Pharmacologic stress testing uses
vasodilators to provide objective evidence of
myocardial ischemia.
Adenosine and
dipyridamole are nonselective
adenosine receptor agonists that have been associated with
myocardial infarction (MI) during
intravenous infusion. Mechanisms postulated for this effect include coronary steal, transmural steal, global
hypotension, and direct vasoconstriction.
Regadenoson, a direct A2A agonist, was approved for use in stress testing in 2008. We describe a 68-year-old man who presented to our institution with typical angina, relieved by
nitroglycerin. He did not have electrocardiogram (ECG) changes suggestive of myocardial pathology, and laboratory testing did not reveal a significant rise in
troponin-I levels. To further assess the etiology of his symptoms, he underwent a pharmacologic stress test with
regadenoson followed by
technetium 99 m sestamibi. Six minutes after
regadenoson infusion, the patient developed severe retrosternal
chest pain accompanied by ST elevations on ECG. Sublingual
nitroglycerin was administered that resolved both the
pain and ECG changes. The patient subsequently underwent urgent coronary angiography and was found to have a 95% critical
stenosis involving the left anterior descending artery. We conclude this case represents a MI secondary to coronary steal phenomenon induced by
regadenoson infusion. Clinicians should be aware this adverse effect can occur despite the improved side-effect profile of
regadenoson. Continuous monitoring of vital signs and the ECG with regular assessment of symptoms is imperative to identify this rare but potentially devastating adverse event.