Uses and limitations of exercise doppler echocardiography in the diagnosis of ischemic heart disease

This study tested the hypothesis that coronary artery disease might be identified by a decrease in Doppler measurements of flow velocity and acceleration. The response of aortic blood flow velocity and acceleration to exercise was determined in 102 subjects (28 young control subjects and 74 older patients) who underwent continuous wave Doppler echocardiographic examination before, during and immediately after near maximal treadmill exercise. Patients were grouped according to the results of thallium perfusion imaging: Group I = normal, Group II = ischemia with or without prior infarction and Group III = prior infarction only. A significant decrease in the level of velocity and acceleration achieved with exercise was observed both in patients in Group I (normal thallium study) (1.2 ± 0.3 m/s and 36.8 ± 14 m/s per s, p < 0.005) and in patients in Group II (ischemia) (1.1 ± 0.3 m/s and 27.7 ± 11 m/s per s, p < 0.0005) compared with values in young control subjects (1.4 ± 0.2 m/s and 52.7 ± 16 m/s per s). When groups of patients of similar age who differed in the presence (Group II) or absence (Group I) of ischemia on thallium scintigraphy were compared, no difference was found for maximal velocity (1.1 ± 0.3 versus 1.2 ± 0.3 m/s, p = NS), but acceleration was significantly lower in Group II (27.7 ± 11 versus 36.8 ± 14 m/s per s, p < 0.05). When values in Groups I and II were normalized for exercise capacity on the basis of heart rate reached, a reduction was observed only for peak acceleration in Group II patients with multivessel coronary disease. It is concluded that aortic flow velocity and acceleration increase progressively with exercise in young healthy subjects. Because qualitatively similar responses are elicited in patients with normal and ischemic responses to thallium perfusion scintigraphy, a reduction in aortic blood flow by exercise Doppler recordings cannot be reliably used to identify individual patients with coronary artery disease. As a group, patients with evidence of impaired perfusion by thallium scintigraphy achieve a lower peak acceleration than do those with normal scans, a finding particularly marked in those with multivessel disease.