Mitral teer in degenerative mitral regurgitation: comparison between fibroelastic deficiency and myxomatous disease on clinical outcomes and procedural results

Background Degenerative mitral regurgitation (DMR) has a wide spectrum of heterogeneous degenerative disorders, from fibroelastic deficiency (FED) to barlow disease (BD). The implications for possible different procedural outcome for transcatheter edge-to-edge repair (TEER) approaches, according to this heterogeneity, are yet to be defined. Study design and methods: The study cohort enrolled 125 patients with severe symptomatic DMR who underwent percutaneous repair at San Raffaele Hospital from 2020 to 2024. Patients were retrospectively divided into 2 groups according to the degenerative disorders (FED vs BD). All patients included in the study signed a written informed consent. Acute technical success and 30-day and 12 months device and procedural outcome were defined as recommended by the Mitral Valve Academic Research Consortium. Results One hundred twenty-five (125) patients with severe symptomatic DMR who underwent M-TEER with the system Mitraclip (Abbott Vascular, Santa Clara, CA, USA) were retrospectively enrolled. Briefly, patients with FED exhibited a smaller flail width and IC annular diameter, along with a smaller non statistically significant mitral valve area and AP annular diameter when compared with patients with BD. Additionally, when evaluating the ratio between the flail width and the intercommisural (IC) annular diameter, higher values were found in patients with BD (flail width/IC diameter BD 0.328±0.09 vs FED 0.28±0.07; p = 0.01) (Figure 1). The mean number of clips implanted was higher in patients with BD (BD 1.82±0.6 vs FED 1.53±0.6; p = 0.01). Furthermore, a higher prevalence ≥2 clips implantation was noted in patients with BD (≥2 clips: BD 76% - 26/34 vs FED 46% - 42/91; p = 0.0026). The postoperative MV gradient was not statistically different.The primary composite endpoint of early device success at 30 days consisting of technical success, freedom from all-cause mortality, surgery or intervention related to the device and optimal device performance was similar in the two groups (BD: 29/34 - 85% vs FED: 80/91 88%, p = 0.76). Contrarily, at 12 months follow-up evaluation Kaplan–Meier curve of event-free survival in the two subgroups (BD and FED) showed that patients undergoing Mitral teer with FED exhibited a significantly higher survival free from MACE and recurrent MR compared to patients with Barlow disease (log-rank: HR 3.13, 95% CI 1.2–8.7; P = 0.03) (Figure 2). Conclusion This is the first study addressing the early procedural and clinical outcomes of MitraClip procedures in patients with DMR exploring the heterogenous aspect of BD versus FED. Despite the different anatomical characteristics, MitraClip procedure for patients with BD has the same feasibility and safety as FED patients. However, a higher number of Clips and a higher prevalence of post-procedural MR≥2+ was noted in patients with mixomatous disease, along with a worse 1-year event free survival after mitral TEER.