BackgroundQuantitative echocardiographic (echo) measures of ventricular function predict mortality in pediatric pulmonary hypertension (PH), but studies in congenital diaphragmatic hernia (CDH)-related PH are limited. Few studies report quantitative echo data beyond the first week of life in CDH non-survivors. MethodsA single-center retrospective, cross-sectional, cohort study included CDH patients born between January 2013 and April 2022 who survived to surgical repair but died during the neonatal hospitalization. Quantitative measures of right (RV) and left ventricular (LV) size and function including tricuspid annular plane systolic excursion Z-score (TAPSEZ), RV fractional area change (FAC), RV/LV ratio, LV eccentricity index, LV M-mode dimensions, and RV/LV systolic strain were performed offline on the last echocardiogram before death. Data were compared between patients who died ≤30 days after repair (“early”) vs. >30 days after repair (“late”) using the Wilcoxon rank sum test. ResultsTwenty-five (11 early, 14 late) deceased patients had echo images available for analysis. LV size by end-diastolic dimension Z-score was smaller in patients who died early vs. late after repair [-3.03 (−3.93, −2.51) vs. −0.24 (−2.11, 0.53), p = 0.021]. There were trends toward worse RV function (TAPSEZ, RVFAC, RV global and free wall strain) and LV function (apical 4 chamber strain) in patients who died early vs. late after repair. ConclusionThese preliminary findings support future study of the impact of ventricular hypoplasia and dysfunction on mortality and opportunities for risk stratification based on quantitative echo findings in CDH. Level of EvidenceCohort study, 4.