One of the major complications of heart surgery is kidney injury, which occurs in up to 30% of patients and is associated with poor outcomes including death. We have found that patients whose hemoglobin concentration before surgery is lower than normal (i.e., are anemic) are at particularly high risk for this complication, likely because their hemoglobin concentration drops to very low levels during surgery, which reduces delivery of oxygen to the kidneys, increases blood loss, and necessitates blood transfusions. We and others have shown that these events are individually harmful to the kidneys, and can lead to kidney injury. We believe that we can prevent these events from occurring, and as a result reduce the risk of kidney injury, if we transfuse anemic patients at least 1 day before surgery rather than during surgery.

In anemic patients undergoing cardiac surgery, prophylactic transfusion of red blood cells (RBCs) before surgery will reduce the risk of acute kidney injury (AKI) after surgery by mitigating three inter-related risk factors for AKI.

Inclusion Criteria:

• Patients undergoing non-emergent aortocoronary bypass (ACB) surgery, or valve surgery, combined ACB and valve, or aortic root repair requiring CPB with a preoperative Hb concentration between 100 and 120 g/L.

Exclusion Criteria:

• Any conditions that may limit the ability of patients to tolerate the intervention:
• Severe aortic or mitral valve stenosis
• History of congestive heart failure within 30 days of surgery or severe ventricular dysfunction (ejection fraction < 30%)
• Severe (> 60%) left main coronary artery stenosis or unstable angina within 30 days of surgery