[Use of intravascular ultrasound for the assessment and treatment of left main disease]

: Left main coronary artery (LMCA) disease is a pathological condition of great clinical relevance due to its significant impact on both morbidity and mortality of patients with ischemic heart disease. Due to its bidimensional nature, angiography does not enable an accurate evaluation of the extension, distribution and morphology of LMCA disease. Intravascular ultrasound (IVUS) is the invasive imaging modality of choice for the evaluation of LMCA disease, due to its ability to accurately characterize atherosclerotic disease in all the segments of LMCA bifurcation (including LMCA ostium). IVUS is therefore useful in each step of LMCA procedures: (i) to assess stenosis severity and to evaluate the need for revascularization; (ii) to select the appropriate treatment strategy of LMCA bifurcation (e.g. single vs two stents); (iii) to guide all steps of percutaneous coronary intervention (PCI) (e.g. lesion preparation, decision of the landing zone, stent sizing, proximal optimization, side branch rewiring, kissing balloon); (iv) to optimize stent result (e.g. expansion, apposition, geographical miss, major dissections). Although data obtained from randomized clinical trials are limited, several meta-analyses and registry studies suggest the superiority of IVUS-guided LMCA PCI as compared with LMCA PCI guided by angiography alone in terms of mortality, non-fatal myocardial infarction, stent thrombosis, restenosis, and target lesion revascularization.