Preoperative Serum Cystatin C as a Predictor of Acute Kidney Injury after Thoracic Aortic Surgery with Deep Hypothermic Circulatory Arrest

 

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Introduction: Acute kidney injury (AKI) is a common complication following thoracic aortic surgery with deep hypothermic circulatory arrest (DHCA) being associated with increased mortality and morbidity. Currently, prediction of AKI with classical tools remains uncertain, but cystatin C has been suggested as a new biomarker for the detection of AKI in other patient populations. Therefore, it was the aim of the present study to evaluate the role of cystatin C in patients after DHCA.

Methods: In a prospective cohort study, 102 consecutive patients undergoing thoracic aortic surgery with DHCA at a single center were enrolled. Measurements of cystatin C in the blood were performed preoperatively and in the early postoperative course. Primary end point was the occurrence of AKI any stage according to the KDIGO classification.

Results: Mean age of patients was 69.1 ± 10.9 years, 35 patients were female (34%). Mean EuroSCORE II and STS-Score were 7.3 ± 7.4 and 3.7 ± 3.6, respectively. Twenty-eight patients (27%) met the primary end point with AKI any stage, 14 patients (14%) developed AKI 2 or 3, and 11 patients (11%) required renal replacement therapy (RRT). Patients with AKI had a higher incidence of bleeding and infectious complications, a prolonged intensive care unit stay (6.9 ± 7.4 vs. 2.5 ± 3.1, p < 0.001) as well as a higher 30-day mortality (9/28 vs. 1/74, p < 0.001) than patients without AKI. Preoperative cystatin C and serum creatinine were significantly higher in patients who developed AKI in the further course (creatinine: 126.8 ± 95.5 vs. 86.7 ± 28.4 µmol/L, p < 0.001; cystatin C: 1.8 ± 1.1 vs. 1.1 ± 0.3 mg/dL, p < 0.0001). Using ROC analyses, preoperative cystatin C showed a sensitivity (sens.) of 79.0% and a specificity (spec.) of 76.8% for predicting AKI any stage (area under the curve [AUC] 0.828, p < 0.001) being superior to the prognostic performance of serum creatinine (AUC 0.686, p = 0.002, sens. 42.9%, spec. 93.2%) in deLong testing (p = 0.0211). In addition, the predictive capacity of cystatin C for AKI stage 2/3, AKI with need for RRT, and 30-day mortality was very strong (AKI 2–3: AUC 0.933, p < 0.001, sens. 80%, spec. 95.5%; RRT: AUC 0.919, p < 0.001, sens. 85.7%, spec. 92.8%; 30-day mortality: AUC 0.887, p < 0.001, sens. 85.7, spec. 92.8%).

Conclusion: Cystatin C represents a sensitive and specific biomarker to predict AKI in patients undergoing thoracic surgery with DHCA. A single preoperative measurement of cystatin C allows identifying patients who develop postoperative AKI, especially those with severe AKI.