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.