 FD-OCT St. Jude Medical ILUMIEN OCT System will be performed in all the three main epicardial coronary arteries prior to target vessel PCI after administration of glyceryl trinitrate. Data will be acquired in a designated, secure compute and sent to a corelab for analysis. Quantitative measurements will include endoluminal area, plaque area, as well as plaque parameters including thin- capped fibroatheromas TCFA, fibrous tissue, lipid core and calcium. TCFA will be defined by lipid-rich plaque with cap thickness 65μm. 