The Utility of Preoperative Level of Erythrocytosis in the Prediction of Postoperative Blood Loss and 30-day Mortality in Patients with Tetralogy of Fallot

BACKGROUND: Postoperative major bleeding is a relatively common complication of patients undergoing corrective surgery of tetralogy of Fallot (TOF). Life-threatening blood losses can lead to aggressive transfusions or reoperation. Little is known about the risk factors associated with a bleeding tendency in TOF patients. This study aimed to establish predictive models for postoperative blood loss and mortality in TOF patients. METHODS: We conducted a retrospective observational study involving patients with TOF who were posted for corrective cardiac surgery in a single hospital between 2010 and 2015. Hospital records including sociodemographic, pre- and intra-operative characteristics were extracted. Postoperative blood loss (within 24 and 48 h) and 30-day mortality were the primary and secondary outcomes, respectively. Multivariate linear and logistic regression models were used to identify determinants of outcomes. RESULTS: A total of 60 patients were included in this study. The median age was 1 year (interquartile range = 0.62–5) and the male to female ratio of 1.7:1. Mean postoperative blood loss within 24 h was 283 ± 212 mL. In multivariate linear regression, preoperative hematocrit (β = 6.63, P = 0.042) and duration of intraoperative oxygenator with CPB (β = 5.16, P = 0.025) were significantly correlated with postoperative blood loss within 24 h. After adjusting for sociodemographic, intra- and post-operative characteristics, preoperative hematocrit (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.01–1.21), and postoperative red blood cell transfusions (OR = 3.88, 95% CI = 1.16–12.9) showed statistically significant association with 30-day mortality. The area under the receiver operating characteristic curve of the multivariable model was 0.863. CONCLUSIONS: Preoperative levels of erythrocytosis appear to predict postoperative blood loss and short-term mortality in TOF patients undergoing corrective surgery.