Mild acute kidney injury is associated with increased mortality after cardiac surgery in patients with eGFR < 60 mL/min/1.73 m(2).

BACKGROUND: A small increase in serum creatinine after cardiac surgery has been associated with increased mortality. However, it is unclear whether this association varies with baseline renal function. METHODS: We retrospectively reviewed data on 1359 patients who underwent cardiac surgery over a 4-year period in two tertiary care hospitals including demographic data, comorbid conditions, and intra- and postoperative complications using a standardized form. We followed patients for 90 days postoperatively and death rates and length of hospital stay were noted. RESULTS: The incidence of acute kidney injury (AKI) after cardiac surgery was 40.2%. Patients were grouped into terciles based on change in serum creatinine. Kaplan-Meier survival analysis and Cox regression analysis showed that the development of AKI with a small increase in serum creatinine of more than 0.3 mg/dL from baseline (tercile 3) was associated with a higher risk of mortality within 90 days and 7 days longer hospitalization following a cardiac surgery. Stratified analysis showed that only patients with baseline eGFR < 60 mL/min/1.73 m (2) had fivefold higher mortality with rise of serum creatinine >0.3 mg/dL. CONCLUSIONS: Patients with baseline eGFR < 60 mL/min/1.73 m(2) had increased risk of mortality after cardiac surgery with a small increase in serum creatinine whereas a similar increase in serum creatinine in those with eGFR ≥ 60 mL/min/1.73 m(2) did not increase mortality.

Preoperative use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers is associated with increased risk for acute kidney injury after cardiovascular surgery.

BACKGROUND AND OBJECTIVES: Acute kidney injury (AKI) occurs commonly after cardiac surgery. Most patients who undergo cardiac surgery receive long-term treatment with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARB). The aim of this study was to determine whether long-term use of ACEI/ARB is associated with an increased incidence of AKI after cardiac surgery. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a retrospective cohort study of 1358 adult patients who underwent cardiac surgery between January 1, 2001, and December 31, 2005, in two tertiary care hospitals in Buffalo, NY. The incidence of AKI was determined after cardiac surgery. Clinical data were collected using a standardized form that included comorbid condition, use of ACEI/ARB, and intraoperative and postoperative complications. RESULTS: Overall, 40.2% of patients developed AKI. Preoperative variables that were significantly associated with development of AKI included increasing age; nonwhite race; combined valve surgery and coronary artery bypass grafting compared with coronary artery bypass grafting alone; American Society of Anesthesiologists (ASA) Risk Score category 4/5 compared with 2 to 3; presence of diabetes, congestive heart failure, or neurologic disease at baseline; use of ACEI/ARB; and emergency surgery. Intra- and postoperative factors that were associated with postoperative AKI were hypotension during surgery, use of vasopressors, and postoperative hypotension. Multiple regression logistic model confirmed an independent and significant association of AKI and preoperative use of ACEI/ARB. This was confirmed using a bivariate-probit and propensity score model that adjusts for confounding by indication of use and selection bias. CONCLUSIONS: Preoperative use of ACEI/ARB is associated with a 27.6% higher risk for AKI postoperatively. Stopping ACEI or ARB before cardiac surgery may reduce the incidence of AKI.