Regadenoson is used as a pharmacologic stress agent in myocardial perfusion imaging (MPI) to evaluate coronary artery disease in patients who are unable to undergo adequate exercise stress. It selectively stimulates A2A adenosine receptors, causing coronary vasodilation and increasing blood flow to heart muscle. This allows imaging techniques to detect areas with reduced blood flow, indicating possible blockages. Due to its short half-life and receptor specificity, regadenoson offers a well-tolerated, rapid-onset option with fewer side effects compared to older agents. It is typically administered as a single bolus injection during cardiac imaging protocols.