Update on myocardial perfusion imaging: role of regadenoson

Robert C Hendel

Midwest Heart Specialists, Central DuPage Hospital, Winfield, Illinois, USA

Abstract: Pharmacologic stress myocardial perfusion imaging (MPI) is a noninvasive method for the evaluation of coronary artery disease in patients unable to exercise adequately. Commonly used pharmacologic stress agents (adenosine, dipyridamole, and dobutamine) have a high incidence of bothersome and potentially serious side-effects, several contraindications to testing, and require continuous infusion with weight-adjusted doses. Newer agents are, therefore, needed. Selective activation of A_2A adenosine receptors on the coronary vasculature should provide coronary vasodilation for MPI with fewer or less severe side-effects associated with nonspecific agonists, such as adenosine and dipyridamole. Regadenoson is the first selective A_2A receptor agonist to be approved as a pharmacologic stress agent for use with radionuclide MPI. Regadenoson is administered at a standard, fixed dose of 400 μg from a prefilled syringe or single-use vial by intravenous injection over 10 seconds. In clinical trials, regadenoson provided good quality images yielding accurate diagnostic information, and was safe and well tolerated. No infusion pump is required and the stress protocol is brief. Further studies are now required to evaluate regadenoson as a stress agent in combination with low-level exercise, with prior caffeine intake, and in patients with asthma or chronic obstructive pulmonary disease.

Keywords: myocardial perfusion imaging, pharmacologic stress, A_2A receptor agonist, regadenoson, ischemic heart disease, SPECT, diagnosis