Background: Percutaneous edge-to-edge mitral valve repair (Mitraclip) is an evolving therapy for patients with symptomatic severe mitral regurgitation (MR). Whether this leads to secondary changes in the mitral annulus is unknown.Methods: We studied changes in mitral annular geometry before and immediately after Mitraclip implant in a cohort of high-risk patients (n=20) with symptomatic MR (≥ grade 3+). Mitral valve quantification software (MVQ) and 3D transoesophageal echocardiography were used to measure the following mitral annular parameters, (1) anterior-posterior diameter (DAP, mm), (2) intercommissural diameter (DAlPm, mm), (3) 3D circumference (C3D, mm), (4) 3D area (A3D, mm2) (5) height (H, mm) and (6) sphericity index (DAP/DAlPm ratio) in both functional and degenerative MR aetiology.Results: There was a significant reduction in all annular parameters (except height, H) immediately post Mitraclip deployment. Functional MR patients had a greater reduction in DAP and sphericity index compared with degenerative MR patients (DAP: 7.7 ± 3.1 vs. 4.3 ± 3.6 mm, p=0.04) (DAP/DAlPm ratio: 0.15 ± 0.09 vs. 0.07 ± 0.07, p=0.03). All other annular measurements did not differ between the 2 groups. In this small number of patients, DAP and sphericity index did not significantly predict adverse outcomes at 6 months, although we observed a trend towards larger pre-Mitraclip DAP where adverse outcomes occurred.Conclusion: Mitraclip implant leads to acute changes in mitral annular geometry, in particular, a significant reduction in AP diameter that differs according to MR aetiology. The impact of these acute changes on longer term success rates, durability of MR reduction and adverse events merits further investigation.