Abstract Body (Do not enter title and authors here): Background
Pediatric patients in which an aortic valve replacement (AVR) is required, the standard treatment would be an autologous AVR (aAVR), most often a pulmonary autograft. However, aortic valve pathologies have significant variabilities and patients ≤ 5 years old are at high risk for aAVR ineligibility due to numerous cardiac and pulmonary anomalies and fewer graft options in a growing child.

Hypothesis
We hypothesize that patients who received a prosthetic AVR (pAVR) will be significant in number and display poorer outcomes, thus warranting use of surgical alternatives such as a living homograft.

Materials
We performed a retrospective review of the Pediatric Health Information System (PHIS) between March 2020 to March 2025 for all patients ≤5 years of age who received an AVR. Procedures were determined using the International Classification of Diseases, 10^th revision (ICD-10) procedure code for AVR including all graft types (autologous, non-autologous, zooplastic and synthetic). All grafts that weren’t autologous were grouped as pAVRs and outcomes were compared to aAVR patients. Univariate analysis and multivariable regression were used to evaluate these cohorts.

Results
A total of 290 patients received an AVR with 227 (78%) patients receiving an aAVR and 63 (22%) patients receiving a pAVR. The two cohorts did not have a significant difference in length of follow-up or admit age at procedure, however, pAVRs did have higher number of hospitalizations (p = .0103), and were inpatient more days that aAVRs (p = .0001). Additionally, Kaplan-Meier curves showed a significant difference in mortality probability (p = .0004). When adjusting for demographics and disease severity, Cox hazard regression showed 3.25 higher risk of mortality for pAVRs (p = .0012; CI = 1.60-6.62).

Conclusion
pAVRs make up about one-fifth of all AVRs in patients under the age of 5. Young patients unable to receive an aAVR have 3x higher likelihood of mortality after adjusting for age, ethnicity, gender, and severity of condition. More research needs to be done on the long-term impact of living homograft procedures in this population.