The purpose of this study is to observe clinical courses for long-term in patients with unprotected LMCA disease and to evaluate comparative results of medical treatment, coronary stenting with drug-eluting stents, and CABG for the treatment of an unprotected LMCA stenosis in the "real world" daily practice.

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

Inclusion Criteria:

• Significant unprotected left main stenosis (>50% by visual estimation)

  • The LMCA is considered unprotected if there are no patent coronary artery bypass grafts to the left anterior descending artery or the left circumflex artery.

• No limitation of clinical or lesion characteristics

• Age >18 years

• The patient or guardian agrees to the study protocol and the schedule of clinical follow-up, and provides informed, written consent, as approved by the appropriate Institutional Review Board/Ethics Committee of the respective clinical site.

Exclusion Criteria:

• Protected left main stenosis

Consecutive patients with unprotected LMCA diseases at participating centers will be evaluated for the entry into the study.

This is not a publicly funded trial