Safety and Efficiency Study of Loading Dose Atorvastatin in Cardiac Surgery

• acute kidney injury [ Time Frame: 72 hours after surgery ] [ Designated as safety issue: No ]
  Proportion developing AKI using AKIN criteria(stage 1,stage 2, stage3).we plan to measure serum creatinine in baseline, ICU admission,postoperative 6h、Day 1、Day 2 and Day 3.If multiple SCr was measured in one day ,then the highest value will be recorded.Also, we measure creatinine clearance via Cock-croft-Gault formula.
  
  

• Change of inflammatory biomarkers [ Time Frame: 48h after surgery ] [ Designated as safety issue: No ]
  we plan to measure IL-6,IL-10,TNF-α and hsCRP at 6 time points: before surgery、after chest closure、postOp.6h、12h、24h and 48h.Compare levels of cytokines between the two arms
  
  
• Requirement of renal replacement therapy [ Time Frame: participants will be followed for the duration of hospital stay , an expected average of 2 weeks ] [ Designated as safety issue: No ]
  proportion need renal replacement therapy in hospital
  
  
• liver function [ Time Frame: participants will be followed for the duration of hospital stay , an expected average of 2 weeks ] [ Designated as safety issue: Yes ]
  liver dysfunction defined as transaminase>3UNL normal level
  
  
• death [ Time Frame: 30 days after discharge from hospital ] [ Designated as safety issue: No ]
  
• MACCE events [ Time Frame: 30 days after discharge from hospital ] [ Designated as safety issue: No ]
  
• length of stay in intensive care unit [ Time Frame: From admission to discharge from ICU ] [ Designated as safety issue: No ]
  An average of 2 days
  
  
• length of stay in hospital after surgery [ Time Frame: From surgery to discharge from hospital, an expected average of 7 days ] [ Designated as safety issue: No ]
  

Acute kidney injury occurs up to 30% in cardiac surgery which influenced patients' mid-term and long-term outcomes. Furthermore, evidence shows patients who initiate renal placement therapy in hospital have higher mortality and morbility. The pathologies of Cardiac surgery-associated acute kidney injury (CSA-AKI) is not clear yet ,many researches find cardiopulmonary bypass is an independent risk factor in developing AKI, and inflammatory bursts during cardiopulmonary bypass (CPB) may play an important role in CSA-AKI.

Statins are reported to have anti-inflammatory reaction in many researches. In Some multicenter RCTS, Statins are reported to reduce myocardial infarction,atrial fibrillation and have renoprotective effects due to pleiotropic effects in percutaneous coronary intervention. While in the cardiac surgery settings, the renoprotective effect of statin is still controversial. The investigators believe the differences between surgery and PCI may contribute to the discrepancy. The investigators plan to test the renoprotective effect of atorvastatin in a randomized,double-blind control manner and try to explore the mechanism of this protective effect.

The investigators hypothesise loading dose atorvastatin pretreatment in elective coronary artery bypass grafting surgery may attenuate inflammatory response in CPB and therefore reduce postoperative AKI or help recovery from AKI.

The investigators randomize patients into two arms, the Atorvastatin group takes Atorvastatin 80mg 12h before surgery with another 40mg 2h before operation, the control arm takes placebo in the same regime. The investigators plan to compare the inflammatory cytokines at different time points and the incidence of AKI between the two groups. The investigators hope Atorvastatin group can decrease AKI incidence and has a lower level of inflammatory cytokines, what's more, the two have a good correlation in the time frame.