Physiological Assessment of Severe Coronary Stenosis for Informing Planned PCI

Inclusion Criteria: * Age \>/= 18 years * Patient provides written informed consent * Clinical presentation with stable coronary artery disease or acute coronary syndromes (unstable angina, Non-ST Elevation Myocardial Infarction (NSTEMI), or ST Elevation Myocardial Infarction (STEMI)) * Scheduled for clinically indicated cardiac catheterization * At least one lesion with angiographic severity visually estimated to be \>/= 70% diameter stenosis that is deemed suitable for PCI * The operator plans to perform PCI on an ad hoc or planned basis * The target lesion is not planned for assessment by invasive physiology Exclusion Criteria: * Failure to provide signed informed consent * Culprit vessel of acute ST Elevation Myocardial Infarction (STEMI) * Culprit vessel of Non-ST Elevation Myocardial Infarction (NSTEMI) * Thrombolysis In Myocardial Infarction (TIMI) flow less than grade 3 at baseline or visible thrombus * Chronic total occlusion (CTO) in the target vessel * Target vessel is supplied by major collaterals or supplies major collaterals to a CTO * Target lesion involves the left main coronary artery * Prior history of coronary artery bypass grafting (CABG) to the target vessel, except if bypass graft is occluded * Previously known untreated severe valvular heart disease * Previously known left ventricular ejection fraction \<30% * Sustained ventricular arrhythmias * Patients who are currently pregnant (pregnancy testing will be performed as per standard cardiac catheterization laboratory protocol)