Abstract Body (Do not enter title and authors here): Background
There is increasing recognition of the mental health burden experienced by pediatric heart transplant (HTx) recipients. Mental health concerns can impact physical health and increase risk of poor health outcomes. Using the Pediatric Heart Transplant Society (PHTS) database, we assessed the use of psychoactive medications as a proxy for mental health issues. We assessed the prevalence of psychoactive medication usage, pre- and post HTx factors, and post HTx outcomes associated with psychoactive medication usage.

Methods:
We queried the PHTS database for patients >5 years of age at time of follow-up who underwent HTx between January 2015 and June 2023. Patients with use of any psychoactive medication were identified. Sub-analyses were performed for use of antianxiety/antidepressant and attention-deficit/hyperactivity disorder (ADHD) medications. Multivariate logistic regression models were utilized to assess risk factors and impact on outcomes, including graft survival, coronary artery vasculopathy (CAV), and rejection at 1, 3, and 5 years post-HTx.

Results
Among 1792 patients older than 5 at 1 year post HTx, 301 (16.8%) were prescribed at least one psychoactive medication; 246 (13.7%) were prescribed medication for antianxiety/antidepressant medications and 59 (3.3%) for ADHD. Utilization of psychoactive medication decreased at 3 years (14.8%, N= 240 of 1629) and 5 years post HTx (11.3%, N=230 of 2029).
Patients on psychoactive medications at 1 year post HTx tended to be older (OR=2.1, p<0.001), had higher priority listing status (OR=2.3, p<0.05), and longer bypass time (OR=1.6, p<0.05). Black patients were less likely to be prescribed psychoactive medication at 3-years post HTx than white patients (OR=0.57, p<0.05) or other races (OR=0.43, P <0.001).
There was no association of psychoactive medication usage on graft survival, CAV, or rejection at 1 year post HTx. At 3 years post HTx psychoactive medication usage was associated with significantly higher prevalence of CAV (p<0.05). At 5 years post HTx graft loss (p<0.005) and CAV (p<0.05) were significantly increased in patients on psychoactive medications.

Conclusions
A significant proportion of pediatric HTx patients take psychoactive medications. This population may be at risk for worse long-term outcomes. There is a need to assess the mental health burden of pediatric HTx and to identify modifiable factors to improve assessment and treatment of mental health issues and its impact on outcomes.