1Herzzentrum der Universität zu Köln Klinik III für Innere Medizin Köln, Deutschland; 2Herzzentrum der Universität zu Köln Klinik für Kardiologie, Angiologie, Pneumologie und Internistische Intensivmedizin Köln, Deutschland; 3Universitätsklinikum Köln Klinik III für Kardiologie, Angiologie, Pneumologie und Internistische Intensivmedizin Köln, Deutschland
Atrial functional mitral regurgitation (AFMR) constitutes of two subtypes. One is characterized by Carpentier type I leaflet motion with isolated annulus dilation (IAD), termed AFMR-IAD. The other subtype is characterized by atriogenic hamstringing (AH) of the posterior mitral leaflet (PML), leading to restricted PML motion (Carpentier IIIb), termed AFMR-AH. It is unclear whether these subtypes show differences beyond leaflet motion. Furthermore, the impact of AFMR subtypes on mitral valve transcatheter edge-to-edge repair (M-TEER) outcomes remains to be elucidated. Distinguishing echocardiographic features of these subtypes are lacking, especially data on 3-dimensional (3D) assessment.
Methods
Of 1,047 consecutive patients who underwent M-TEER between 2014 and 2022 in our center, we identified 128 (12.2%) with AFMR. Of those, 75 (58.6%) were identified as AFMR-IAD and 53 (41.4%) as AFMR-AH according to leaflet motion pattern . In a subset of 22 patients with AMFR-IAD and 19 patients with AFMR-AH, 3D assessment of the mitral valve was performed based on pre-procedural transesophageal echocardiography (TEE) using a dedicated semi-automated 3D module of Image-Arena (Version 4.6, TOMTEC Imaging Systems, Unterschleißheim, Germany). Image A shows a 3D model of IAD and image B of AH. The rate of technical success, MR grade at discharge, and the loss of leaflet insertion (LLI) rate after M-TEER were collected.
Results
The mitral anteroposterior (AP) and anterolateral (AL) annulus diameter, as well as the annular height, annular circumference, and annular area did not differ between the two subtypes. However, the sphericity index (AP diameter/ AL diameter ) was significantly greater in AFMR-IAD (0.96 [0.90 to 1.04 ]) than in AFMR-AH (0.92 [0.86 to 1.00]), p=0.025. In addition, the indexed anterior mitral leaflet (AML) area (AFMR-IAD: 4.2 [3.4 to 4.8] cm²/m² vs. AFMR-AH: 4.5 [4.0 to 5.0] cm²/m², p=0.041) was significantly larger in patients with AMFR-AH, whereas the indexed PML area did not differ between the subtypes (p=0.745). The PML angle was significantly steeper in AFMR-AH (43.1 [37.3 to 48.9] °) than in AFMR-IAD (29.0 [22.4 to 35.4] °), p<0.001. The tenting volume was greater in AFMR-AH (4.4 [2.9 to 6.0] cm³ vs. 2.8 [2.0 to 3.8] cm³ vs., p=0.018). The 3D vena contracta area (3DVCA) was larger in AFMR-AH (0.9 [0.6 to 1.0] cm² vs. 0.5 [0.4 to 0.6] cm², p<0.001). In multivariable binary logistic regression analysis, PML angle was the only parameter which was independently associated with AFMR subtype (OR 1.1 95% CI [1.03-1.24], p=0.01). Technical success in the total AFMR cohort was more frequently achieved in patients with AFMR-IAD (99% vs. 89%, p=0.020) and only patients treated for AFMR-AH had a LLI at discharge (0% vs. 8%, p=0.024). MR ≤II at discharge was achieved significantly more frequently in patients with AFMR-IAD (92% vs. 72%, p=0.005 ).
Conclusion
Various 3D mitral valve parameters were significantly different between AFMR subtypes in patients undergoing M-TEER. Importantly, there were worse procedural outcomes after M-TEER in patients with AFMR-AH. Most strikingly the steeper PML angle holds the potential to serve as a marker for the AFMR-AH subtype, whereas the higher 3DVCA in this subtype indicates a more severely insufficient mitral valve leaflet coaptation.