A rare complication of a common stress test

In 2008, regadenoson, a selective adenosine2A (A_2A) receptor agonist, was approved by the US Federal and Drug Administration for use as a pharmacologic stress agent in myocardial perfusion studies. By stimulating A_2A receptors in coronary smooth muscle, it can increase coronary blood flow by 2.5-fold or greater. Previous data showed non-inferiority of regadenoson in detecting reversible myocardial ischemia, compared to adenosine. Given less serious adverse effects, being better tolerated and easily administered, regadenoson has been widely used for myocardial perfusion imaging. As adenosine receptors have many sub-types and are located in multi-organ systems, regadenoson can cause various adverse effects, including bronchospasm, atrioventricular block, or hypotension. However, adverse effects on the central nervous system are rarely reported. As adenosine receptors (A₁ and A_2A receptors) play a major role in neuron-glial cells interaction, regadenoson can provoke seizure through A_2A receptor activation. We hereby report a case of regadenoson associated-seizure and review seizure mechanism. This may raise more concern for a rare serious adverse effect of regadenoson which should be taken into consideration when selecting cardiac stress modalities. <Learning objective: Regadenoson can provoke seizure through central A_2A receptor activation. This should be taken into consideration when selecting cardiac stress test modalities, particularly in patients with known seizure disorder or history of organic brain disease.>.