Noninvasive Evaluation

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In women with acute coronary syndromes, in whom symptoms stabilize or in whom the diagnosis of coronary artery disease is uncertain, noninvasive testing is usually performed. In general, noninvasive evaluation of coronary artery disease in women is less accurate than in men, owing primarily to the lower prevalence of disease in women. The most widely employed and best studied diagnostic modality is the exercise treadmill test (28), and it is predictably problematic in women due to a lower prevalence of coronary artery disease in premenopausal women, a higher prevalence of mitral valve prolapse and hyperventilation-induced ST-segment depression, a higher incidence of hypertensive heart disease, and limited ability to exercise to an adequate heart rate response. In contrast to what is observed in men, resting ST-T wave abnormalities on an electrocardiogram in women do not predict exercise stress test outcome independent of other clinical risk factors of coronary disease (Fig. 4) (29).

Myocardial perfusion imaging with thallium has improved the diagnostic accuracy of noninvasive stress testing and increased sensitivity to 84-90% and specificity to 75-87% in women, but the diagnostic accuracy may be reduced in patients who are obese or have large breasts. Accuracy may be improved further with technetium-99m (Tc-99m) ses-tamibi, which has a similar sensitivity (85-90%) to thallium, while the specificity of Tc-

Fig. 4. Results of exercise electrocardiogram utilizing coronary angiography and myocardial perfusion imaging as a reference standard in women. In 3213 women evaluated by exercise ECG stress testing, sensitivity remains low whether myocardial perfusion imaging or coronary angiography is used as the reference standard. ECG, electrocardiogram; CAD, coronary artery disease; NL image, normal myocardial perfusion image; AbNL image, abnormal myocardial perfusion image (31).

Fig. 4. Results of exercise electrocardiogram utilizing coronary angiography and myocardial perfusion imaging as a reference standard in women. In 3213 women evaluated by exercise ECG stress testing, sensitivity remains low whether myocardial perfusion imaging or coronary angiography is used as the reference standard. ECG, electrocardiogram; CAD, coronary artery disease; NL image, normal myocardial perfusion image; AbNL image, abnormal myocardial perfusion image (31).

99m is higher (84-94%) than that of thallium (71%) (30). A study of 8671 patients (3213 women, 5458 men) who underwent exercise treadmill stress testing with myocardial perfusion imaging confirmed that more women than men had a false-positive test, while the false-negative rate was significantly lower in women than men. Compared with men, women had lower test sensitivity and positive predictive value, but higher test specificity, negative predictive value, and accuracy. In patients with a false-negative exercise electrocardiogram, "high-risk" scans were less prevalent in women (31).

Diagnostic noninvasive stress testing has an improved accuracy when multiple risk parameters, including ST deviation, chest pain, and exercise time, are included in the test interpretation. For women, a low-risk Duke treadmill score is associated with a 97% 5-yr survival, with 80% of these patients having no evidence of epicardial coronary artery disease at angiography. Multivessel disease is confirmed in 70% of women with a high-risk treadmill score; however, owing to early intervention is associated with a 90% 5-yr survival rate. For tests performed with nuclear imaging, 3-yr cardiac survival ranged from 99 to 85% for 0 to 3 vascular territories with perfusion abnormalities, respectively (32).

Exercise echocardiography appears promising in women and is more specific than exercise electrocardiography (33). Stress echocardiography is reported to have a high sensitivity (86%) and specificity (86%), but often examiners stop the test before detecting less severe areas of damage (30). Similarly, the presence of a new echocardiographic wall motion abnormality following dobutamine administration has been found to be a highly specific manifestation of ischemia, even in women (34). The sensitivity of dobut-amine stress echocardiography is as good as what is reported for exercise treadmill stress testing, while the specificity and accuracy are increased significantly (35). The prognostic significance of stress echocardiography was evaluated in 135 women with a high probability of coronary artery disease. In women with a high pretest likelihood of coronary heart disease, a negative stress echocardiography exam identified a subgroup of women who were at low risk of cardiac events and, therefore, were not recommended for further invasive investigation, while a positive stress echocardiography exam identified a subgroup of women at increased risk for subsequent cardiac events (36). Furthermore, three-dimensional imaging with magnetic resonance imaging, positron emission tomography, and electronic beam computed tomography are under active investigation in women (37), yet recent studies demonstrate that presently, the diagnostic accuracy of electron beam computed tomography reveals a sensitivity of 88% and a specificity of only 49% (32).

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Insider Tips How To Buy a Treadmill Online

Insider Tips How To Buy a Treadmill Online

When it comes to pieces of aerobic equipment to buy, treadmills continue to be the most popular and the most valuable. And why not? They are simple to use and naturally intuitive. They burn calories effectively and offer a wide range of exercise options, whether walking, climbing, or jogging.

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