Acute kidney injury after cardiac surgery is a major complication after cardiac surgery and has been reported to be associated with adverse outcome. There have been many studies reporting risk factor of acute kidney injury after cardiac surgery, but the influence of perioperative variables related to anesthesia and perioperative medication has not been evaluated fully. The investigators attempt to evaluate the influence of perioperative clinical variables including preoperative medication, preoperative albumin level, uric acid concentration, anesthesia technique, use of hydroxyethyl starch, blood glucose level, intraoperative medication, perioperative cardiac function (systolic and diastolic function) and hemodynamic variables during surgery on the incidence of acute kidney injury after coronary artery bypass graft.

Acute kidney injury (AKI) after cardiac surgery is a major complication after cardiac surgery and has been reported to be associated with adverse outcome. There have been many studies reporting risk factor of acute kidney injury after cardiac surgery, but the influence of perioperative variables related to anesthesia and perioperative medication has not been evaluated fully. The investigators attempt to evaluate the influence of preoperative medication, preoperative albumin level, uric acid concentration, NL ratio, anesthesia technique, use of hydroxyethyl starch, blood glucose level, intraoperative medication, perioperative cardiac function (systolic and diastolic) and hemodynamic variables during surgery on the incidence of acute kidney injury after coronary artery bypass graft. Preoperative and postoperative diastolic dysfunction may be associated with postoperative AKI. In addition, preoperative neutrophil-lymphocyte ratio (NLR) which has been reported to be a marked for systemic inflammation and was associated with prognosis in cardiac patients undergoing coronary artery bypass graft or percutaneous coronary intervention. This preoperative or immediate postoperative NLR might be able to predict AKI after coronary artery bypass surgery.

Inclusion Criteria:

• patients who underwent coronary artery bypass surgery during between 2010 and 2012 in Samsung Medical Center

Exclusion Criteria:

• lack of postoperative creatinine or urine output data
• patients who expired within 24hours after surgery

patients who underwent coronary artery bypass surgery during between 2010 and 2012 in Samsung Medical Center