Abstract Background Myocardial perfusion single-photon emission computed tomography (SPECT) imaging with stress is a useful examination for detecting coronary artery disease. Since the presence of artifacts is remaining challenges, we aimed to define the minimum intensity of low-grade exercise stress levels combined with drug stress to reduce undesired artifacts and their related factors. Methods We divided patients with suspicious coronary artery disease into 4 groups as follows: group A, adenosine triphosphate (ATP) for 6 min; group A + 25 W, ATP + 25 W exercise for 6 min; group A + 35 W, ATP + 35 W exercise for 6 min; group A + 45 W, ATP + 45 W exercise for 6 min) and enrolled only those whose summed stress scores were