The purpose if this study is to examine how effective Regadenoson is in detecting coronary artery disease during a stress echocardiogram when Optison is administered. Optison is a contrast agent that improves the images of the heart on the echocardiogram (echo) machine. Optison is approved by the Food and Drug Administration (FDA) to use during stress echocardiograms. Regadenoson is a commercially available rapid acting stress agent that is used to chemically increase the heart rate and is approved for nuclear imaging tests. Regadenoson is a FDA approved drug but not for the intended use in this study.

Stress perfusion imaging has primarily been done with radionuclide scintigraphy or single photon emission computed tomography (SPECT) and has not reached its full clinical potential because of the poor spatial resolution of SPECT, increased expense of this procedure, patient exposure to ionizing radiation, and lack of availability. The A2A receptor agonist Regadenoson has been utilized to detect myocardial perfusion abnormalities during SPECT myocardial perfusion imaging.

A 100 patient pilot study (Regadenoson Real Time Perfusion Imaging Trial, IRB #566-08-FB) demonstrated the feasibility and accuracy of real-time perfusion echocardiography (RTPE) in detecting coronary artery disease following Regadenoson bolus injection and Definity as an ultrasound contrast agent. The aim of this study is to determine whether similar feasibility and accuracy can be achieved with Optison (a Food and Drug Administration approved ultrasound contrast agent that differs slightly in microbubble size and composition) in detecting coronary artery disease (CAD) following Regadenoson bolus injection. As with the original study, sensitivity, specificity, and accuracy of perfusion and wall motion analysis to identify a coronary stenosis >50% in diameter by quantitative angiography will be analyzed.

Inclusion Criteria:

• Male or female. Age ≥ 30 years.
• Resting Left Ventricular Ejection Fraction > 40% using Simpson's biplane measurement.
• Scheduled for coronary angiography within 30 days of the Regadenoson stress test.
• Negative urine pregnancy test within 2 hours of ultrasound contrast administration required of females of childbearing age unless post-menopausal or with evidence of surgical sterilization.
• Be conscious and coherent, and able to communicate effectively with trial personnel.
• Agreeable to undergo the additional stress test (which is being performed for research purposes only, not for clinical care) and coronary angiography (which is being performed for clinical care) based on the following clinical profile: Have at least an intermediate likelihood of coronary disease based.
• Good apical echo images with at least 50% of each coronary artery territory well visualized.

Exclusion Criteria:

• Known or suspected hypersensitivity to ultrasound contrast agent used for the study.
• Pregnancy or lactation.
• Complicated hemodynamic instability (i.e., NYHA Class IV heart failure, unstable angina at rest despite medical therapy).
• Life expectancy of less than two months or terminally ill.
• Congestive (idiopathic) or hypertrophic cardiomyopathy.
• Known left main disease.
• Heart transplant recipient, hypertrophic cardiomyopathy, acute myo- or pericarditis.
• Resting Left Ventricular Ejection Fraction < 40%
• Large inducible perfusion defects or wall motion abnormalities during prior stress imaging study associated with left ventricular cavity dilatation.
• Early positive treadmill ECG within the first stage of the test.
• History of > 1st degree heart block, sick sinus syndrome or high grade AV block without a pacemaker.
• Dipyridamole use within 30 hours of stress test, or consumption of methylxanthines within 12 hours, or use of sublingual nitroglycerin within two hours.
• Participation in another investigational study within one month of this study.
• Anyone in whom a stress test should not be performed prior to cardiac catheterization.