Study Objective is to correlate the results of preoperative platelet mapping derived from modified TEG with clinically significant postoperative bleeding and consumption of blood products.

Study Design:

Prospective observational study with blinded assessment of study endpoint variables. Collection of information concerning study endpoints will be performed by the investigator blinded to the results of preoperative testing of platelet function. The information will be collected from 60 patients undergoing cardiac surgery in the Department of Cardiac Surgery of Sheba Medical Center.

Study endpoints

1. Primary endpoint- resternotomy for bleeding after the surgery.
2. Secondary endpoints- chest tube output during first 24 hours after the surgery; consumption of blood products during first 3 postoperative days.

Inclusion Criteria:

• Patients undergoing cardiac surgery with the history of aspirin and/or ADP receptor antagonist for at least 7 days prior the surgery

Exclusion Criteria:

• Emergent surgery
• Heart transplant surgery
• Implantation of ventricular assist devices
• Enrollment into conflicting study

Patients with the history of ingestion of aspirin and/or ADP receptor antagonist (clopidogrel or ticlopidine) for at least 7 days prior the surgery. All patients undergoing cardiac surgery with the use of cardiopulmonary bypass on elective and urgent basis.