DEFINE PCI: Physiologic Assessment of Coronary Stenosis Following PCI

• Subject must be \> 18 years old

• Subjects presenting with stable angina, silent ischemia or non-ST-elevation ACS (acute coronary syndrome) (unstable angina or biomarker positive)

• Single vessel CAD with at least 2 separate lesions (≥10 mm apart) of ≥40% stenosis or a single long lesion of ≥20mm OR multi-vessel CAD, defined as at least 2 vessels with ≥40% stenosis

• Pre-PCI iFR performed in all vessels intended for PCI

• Pre-PCI iFR of \<0.90 of at least 1 stenosis

• Subjects are able and willing to comply with scheduled visits and tests and to provide informed consent.