Major morbidity composite defined as a composite of any one or more of the following: 1. Postoperative mortality (deaths occurring within 30 days of the operation or occurring during the primary hospitalization). 2. Stroke (clinical diagnosis of focal or global neurological deficit of abrupt onset caused by disturbance in cerebral blood supply). 3. Acute kidney injury (increase of serum creatinine levels to \>2.0 mg/dL and twice the baseline level or a new requirement for dialysis postoperatively). 4. Surgical reexploration (return to operating room because of bleeding, tamponade, graft occlusion or other cardiac reason). 5. Arterial or venous thromboembolic event (perioperative myocardial or mesenteric infarction, peripheral thromboembolism, acute coronary graft thrombosis, intracardiac thrombosis, deep vein thrombosis, pulmonary embolism). 6. Prolonged mechanical ventilation (\>24 hours). 7. Infection (deep sternal-wound infection and/or bloodstream infections).