Risk factors of acute kidney injury after heart valve surgery in elderly patients and their impact on prognosis

Abstract:

Objective To investigate the risk factors of acute kidney injury（AKI） after heart valve surgery in elderly patients ≥ 65 years old and their effects on prognosis.Methods A retrospective analysis was performed on elderly patients aged 65 years and above who underwent heart valve surgery in Guangdong Provincial People's Hospital from January 2013 to May 2014. The patients who received renal replacement therapy before surgery and whose serum creatinine value was missing were excluded，and the selected cases were recorded. The preoperative，intraoperative，and postoperative clinical data were collected，and regular telephone follow-up was conducted. The primary endpoint was the incidence of AKI，and the secondary endpoint was follow-up mortality. Patients were divided into AKI group and control group according to whether they complicated with stage ≥ 2 AKI. Univariate analysis and logistic regression multivariate analysis were used to explore the risk factors of postoperative AKI，Kaplan-Meier survival analysis was used to show the effect of AKI on follow-up death，and multivariate Cox regression model was used to analyze the risk factors of postoperative follow-up death.Results A total of 225 patients were included in this study，including 110 women（58.89%），and the incidence of AKI was 26.22%（n=59）. The in-hospital mortality in the AKI group was significantly higher than that in the control group（13.6% and 0.0%，P<0.001）. The longest follow-up time was 9 years，and the follow-up mortality in the AKI group was significantly higher than that in the control group（42.4% and 9.6%，P<0.001）. Kaplan-Meier survival analysis showed that the follow-up mortality in the AKI group was significantly higher than that in the control group（P<0.001）. Univariate and logistic regression multivariate analysis showed that the independent risk factors for postoperative AKI were lower preoperative platelet count（OR=0.99，P=0.011） and larger amount of perioperative red blood cell transfusion（OR=1.11，P<0.001）. Univariate and multivariate Cox regression model analysis showed that the risk factors for follow-up death were lower preoperative albumin level（HR=0.90，P=0.028），use of intra-aortic balloon pump（HR=7.38，P=0.003） and postoperative AKI（HR=2.88，P=0.006）.Conclusion Lower preoperative platelet count and larger amount of perioperative red blood cell transfusion might increase the risk of AKI after heart valve surgery in elderly patients ≥ 65 years old，and postoperative AKI could increase in-hospital mortality and follow-up mortality.