1010-120 Comparison of Arbutamine Stress and Treadmill Exercise Thallium-201 SPECT: Hemodynamics and Diagnostic Accuracy

Arbutamine (ARB). a new β-agonist developed as a pharmacologic stress agent, was compared with treadmill exercise testing (Ex) in a multicenter study using thallium-201 (TI) SPECT A total of 75 patients (pts) performed both forms of stress. Of the 73 pts having quantitative angiography, 68 (93%) had coronary artery disease (≥50% stenosis). TI scans were obtained in 68 pts and were scored by a central laboratory using a twenty segment (seg)/scan visual analysis (5 point system: 0=normal, 4=absent uptake; segmental score≥2=defect). Stress TI segs with defects were further classified as reversible (rev) or nonreversible (nonrev). Hemodynamic response was summarized for 75 pts. Maximum heart rate (HR) by ARB and Ex was 122 vs 141 bpm, respectively (p<0.05); mean %HR change from baseline was similar (79% vs 82%, respectively). Maximum systolic BP for ARB and Ex was 173 vs 176mmHg, respectively and mean %change from baseline was 31% vs 26%, respectively (p=NS for both). In the 68 pts with angiographic CAD, sensitivity for detecting CAD by ARB TI was 94% and 97% by Ex TI-SPECT (p=NS). Stress TI-SPECT segmental agreement for presence or absence of defect between ARB and Ex in 1360 segs (68 pts) was 94% (k=0.7). Of 76 discordant segs, 38 (50%) were normal by ARB and abnormal by Ex. Exact segmental stress TI score (0–4) agreement was 85% (k=0.7). Of the 199 segs with discordant scores, the ARB-TI score was higher in 98 (49%), Among 346 segs with stress defects by both ARB and Ex, defect rev agreement was 86% (k=0.7). Of the 50 discordant segs, 25 (50%) were rev by ARB and nonrev by Ex. Adverse events were mostly mild. Sustained arrhythmias were not observed; 3 pts had nonsustained ventricular tachycardia with ARB and 1 with Ex.ConclusionIn this patient population, arbutamine and treadmill exercise produced a similar degree of hemodynamic response compared to baseline. The two forms of stress yielded similar diagnostic accuracy and high agreement for the presence, extent, severity and reversibility of stress myocardial perfusion abnormalities