Acute kidney injury after heart valve surgery: Incidence and impact on mortality based on serum creatinine and urine output criteria

Background

The reported incidence of postoperative acute kidney injury (AKI) after cardiac surgery varies depending on the definition used. This study assessed the incidence and predictors of AKI and examined its association with clinical outcomes in patients undergoing heart valve surgery with the use of cardiopulmonary bypass (CPB).

Methods

We analyzed 4044 consecutive patients (mean age 60.1 ± 13.3 years; 1862 females) who underwent heart valve surgery between 2013 and 2021. Patients on hemodialysis or mechanical circulatory support and patients undergoing circulatory arrest were excluded. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Logistic regression analysis was performed to identify predictors of AKI and estimate its probability.

Results

AKI occurred in 1261 patients (31.2%), with KDIGO stage 1 the most prevalent (n = 791; 19.6%). Operative mortality was proportionately higher in patients with more severe stages of AKI (2.6% in stage 2% and 17.7% in stage 3). A total of 502 patients died during a median follow-up of 5.7 years. AKI stage 2 (hazard ratio, 2.01; P < .001) and stage 3 (hazard ratio, 4.31; P < .001) were significantly associated with an increased risk of mortality. Decreased renal function and prolonged CPB time were independent predictors of severe AKI (stage 2 or 3). The estimated risk of severe AKI due to CPB use showed distinct patterns stratified by preoperative renal function.

Conclusions

AKI occurs in 31.2% of patients after heart valve surgery, as defined by the KDIGO criteria. Severe AKI is associated with increased overall mortality. Prolonged CPB time is related to severe AKI, particularly in patients with preoperative renal dysfunction.