Patients with long-standing diabetes mellitus and end-organ damage, severe peripheral vascular disease (eg, abdominal aortic aneurysm), or previous chest (mantle) radia- tion therapy may have severe CAD particularly when ischemic symptoms are present.28 31 Patients with a combination of typical angina, transient heart failure, pulmonary edema, or exertional or unheralded syncope may have severe CAD. Noninvasive test- ing, such as rest echocardiography revealing multiple regional wall motion abnormalities or electrocardiography with diffuse ischemic changes in multiple territories, may reflect CAD with a large ischemic burden and justify diagnostic angiography with- out prior stress testing. The writing group has found that creat- ing a recommendation governing the use of angiography for such high-risk patients remains controversial. The writing group recognizes, however, that many clinicians believe that prompt diagnostic angiography and revascularization, instead of initial stress testing, are appropriate for such high-risk patients who are likely to have underlying severe CAD for which revascularization would confer a survival advantage. Coronary angiography is not routinely performed after ade- quate stress testing has been negative for ischemia. Still, stress tests can be falsely negative and, in a patient with high pretest likelihood of CAD, Bayes theorem predicts that a high post- test likelihood of CAD will remain as well. Therefore, when clinicians strongly suspect that a stress test is falsely negative (eg, a patient with typical angina who also has multiple risk factors for CAD), diagnostic angiography may be warranted. When stress testing yields an ambiguous or indeterminate result in a patient with a high likelihood of CAD, coronary angiography may be preferable to another noninvasive test and may be the most effective means to reach a diagnosis. 