Intravascular ultrasound-guided percutaneous coronary intervention in left main coronary bifurcation lesions: a review Michael Jansen Sulaiman, Shao-Liang Chen Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China Abstract: Drug-eluting stent (DES) intervention is now emerging as an alternative approach for unprotected left main coronary artery (ULMCA) other than coronary artery bypass graft (CABG). Untreated left main (LM) coronary occlusion is always associated with poor prognosis and high mortality rate. Collective data from numerous worldwide registries and results from randomized Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) trial demonstrated that percutaneous coronary intervention (PCI) of ULMCA is a viable alternative in selected patient groups. Intravascular ultrasound (IVUS) provides valuable luminal and plaque details of coronary lesion, which enable precise lesion severity assessment compared to angiographic assessment. IVUS is important to assess intermediate lesion severity, optimizing stent deployment in complex lesions; therefore, reducing poststenting complication has been shown to improve acute procedural result and subsequent clinical outcomes. In the current review, we aimed to focus on the role of IVUS in LM coronary bifurcation lesions. Keywords: intravascular ultrasound, left main coronary artery, bifurcation, ostial lesion, mid-shaft lesion, crush techniques