Exercise testing: electrocardiography and radionuclide cineangiography
Although coronary artery stenosis detected by coronary arteriography can define regions of potential ischemia, assessment of the presence of ischemia requires testing of cardiac function. However, in patients with stable coronary artery disease, ischemia seldom is present with the patient at rest. Therefore, in such patients, accurate assessment of the presence and extent of ischemic heart disease requires evaluation during stress, such as that imposed by exercise.
Electrocardiography during exercise provides one method for such assessment. However, comparison of the exercise ECG with coronary arteriographic studies performed at many large medical centers indicates that the exercise ECG is relatively insensitive (sensitivity 50% to 80%) in identifying symptomatic patients with large vessel coronary artery disease.1 Moreover, our study of 30 asymptomatic subjects with positive exercise ECGs revealed that only 39% of these patients had angiographically demonstrable coronary artery stenoses of ≥ 50% of the coronary lumen. Thirty percent had no coronary abnormalities and 30% had minor wall irregularities. These findings are indistinguishable from those of Froehlicher et al2, who have performed the only other published assessment of asymptomatic subjects with positive exercise ECGs.
Clearly, therefore, although the exercise ECG is valuable in epidemiologic studies and, when combined with other tests, may be a valuable adjunct in determining prognosis, it is not by itself sufficiently accurate to be used as an indicator either of the presence or of the severity of coronary artery disease.
Because of these considerations, we have developed a noninvasive real-time radionuclide cineangiographic procedure permitting cutaneous monitoring and analysis . . .