Comparison between dipyridamole and adenosine as pharmacologic coronary vasodilators in detection of coronary artery disease with thallium 201 imaging

Abstract

Background: Both dipyridamole and adenosine are widely used as pharmacologic stressors with 201Tl imaging for detection of coronary artery disease. The purpose of this study was to compare dipyridamole and adenosine 201Tl imaging directly in patients with angiographically proved coronary artery disease.

Methods and results: Fifty-four patients were submitted to two planar 201Tl studies: one with dipyridamole and the other with adenosine. The interval between the two studies varied from 2 to 7 days and the order was assigned randomly. Three standard planar views were obtained 10 minutes and 4 hours after the injection of 3.0 mCi 201Tl. Administration of dipyridamole was as follows: 0.142 mg/kg/min during 4 minutes, followed by a slight exercise and 201Tl injection. The infusion of adenosine was as follows: 0.140 mg/kg/min during 6 minutes with injection of 201Tl after the third minute of infusion. Patients were asked to give their preference considering the number, type, severity, and duration of side effects on a scale from 0 (worst) to 5 (best). Reading was done by two experienced observers. The heart was divided into three segments per view. The change in systolic blood pressure was -12 +/- 11 mm Hg for adenosine and -5 +/- 10 mm Hg for dipyridamole (p < 0.001), and the change in heart rate was 18 +/- 10 beats/min for adenosine and 8 +/- 7 beats/min for dipyridamole (p < 0.001). With regions of interest, ischemic/normal wall ratios were determined: 0.78 +/- 0.06 for adenosine and 0.83 +/- 0.08 for dipyridamole (p < 0.001). Adenosine detected 295 normal, 170 ischemic, and 21 scar segments, whereas dipyridamole detected 326, 135, and 25 segments, respectively. Patients preferred adenosine (4.3 +/- 1.0 for adenosine vs 3.8 +/- 1.5 for dipyridamole; p < 0.04) mainly because of the short duration of side effects.

Conclusion: This study shows that the use of adenosine with 201Tl imaging may have some advantages over dipyridamole.