LEMON aim is to evaluate the feasibility, efficiency and security of a standardized Optical Coherence Tomography (OCT) - guided protocol for completion and optimization of Left Main (LM) Percutaneous Coronary Intervention (PCI).

The LEMON study (LEft Main Oct-guided iNterventions) is a prospective, multicentre, open-label, interventional , non-randomized trial that investigates the feasibility and efficiency of OCT guidance for left main PCI in 10 active French interventional cardiology centres. The aim of the study is the appliance of a pre-defined standardized protocol for LM PCI . The LM PCI strategy is guided by 3 OCT runs, according to a pre-determined protocol. The first OCT run (run1) is performed before any stent implantation, the second run (run2) is performed after the stent is implanted, POT (proximal optimization technique) is applied and side branch iss rewired through stent struts. The third run (run3) is performed after PCI optimization. In case of additional stent optimization, a supplementary OCT run is applied in order to assess final result.

Inclusion Criteria:

• age >18
• stable or non-stable distal Left Main lesion (with or without previous Coronary Artery Bypass Graft), involving or not Left Anterior Descending and Coronary Circumflex ostias and requiring Percutaneous Coronary Intervention with a one or two stents strategy
• stable or non-stable ostial Left Anterior Descending and/or Coronary Circumflex lesion requiring Percutaneous Coronary Intervention with involvement of distal Left Main
• SYNTAX angiographic score <23
• informed consent

Exclusion Criteria:

• ostial Left Main lesion
• on-going acute STEMI
• on-going cardiogenic shock
• severe chronic renal failure (Cr Cl <30 ml/min/m2)
• anticipated technical contra-indication to OCT (highly calcified lesions, severe proximal tortuosity)