Favorable intensity of short-duration exercise stress combined with adenosine triphosphate to avoid artifacts in myocardial perfusion single-photon emission computed tomography

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 <3. Undesired artifacts were evaluated on the basis of heart-to-liver activity (H/L) ratio and heart-to-10 pixels below the heart (H/below the H) ratio. Results: The logarithmic values of H/L and H/below the H ratios were significantly higher in groups A+35 W and A+45 W than in group A (p<0.05, each). In all the patients, the logarithmic values of H/L and H/below the H ratios positively correlated with the increment of rate pressure product (RPP, p=0.002 and p=0.005, respectively) after stress in the univariate analysis. The left ventricular end-diastolic volume (LVEDV) after stress (p=0.002) negatively correlated with the logarithmic value of H/below the H ratio, but not H/L ratio. Although the increment of RPP was independently associated with the logarithmic values of both H/L (p=0.001) and H/below the H ratios (p=0.005), LVEDV was also independently associated with the logarithmic value of H/below the H ratio (p<0.001) in multivariate regression analysis under adjusting with age and sex.Conclusion: ATP plus ≥35 W exercise stress for 6 min was useful for reducing undesired artifacts after stress in myocardial perfusion SPECT. LVEDV after stress in addition to the increment of RPP was independently associated with the H/below the H ratio, but not the H/L ratio.