The future of pharmacologic stress: selective a2a adenosine receptor agonists

Adenosine and dipyridamole, the currently available vasodilators for myocardial perfusion imaging, produce hyperemic coronary flow by stimulating A2A adenosine receptors on arteriolar vascular smooth muscle cells. However, both vasodilators nonselectively activate A1, A2B, and A3 adenosine receptors, which contributes to common undesirable effects. In the development of a novel pharmacologic stress agent, more selective agonism of the A2A receptor subtype would be desirable. Currently, 2 selective A2A adenosine receptor agonists are being evaluated in phase 3 studies as pharmacologic stress agents. The highly selective, potent, low-affinity A2A adenosine agonist regadenoson (also known as CVT-3146) holds significant potential as a pharmacologic stress agent, based on available results from experimental and clinical trials. Regadenoson produces maximal hyperemia quickly and maintains it for an optimal duration that is practical for radionuclide myocardial perfusion imaging. Regadenosonʹs simple rapid bolus administration and short duration of hyperemic effect point to an advantage of enhanced control for the clinician.