Excessive bleeding after cardiopulmonary bypass (CPB) operations remains to be a persistent problem. Antiplatelet therapy (APT) is an integral component of perioperative management in patients undergoing cardiac surgery. The impact of drug induced platelet inhibition on early postoperative bleeding extent and transfusion requirements remains difficult to predict.

In addition to, resistance to antiplatelet drugs as well as perioperative increase in platelet reactivity following CPB has been reported but this phenomenon has to be comprehensively investigated.

The best point-of-care platelet function test to predict bleeding complications/transfusion requirements remains unclear. In addition to, the best test platelet function test to monitor resistance to antiplatelet therapy and its impact on clinical outcomes remains elusive.

The aim of this study is:

1. to compare two point-of-care platelet function analyzers (Multiplate and ROTEM Platelet) in regard to prediction of bleeding complications/trasfusion requirements.
2. to compare two point-of-care platelet function analyzers (Multiplate and ROTEM Platelet) in regard to detection of high "on-treatment" platelet reactivity both pre- and postoperatively.

Excessive bleeding after cardiopulmonary bypass (CPB) operations remains to be a persistent problem. Antiplatelet therapy (APT) is an integral component of perioperative management in patients undergoing cardiac surgery. The impact of drug induced platelet inhibition on early postoperative bleeding extent and transfusion requirements remains difficult to predict.

In addition to, resistance to antiplatelet drugs as well as perioperative increase in platelet reactivity following CPB has been reported but this phenomenon has to be comprehensively investigated.

The best point-of-care platelet function test to predict bleeding complications/transfusion requirements remains unclear. In addition to, the best test platelet function test to monitor resistance to antiplatelet therapy and its impact on clinical outcomes remains elusive.

The aim of this study is:

1. to compare two point-of-care platelet function analyzers (Multiplate and ROTEM Platelet) in regard to prediction of bleeding complications/trasfusion requirements.

   Three different tests will be performed on each device simultaneously at three time points:

   T1) Preoperative testing will include ASPI test, ADP test and TRAP test for Multiplate device and ARATEM, ADPTEM and TRAPTEM for ROTEM Platelet device, respectively.

   T2) After declamping of the aorta: ASPI test, ADP test and TRAP test for Multiplate device and ARATEM, ADPTEM and TRAPTEM for ROTEM Platelet device will be performed.

   T3) 5-10 minutes after protamine administration: ASPI test, ADP test and TRAP test for Multiplate device and ARATEM, ADPTEM and TRAPTEM for ROTEM Platelet device will be performed.

   Results obtained with this two platelet function point-of-care devices at the first three timepoints will be tested for correlations with postoperative bleeding amount and intra/postoperative transfusion requirements. Predictibalility of bleeding complications as well as transfusion requirements will be compared between Multiplate tests and ROTEM Platelet tests.

2. to compare two point-of-care platelet function analyzers (Multiplate and ROTEM Platelet) in regard to detection of high "on-treatment" platelet reactivity both pre- and postoperatively.

To compare Multiplate and ROTEM Platelet for assessment of high on treatment platelet reactivity we will use tests being performed preoperatively (T1) and tests performed at fourth postoperative day (T4).

ASPI test (Multiplate) and ARATEM test (ROTEM Platelet) are sensitive to the platelet inhibitory effect of acetylsalicylic acid. Thus, the incidence of resistance to acetylsalicylic acid , measured by Multiplate ASPI test and ROTEM Platelet ARATEM will be compared between device measurements performed at T1 and T4, respectively. Specific subanalysis will be performed for ARATEM test with aim to make laboratory based definition of resistance to acetylsalicylic acid. Specific cut-of value for acetylsalicylic acid resistance has already been defined by our working group for Multiplate ASPI test.

ADP test (Multiplate) and ADPTEM test (ROTEM Platelet) are sensitive to the effect of thienopyridines. For patients being preoperatively exposed to thienopyridines, measurements of Multiplate ADP test and ROTEM Platelet ADPTEM test will be performed at T1 with aim to compare the incidence of high on-treatment platelet reactivity.

Preoperative (T1) and postoperative (T4) measurements obtained with Multiplate and ROTEM Platelet will be compared. Perioperative increase in platelet reactivity will be evaluated.

Inclusion Criteria:

1. > 18 years old
2. Elective cardiac surgery patients
3. Coronary artery disease
4. Aortic valve disease
5. Mitral valve disease
6. Ascendent aorta aneurysm
7. Combine coronary and valve disease
8. Cardiac surgery procedures using cardiopulmonary bypass

Exclusion Criteria:

1. Missing consent
2. Patients with emergent cardiac surgical procedures
3. Patients on antiplatelet therapy other than aspirin , clopidogrel and prasugrel
4. Patients with inaccurate antiplatelet therapy administration documentation
5. Missing data
6. Off-pump procedures
7. Patients younger than 18 years old
8. Patients with severe mental disorders
9. Intrinsic coagulopathy

Adult patients undergoing elective cardiac surgery procedures will be consecutively enrolled.