Atrial mitral regurgitation: Characteristics and outcomes of transcatheter mitral valve edge-to-edge repair

Background: Mitral transcatheter edge-to-edge repair (MTEER) is an established therapeutic approach for mitral regurgitation (MR). Functional mitral regurgitation originating from atrial myopathy (A-FMR) has been described.

Objectives: We sought to assess the clinical, echocardiographic and hemodynamic considerations in A-FMR patients undergoing MTEER.

Methods: From 2014 to 2020, patients undergoing MTEER for degenerative MR (DMR), functional MR (FMR), and mixed MR were assessed. A-FMR was defined by the presence of MR > moderate in severity; left ventricular (LV) ejection fraction (LVEF) ≥ 50%; and severe left atrial (LA) enlargement in the absence of LV dysfunction, leaflet pathology, or LV tethering. The diagnosis of A-FMR (vs. ventricular-FMR [V-FMR]) was confirmed by three independent echocardiographers. Baseline characteristics, procedural outcomes as well as clinical and echocardiographic follow-up are reported. Device success was defined as final MR grade ≤ moderate; MR reduction ≥1 grade; and final transmitral gradient <5 mmHg.

Results: 306 patients underwent MTEER, including DMR (62%), FMR (19%), and mixed MR (19%). FMR cases included 37 (63.8%) V-FMR and 21 (36.2%) A-FMR. Tricuspid regurgitation (≥ moderate) was higher in A-FMR (80.1%) compared to V-FMR (54%) and DMR (42%). Device success did not significantly differ between A-FMR and V-FMR (57% vs. 73%, p = 0.34) or DMR (57% vs. 64%, p = 1.0). The A-FMR cohort was less likely to achieve ≥3 grades of MR reduction compared to V-FMR (19% vs. 54%, p = 0.01) and DMR (19% vs. 49.7%, p = 0.01). Patients with V-FMR and DMR demonstrated significant reductions in mean left atrial pressure (LAP) and peak LA V-wave, though A-FMR did not (LAP -0.24 ± 4.9, p = 0.83; peak V-wave -1.76 ± 9.1, p = 0.39). In follow-up, echocardiographic and clinical outcomes were similar.

Conclusions: In patients undergoing MTEER, A-FMR represents one-third of FMR cases. A-FMR demonstrates similar procedural success but blunted acute hemodynamic responses compared with DMR and V-FMR following MTEER. Dedicated studies specifically considering A-FMR are needed to discern the optimal therapeutic approaches.