These risk factors include a family history of CAD at relatively young ages, an abnormal serum cholesterol profile, cigarette smoking, elevated blood pressure (hypertension), and diabetes mellitus.
Initial screening for CAD commonly involves stressing the heart under controlled conditions. These stress tests are able to detect the presence of flow-limiting blockages in the coronary arteries, generally in the range of at least a 50% reduction in the diameter of at least one of the three major coronary arteries. There are two basic types of stress tests; those that involve exercising the patient to stress the heart (exercise cardiac stress tests), and those that involve chemically stimulating the heart directly to mimic the stress of exercise (physiologic stress testing). Physiologic stress testing can be used for patients who are unable to exercise.
A new (and controversial) noninvasive test for the detection of CAD is electron beam computerized tomography, also known as Ultrafast CT. Unlike the above mentioned stress tests that measure the heart's physiology, Ultrafast CT is designed to measure calcium deposits in the coronary arteries. In patients with CAD, the plaques which make up the blockages contain significant amounts of calcium, which can be detected with Ultrafast CT. This test will identify calcium in blockages as mild as 10-20%, which would not be detected by standard physiological testing. When such mild blockages are detected, however, the only recommended therapy is risk factor modification (cholesterol lowering and cessation of smoking if applicable), and adjunctive use of aspirin and certain vitamins -- such therapy would be advised in all patients with risk factors for CAD, regardless of the results of any noninvasive tests.
A potential limitation of Ultrafast CT is that a "calcium score" for each vessel is reported, and this is not entirely lesion specific - several minor blockages in a given vessel may result in a similar vessel score as one severe blockage in a vessel. The major value of Ultrafast CT appears to be for screening of young patients with one or more risk factors for the development of CAD. Ultrafast CT scanning is of limited value in older patients, in whom some degree of calcification is commonly found. Additionally, for the reasons described above, the detection of some calcification may not be reflective of significant CAD.
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