Abstract
Radionuclide angiography during exercise stress is often used to assess patients suspected of having coronary artery disease. This test, however, is importantly limited by the ability of patients to exercise and by the patient's use of cardioactive drugs. A combination of stresses, which may act through different mechanisms on the heart, may improve the diagnostic value of radionuclide angiography. Accordingly, we evaluated the usefulness of performing radionuclide angiography during a double stress, consisting of supine bicycle exercise with the superimposition of the cold pressor test in the diagnosis of coronary artery disease. Fourteen normal subjects and 39 patients with coronary artery disease had greater increases in arterial pressure and heart rate during the double stress than during exercise alone. The ejection fraction of normal subjects increased from 66 ± 6% at rest to 73 ± 6% during exercise (P < .001), and to 77 ± 8% during double stress (P < .01 v exercise). In patients with coronary artery disease, the ejection fraction did not change from rest (58 ± 11%) to exercise (59 ± 11%), but fell to 55 ± 11% during the double stress (P < .001 v exercise). Left ventricular wall motion index, likewise, did not change from rest (7.1 ± 2.1) to exercise (6.9 ± 2.1) but fell during double stress (6 ± 2.3, P < .001 v exercise). Exercise stress alone provoked abnormalities of wall motion in 11 patients (28%), of ejection fraction in 26 patients (67%), and of either wall motion or ejection fraction in 27 patients (69%). The double stress uncovered abnormalities of wall motion in 26 patients (67%), of ejection fraction in 30 patients (77%), and of either wall motion or ejection fraction in 33 patients (85%). Six patients with coronary artery disease, who had normal results during exercise, were abnormal with exposure to the double stress test. Thus, double stress radionuclide angiography is well tolerated, is easy to perform, and may improve the overall detection of coronary artery disease, especially in patients whose exercise is limited by the use of cardioactive drugs or poor physical conditioning.