The RegEx trial: a randomized, double-blind, placebo- and active-controlled pilot study combining regadenoson, a selective A(2A) adenosine agonist, with low-level exercise, in patients undergoing myocardial perfusion imaging.

Background: Although vasodilator stress myocardial perfusion imaging (MPI) is increasingly performed with exercise, adenosine A(2A) receptor agonists have not been studied with exercise.

Objectives: To determine the safety of administering regadenoson during exercise and, secondarily, to evaluate image quality, patient acceptance, and detection of perfusion defects.

Methods: Patients requiring pharmacologic MPI received a standard adenosine-supine protocol (AdenoSup, n = 60) and were then randomized (2:1) in a double-blind manner to low-level exercise with bolus intravenous injection of regadenoson (RegEx, n = 39) or placebo (PlcEx, n = 21).