Patients with pulmonary atresia and intact ventricular septum (PA-IVS) require intervention early in life, and most survive to a definitive procedure of either Fontan circulation or right ventricle to pulmonary artery (RV-PA) repair. It remains unknown how surgical strategy impacts hemodynamics and comorbidities in adults. Retrospective analysis of adults (age ≥18 years) with PA-IVS undergoing hemodynamic catheterization at Mayo Clinic, MN between January 2000 through January 2020 was performed. Fourteen patients in the RV-PA group (71% biventricular, 29% 1.5 ventricle repair) and 19 post-Fontan patients [9 lateral tunnel (48%), 6 atriopulmonary (32%), and 4 extracardiac (21%)] were identified. Median age was 29 (21, 34) years. There were no differences in demographics and laboratory data (including MELD-XI) between groups. All patients assessed for liver disease had evidence of hepatic congestion or cirrhosis (14 in the Fontan group and 4 in the RV-PA group). Invasive hemodynamics were comparable between groups with the Fontan and RV-PA groups having similar systemic venous pressure (15.7±4.4 vs. 14.3±6.2, p=0.44) and cardiac output (2.2±0.6 vs. 2.0±0.4 L/min/m2, p=0.23). There was no difference in transplant-free survival (p=0.92; 5-year transplant-free survival RV-PA 84%, Fontan 80%). Hemodynamic derangements, namely elevated systemic venous pressure and low cardiac output, are prevalent in patients with PA-IVS undergoing cardiac catheterization regardless of surgical strategy.