71464 , Consequences of Mitral Regurgitation Eradication on Biventricular Physiology: Insights From Invasive Biventricular Pressure-Volume Loop Analysis

Abstract

Background: Transcatheter edge-to-edge repair (M-TEER) has transformed the treatment of mitral regurgitation (MR) for high-risk patients, yet 30% fail to derive benefit despite procedural success rates of 90%. This study evaluates the relationship between MR reduction and biventricular physiology and whether MR eradication leads to a decline in cardiac performance. Method(s): STRESS-MR is a UK multi-centre prospective study of 53 M-TEER patients in 2024. Pre and post M-TEER assessments included invasive biventricular pressure-volume loops (PVL) and cardiac catheterisation. MR severity was measured using transoesophageal echocardiography with conventional grading and 3D vena contracta area (VCA). We hypothesised that the % reduction in MR (by VCA) would not follow a linear trend with PVL indices, and tested the alternative hypothesis modelled as a restricted cubic spline adjusted for MR etiology. Result(s): Intraprocedural change in cardiac index (CI) was not linearly related to % change in VCA (p=0.043). From 44% reduction, a greater reduction in MR led to greater increases in CI, however, beyond 78%, increasing MR reduction was not associated with an increase in CI. The same pattern was observed in measures of right ventricular (RV) contractility (end-systolic elastance, Ees) (p=0.025). Conversely, left ventricular (LV) afterload (Ea) decreased beyond 44% reduction but abruptly increased beyond 78%. Logistic regression modelling demonstrated that a 3-grade MR reduction did not significantly affect LV-aortic coupling (Ees/Ea), whereas a 4-grade reduction caused a significant deterioration (beta: -0.38, p=0.02). While a 3-grade MR reduction improved LV haemodynamic efficiency (stroke work/pressure-volume area, SW/PVA), this benefit was lost with complete MR eradication (p=0.22). MR eradication also impaired LV relaxation properties, as evidenced by an increased isovolumic relaxation time constant (Tau) (p=0.001). Conclusion(s): MR eradication does not always enhance cardiac performance. Beyond 78% reduction, some patients showed deteriorations in CI, LV-aortic coupling, hemodynamic efficiency and LV relaxation. These findings emphasize the need for individualized MR reduction targets to optimize outcomes. Copyright © 2025