Regadenoson, a selective A2A adenosine receptor agonist, causes dose-dependent increases in coronary blood flow velocity in humans.

Background: Regadenoson is a selective A2A adenosine receptor agonist and vasodilator used to increase the heterogeneity of distribution of coronary blood flow during myocardial perfusion imaging. This study characterized the dose dependence of regadenoson-induced coronary hyperemia.
Methods and Results: An open-label, dose-escalation study of regadenoson (10-500 microg, rapid intravenous bolus) was performed in 34 subjects; in 4 additional subjects, the effect of aminophylline to reverse the response to regadenoson was determined. Intracoronary peak blood flow velocity in either the left anterior descending or left circumflex artery was measured by continuous Doppler signal recording, heart rate, central aortic blood pressure, and adverse effects were recorded. Regadenoson increased peak blood flow velocity by up to 3.4-fold in a dose-dependent manner. The mean duration of the increase in flow velocity of 2.5-fold or greater caused by 400 to 500 microg of regadenoson was 2.3 to 2.4 minutes. Regadenoson (400-500 microg) increased heart rate by up to 21 +/- 6 beats/min and decreased systolic blood pressure (-5 +/- 8 mm Hg to -24 +/- 16 mm Hg) and diastolic blood pressure (-8 +/- 4 mm Hg to -15 +/- 14 mm Hg). Aminophylline (100 mg) attenuated the increase in peak flow velocity but not tachycardia caused by 400 microg of regadenoson.
Conclusion: The results of this study demonstrate the utility of regadenoson as a coronary vasodilator for myocardial perfusion imaging.