 Patient characteristics and numbers, power-analysis, and patient Data collection: Variables will be recorded from patient files: 1 preoperatively: age, gender, race, Society of Thoracic Surgery risk factors, EUROScore, date of consent, and preoperative drugs; 2 intraoperatively: number of coronary artery bypass grafts, duration of cardio-pulmonary bypass, duration of aortic cross clamp, cumulative dose of heparin administered, blood products, and cumulative dose of sympathomimetic and vasopressor drugs; 3 postoperatively: timing of complications, cause and timing of death, hospital and ICU length of stay, duration of postoperative mechanical ventilation, dose of inotropic or vasoactive support. Plate-let count and creatinine levels, as well as anti-platelet therapy will be recorded from 3 days be-fore to 10 days after the surgery. 