Antiplatelet Effect of Low Doses of Aspirin Taken Every 12 Hours in Patients Undergoing Coronary Artery Bypass Graft and/or Aortic Valve Surgery

This study is a randomized open label study that implies the administration of asprin according to three different regimens.

The aims of the study are:

• to establish whether coronary artery bypass surgery and / or aortic valve replacement surgery with bioprostheses is associated with changes in the rate of platelet regeneration that can reduce the effectiveness of aspirin administered at a dose of 100mg/die in terms of inhibition of platelet biosynthesis of thromboxane A2.
• to determine whether these patients need a different (shorter) interval of administration in order to completely and permanently inhibit the platelet COX-1.

The endpoints of this study are:

- To evaluate the changes in the levels of TXB2 and 12-HETE in serum at 12 and 24 hours after administration of aspirin and the changes in the levels of 11-dehydro TXB2 urinary 8-iso-PGF2 alpha urinary, 2-3 dinor-6-chetoPGF1 alpha, Verify-NOW Aspirin, platelets crosslinked at 12 and 24 hours after administration of aspirin

Inclusion Criteria:

• informed consent of the study signed
• coronary artery bypass graft and / or aortic valve replacement surgery with bioprostheses
• age between 55 and 80
• ejection fraction > 30%.

Exclusion Criteria:

• excessive bleeding (> 1000mL / 6 h) or the need of re operation for bleeding
• perioperative myocardial infarction
• stroke or renal failure requiring dialysis and need waiting for post-operative anticoagulation
• patients undergoing coronary artery bypass grafting procedure as a consequence of failed percutaneous coronary intervention
• patients undergoing off-pump coronary artery bypass graft
• overt kidney or liver disease
• therapies that influence the coagulation
• fertile women