This study is a multicenter, large clinical registry to evaluate comparative outcomes of medical therapy, PCI with DES, or CABG for patients with unprotected LMCA stenosis in the Asia-Pacific, as recorded in the MAIN-IRIS Registry. Data will be prospectively collected on approximately 5000 subjects who diagnosed LM disease (>50% by visual estimation) at approximately 65 centers in Korea and Asia-Pacific region. Brief study design is as depicted in the following figure