The Effects of Gestational Age and Size on Management Strategies and Outcomes in Neonatal Tetralogy of Fallot

Introduction: Data suggests there are benefits to both staged (SR) and complete repair (CR) for neonatal Tetralogy of Fallot (nTOF), though data is lacking on whether high-risk groups would benefit from one strategy over another. In a large state with variable practice patterns, we studied the impact of gestational age (GA) and weight by GA (birth weight z-score: BWz) at birth on surgical strategy and outcomes in nTOF, hypothesizing that GA and BWz would influence these outcomes. Methods: Population-based cohort study (2011-2017) of infants with nTOF (defined as catheter or surgical intervention prior to 44 weeks corrected GA) was performed. BWz was categorized as appropriate, small or large for GA. Surgical strategy and timing were compared by GA ( < 36 weeks preterm (n= 96), 37-38 weeks early term (n= 97), > 38 weeks full term (n= 152)) and BWz. Multivariable (MV) models were constructed to evaluate composite outcome of mortality or significant morbidity (BPD, IVH, NEC, PVL etc.) at 1 year and total number of hospital days in first year of life. Results: There were 345 patients included (SR= 194; CR= 151). Surgical strategy did not differ by GA or BWz. Within CR group, full term and early term neonates underwent surgery 20 (95%CI: -27.1, -14.1; p<0.001) and 15 days (95%CI: -22.1, -8.2; p<0.001) sooner than preterm neonates. BWz was not associated with surgical timing. A stratified analysis trended toward lower survival probability among preterm neonates undergoing CR vs. SR (p= 0.1). In a MV model including GA, BWz, surgical approach and DOL surgery, only GA was associated with the composite outcome. The odds of a poor outcome was 0.45 (95%CI:0.24,0.86) times lower in full term vs. preterm neonates, p= 0.02. The adjusted total burden of hospital days in the first year was 32 (95%CI: -47.7,-16.9; p<0.001) and 22 (95%CI: -36.5,-7.7; p= 0.003) days less in early term and full term compared to preterm neonates. Conclusions: In nTOF, GA and BWz were not associated with surgical strategy though premature neonates were more likely to wait longer for their initial intervention. One-year outcomes appear to be strongly influenced by GA and not surgical strategy; however, there was a trend to suggest that SR may result in better survival probability among premature neonates.