Predictors of Transplant-Free Survival After the Norwood Procedure

Background. Birth weight, preterm delivery, and size for gestational age are surrogate markers for development that are commonly used in congenital heart surgery. Understanding the associations of these variables with patient outcomes is of great importance. Methods. This study included all patients with hypoplastic left heart syndrome who underwent a Norwood procedure at a single institution from 1995 to 2018. Low birth weight was defined as weight less than 2.5 kg, 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 procedure. Secondary analyses evaluated the association of development measures with postoperative length of stay and ventilator duration. Results. In total, 303 neonates (60% male) underwent the Norwood procedure and were followed for a median of 3.9 years (interquartile range, 0.5 to 10.4 years). Median birth weight was 3.1 kg (interquartile range, 2.8 to 3.4 kg). Patients with low birth weight had decreased transplant-free survival compared with patients with a normal birth weight (hazard ratio, 1.7; 95% confidence interval, 1.03 to 2.82; P = .039). When conditioning on survival to second-stage palliation, patients born small for gestational age had decreased transplant-free survival compared with patients born at appropriate size for gestational age (hazard ratio, 2.8; 95% confidence interval, 1.31 to 6.09; P = .008). Patients delivered preterm had a longer hospital length of stay (median, 55 days vs 31 days; P = .02) and more ventilator days compared with patients delivered at term (median, 7 days vs 4 days; P = .004). Conclusions. Various developmental markers have differing prognostic importance for patients undergoing the Norwood procedure. Understanding these differences can help guide preoperative decision making and patient selection. (C) 2021 by The Society of Thoracic Surgeons