CONTRAST (Can cONTrast Injection Better Approximate FFR compAred to Pure reSTing Physiology?)

Inclusion Criteria: * Age 18 years or older. * Undergoing FFR assessment for standard clinical indications. * Ability to understand and willingness to sign a written informed consent. Exclusion Criteria: * Prior coronary artery bypass grafting (CABG). * Extremely tortuous or calcified coronary arteries precluding intracoronary physiologic measurements. Operators may exclude subtotal or similar high-grade lesions, which in their judgment may be threatened by pressure wire placement. * Known severe left ventricular hypertrophy (septal wall thickness at echocardiography of \>13 mm). * Inability to receive adenosine (for example, severe reactive airway disease, marked hypotension, or advanced atrioventricular block without pacemaker). * Recent (within 3 weeks prior to cardiac catheterization) ST-segment elevation myocardial infarction (STEMI) in any arterial distribution (not specifically target lesion). * Culprit lesions (based on clinical judgment of the operator) for either STEMI or non-STEMI cannot be included. * Severe cardiomyopathy (ejection fraction \<30%). * Renal insufficiency such that an additional 12 to 20 mL of contrast would, in the opinion of the operator, pose unwarranted risk to the patient.