O1011: Longitudinal Assessment of Growth 10 Years After the Norwood Procedure: Results From the Single Ventricle Reconstruction Trial (SVRIII)

Background: Poor growth after the Norwood is well-documented in children with single ventricle congenital heart disease but has been understudied beyond this period. In a secondary analysis of the SVRIII study, we characterized longitudinal somatic growth in transplant-free survivors with hypoplastic left heart syndrome who underwent the Norwood procedure.

Methods: Using z-scores adjusted for age, we compared weight (WAZ), height (HAZ), and BMI (BMIZ) with a normative population using a one-sample t-test. Univariable and multivariable repeated measures linear regression models determined effects of clinical and non-clinical variables on z-scores at age 10 years and change in (∆) z-score between birth and 10 years.

Results: Of 555 subjects enrolled in the SVR trial, 191 transplant-free survivors had 10-year growth data: At age 10 years, the mean WAZ and HAZ were below the normative population, with values of -0.3±1.3 (p < 0.001) and -0.8±1.2 (p=0.002), respectively, while BMIZ did not differ from the normative population, with a mean value of 0.0±1.3 (p=0.87). WAZ and HAZ were <-2 in 9% and 13% respectively; BMIZ was <-2 in 4% and >2 in 5%. Factors associated with lower WAZ, HAZ, and BMIZ included more post-Norwood complications, longer Norwood length-of-stay, and post-Norwood gastrostomy-tube feeds. Birth weight percentiles >30th% and ≥70th% had greater WAZ and BMIZ, compared to those < 30th% (p < 0.05). Shunt type was not associated with growth at 10 years (Table 1). On multivariable analysis [coefficient (95% CI)], only higher birthweight [2.16 (-0.5,-0.09)], longer Norwood length-of-stay [-0.02 (-0.03,0)], and extracorporeal membrane oxygenation after Norwood [-1.56 (-2.91,-0.21)] were associated with lower HAZ (p < 0.05 for all).

From birth to 10 years, ∆WAZ and ∆HAZ decreased, while ∆BMIZ increased compared to the normative population. Factors associated with a greater decrease in ∆WAZ included more post-Norwood complications, longer Norwood length-of-stay, post-Norwood tube feeding, and post-Fontan protein-losing enteropathy (p < 0.05 for all). Birthweight < 2.5 kg was associated with a greater increase in ∆WAZ, ∆HAZ, and ∆BMIZ (p <.05 for all, Table 2). On multivariable analysis, lower birthweight was associated with greater ∆WAZ [1.38 (0.68,2.08)], while longer Norwood length-of-stay [-0.01 (-0.02,0)] was associated with lower ∆WAZ (p < 0.05 for all).

Conclusion: Compared to the normal population, at age 10 years, transplant-free Norwood survivors had lower WAZ and HAZ but similar BMIZ. Shunt type was not associated with growth outcomes. No modifiable clinical risk factors associated with ∆growth parameters were identified. Tube feeding at Norwood discharge did not mitigate growth impairment.