"Recovery only" ST-segment depression and the predictive accuracy of the exercise test

Article Abstract:

An important method of diagnosing coronary artery disease is exercise testing; patients typically walk on a moving treadmill while their vital signs are monitored. Electrocardiography (ECG), which measures and records the electrical activity of the heart, is used during exercise testing. When exercise ECG was first utilized, it was only possible to take accurate readings after the exercise session, during recovery. Later, it became possible to take reliable readings during exercise, so emphasis shifted away from the recovery period. Currently, most procedures for interpreting ECG results look at abnormalities in the ST-segment (one phase of heart electrical activity) that occur during exercise but not those that happen in recovery; some physicians believe that ST-segment changes, such as ST-segment depression, that only occur in recovery represent a false-positive test result. This issue is controversial, however. The meaning of ST-segment depression in recovery only was evaluated in a group of 328 male patients. Of these patients, 168 had abnormal ST-segment responses and a subset of 26 men had these abnormalities only in the recovery period. The condition of the coronary arteries was then evaluated by angiography, an imaging technique. The value of ST-segment changes during recovery only for predicting coronary artery disease as shown by angiography was as good (84 percent) as the predictive value of ST-segment changes during exercise (87 percent); these predictive values did not differ significantly. Thus the ST-segment changes during recovery only a false-positive diagnosis of coronary artery disease, but instead they improved the diagnostic sensitivity of exercise ECG testing. (Consumer Summary produced by Reliance Medical Information, Inc.)

Heart, Electric properties

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Comparison of silent and symptomatic ischemia during exercise testing in men

Article Abstract:

Coronary artery disease may cause myocardial ischemia (deficient blood flow to the heart muscle), which is usually experienced as angina (chest pain) and is often detected by changes in a patient's electrocardiogram (ECG; a recording of the heart's electrical activity). Occasionally, these electrocardiographic changes are seen in patients with ischemia who are not having angina. This phenomenon is known as silent ischemia. Over 400 men undergoing exercise stress testing to screen for the presence of coronary artery disease were studied to see if they had symptoms of ischemia, ECG abnormalities, or both. If the patient's stress test resulted in significant symptoms, a markedly abnormal ECG, or both, he generally went on to have coronary angiography (a radiographic examination of the coronary arteries that uses a contrast dye). This study shows that patients who had abnormal ECGs during exercise, regardless of the presence or absence of symptoms, were most likely to have significant coronary artery disease, as seen with angiography. Patients with angina and no ECG abnormalities had the least coronary artery disease, those with ECG abnormalities alone (silent ischemia) had an intermediate degree of coronary artery disease, and those who had both angina and ECG abnormalities had the worst coronary artery disease at angiography. A review of other studies indicated that while silent ischemia does increase a person's risk of having coronary artery disease, it is not a worse prognostic sign than angina accompanied by an abnormal ECG. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Physiological aspects, Prognosis, Angiography, Exercise tests, Angina pectoris, Silent myocardial ischemia

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The electrocardiographic exercise test in a population with reduced workup bias: diagnostic performance, computerized interpretation, and multivariable prediction

Article Abstract:

The electrocardiographic exercise test can still be useful if other measurements besides ST-segment measurements are made. Elevation or depression of the ST segment on a ECG during exercise can reveal reduced blood flow to the heart. Researchers measured heart rate, blood pressure and other hemodynamic variables as well as ST-segment changes in 814 patients who had chest pain. The patients then had coronary angiography, a technique to detect coronary artery disease. The addition of other measurements reduced the ability of the test to detect coronary artery disease but increased its ability to rule out the disease.

Analysis, Measurement, Electrocardiogram, Hemodynamics

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