves it, typically within 30 seconds to several minutes. After the history is obtained, the clinician should classify the chest pain. Typical angina has the following characteristics: 1) substernal chest discomfort with a characteristic quality and duration that is 2) provoked by exertion or emotional stress and 3) relieved by rest or nitroglycerin. Atypical angina has two of the three characteristics of typical angina, while noncardiac chest pain has one or none of the characteristics of typical angina. The term noncardiac chest pain means that the probability of CAD is low. The term nonspecific chest pain more accurately describes this situation, but tradition prevents its use. In patients with angina, the severity of pain should be graded according to the Canadian Cardiovascular Society (CCS) classification system (Table 1) (6). Although grading chest pain is less useful for establishing a diagnosis or estimating risk, it is essential for evaluating the effects of therapy. Table 1. Grading of Angina by the Canadian Cardiovascular Society Classification System In patients with angina, the stability of pain should be assessed. Patients have unstable angina if the pain started recently; is more easily provoked; or occurs with increased frequency, severity, or duration (7). Some patients with unstable angina have a measurable risk for short-term death (8). Those characterized as high risk have a 1.7% probability of dying within 30 days, and those characterized as moderate risk have a 1.2% probability. These patients have pain at rest, nocturnal pain, signs or symptoms of heart failure, or new or ischemic changes on resting electrocardiography (ECG). They should be evaluated in the inpatient setting. However, patients with unstable angina whose pain has been present for at least 2 weeks and who lack any of angina's more worrisome clinical features, including ECG changes, can be evaluated in an outpatient setting because their probability of death or myocardial infarction within 30 days is indistinguishable from zero. The initial history should also include information about the risk factors for CAD, such as smoking, hyperlipidemia, diabetes, hypertension, and a family history of premature CAD. Findings on physical examination are often normal in patients with stable angina (9). During an episode of pain, however, there uncommonly may be an S4 or S3 gallop, a mitral regurgitant murmur, a paradoxically split S2, bibasilar rales, or a chest wall heave. Each of these findings makes CAD more likely, especially if the finding disappears when the pain goes away (10). Evidence of noncoronary atherosclerotic disease, such as a carotid bruit, diminished pedal pulses, or an abdominal aneurysm, increases the likelihood of CAD. Elevated blood pressure, xanthomas, and retinal exudates identify CAD risk factors. Table 2 lists recommendations for the tests and procedures that we believe should be used in the initial evaluation of patients with suspected chronic stable angina. Resting, 12-lead ECG should be performed, although the results will be normal in 50% of patients with chronic stable angina (11). Therefore, results on normal resting ECG do not exclude CAD. Evidence on ECG of left ventricular hypertrophy or ST T-wave changes consistent with myocardial ischemia favor the diagnosis of angina (12). The presence of arrhythmias, such as atrial fibrillation or ventricular tachyarrhythmias, also increases the probability of CAD, but other types of cardiac disease frequently cause these arrhythmias. Q waves suggesting a previous myocardial infarction make CAD very likely, although an isolated Q wave in lead III or a QS pattern in lead V1 and V2 is often nonspecific. Atrioventricular block may suggest multivessel CAD but is also nonspecific. Table 2. Recommendations for Initial Laboratory Tests, Electrocardiography, and Chest Radiography for the Diagnosis of Chronic Stable Angina Results on ECG performed during chest pain are abnormal in approximately 50% of patients with angina who have normal results on resting ECG. Sinus tachycardia occurs commonly; bradyarrhythmias are less common. ST T-wave depression or inversion on resting ECG or pseudo-normalization of these abnormalities during pain is another indicator of CAD (13). Tachyarrhythmias, atrioventricular blocks, left anterior fascicular block, or bundle-branch block occurring with chest pain also increases the probability of coronary heart disease. ST-segment elevation or depression also increases the probability of CAD, and it increases the risk for myocardial infarction or death because there is ischemia at a low workload. Results of chest radiography are often normal in patients with stable angina, and its usefulness as a routine test is not well established. Ultra-fast electron-beam computed tomography is now frequently used to detect coronary artery calcification, which is a sensitive indicator of coronary stenosis (14). However, the specificity of electron-beam computed tomography is in the range of 41% to 76%, which means that many results are false positive. Moreover, the reliab