European Bifurcation Club 2019, EBC 2019 - Barcelona, Spain CORONARY BIFURCATION IMAGING A randomized trial evaluating on line three dimensional of guided pci vs angiography guided pci in bifurcation lesions: optium study Author: Yoshinobu Onuma, MD, PhD, Erasmus Medical Center, The Netherlands BACKGROUND In bifurcation PCI, re-crossing the distal cell with a wire after main vessel stenting is important to avoid creating a de novo metal carina1. Those protruded/malapposed struts result in lower tissue strut coverage of the side branch ostium and more overhanging metal into the main branch after implantation of the stent. Angiography guided PCI is limited in recognizing the recrossing position, while intracoronary imaging during PCI has a potential to visualize the recrossing point and to optimize the acute results.  The feasibility of off-line 3-dimensional optical frequency domain imaging (OFDI) in bifurcation and its potential benefits were demonstrated in retrospective studies. However, the feasibility and efficacy of on-line 3D OFDI guided PCI in bifurcation lesion has not yet been fully investigated. OBJECTIVE To determine whether bifurcation PCI guided by on-line 3D- OFDI is superior to bifurcation PCI with angiographic guidance in terms of incomplete stent apposition (ISA) in bifurcation segment. CONCLUSION In the randomized trial of bifurcation PCI, 3D-OFDI guidance was superior to angio-guidance in acute incomplete strut apposition (creation of metal carina) of bifurcation segment (3D-OFDI 19.5±15.8% vs. angio: 27.5%±14.2%, p=0.008). Excellent feasibility of online 3D-OFDI was demonstrated (98%). After mandatory POT, the first wiring position was not optimal in 45% of cases, requiring 2nd attempt to redirect the wire into the optimal cell when 3D-OFDI guidance was used. On-line 3D OFDI images help operator to undergo rewiring to the optimal cell, resulting in a lower rate of malapposition compared with angiography guided PCI.