Adenosine is an effective vasodilator used in SPECT-Myocardial Perfusion Imaging (SPECT-MPI). However, it produces transient symptoms that are poorly tolerated by most subjects. This is a multi-center, randomized double-blind study to compare the tolerability and effectiveness of apadenoson to adenosine (Adenoscan®) in SPECT-MPI. Subjects who are clinical candidates for SPECT-MPI will be enrolled to undergo two sequential SPECT-MPI studies. The first study will use adenosine as the stress agent in approximately 1250 subjects. Eligible subjects will then be randomized in a 1:1 assignment ratio to receive a second SPECT-MPI using either adenosine or apadenoson as the pharmacologic stress agent, with the goal of obtaining a total of 670 subjects who complete both studies. The agreement of the results from the two adenosine:adenosine stress tests will be compared to that from the adenosine:apadenoson tests to assess efficacy. The incidence and intensity of commonly reported side effects will be compared to evaluate improved tolerability.
