Japan Study of Distal Evaluation of Functional Significance of Intra-arterial Stenosis Narrowing Effect

Inclusion Criteria: * Age\>=20 years old. * Patient who can understand informed consent of the clinical study and signed the consent. * Patient who is adaptable to CAG and/or coronary revascularization * Patient who has evaluated stenotic lesion (stenosis\>50% in visual judgment) by CAG at main epicardial vessel and its branch or who suspected to have it. Exclusion Criteria: * Patient with known contraindications to Adenosine Triphosphate(ATP) and/or papaverine hydrochloride * Target vessel diameter\<=2.0mm * Lesion with Chronic Total Occlusion(CTO) (registration allowed if other branch has stenosis more than 50% in visual judgment) * Patient with temporary/permanent artificial pacemaker implantation, left bundle branch block, second-degree and third-degree atrioventricular block. * Acute Myocardial Infarction(AMI) patient * Patient who is disqualified for FFR and coronary revascularization by the investigator. * Lesion is disqualified for Percutaneous Coronary Intervention(PCI) by the investigator. * Patient who has critical valvular disease of heart. (moderate or severe Aortic valve stenosis(AS)/Aortic Regurgitation(AR)/Mitral Stenosis(MS)/Mitral Regurgitation(MR)） * Patient with a prior Coronary Artery Bypass Graft(CABG) on target vessel. * Patient with severe renal dysfunction. (serum creatinine\>=2.0mg/dl) * Patient on hemodialysis. * Body weight\>=200kg * Patient who needs ventricular assist device to ensure hemodynamic stability (heart rate\<50/min, SBP\<90mmHg) * Patient who expects to live less than 2 years at the registration * Patient with contraindications to an antithrombotic therapy or an anticoagulant therapy. * Patient who is poor compliance with drug treatment. * Patient who is allergic to contrast agent. * Left Ventricular Ejection Fraction(LVEF)\>=30% * Patient who has the history of PCI with Drug-Eluting Stent(DES) in recent 3 months before registration. * Patient who has the history of PCI with Bare Metal Stent(BMS) or Plain Old Balloon Atherectomy(POBA) in recent 1 year before registration. * Patient who has possibility of pregnancy, under breast-feeding and positive pregnancy test in 14days prior to the PCI. * Patients with inadequacy to join this clinical study. * Patient who has been enrolled any other clinical study.