Current concepts of optical coherence tomography assessment of left main coronary artery during coronary interventions

Conventional angiography is poor in assessing type of plaque, plaque volume, disease extent, severity and features associated with optimization of percutaneous coronary intervention (PCI), whereas Intra-Vascular Ultra-Sound (IVUS) and optical coherence tomography (OCT) overcome these limitations by providing cross sectional images of vessel wall, and longitudinal extent of disease. OCT provides high-resolution images at the cost of limited penetration compared with IVUS with an axial spatial resolution of 10–20 μm versus 100–200 μm, lateral resolution of 20 μm versus 200 μm, and penetration depth 1–2.5 mm versus 10 mm, respectively. OCT measurements were proved to be nearer to the actual luminal areas whereas IVUS measurements were overestimated and were less reproducible in the phantom model. OCT and IVUS are proved to be a valid guidance for optimization of PCI. However, usefulness of OCT in day to day practice is very limited in the assessment of Left Main disease. Both imaging technologies have different distinct features, these are complementary and should be opted carefully for each patient based on pros and cons, and clinical indications of each technique.