Predictors of Transplant-Free Survival Following Norwood Procedure

Abstract Background Birth weight, preterm delivery, and size for gestational age are surrogate markers for development commonly used in congenital heart surgery. Understanding the associations of these variables with patient outcomes are of great importance. Methods We included all patients with hypoplastic left heart syndrome (HLHS) who underwent a Norwood procedure at a single institution from 1995-2018. Low birth weight was defined as less than 2.5 kilograms and preterm delivery occurred at less than 37 weeks gestation. Overall and conditional analyses were performed to evaluate for association with outcomes after the Norwood. Secondary analyses evaluated the association between development measures and post-operative length of stay (LOS) and ventilator duration. Results In total 303 neonates (60% male) underwent the Norwood procedure and were followed for a median 3.9 years (IQR 0.5-10.4). Median birth weight was 3.1 kilograms (interquartile range [IQR] 2.8-3.4). Patients with low birth weight had decreased transplant-free survival compared to patients with a normal birth weight (HR 1.7, 95%CI 1.03-2.82, p=0.039). When conditioning on survival to second stage palliation, patients born small for gestational age had decreased transplant-free survival compared to patients born at appropriate size for gestational age (HR 2.8, 95%CI 1.31-6.09, p=0.008). Patients delivered preterm had longer hospital LOS (median 55 days vs 31 days, p=0.02) and more ventilator days compared to patients delivered at term (median 7 days vs 4 days, p=0.004). Conclusions Various development markers have differing prognostic importance for patients undergoing the Norwood procedure. Understanding these differences can help guide pre-operative decision-making and patient selection.