Abstract 4144798: Hemodynamic Insights Using Pressure Volume Loops into Transcatheter Repair Effects on Left Ventricular Function in Patients with Primary Mitral Regurgitation

Background: Mitral transcatheter edge to edge repair (M-TEER) is an effective treatment for high surgical risk patients with primary mitral regurgitation (MR). Some patients have persistently elevated left atrial (LA) pressures despite successful reduction of MR. We sought to study the underlying reasons for elevated LA pressures after M-TEER. Methods: LV systolic and diastolic functions were evaluated using conductance catheters to obtain pressure volume loops in 22 patients with primary MR and control group of 17 heart transplant recipients with normal function and normal LV EDP response to exercise. LA pressures and LA operating chamber stiffness were obtained, and MR severity was assessed by echocardiography. Results: In comparison with the control group which had all indices of LV systolic and diastolic function in the normal range at rest and with exercise, primary MR patients had increased LV volumes and diastolic pressures, time constant of LV relaxation (t), and LV chamber stiffness constant (all P≤0.01). After M-TEER, LV and LA volumes and pressures, LA operating chamber stiffness, and MR regurgitant volume decreased (all P<0.05), without significant change in LV chamber stiffness constant. Post M-TEER. patients with LA V pressure ≥20 mmHg had significantly higher LA operating chamber stiffness [0.32 (0.13-0.7) vs 0.08 (0.05-0.21) mmHg/mL], time constant of LV relaxation (59±6 vs 48±12 ms), and LV chamber stiffness constant (0.07±0.02 vs 0.05±0.02) versus patients with V pressure <20 mmHg (for all 3 variables: P<0.05). However, there were no significant differences in heart rate, LV systolic function indices (including LV EF), LV volumes, LV energetics, LA volumes, mitral valve area, and residual MR regurgitant volume. Conclusion: After M-TEER, there is no significant change in invasive indices of LV contractility. LV chamber stiffness constant is abnormally increased before M-TEER without a significant change afterwards. Patients with LA V pressure ≥20 mmHg after M-TEER, have worse LV diastolic function and higher LA operating chamber stiffness in comparison with patient having LA V pressure <20 mmHg post M-TEER.