Safety and Accuracy of Regadenoson-Atropine Stress Echocardiography in CAD

Inclusion Criteria: 1. Age \> 18 years old 2. Able to provide consent 3. Scheduled for cardiac catheterization either with or without a prior functional stress imaging study Exclusion Criteria: 1. Any history of acute myocardial infarction, prior PCI in last 3 months, bypass surgery, 2. History of greater than first degree AV block, sick sinus syndrome in patients 3. Patients with a pacemaker/LBBB 4. History on uncontrolled arrhythmias 5. Patients with significant pulmonary disease, known or suspected bronchoconstrictive or bronchospastic lung disease or other hypersensitivity to adenosine 6. History of cardiac transplantation, hypertrophic cardiomyopathy, acute myocarditis or pericarditis, severe valvular heart disease 7. Hemodynamically unstable patients 8. Dipyridamole use within 30 hours, consumption of methylxanthines (e.g., tea, coffee, caffeinated soft drinks, chocolate, or cocoa) within 12 hours, or use of sublingual nitroglycerin within 2 hours 9. History of glaucoma or obstructive uropathy 10. Allergy or hypersensitivity to atropine 11. Participation in another investigational drug study within 1 month or participation in any previous regadenoson trial 12. Pregnancy, breast feeding, or not using an acceptable method of birth control (if premenopausal) 13. . History of end-stage renal disease on hemodialysis or peritoneal dialysis