Background: Stress echocardiography has become an accepted methodology for the evaluation of coronary artery disease. One potential advantage of dobutamine over other stressors used with echocardiography is the possibility of assessing the ischemic threshold. However, whether this measurement correlates with indices associated with adverse outcome has not been established.
Methods and results: One hundred four patients (91 men and 13 women; age, 61 +/- 9 years) with coronary artery disease were studied with transesophageal echocardiography during infusion of dobutamine 2.5 to 40 microgram/kg per minute. When regional dyssnergy developed, the dobutamine ischemic threshold (the dose of dobutamine at which induced regional wall motion abnormalities were first detected) was identified. The dobutamine stress echocardiogram was abnormal in 90 patients (sensitivity, 87%). The dobutamine ischemic threshold was 25.4 +/- 11.2 micrograms/kg per minute in patients with single-vessel disease, 14.4 +/- 7.9 in patients with two-vessel disease, and 9.1 +/- 7.9 in patients with three-vessel disease (P < .0001). The dobutamine ischemic threshold correlated with the ejection fraction response to exercise measured by radionuclide angiography: Patients with low ischemic threshold had a mean fall in ejection fraction, and patients with high ischemic threshold or normal tests had a mean increase in ejection fraction.
Conclusions: In patients with coronary artery disease, the ischemic threshold measured during dobutamine stress echocardiography correlates with both the number of stenosed vessels and the left ventricular ejection fraction response to exercise. Because these variables are associated with poor prognosis, these findings provide further support regarding the utility of dobutamine stress echocardiography in the clinical evaluation of patients with chronic coronary artery disease.