Excluding heart disease in the patient with chest pain.

Angina pectoris is chest discomfort associated with myocardial ischemia. When coronary blood flow is inadequate to meet myocardial tissue demand, lactate accumulates, resulting in diastolic and systolic left ventricular dysfunction. This leads to ST-segment abnormalities and eventually to angina pectoris. Angina, most commonly a pressure-type sensation in the midanterior chest precipitated by exercise, stress, or cold, typically lasts 1-5 minutes and is alleviated by rest or nitroglycerin. Diagnostic studies to assess myocardial ischemia include treadmill exercise testing, Holter monitoring, and coronary angiography. Treadmill exercise testing has a relatively low accuracy for diagnosing coronary artery disease. This can be improved by combining exercise with thallium-201 imaging, two-dimensional echocardiography, or positron emission tomography (PET). Thallium-201 scintigraphy and exercise echocardiography have reported sensitivities of 70-85% and specificities of 50-60% when applied to low-risk, asymptomatic populations. PET scanning has a high predictive accuracy (sensitivity 90%, specificity 90-95%) and is more useful as a screening test; it can also assess the functional significance of coronary artery stenoses and differentiate viable myocardium from infarcted tissue. Holter monitoring is too insensitive and nonspecific to be used as a screening test for coronary artery disease; it can, however, assess the total ischemic burden in patients with known coronary artery disease and correlate symptoms and ST-segment abnormalities during episodes of pain at rest. Coronary angiography has been the gold standard for diagnosing coronary artery stenoses. Quantitative angiography has improved the assessment of coronary artery narrowing but is still limited in evaluating coronary blood flow. Doppler flow studies provide useful information regarding coronary flow reserve. Myocardial ischemia as a cause of chest pain is determined by evaluating the clinical characteristics consistent with angina, correlating electrocardiographic abnormalities with perfusion defects or wall motion abnormalities, and determining the extent and functional significance of coronary artery stenoses by coronary angiography.