Abstract
Regadenoson is a selective A2A adenosine receptor agonist vasodilator that is widely used for pharmacologic cardiac stress testing. Although generally considered safe with less side effects than adenosine, regadenoson can have serious side effects. We report here 4 patients who developed ST-segment elevation myocardial infarction (STEMI) or STEMI equivalent due to acute thrombotic occlusion of variable coronary arteries including left main coronary artery, normal and anomalous right coronary artery, and left circumflex coronary artery, with characteristic electrocardiogram abnormalities. The STEMI occurred as early as 1 minute and as late as 30 minutes after regadenoson administration. Therefore, development of localizing acute ST-segment elevation (STE) or STE in aVR with reciprocal ST-segment depression on the electrocardiograms as seen in these cases portends underlying acute coronary obstruction. Attention should also be paid to potential late occurring STEMI. When used in cardiac stress testing, discussing potential serious side effects of regadenoson including STEMI should be part of informed consent.