Safety and Efficacy Study of Cilostazol to Treat Vasospastic Angina

Inclusion Criteria: 1. Male or female subjects aged 20 to 80 years, and subjects whose age at the time of enrollment was 80 in 021-KOA-1301i clinical trial and is 81 in this clinical trial 2. Subjects who completed 021-KOA-1301i clinical trial 3. Women of childbearing potential with negative pregnancy test at enrollment and who agree to practice a contraceptive measure throughout the clinical trial (e.g., hormonal contraceptives, intrauterine devices, condom + spermicidal agents, diaphragm + spermicidal agents, and partner's infertility) 4. Subjects who signed a written agreement indicating that they were given full explanations of the clinical trial and are willing to participate in the clinical trial Exclusion Criteria: 1. Subjects who fell under one of the exclusion criteria at the time of enrollment for 021-KOA-1301i 2. Subjects who reported any of the following events, which fall under the exclusion criteria for KOA-1301i, between the initiation of 021-KOA-1301i participation and enrollment visit for 021-KOA-1302i * Myocardial infarction or myocardial infarction induced by vasospastic angina * Life-threatening vasospastic episodes (e.g., ventricular tachycardia, ventricular fibrillation, or syncope) * Stroke, intracranial hemorrhage, or transient ischemic attack (TIA) * Hemorrhage (hemophilia, capillary fragility, intracranial hemorrhage, upper gastrointestinal bleeding, urinary tract bleeding, hemoptysis, vitreous hemorrhage, etc.) 3. Subjects who are currently using any of the medications contraindicated in 021-KOA-1301i (excluding the investigational product of 021-KOA-1301i) at baseline 4. Subjects who meet the following criteria for baseline laboratory findings * severe anemia with hemoglobin ≤6.5 g/dl at baseline * Creatinine level ≥ 1.5 mg/dL at baseline * AST or ALT \>3x ULN at baseline * Platelet count \< 100,000mm3 at baseline 5. Pulse rate exceeding 100 bpm when measured for vital signs at baseline: Tachycardia 6. Hypotension with systolic pressure \< 90mmHg at baseline 7. Uncontrolled hypertension defined as systolic pressure ≥ 160 mmHg or diastolic pressure ≥ 100 mmHg at baseline 8. QT prolongation defined as QTcB \> 450 msec for men and QTcB \> 470 msec for women at baseline 9. Women of childbearing potential with positive pregnancy test at baseline 10. Women who do not agree to practice a contraceptive measure, or are pregnant or lactating 11. Subjects who are not expected to have the potential to benefit from additional administration of Cilostazol, according to the investigator's judgment 12. Subjects otherwise judged by the investigator to be inappropriate for inclusion in the trial