Observational Study for Left Main Disease Treatment

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