Background: Significance of electrocardiogram (EKG) changes associated with regadenoson as well as side effects compared to adenosine in a real world, unselected population is unknown. Methods and results: Three hundred ninety six consecutive patients undergoing either adenosine or regadenoson-based single-isotope (Technetium 99c) nuclear images were evaluated. A standard form documenting side effects was filled immediately following administration. The EKGs and nuclear scans were reviewed in a blinded-fashion. Commonest symptoms reported were flushing (64%), chest pain (36%) and dyspnea (36%). Flushing and chest pain were significantly more common with adenosine (73% vs. 57%, P < 0.01 and 53% vs. 47%, P = 0.06) and dyspnea more with regadenoson (40% vs. 31%, P = 0.05). Sixty (29%) patients carried a diagnosis of chronic bronchitis or asthma but only 4 (2 with each) required aminophylline. There was no significant correlation between chest pain induced by either agent or ischemia on nuclear imaging. EKG changes occurred infrequently (16% with regadenoson and 10% with adenosine), and had low sensitivity for detecting ischemia (7% for regadenoson and 11% for adenosine). Conclusions: EKG changes with adenosine and regadenoson occur infrequently and have low sensitivity for detecting ischemia. Chest pain is frequently induced by both, and is not predictive of ischemia on nuclear imaging
Key words: Adenosine. Electrocardiographic changes. Regadenoson.