Autologous Cold-stored Apheresis Platelets

• Autologous Cold-Stored Platelets (Biological): Two units of autologous platelets will be collected via an apheresis machine that draws blood from an intravenous (IV) line over 1-2 hours, isolates and leukoreduces the platelets by centrifugation and returns the remaining blood back to the patients. Collected autologous platelets will be stored at 1-6℃ without agitation until they are needed during or after surgery or 14 days have elapsed since their collection, after which they will be destroyed as per standard institutional procedures for expired blood products. For the first two platelet orders within 24 hours of cardiopulmonary bypass (CPB) termination, patients will receive their autologous cold-stored platelets. For the third and subsequent doses, patients in the intervention group will receive allogeneic room temperature-stored platelets (standard of care).
• Allogeneic Room Temperature-Stored Platelets (Standard of Care) (Biological): Allogeneic platelets will be collected by Canadian Blood Services as per their standard operating procedures. Room temperature stored platelets will be stored at 20-24°C with constant agitation for up to 7 days as per current practices. For any platelet orders within 24 hours of cardiopulmonary bypass (CPB) termination, patients in the control group will receive allogeneic platelets as per usual care.

Primary outcomes

• Primary Efficacy Endpoint [up to 24 hours after termination of cardiopulmonary bypass (CPB)]: The incidence of allogeneic platelet transfusion during the treatment period

Sex: All, ages: 18 Years to any

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