Preoperative vascular dysfunction is associated with acute kidney injury after cardiac surgery.

Background: Cardiac surgery-associated acute kidney injury (CSA-AKI) results in poor prognosis. Several risk factors for CSA-AKI have been reported, including preoperative creatinine level, cardiopulmonary bypass time, and perioperative blood pressure management. Only few studies have reported the effect of vascular stiffness on the incidence of CSA-AKI, and there are is no study reporting on endothelial function and its association with CSA-AKI. The purpose of this study was to evaluate the association between preoperative vascular function, including vascular stiffness and endothelial function, and incidence of CSA-AKI.

Methods: In this prospective observational study, 40 consecutive patients undergoing valve surgery were enrolled. Flow-mediated dilation (FMD) and pulse wave velocity (PWV) were measured before surgery for the evaluation of endothelial function and vascular stiffness. Blood test was also performed for the measurement of serum biomarkers including asymmetric dimethylarginine (ADMA) and vascular cell adhesion molecule-1 (VCAM-1). CSA-AKI was diagnosed by using the Kidney Disease Improving Global Outcomes (KDIGO) criteria.

Results: The mean age of the patients was 72±8.2 years old and 60% were male. All patients underwent valve surgery with two patients undergoing concomitant coronary artery bypass grafting. Preoperative FMD and PWV were 6.3%±2.58% and 1,554±386.6 cm/s respectively. ADMA and VCAM-1 were significantly correlated (r=0.50, P=0.001), and there was a significant correlation between FMD and ADMA (r=-0.42, P=0.007), and FMD and VCAM-1 (r=-0.42, P=0.007). Eleven patients (27.5%) developed CSA-AKI. FMD was lower in patients with CSA-AKI (no AKI: 6.9%±2.57% vs. AKI: 4.6%±1.77%, P=0.009) and PWV was higher in patients with CSA-AKI (no AKI: 1,467±296.4 cm/s vs. AKI: 1,784±506.7 cm/s, P=0.02). Further, VCAM-1 was higher in patients with CSA-AKI (no AKI: 696±247.5 ng/mL vs. AKI: 879±196.2 ng/mL, P=0.03). Multivariable analysis showed that preoperative FMD was an independent risk factor for CSA-AKI (odds ratio: 0.54, P=0.049).

Conclusions: VCAM-1, FMD, and PWV were associated with incidence of CSA-AKI. These measurements may be useful in evaluation of potential risk of CSA-AKI in patients undergoing valve surgery.