Left atrial remodeling and diastolic unloading after transcatheter tricuspid repair

Background Severe tricuspid regurgitation (TR) induces adverse ventricular interaction that may conceal left-sided diastolic dysfunction. Objectives Whether relief of TR by transcatheter tricuspid edge-to-edge repair (T-TEER) leads to true diastolic improvement or unmasks residual left-sided constraint remains unknown. We sought to define the longitudinal effects of T-TEER on left atrial (LA) remodeling and diastolic physiology. Methods We performed a single-center retrospective analysis of a prospectively enrolled cohort of 125 patients undergoing T-TEER between March 2021–December 2025. Serial transthoracic echocardiography was analyzed by a blinded core laboratory at baseline, pre-discharge, 6 months, and 12 months. LA volume index (LAVI), peak atrial longitudinal strain (PALS), E/e′ ratio, and left atrial stiffness index (LASI) were analyzed using linear mixed-effects models. Results T-TEER resulted in immediate LA volume reduction (−8.1 mL/m² at pre-discharge, Padj=0.033), without sustained reverse remodeling. In contrast, LA reservoir function declined early and remained persistently impaired at 12 months (PALS −1.2%, Padj=0.029). Left-sided filling pressure surrogates increased acutely (E/e′ +3.26, Padj<0.001) and only partially normalized, with LASI remaining elevated at long-term follow-up. Forward flow indices were preserved. Early mitral regurgitation changes were common but transient and unrelated to diastolic indices. Conclusions Relief of severe TR by T-TEER induces early anatomical left atrial unloading but simultaneously unmasks latent left-sided diastolic constraint, evidenced by persistent atrial stiffness and impaired reservoir function. This dissociation highlights the limitations of volume-based assessment and positions LA strain as a key marker of diastolic reserve after tricuspid intervention.