Abstract Body (Do not enter title and authors here): Background: Ventricular assist devices (VADs) are becoming a standard part of advanced heart failure therapy in children. They are utilized mostly as a bridge to transplant (HTx) but also can be used for recovery. While information on complications during VAD therapy is available, there is limited information on long term outcomes in this patient population, specifically neurodevelopmental outcomes.

Research Question: To determine the prevalence of ‘optimal neurodevelopmental outcomes’ in 2-year-old children previously treated with a VAD.

Methods: Patients were followed through the Complex Pediatric Therapies Follow-Up Program. This study included patients born between January 2006 and December 2022, implanted with a VAD at <15 months of age and surviving to 2 years of age. A modified optimal neurodevelopmental outcome was defined as the Cognitive, Language and Motor Composite Scores on the Bayley Scales of Infant and Toddler Development and the Adaptive Behaviour Assessment System - General Adaptive Composite Score ≥ 80 each, with the absence of cerebral palsy, permanent hearing loss, visual impairment, or seizure disorder.

Results: There were 56 patients who met inclusion criteria with 40 patients surviving to the age of 2 years. Of the survivors, the median (IQR) gestational age (GA) was 38 [37, 39] (4 [7.1%] <37completed weeks GA), 70% were male and 7.5% had a chromosomal abnormality. The median age of implant was 0.39 [0.19, 0.64], years and weight 5.8Kg [4.1, 7.5]. The majority of patients did not have congenital heart disease (62.5%). The most common implant strategy was a left VAD (87.5%) with paracorporeal continuous support (42.5%). Most patients were supported with ECMO (55%) pre- or post-VAD implant. One-third of the cohort had a neurological insult either pre- or post-implant. Total duration of support was a median 32 days [8, 93] with 65% undergoing HTx and 35% decannulated for recovery. Thirty-nine patients underwent full neurodevelopmental testing at 2 years of age with only 25.6% (n=19) of the patients classified as having an optimal neurodevelopmental outcome with 43.6% (n=17) having a Bayley cognitive score <80.

Conclusion: Optimal neurodevelopmental outcome at 2 years of age was present in only one-quarter of children following a treatment pathway that included VAD therapy in infancy. Important next steps will be to identify associations, including modifiable risk factors, for optimal neurodevelopmental outcomes.