A COMPARISON OF ADENOSINE AND EXERCISE STRESS TL-201, SCINTIGRAPHY

A detailed comparison of stress thallium images utilizing exercise (sy mptom-limited bicycle ergonometer) and adenosine (infused at 50 mug kg -1 min-1 increasing by 25 mug kg-1 min-1 every 2 min to a maximum tole rated dose) was performed in 20 patients with angiographically documen ted coronary disease. Ten patients were receiving beta-blockade at the time of both tests. Triple-, double- and single-vessel disease was pr esent in eight, seven and five patients, respectively. Exercise produc ed a large increase in double product (8970 +/- 288 to 20984 +/- 690 m m Hg min-1) while adenosine produced no significant change (8440 +/- 2 80 to 9086 +/- 600 mm Hg min-1). Each of the three gated planar images (anterior 40-degrees and 70-degrees left anterior oblique) was divide d into five equal segments. Exercise produced 44/90, 44/95 and 45/95 a bnormal segments in the anterior, 40-degrees and 70-degrees views whil e adenosine produced 53/100, 44/100 and 52/100 abnormal segments for t he same views. The total number of abnormal segments was similar in bo th groups (133/280 exercise and 149/300 adenosine). Each abnormal segm ent was analysed for degree of change between stresses using a five-po int scoring system. Exercise produced eight segments which were larger by one point and 44 segments larger by two points while adenosine pro duced 17 and 44 segments larger by one and two points respectively. Le ft ventricular uptake (as % injected dose) was significantly greater i n the adenosine group (1.12 +/- 0.06% versus 0.64 +/- 0.05%, P < 0.01) but right ventricular uptake was similar (0.15 +/- 0.1% versus 0.14 /- 0.09%). In summary adenosine does produce thallium defects comparab le to exercise. Despite no significant change in double product with a denosine, thallium defects were of similar size and distribution to th ose produced by exercise. Beta-blocker therapy had no significant effe ct on thallium defects.