Percutaneous Iatrogenic Atrial Septal Defect Closure Post Transcatheter Mitral Valve Repair: Revisiting MITHRAS Trial in a Larger Cohort

Introduction Transcatheter mitral valve repair (TMVR) creates an iatrogenic atrial septal defect (iASD) that may persist and affect hemodynamics. Although the MITHRAS (Closure of Iatrogenic Atrial Septal Defects Following Transcatheter Mitral Valve Repair) trial showed no benefit of routine closure, its small size and selective population limit generalizability, and observational data remain conflicting. We hypothesized that percutaneous iASD closure (PC-iASD) would be associated with differences in in-hospital clinical and hemodynamic outcomes compared with no closure. Methods Using the National Inpatient Sample (NIS), we evaluated national prevalence, baseline characteristics, and in-hospital outcomes of PC-iASD among patients undergoing TMVR from 2020 to 2022. Results We identified 4,965 weighted TMVR hospitalizations; 431 (8.7%) underwent PC‑iASD closure during the same admission. Compared with TMVR only, the closure cohort had a higher prevalence of pulmonary hypertension (245 (56.9%) vs. 1735 (40.5%), p = 0.0034) and heart failure (411 (95.4%) vs. 3767 (87.9%), p = 0.0396). There were no significant differences in chronic obstructive pulmonary disease, coronary artery disease, end-stage renal disease, or tricuspid regurgitation between the two groups. After multivariate adjustment, there was no difference in in‑hospital mortality, cardiogenic shock, acute heart failure, acute right heart failure, cardiac tamponade, or need for mechanical circulatory support among the two cohorts. Conclusion There have been conflicting results over numerous retrospective and prospective studies regarding the outcomes of post-TMVR iASD closure. Potential benefits of right-sided volume overload may be offset by higher left-atrial pressures after closure. The wide confidence (albeit nonsignificant) toward the development of acute right heart failure, pericardial effusion, and cardiac tamponade raises the possibility of better patient selection or some iASD closure procedural modifications that can help improve outcomes.