Direct comparison of adenosine and adenosine 5′-triphosphate as pharmacologic stress agents in conjunction with Tl-201SPECT:: Hemodynamic response, myocardial tracer uptake, and size of perfusion defects in the same subjects

Background Adenosine 5'-triphosphate (ATP), a potent and inexpensive coronary vasodilator, was introduced as a pharmacologic stress agent for thallium 201 single photon emission computed tomography (SPECT). However, there has been no direct comparison of ATP and adenosine as myocardial stressors in the same subjects. Methods and Results. Thirty-six patients underwent consecutive TI-201 SPECT imaging with adenosine and ATP in a randomly assigned order. There were no changes in clinical status and no invasive procedures were performed between the two tests. The hemodynamic response and side effects were monitored, and myocardial tracer uptake was assessed by use of a visual grading system and quantitative analysis via a CEqual map. The hemodynamic changes and adverse effects did not differ significantly between the two groups. There were no changes in the detection of any perfusion defect on a per-subject basis, except in one. The exact agreement rate for the visual grading of the myocardial tracer uptake was 84.8%. However, the average extent of the perfusion defect and the severity score were higher with adenosine. Conclusion. The hemodynamic changes and the degree of myocardial uptake were similar between the adenosine and ATP infusion. However, quantitative analysis by use of a CEqual map revealed smaller perfusion defects and lower severity scores in subjects undergoing TI-201 SPECT with ATP.