The Auto-PLTS Study is a single-centre trial performed at Toronto General Hospital (TGH) that uses a randomized, patient preference design. The recent introduction of cold-stored platelets with a shelf-life of 14 days into clinical practice has made it possible to offer autologous apheresis platelet predonation to patients undergoing elective cardiac (and other high-blood-loss) surgeries while allowing sufficient time to recover platelet count before surgery. The Auto-PLTS Study is designed to assess whether replacing allogeneic platelets with autologous platelets will improve patient outcomes and benefit the healthcare system by reducing the burden on allogeneic platelet supply. The study is also designed to determine whether patients are willing to donate autologous platelets 7-10 days prior to surgery.

Inclusion Criteria:

Adult (≥18 years old) patients who meet all following criteria:

1. Undergoing elective complex cardiac surgery consisting of at least one of the following:

• Repair or replacement of more than one valve (i.e., multiple valves)
• Repair or replacement of any segment of aortic arch
• At least two of any combination of coronary artery bypass grafting (CABG), valve repair/replacement, or aorta (ascending/arch) repair/replacement
• Complex adult congenital repair

Exclusion Criteria:

Patients who meet any of the following criteria are not eligible for the study:

1. Seven days or less from recruitment to surgery (as there will not be sufficient time from platelet donation to surgery for patients to recover their platelet count)

2. Patient factors that preclude platelet donation or increase risk of adverse events after donation, including any of the following:

   • Poor intravenous access
   • Low baseline platelet count (≤150,000 x106/L)
   • Low baseline hemoglobin (<100 g/L) (since approximately 50 mL of red blood cells are lost with each unit of apheresis platelet collection)
   • Inability to tolerate fluid shifts during donation (i.e., severe aortic stenosis with valve area <0.7 cm2, or left main coronary artery stenosis >80%, or left ventricular ejection fraction <30%)
   • Increased risk of bacterial contamination of collected units (i.e., active infection, on antibiotics, dental procedure <72 hours before donation)
   • Attending clinicians deem the patient ineligible for autologous predonation
   • Known positivity for active infectious blood-borne disease (HIV, HCV, HBV, HTLV, Syphilis)

3. Highly specialized procedures such as insertion or removal of ventricular assist devices or repair of thoracoabdominal aneurysm

4. Any history of congenital or acquired bleeding disorder (including any type of thrombocytopenia or platelet refractoriness due to anti-platelet and anti-HLA antibodies or requirement for specially matched platelets)

5. On any anticoagulant or antiplatelet medications, excluding ASA, that cannot be stopped at least 7 days before donation (72 hours for NSAIDs)

6. Refusal of allogeneic blood products due to religious or other reasons

7. Known or suspected pregnancy

All safety outcomes will be collected by blinded research staff and reviewed by blinded assessors.