Comparison of exercise, dipyridamole, adenosine, and dobutamine stress with the use of Tc-99m tetrofosmin tomographic imaging.

PURPOSE: The purpose of this study was to compare defect extent and severity and myocardial uptake with exercise and pharmacologic stress with technetium-99m (Tc-99m) tetrofosmin tomographic myocardial perfusion imaging. BACKGROUND: Detection of stress-induced myocardial perfusion defects depends on both a disparity in blood flow between normal and stenotic vessels and the extraction fraction and linearity of myocardial uptake of the tracer. There are limited clinical data for exercise or pharmacologic stress with Tc-99m tetrofosmin tomographic myocardial perfusion imaging. METHODS: Thirty-one patients with coronary artery disease and 7 with a < 5% likelihood of coronary artery disease underwent on separate days Tc-99m tetrofosmin single-photon emission computed tomographic imaging at rest and after exercise, dipyridamole, adenosine, and dobutamine stress. Images were interpreted by a blinded consensus of 3 experienced readers with a 17-segment model and 5-point scoring system. RESULTS: Compared with exercise, the summed stress score was smaller with dipyridamole (P < .01), and the reversibility score was smaller with both dipyridamole (P < .01) and dobutamine (P < .05), whereas the number of abnormal and reversible segments was less with both dipyridamole (P < .01 and P < .001, respectively) and dobutamine (both P < .05). No significant differences were found in the summed stress or reversibility scores and the number of abnormal or reversible segments between exercise and adenosine. CONCLUSIONS: Compared with exercise, defect extent, severity, and reversibility are less with dipyridamole and dobutamine with Tc-99m tetrofosmin single photon emission computed tomographic imaging.

Direct comparison of arbutamine and dobutamine stress testing with myocardial perfusion imaging and echocardiography in patients with coronary artery disease.

Arbutamine, a new sympathomimetic compound, appears to elicit a more balanced inotropic and chronotropic response than dobutamine, currently used as a pharmacologic stress agent. The present study was performed to compare standard dobutamine stress testing with arbutamine for the detection of myocardial ischemia with technetium (Tc)-99m sestamibi tomographic imaging and 2-dimensional echocardiography in patients with coronary artery disease. Twenty-six patients with evidence of coronary artery disease underwent dobutamine infusion of 5 to 40 microg/kg/min in 3-minute stages. On a separate day, arbutamine was administered by an automated, computerized, closed-loop device monitoring both heart rate and blood pressure. Both infusions were terminated upon achievement of target heart rate, completion of maximal infusion dose (dobutamine), heart rate saturation (arbutamine), or standard clinical end points. Tc-99m sestamibi was injected before termination of both infusions followed by tomographic myocardial perfusion imaging, whereas echocardiography was performed at baseline and throughout the infusions. There were no significant differences in maximal heart rate, blood pressure, and rate-pressure product as well as in the development of anginal symptoms or electrocardiographic changes during both infusions. The location and severity of myocardial perfusion defects and echocardiographic wall motion abnormalities were similar between both agents. It is concluded that arbutamine produces similar imaging results compared with standard dobutamine stress with both Tc-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging and 2-dimensional echocardiography.