Immediate effect of the MitraClip procedure on mitral ring geometry in primary and secondary mitral regurgitation

Percutaneous treatment of mitral regurgitation (MR) has been shown to reduce MR severity and improve functional outcomes. Surgical treatment of MR usually includes mitral annulus reduction. The influence of the MitraClip on annulus geometry is not clear. We wanted to investigate whether the procedure itself reduces annulus diameter and if there may be differences between secondary or functional (SMR) and primary (PMR) MR.

We retrospectively assessed 3D echocardiography (3D-TEE) data of 55 patients acquired during the procedure shortly before and after clip placement for changes in annulus diameter and area. Measurements were done with QLAB software. Patients were categorized as having either SMR (n = 41) or PMR (n = 14). In SMR, we were able to demonstrate a significant reduction in annulus area (meanΔ 1.30 ± 1.44 cm2; P < 0.001), anterior-posterior (AP)-diameter (meanΔ 0.28 ± 0.32 cm; P < 0.001), tenting area (meanΔ 0.39 ± 0.49 cm2; P < 0.001). No significant change could be found for latero-medial (LM)-diameter. In contrast, we could not demonstrate significant changes in any of the parameters described above in patients with PMR.

Percutaneous treatment with the MitraClip device can produce immediate reductions in mitral annulus size in SMR, probably supporting procedural success. It also reduces tenting, which may have prognostic implications. In contrast, these effects on mitral geometry cannot be demonstrated in PMR. Knowledge of this difference between SMR and PMR may be important to improve procedural strategies.