Hyperbilirubinemia After Redo Valve Surgery: Incidence, Risk Factors, and Early Clinical Outcomes

Background: Postoperative hyperbilirubinemia is a serious complication after cardiac surgery and has been associated with increased perioperative morbidity and mortality. However, data specifically addressing patients undergoing redo valve surgery remain limited. This study aimed to determine the incidence and risk factors of postoperative hyperbilirubinemia after redo valve surgery, and evaluate its association with early postoperative outcomes. Methods: We retrospectively reviewed 259 adult patients who underwent elective redo valve surgery under cardiopulmonary bypass (CPB) between March 2018 and July 2024. Postoperative hyperbilirubinemia was defined as a serum total bilirubin level > 3 mg/dL at any time after surgery. Patients were divided into a hyperbilirubinemia group and a non-hyperbilirubinemia group. Perioperative variables were compared between groups. Univariable and multivariable logistic regression analyses were performed to identify risk factors for postoperative hyperbilirubinemia. Postoperative complications and in-hospital mortality were also compared. Results: Postoperative hyperbilirubinemia occurred in 101 of 259 patients (39.0%). Compared with patients without hyperbilirubinemia, those with hyperbilirubinemia had longer mechanical ventilation and intensive care unit stay, and higher rates of pneumonia, reintubation, tracheostomy, continuous renal replacement therapy, and in-hospital mortality. Univariable logistic regression showed that higher EuroSCORE II, higher preoperative total bilirubin and direct bilirubin levels, lower hemoglobin and platelet count, pulmonary hypertension, anemia, longer operative time, CPB duration, and aortic cross-clamp time, lower nasopharyngeal temperature, greater intraoperative blood loss, larger red blood cell and plasma transfusion volumes, and concomitant surgery on all three valves were associated with postoperative hyperbilirubinemia. Multivariable analysis identified elevated preoperative direct bilirubin, prolonged CPB duration, and more plasma transfusion as independent risk factors. Receiver operating characteristic analysis showed that peak postoperative total bilirubin was associated with in-hospital mortality, with an optimal cut-off value of 3.95 mg/dL (AUC 0.756, sensitivity 66.7%, specificity 80.2%, p = 0.003). Conclusions: Postoperative hyperbilirubinemia is common after redo valve surgery and is associated with worse early postoperative outcomes and higher in-hospital mortality. Elevated preoperative direct bilirubin, prolonged CPB duration, and more plasma transfusion are independent risk factors for postoperative hyperbilirubinemia in this high-risk population.