title: Evaluation of Cystatin C as a marker of renal injury following on-pump and off-pump coronary surgery.
abstract: OBJECTIVE
  Cardiopulmonary bypass is regarded as an important contributor to renal injury, whereas off-pump surgery is considered less damaging. Cystatin C, a cystine protease inhibitor, is more sensitive and specific than creatinine in the assessment of renal function. We assessed the value of Cystatin C in quantifying clinical and subclinical renal injury following on-pump and off-pump cardiac surgery.
  
  
  METHODS
  Sixty consecutive patients were recruited: 30 patients undergoing on-pump CABG and 30 patients undergoing off-pump CABG. Blood samples were collected pre-operatively and on days 1, 2 and 4 postoperatively to measure serum creatinine and serum Cystatin C. Urinary samples were collected concurrently to measure microalbumin and N-acetyl-beta-glucosaminidase, denoting changes in renal glomerular and tubular function respectively.
  
  
  RESULTS
  The off-pump group were older (65+/-11 vs. 61+/-8 years; P=0.046), had a higher mean Parsonnet score (9.4+/-6.2 vs. 5.4+/-3.6, P<0.01) and received fewer grafts (2.4+/-0.9 vs. 3.1+/-0.7; P<0.01) compared to the on-pump group. The groups were otherwise matched with respect to preoperative renal function and left ventricular function. Patients undergoing on-pump CABG had greater increases in all four parameters of renal injury. Adjustment for preoperative differences increased the size and significance of the effect of off-pump vs. on-pump surgery (percent difference 13%; 95% CI 2-26 for creatinine, and 16%; 95% CI 4-29 for Cystatin C). Cystatin and creatinine were strongly correlated with each other.
  
  
  CONCLUSIONS
  Avoidance of cardiopulmonary bypass may reduce renal injury particularly in higher risk patients. Cystatin C proved to be a simple and sensitive measure of overall renal function and can be used in the routine assessment of renoprotective strategies.
authors.affiliation: Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford OX3 9DU, UK.
authors.forename: Yasir
authors.initials: Y
authors.lastname: Abu-Omar
authors.forename: Shafi
authors.initials: S
authors.lastname: Mussa
authors.forename: Madhava J
authors.initials: MJ
authors.lastname: Naik
authors.forename: Noel
authors.initials: N
authors.lastname: MacCarthy
authors.forename: Sue
authors.initials: S
authors.lastname: Standing
authors.forename: David P
authors.initials: DP
authors.lastname: Taggart
mesh_terms: D000368:Aged; D000419:Albuminuria; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects; D003327:Coronary Disease / Q000097:blood / Q000601:surgery*; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011184:Postoperative Period; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D003404:Creatinine