title: Pulse wave velocity and neutrophil gelatinase-associated lipocalin as predictors of acute kidney injury following aortic valve replacement.
abstract: BACKGROUND
  Accurate prediction, early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes. This study aimed to examine the role of aortic stiffness and neutrophil gelatinase-associated lipocalin (NGAL) as predictors of AKI or need for early medical renal intervention following aortic valve replacement (AVR).
  
  
  METHODS
  Aortic pulse wave velocity and plasma NGAL were measured pre-operatively in recruited patients undergoing AVR for aortic stenosis (AS). Plasma NGAL was also measured at 3 and 18-24 hours after cardiopulmonary bypass (CPB). AKI was defined using RIFLE criteria. Early medical renal intervention included diuretics or dopamine infusion exclusively for renal causes.
  
  
  RESULTS
  Fifty-three patients aged 71 ± 9 years were included. Sixteen (30%) developed AKI (AKI-Yes) and 24 patients (45%) received early medical intervention (Intervention-Yes). There was no significant difference in the demographic, clinical or operative characteristics between the two groups for either outcome. PWV did not significantly correlate with AKI (r = 0.12, P = 0.13) or early intervention (r = 0.18, P = 0.18). At 3 h post-CPB, plasma NGAL was a much stronger predictor of both AKI and the need for early medical intervention than conventional markers such as creatinine (AKI: AUC 83%, 95% CI 0.70-0.95 vs. AUC 65%, 95% CI 0.47- 0.82; Medical intervention: AUC 84%, 95% CI 0.72-0.96 vs. AUC 56%, 95% CI 0.38-0.73). Post-CPB (3 hr) plasma NGAL was also significantly associated with AKI (r = 0.68, P < 0.001) at levels above 150 ng/ml; and significantly associated with early intervention (r = 0.64, P < 0.001) above 136 ng/ml. Simple linear regression showed no relationship between PWV and NGAL levels.
  
  
  CONCLUSIONS
  Aortic PWV does not correlate significantly with post-operative AKI or plasma NGAL levels in surgical AS patients. Post-operative NGAL is however an early and powerful predictive biomarker of both post-operative AKI and the need for early medical renal intervention and should consequently be considered in prediction models for AKI after cardiac surgery.
authors.forename: Emaddin
authors.initials: E
authors.lastname: Kidher
authors.affiliation: The Department of Surgery and Cancer, Imperial College London, St Mary's Hospital, 10th Floor, QEQM Wing, St Mary's Hospital, Praed Street, London W2 1NY, UK. leanne.harling00@imperial.ac.uk.
authors.forename: Leanne
authors.initials: L
authors.lastname: Harling
authors.forename: Hutan
authors.initials: H
authors.lastname: Ashrafian
authors.forename: Hatam
authors.initials: H
authors.lastname: Naase
authors.forename: Andrew
authors.initials: A
authors.lastname: Chukwuemeka
authors.forename: Jon
authors.initials: J
authors.lastname: Anderson
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.forename: Thanos
authors.initials: T
authors.lastname: Athanasiou
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D000209:Acute-Phase Proteins; D000368:Aged; D001013:Aorta, Thoracic / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000601:surgery; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity / Q000502:physiology*; D042241:Early Diagnosis; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood*; D008297:Male; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000097:blood*; D063177:Pulse Wave Analysis / Q000379:methods*; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins