Patients who diagnosed obstructive coronary artery disease and treated by DES with FFR examination would be enrolled, consecutively. FFR measurement would be required at the baseline and at the end of index PCI procedure. PCI procedure would be performed upon local routine. Any available DES could be used. Informed consent should be obtained and protocol should be approved by each collaborator's institutional review board (IRB). Web-based electronic-case record form (CRF) system will be used for collecting data. All data will be handled and analyzed by blind fashion at independent core lab. Patient will be followed-up at each collaborator's hospital at least 2 year after index procedure. Any adverse event will be reported and addressed immediately by appropriate medical treatment to protect patient.