<p>Though major complications during transcutaneous pulmonary valve replacement (TPVR) are rare, clinically-significant ventricular arrythmia (CSVA) has been reported following self-expanding valve placement. We assess whether alterations in valve frame dimensions and geometry within the right ventricular outflow tract (RVOT) post-implantation in patients who underwent TPVR with Harmony TPV25 or Alterra contribute to CSVA risk. A single center review was performed of patients who underwent TPVR with either Harmony TPV25 or Alterra Pre-stent between August 2019 and April 2023. Using post-procedural 3D rotational acquisitions, minimum and maximum diameters were measured at 5 locations along the valve frame and perimeter and cross-sectional area (CSA) were measured closest to the pulmonary artery bifurcation and right ventricular (RV) cavity. To assess the relationship between the RVOT and valve frame, a RVOT-to-valve frame ratio together with percentage expansion, circularity and expansion ratios, and eccentricity indices were calculated. Twenty-eight patients were included (14 Harmony TPV25, 14 Alterra pre-stent). CSVA was seen more often in patients with congenital pulmonary stenosis (<i>p</i> = 0.02). CSVA was associated with a larger mean valve frame perimeter (118.3 vs 108.6&#xa0;mm, <i>p</i> = 0.03) and CSA (1124.5 vs 926.2mm², <i>p</i> = 0.03) closest to the RV cavity. No associations between difference in diameters, RVOT-to-valve frame ratio, parameters evaluating valve frame geometry, and level of implant and CSVA were demonstrated. No single mechanism was identified that contributed to CSVA in patients following self-expanding valve implantation. Future studies implementing these mathematical constructs and measurements to a larger cohort of self-expanding valve patients may yield more instructive results.</p>