Thorac Cardiovasc Surg 2012; 60 - V166
DOI: 10.1055/s-0031-1297556

Increase of Neutrophil gelatinase-associated Lipocalin and Cystatin C after cardiac surgery – new options for detecting acute kidney injury

H Baumgarten 1, C Liebetrau 2, A Van Linden 1, B Njezic 1, T Walther 1, HM Nef 2, C Hamm 2
  • 1Kerckhoff Klinik, Herzchirurgie, Bad Nauheim, Germany
  • 2Kerckhoff Klinik, Kardiologie, Bad Nauheim, Germany

Objectives: Acute kidney injury (AKI) is a common complication after cardiac surgery with incidence up to 20%. Neutrophil gelatinase-associated lipocalin (NGAL) represents an early biomarker for the prediction of AKI. However, existing data are varying (AUC values ranging from 0.67 to 0.87) for the prediction of CSA-AKI.

Therefore, the aim of the present study is to examine whether a rise of urinary NGAL-levels after cardiac surgery predicts subsequent AKI.

Methods: 141 consecutive patients undergoing cardiac surgery using cardiopulmonary bypass (CPB) were included into the study. Samples for measurement of urinary NGAL were collected before as well a 4–6 hours and 3–4 days after surgery. The samples were stored at –80°C until analysis.

Results: AKI was observed in 15 patients (10.6%) after cardiac surgery. Baseline NGAL levels were higher in patients with AKI (22.5 [8.9–45.7] vs. 7.2 [2.9–15.9]; p=0.024). There was no difference in standard baseline characteristics (creatinine, blood urea nitrogen (BUN) and glomerular filtration rate (GFR)) between patients with and without AKI. In patients with AKI NGAL levels rise significantly at 2–4 hours postoperatively (22.5 [8.9–45.7] (baseline) vs. 84.4 [40.5–262.7] (postoperative); p<0.001) and correlated with the duration of CPB (R=0.294, p=0.002) and GFR (R=-0.28, p=0.029). NGAL was an independent predictor of AKI with an area under the receiver-operating characteristic curve (AUC) of 0.884 for the 2–4-h NGAL measurement. The mortality rate among patients with AKI at six months follow-up was 20% versus 2.4% (LogRank 6.68; p=0.01, multivariate Cox-Regression analysis 95% CI 1.27–31.40; p=0.024) in patients without AKI.

Conclusions: AKI is related to higher mortality rates during 6 month follow-up. Urinary NGAL represents a biomarker for the very early postoperative detection of AKI as well as for potential preoperative screening of patients at increased risk for AKI. The early treatment of AKI after cardiac surgery may prevent morbidity and mortality.