Increase of urinary TIMP-2 and IGFBP7 as potential predictor of acute kidney injury requiring renal replacement therapy and patients' outcome following complex endovascular and open thoracic abdominal aortic aneurysm surgery - a prospective observational study.

Background: Acute kidney injury (AKI) as complication after open and endovascular repair of thoracoabdominal aortic aneurysm (TAAA) is one major predictor of mortality and postoperative complications. We evaluated tissue inhibitor of metalloproteinase 2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) as combined early biomarker for AKI detection and predictor of patients' outcome. Patients and methods: Between 2014 and 2015, 52 patients have been enrolled in this observational study, of whom 29 (55.8%) underwent elective open repair and 23 (44.2%) endovascular repair. TIMP2 × IGFBP7 were measured until 48 hours after admission on intensive-care unit (ICU) and were analyzed regarding their predictive ability for AKI (defined according to the KDIGO criteria) requiring temporary renal replacement therapy (RRT) and 90-day mortality using ROC curves. Results: Mean patient age was 64.5 years (Min: 43, Max: 85), endovascular treated patients were older (p <0.0001). 40.4% (n = 21) developed AKI, and 21.2% (n = 11) required renal replacement therapy. In-hospital and total mortality rates were 7.7% (n = 4) and 9.6% (n = 5), respectively. At no time a significant difference in TIMP2 × IGFB7 levels between patients undergoing open or endovascular surgery was observed. The predictive quality of the TIMP2 × IGFBP7 value on ICU admission was sound regarding AKI requiring temporary renal replacement therapy (sensitivity: 55.56% [38.1-72.1%], specificity: 90.91% [58.7-99.8%] with an area under the curve [AUC]: 0.694 [0.543-0.820]). Mean follow-up was 13.2 months (Min: 2, Max: 20), regarding the 90-day mortality, the predictive property of the TIMP2 × IGFBP7 value was not sufficient (sensitivity: 80% [28.4-99.5%], specificity: 52.38% [36.4-68%], and AUC: 0.607 [0.454-0.746]). Conclusions: TIMP2 × IGFBP7 level measured 6-12 hrs postoperatively may be useful as an early detectable biomarker for AKI requiring temporary renal replacement therapy. It seems not suited to predict patients' outcome following complex thoracoabdominal aortic surgery, regardless if performed by open or endovascular repair.