Impact of limited treadmill exercise on adenosine Tc-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging in coronary artery disease

Limited exercise combined with dipyridamole increases myocardial perfusion defect severity compared with dipyridamole alone. The impact of limited exe rcise combined with adenosine on myocardial perfusion defect severity is un known. This study compares myocardial perfusion defect severity with adenos ine alone and adenosine combined with limited exercise. Thirty-two patients with coronary artery disease underwent on separate days and in randomized order technetium-99m sestamibi (25 to 30 mCi) single-photon emission comput ed tomographic imaging at rest, after adenosine (140 mu g/kg/min x 6 minute s), and after adenosine (140 mu g/kg/min x 4 minutes) during 6 minutes of m odified Bruce treadmill exercise (adenosine-exercise). Radiopharmaceutical was injected at 3 and 5 minutes during adenosine and adenosine-exercise, re spectively. Images were interpreted by a consensus agreement of 3 nuclear c ardiologists without knowledge of patient identity, stress protocol, or cli nical data using a 17-segment model and 5-point scoring system. A summed st ress score (SSS), summed rest score (SRS), and summed difference (SSS-SRS) score (SDS) were calculated for each image. Peak stress heart rate and rate -pressure product were higher for adenosine-exercise than adenosine (102 +/ - 19 vs 81 +/- 11 beats/min and 13,972 +/- 4,265 vs 10,623 +/- 2,131, respe ctively; both p < 0.001). Sensitivity for detection of greater than or equa l to 50% coronary stenosis was 75% and 72% for adenosine-exercise and adeno sine, respectively (p = NS). There were no differences in SSS and SDS betwe en adenosine-exercise and adenosine (8.2 +/- 5.9 vs 8.1 +/- 6.3 and 4.9 +/- 4.1 vs 5.2 +/- 4.6, respectively; both p = NS). Thus, in patients with cor onary artery disease, limited treadmill exercise combined with adenosine do es not increase myocardial perfusion defect severity compared with standard adenosine technetium-99m sestamibi single-photon emission computed tomogra phic myocardial perfusion imaging. (C) 1999 by Excerpta Medico, Inc.