Serious complications associated with regadenoson administration for myocardial perfusion imaging: a commentary.

In this issue of the journal Rosenblatt et al report on two cases of asystole following regadenoson administration for myocardial perfusion imaging (MPI). Recent reports have described serious complications with regadenoson including high-grade atrioventricular block/asystole, myocardial infarction (MI), and seizures. One of us summarized the available data on the safety of regadenoson with respect to MI and asystole from clinical trials and post-marketing surveillance and detailed the limitations posed by these sources on our understanding of risk associated with regadenoson use. Underwood et al, in a letter to the editor, describe their experience with regadenoson in Europe. During the first year of using regadenoson for MPI at their center (1,581 consecutive patients, 90% of all patients stressed) they encountered no deaths, MIs, or hospital admissions following MPI but eight patients had adverse events; one experienced bronchospasm and seven had symptomatic hypotension with inappropriate bradycardia. While one case occurred prior to regadenoson administration and was likely related to intravenous cannulation, two cases progressed to sinus arrest and asystole and required cardiopulmonary resuscitation. After the first year of using regadenoson, Underwood et al report that they continued to experience such events (which they label as vasovagal) at very low frequency. Although they have not been able to identify patients that are at higher risk, they speculate that these events are driven by vagal stimulation and propose that atropine may be more effective at reversing these hemodynamic effects than aminophylline. Agarwal and DePuey, who have recently reported a case of advanced degree atrioventricular block and altered mental status (unresponsiveness) after regadenoson MPI, stress the risk of seizures with regadenoson use in their editorial. Page et al have recently reported a case series of seizures associated with regadenoson use. As Agarwal and DePuey point out, the package insert of regadenoson has been recently updated to warn of the possibility that regadenoson may lower the seizure threshold. The package insert also states that fatal and nonfatal MI, ventricular arrhythmias, and cardiac arrest have occurred following regadenoson injection and that regadenoson should be avoided in patients with symptoms or signs of acute myocardial ischemia, such as unstable angina or cardiovascular instability, since these patients may be at greater risk of serious cardiovascular reactions to regadenoson. Finally, the updated package insert indicates that new-onset or recurrent atrial fibrillation with rapid ventricular response, atrial flutter, and cerebrovascular accidents have been reported following regadenoson injection. It has to be appreciated that the patients referred for regadenoson MPI are high-risk patients that may have similar complications with other stress modalities (exercise, dobutamine, adenosine, dipyridamole) or even during observation with no intervention. Current ASNC guidelines discuss the absolute and relative contra indications for stress testing and clearly patients with unstable symptoms should not be stressed with Reprint requests: Fadi G. Hage, MD, FASH, FACC, Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Lyons Harrison Research Building 314, 1900 University BLVD, Birmingham, AL 35294; fadihage@uab.edu J Nucl Cardiol 2014;21:877–9. 1071-3581/$34.00 Copyright 2014 American Society of Nuclear Cardiology.