Atrial Functional Mitral Regurgitation Subtypes Undergoing Transcatheter Edge-to-Edge Repair: Suboptimal Outcomes in Atriogenic Hamstringing.

Background: Two subtypes of atrial functional mitral regurgitation (AFMR) have been described, one is characterized by Carpentier type I and the other by Carpentier type IIIb leaflet motion.

Objectives: The authors sought to analyze echocardiographic characteristics and outcomes of AFMR subtypes undergoing mitral valve transcatheter edge-to-edge repair (M-TEER).

Methods: Of 1,047 consecutive patients who underwent M-TEER, the authors identified those with isolated mitral annulus dilation (Carpentier I), termed AFMR-IAD, and those with atriogenic hamstringing characterized by restricted posterior mitral leaflet motion (Carpentier IIIb), termed AFMR-AH. Echocardiographic baseline characteristics and outcomes up to 1-year were analyzed.

Results: A total of 128 patients (12.2%) met AFMR criteria; 75 (58.6%) were identified as AFMR-IAD and 53 (41.4%) as AFMR-AH. AFMR-AH displayed greater left atrial and left ventricular volumes, greater mitral annulus, shorter and steeper posterior mitral leaflet, and more pronounced MR (all P < 0.05). Technical success was achieved in 98.7% (AFMR-IAD) and 86.8% (AFMR-AH) of patients (P = 0.009). At discharge, device detachments were exclusively observed in AFMR-AH (10.0%). MR ≤II was achieved in 95.6% and 78.6% at 30 days (P = 0.009) and in 93.0% and 74.1% at 1 year (P = 0.038) in patients with AFMR-IAD and AFMR-AH, respectively. AFMR-AH was associated with procedural failure (OR: 1.17 [95% CI: 1.00-1.38]; P = 0.045) at 30 days (43.4% vs 24.0%; P = 0.023) and all-cause mortality (HR: 2.54 [95% CI: 1.09-5.91]; P = 0.031) at 1 year (77% vs 92%, Kaplan-Meier estimated 1-year survival; P = 0.017).

Conclusions: AFMR-AH shows worse procedural and clinical outcomes following M-TEER than AFMR-IAD. Thus, vigilance regarding this pathology is warranted and alternative mitral valve therapies might need to be considered.