Preterm Birth Is Associated With Adverse Cardiac Remodeling and Worse Outcomes in Patients With a Functional Single Right Ventricle

Objective To assess the effects of preterm birth on cardiac structure and function and transplant-free survival in patients with hypoplastic left heart syndrome and associated anomalies throughout the staged palliation process. Study design Data from the Single Ventricle Reconstruction trial were used to assess the impact of prematurity on echocardiographic measures at birth, Norwood, Stage II, and 14 months in 549 patients with a single functional right ventricle. Medical history was recorded once a year using medical records or telephone interviews. Cox regression models were applied to analyze transplant-free survival to age 6 years. Causal mediation analysis was performed to estimate the mediating effect of birth weight within this relationship. Results Of the 549 participants, 64 (11.7%) were born preterm. Preterm-born participants had lower indexed right ventricle end-diastolic volumes at birth but higher volumes than term-born participants by age 14 months. Preterm-born participants had an increased risk of death or heart transplantation from birth to age 6 years, with an almost linear increase in the observed risk as gestational age decreased below 37 weeks. Of the total effect of pretermbirth on transplant-free survival, 27.3% (95% CI 2.5-59.0%) was mediated through birth weight. Conclusions Preterm birth is associated with adverse right ventricle remodeling and worse transplant-free survival throughout the palliation process, in part independently of low birth weight. Further investigation into this vulnerable group may allow development of strategies that mitigate the impact of prematurity on outcomes in patients with hypoplastic left heart syndrome. (J Pediatr 2023;255:198-206).

Automated summary

This study aimed to evaluate the effects of preterm birth on cardiac structure and function as well as transplant-free survival in infants with hypoplastic left heart syndrome and associated anomalies. The results, obtained from the Single Ventricle Reconstruction trial, showed that preterm-born infants had lower echocardiographic measures at birth but higher measures at 14 months compared to term-born infants. Preterm-born infants had an increased risk of death or heart transplantation from birth to age 6, with a higher risk as gestational age decreased below 37 weeks. Approximately 27.3% of the total effect of preterm birth on transplant-free survival was mediated through birth weight.