Treadmill exercise during adenosine infusion is safe, results in fewer adverse reactions, and improves myocardial perfusion image quality

Background, Combining low-level treadmill exercise,vith adenosine infusion may result in fewer bradyarrhythmic complications by increasing sympathetic tone and may improve myocardial perfusion image quality by decreasing back ground activity. Methods. Patients referred for outpatient pharmacologic stress myocardial p erfusion imaging performed simultaneous treadmill exercise (mean 2.2 metabo lic equivalents) throughout 6-minute adenosine infusion (adenosine-exercise n = 507), Patients unable to exercise and those with left bundle branch bl ock received adenosine infusion alone (adenosine-nonexercise n = 286), Adve rse reaction data were collected on all patients and compared by sex. Backg round-to-target activity was calculated in a blinded fashion on 200 randoml y selected patients. Results. During the period from April 1996 to December 1998, 507 patients ( 64%) underwent adenosine-exercise testing, whereas 286 (36%) underwent aden osine-nonexercise testing. Hypotensive and arrhythmic (atrioventricular blo ck, sinus bradycardia, and new onset atrial fibrillation or flutter) advers e reactions occurred less often during adenosine-exercise than during adeno sine-nonexercise. Neither death nor myocardial infarction occurred in eithe r group. In the adenosine-exercise group, 2.8% of patients experienced an a dverse reaction versus 5.6% of the adenosine-nonexercise group (P = .04), T he reduction in adverse reactions occurred in both men and women, although women had significantly more adverse reactions than men (5.7% vs 1.8%, P = .004). Liver/heart and gut/heart ratios were lower in the adenosine-exercis e group (1.05 +/- 0.42 vs 1.21 +/- 0.55, P = .01; 0.61 +/- 0.21 vs 0.69 +/- 0.24, P = .03, respectively). Conclusions. Compared with adenosine infusion alone, combining low-level tr eadmill exercise with adenosine in outpatients is safe, better tolerated, a nd improves image quality. Women were more likely to experience adverse rea ctions than men.