Cardiac surgery associated acute kidney injury (CSA-AKI) has been recognized as the second most common cause of hospital acquired AKI. The development of CSA-AKI is independently associated with an increased risk of in-hospital death. There are currently no biomarkers that could identify patients at higher risk for AKI and current risk predictor scores that are based on clinical and demographic information are inadequate. Therefore, a diagnostic test for predicting AKI risk in this clinical context would assist clinicians to optimize surgical strategy and postoperative care to prevent CSA-AKI occurrence and improve patient outcomes.

The primary purpose of this study is to validate a panel of biomarkers identified in the discovery study (referred to as AKI-Sapere prognostic) to identify patients at risk for all stages of CSA-AKI.

Inclusion Criteria:

• Adult patients (>40 years) undergoing non-emergency (urgent or scheduled) cardiac surgery using cardiopulmonary bypass (CABG or combined CABG/valve).
• Patients must be able to understand English and be willing to sign informed consent.

Exclusion Criteria:

• Emergency surgery
• Off-pump coronary bypass grafting
• Aortic aneurysm repair
• Congenital heart disease repair
• Heart transplant or left ventricular assist device patient
• Severe heart failure (left ventricular ejection fraction <25%)
• Hemodynamic instability or requiring preoperative vasopressors or IABP
• Pre-existing kidney disease (eGFR <30 mL/min/1.73 m2) or renal transplantation.
• Presence of major active infection (chronic or acute, eg, sepsis, HIV, pneumonia)
• Chronic liver disease/cirrhosis
• Participation in an additional trial at the time of surgery or anytime within 30d of surgery where intervention could potentially alter renal health (unless in the control arm)

All subjects entered into this study will be patients at the participating institutions.