A Study of Regadenoson in Subjects Undergoing Stress Myocardial Perfusion Imaging (MPI) Using Multidetector Computed Tomography (MDCT) Compared to Single Photon Emission Computed Tomography (SPECT)

Inclusion Criteria: * Male subjects must be ≥ 45 years of age * Female subjects must be ≥ 50 years of age * Subject has met at least one of the following three criteria: * has a suspected (clinical impression) or known diagnosis of coronary artery disease (CAD) with typical angina that has been referred from nuclear cardiology lab schedule or cardiac computed tomography (CT) schedule * has stable symptoms with possible elective catheterization procedure scheduled and where further imaging may be beneficial; * has known CAD from a previous invasive coronary angiography (ICA) performed more than 12 weeks prior to screening who now present with new cardiac symptoms * Subject has been referred for a clinically indicated myocardial perfusion imaging procedure or Cardiac CT procedure for suspected moderate or high risk CAD * Subject must abstain from eating and drinking 30 minutes prior and 30 minutes post study drug administration * Subject must abstain from smoking 3 hours prior and 8 hours post study drug administration * Subject must abstain from any intake of methylxanthine-containing foods and beverages within 12 hours prior to Day 1 visit through the Day 3 Follow-Up Visit, as these foods may alter regadenoson effects. Subject is able to safely abstain from theophylline use for 12 hours prior to study drug administration Exclusion Criteria: * Subject is concurrently participating in another drug study or has received an investigational drug within 30 days prior to Screening * Subject has a history of a clinically significant illness (other than CAD), medical condition, or laboratory abnormality, which would preclude participation in the study * Subject has renal dysfunction demonstrated by a glomerular filtration rate (GFR) \< 45 mL/min (calculated using Cockroft-Gault formula Note: Subjects with a GFR 45-60 mL/min will undergo a hydration procedure * Female subject who is pregnant, lactating or of childbearing potential that refuses to use a medically acceptable form of contraception until the Telephone Follow up Visit is complete * Female subject has a positive pregnancy test prior to randomization * Subject has a history of second or third degree heart block or sinus node dysfunction unless the subject has a functioning pacemaker * Subject has symptomatic hypotension (temporary and reversible conditions that no longer exist are allowed) * Subject is allergic or intolerant to aminophylline, nitroglycerin or metoprolol * Subject is allergic or intolerant to regadenoson or any of its excipients * Subject is unable or unwilling to comply with the procedure schedule * Subject has previously enrolled in this study or was enrolled in another regadenoson study sponsored by Astellas * Subject has atrial fibrillation or significant arrhythmias which may result in decreased image quality for the imaging studies (CT and SPECT) * Subject has high heart rate (\> 65 beats per minute) and contra-indications to administer beta-blockers (severe chronic obstructive pulmonary disease (COPD) or asthma, second and third degree atrioventricular block)