Factors Influencing Weight Gain at Different Stages of the Fontan Pathway for Children with Functionally Single Ventricle Heart Disease

Outcomes for functionally single ventricle heart (f-SV) conditions rely on careful management of staged surgical palliation. Studies report a decrease in weight-for-age z-score (WAZ) before Stage 2 (Glenn) procedure, with weight gain thereafter, however factors influencing WAZ changes remain unclear. Using National Congenital Heart Disease Audit data, we developed regression models to explore WAZ changes from Stage 1 (S1) to Stage 2 (S2), and S2 to Stage 3 (S3), on the single ventricle (Fontan) pathway for 3292 operated f-SV patients born 2000 to 2018 in England and Wales. Mean WAZ decreased from - 1.20 (SD 1.60) at S1 to - 1.47 (SD 1.32) at S2, with recovery to - 0.57 (SD 1.16) by S3 Fontan-type surgery. In a multivariable model including 2012 children surviving to S2, female sex and older age at S1 were associated with increased WAZ from S1 to S2 while non-cardiac anomalies and higher WAZ at S1 were associated with decreasing WAZ. In a second model, including 1244 survivors to S3, weight gain between S2 and S3 was associated with preterm birth and Black ethnicity; whereas female sex, unbalanced AVSD diagnosis, older age or higher WAZ at S2, and greater weight gain between S1 and S2 were associated with WAZ decrease. Analyses confirmed that mean WAZ decreases prior to S2, increases after S2 surgery, and is influenced by age and weight at each procedure. Factors associated with weight gain varied across the single ventricle pathway. Further investigation is needed to understand wider influences on growth, including intensive interstage nutrition.