Background: There are limited data about changes in cardiac function (cardiac reverse remodeling) and heart failure indices after transcatheter tricuspid valve-in-valve replacement (TT-VIVR). The purpose of this study was to evaluate cardiac reverse remodeling and temporal changes in heart failure indices after TT-VIVR in adults with congenital heart disease.Methods: Retrospective cohort study of adults with congenital heart disease that underwent TT-VIVR and had >6 months of follow-up (January 1, 2011, to April 30, 2023). Echocardiographic indices of cardiac remodeling and heart failure indices (New York Heart Association class, NT-proBNP (N-terminal pro-brain natriuretic peptide), glomerular filtration rate, and model for end-stage liver disease excluding international normalized ratio score) were assessed preintervention and at 1-, 3-, and 5-year postintervention.Results: Of 39 patients (age 39 [32-46] years), 14 (36%) and 25 (64%) received Melody valve and Sapien valve prosthesis, respectively. At 1-year post-TT-VIVR, there was a temporal improvement in right atrial reservoir strain (17 +/- 8% versus 22 +/- 8%, P<0.001), right atrial volume (81 [59-108] versus 63 [48-82] mL/m(2), P<0.001), right atrial pressure (12 +/- 4% versus 6 +/- 4%, P<0.001), and right ventricular global longitudinal strain (-15 +/- 7% versus -20 +/- 7%, P<0.001). Similarly, there was a temporal improvement in NT-proBNP, glomerular filtration rate, model for end-stage liver disease excluding international normalized ratio score, and New York Heart Association class. The temporal improvements in heart failure indices and valve function were maintained at 3- and 5-year post-TT-VIVR.Conclusions: Considering the significant mortality risk associated with reoperations for tricuspid valve replacement, these data suggest favorable outcomes after TT-VIVR, and support TT-VIVR as a viable alternative to surgical tricuspid valve replacement, especially in high-risk patients.