Feasibility of Transcatheter Mitral Valve Repair for Non-A2P2 Mitral Regurgitation

Background. MitraClip is approved for treatment of both degenerative and functional mitral regurgitation (MR). The landmark trials for this device included only patients with A2P2 location of MR. Initial commercial experience showed A2P2 location was associated with higher technical success as compared with non-A2P2 location. We intended to compare technical success of A2P2 vs non-A2P2 MitraClip procedures in terms of residual MR and transmitral gradient (TMG) in the contemporary setting as the operator experience has increased. A total of 159 patients with complete data were included in the study. A total of 129 patients were in the A2P2 MitraClip group and 30 patients were in the non-A2P2 MitraClip group. Post implantation, there was a significant increase in TMG in both A2P2 and non-A2P2 groups (0.73 ± 1.42 and 0.94 ± 1.85, respectively; both P<.01). However, postimplantation TMG was not different between the 2 groups (3.6 ± 1.9 A2P2 vs 3.7 ± 1.7 non-A2P2; P=.56) and there was no difference in residual MR (P=.40). At 1-month follow-up of 82 patients (64 A2P2 and 18 non-A2P2), the results were similar; TMG (3.7 ± 1.6 A2P2 vs 3.7 ± 2.1 non-A2P2; P=.96) and residual MR (P=.41). Our data showed similar technical success of MitraClip procedures in both types of MR.

J INVASIVE CARDIOL 2021;33(12):E968-E969. Epub 2021 October 7.

Key words: mitral regurgitation, transcatheter mitral valve repair

Over a decade ago, surgical mitral valve (MV) repair was the mainstay of treatment for mitral regurgitation (MR).¹ Transcatheter edge-to-edge MitraClip device (Abbott) revolutionized the treatment of MR by providing a robust treatment option in patients with high or inoperable surgical risk. The key anatomical inclusion criteria for degenerative MR in the pivotal EVEREST II trial was A2P2 pathology.² Non-A2P2 pathology was excluded from all landmark studies.³ Moreover, the initial commercial United States experience showed that A2P2 location was associated with a higher postimplantation success rate (odds ratio vs other location, 2.29; 95% confidence interval, 1.20-4.36; P=.02).⁴ This heterogeneity in treatment efficacy is partly due to the acquisition of a unique skillset required for these procedures, and technical challenges with non-A2P2 grasp using the original MitraClip device. Since commercial approval, the collective experience of the interventional community has allowed for the treatment of more challenging mitral valve lesions. Moreover, the newer iterations of the MitraClip device (NT, NT-R, XT-R) provide improved steerability and leaflet grasping, allowing for improved trajectory and treatment of challenging anatomies. As such, we decided to examine the impact of non-A2P2 grasps on contemporary MitraClip outcomes.

This was a single-center study of patients undergoing MitraClip procedure between November 2015 and March 2020. Patients were divided into A2P2 and non-A2P2 groups. Fisher’s exact test was used to analyze difference in postimplantation MR between the 2 groups. We used analysis of covariance models to include pre-MitraClip transmitral gradient (TMG) and location of MitraClip to see if those factors had any influence on residual MR and residual TMG. GraphPad Prism 8 and RStudio, version 1.3.1056 software were used for statistical analysis.

A total of 159 patients with complete data were included in the study (129 in the A2P2 MitraClip group and 30 in the non-A2P2 MitraClip group). There was a significant increase in TMG in both A2P2 and non-A2P2 groups (0.73 ± 1.42 and 0.94 ± 1.85, respectively; both P<.01) (Figure 1A). Postimplantation TMG (3.6 ± 1.9 A2P2 vs 3.7 ± 1.7 non-A2P2; P=.56) (Figure 1A) and residual MR (P=.40) (Figure 1B) were not significantly different between the 2 groups. The results were similar at 1-month follow-up of 82 patients (64 A2P2 and 18 non-A2P2); TMG (3.7 ± 1.6 A2P2 vs 3.7 ± 2.1 non-A2P2; P=.96) and residual MR (P=.41).

Due to the exclusion of patients with non-A2P2 lesions from the pivotal MitraClip studies,^2,3 the efficacy of transcatheter edge-to-edge repair in this patient population is not well established. These patients comprise around 21% of the Transcatheter Valve Therapy registry population who underwent MitraClip,⁴ with initial commercial data suggestive of lower success rates.⁴ Newer generations of the MitraClip device and the cumulative experience with transcatheter technologies have allowed for improved treatment of challenging anatomies and non-A2P2 lesions. Our study suggests similar procedural success rates without an adverse increase in mean gradient. A larger study is needed to confirm these findings.

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