Evaluation of Effectiveness and Safety of Antegrade and Retrograde Approach of Percutaneous Coronary Intervention for Chronic Total Occlusions

Inclusion Criteria:

• Patients aged>=19

• Patients who have a CTO lesion in at least one or more epicardial coronary artery 2.5 mm in blood vessel diameter

• Patients who have symptoms of angina or objectively proven myocardial ischemia (asymptomatic myocardial ischemia, stable or unstable angina, non - -ST-segmentelevation myocardial infarction)

• Patients who voluntarily agreed to the protocol and the clinical follow-up plan (orlet their representative do this), and signed the informed consent form approved bythe IRB of each study institute

Exclusion Criteria:

• Patients who are pregnant or lactating or have childbearing potential Patients inwhom contrast medium and heparin are contraindicated or who are hypersensitive tothem

• Patients in whom aspirin, clopidogrel, ticagrelor and prasugrel, cilostazol arecontraindicated

• Patients scheduled to undergo a surgery, etc. that requires discontinuance of anantiplatelet drug within 12 months after participation in the study

• Acute ST elevation myocardial infarction at the time of hospitalization

• Terminally ill patients with their life expectancy < one year

• Patients who have serious diseases other than cardiac diseases that may affectlimitation of residual life time or observation of the protocol (e.g.oxygen-independent chronic obstructive pulmonary disease, persisting hepatitis orserious hepatic insufficiency, severe renal disease, etc. Be left up to thediscretion of the investigator.)