To compare the diagnostic value of dobutamine stress echocardiography with dipyridamole thallium-201 single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), we performed both tests on 54 patients who also underwent coronary arteriography. Dobutamine was infused at an incremental regimen of 5, 10, 20, 30 and 40 micrograms.kg-1.min-1. Dipyridamole was infused at a rate of 0.14 mg.kg-1.min-1 over 4 min. Dobutamine stress echocardiography detected 40 (93%) and SPECT 42 (98%, P = ns) of the 43 patients with significant CAD, defined as > or = 50% diameter stenosis. The specificity was 73% (8 of 11) for both tests. The sensitivity for detecting individual coronary artery stenosis with dobutamine stress echocardiography was 81% (30 of 37) for the left anterior descending artery, 75% (24 of 32) for the right coronary artery, and 61% (17 of 28) for the left circumflex artery. For SPECT it was 89%, 97% (P < 0.05 vs dobutamine stress echocardiography) and 75%, respectively. Among the 97 stenotic coronary arteries, 17 had mild to moderate stenosis (50%-69% diameter stenosis) and 80 had severe stenosis (> or = 70% diameter stenosis). With dobutamine stress echocardiography, 53% of the arteries with mild to moderate stenosis were identified vs 78% of those with severe stenosis (P < 0.05). With SPECT, the sensitivity was 82% (14 of 17) in mild to moderate stenosis and 89% (71 of 80) in severe stenosis (P = ns). No major side effects occurred during either test. Thus, both dobutamine stress and SPECT are highly sensitive for detection and localization of CAD.(ABSTRACT TRUNCATED AT 250 WORDS)