Nicorandil-CKD study

INTERVENTION: Patient were divided into 2 groups, the saline group and Nicorandil group. In both group, saline was infused 1ml/kg/h 4 hours prior to PCI and after 20hours. To Nicolandil group, Nicolandil was infused at 0.096mg/kg/hr 4hours prior to PCI and after 20hours. CONDITION: coronary artery disease PRIMARY OUTCOME: Incidences of CIN during 1 month SECONDARY OUTCOME: Percent rise in serum creatinine; Percent rise in estimated GFR INCLUSION CRITERIA: Patients who subsequently undergo PCI and who had higher cystatin C level than normal cyctatin C level(male 0.95mg/L, female 0.8mg/L).