Hyperbilirubinemia and Hepatic Dysfunction in Patients Undergoing Cardiac Surgery: Predictors and Outcome - A single Centre Prospective Study

Background: We aim to assess the incidence and perioperative risk factors for hyperbilirubinemia and hepatic dysfunction after cardiac surgery and determine its influence on early operative outcome. Methods: This prospective observational study was conducted on 485 patients who underwent cardiac surgical procedures from June 2022 to October 2023. Postoperative hyperbilirubinemia was defined as serum total bilirubin >2.0 mg/dl. Results: The overall incidence of post operative hyperbilirubinemia was 24.5% (119 patients). Total and indirect bilirubin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase was measured preoperatively and at day 1, day 2 and day 5. Patients undergoing valve repair or replacement had the highest incidence of hyperbilirubinemia (37.1%), followed by coronary artery bypass grafting with concomitant valve surgery (35.3%), congenital heart surgery (24.5%), and coronary artery bypass alone (12.4%). Post operative hyperbilirubinemia was associated with increased duration of inotropic support (p=0.0001), mechanical ventilation (p=0.0001), intensive care unit stay (p=0.001), hospital stay (p=0.006), and mortality (p=0.014). The perioperative factors associated with postoperative hyperbilirubinemia were increased preoperative bilirubin level (p<0.0001), preoperative prothrombin time (p<0.0001), cardiopulmonary bypass time (p=0.026), aortic cross clamp time (p=0.004), and blood transfusion units (p=0.0001). A significant increase of total bilirubin, aspartate aminotransferase, and alkaline phosphatase were noted in the second postoperative day. Significant relation was seen between hypotension and alkaline phosphatase, and aspartate aminotransferase change but hypothermia had not affected alanine aminotransferase, total bilirubin and indirect bilirubin change. Conclusions: Post operative hyperbilirubinemia is seen in patients undergoing cardiopulmonary bypass and is associated with high hospital mortality. The factors associated with its occurrence are increased preoperative bilirubin level, preoperative prothrombin time, cardiopulmonary bypass time, aortic cross clamp time, and blood transfusion units. Persistent hyperbilirubinemia is associated with a worse outcome than early transient hyperbilirubinemia.