Background Multiple studies illustrated that mitral valve (MV) leaflet presented variations, and there is little known about the posterior mitral leaflet (PML) anatomical variation affecting residual MR in interventional mitral valve edge-to-edge repair (TEER) with the ValveClamp system in patients with degenerative mitral regurgitation (DMR) using three-dimensional transesophageal echocardiography (3D TEE). Method Fifty-five DMR patients treated with TEER were included and performed 3D TEE pre- and post-procedure immediately. 3D TEE images were proceeded to characterize the posterior mitral leaflet anatomy and investigate the relationship between variations and residual mitral regurgitation (MR). Results Variations in PML were found in 16 patients (32%) of this series, including 3 cases (6%) of one scallop, 8 cases (16%) of two scallops, and 5 cases (10%) of four scallops. Residual MR ≥ 2+ were found in 3 patients with variant PML and 8 patients with classical PML post procedures, while other patients were all < 2+. The Chi-square test results showed no correlation between residual MR and PML variants (18.8% vs. 23.5, ᵪ ² = 0, p = 0.988). Of the 5 patients with 4 scallops, 3 had poor clinical outcomes. Two patients were converted to surgical mitral valve repair and one died 1 month after implantation. Conclusions 3D TEE provides a novel and non-invasive method to characterize and classify PML variations. Variations in PML are relatively common and not associated with residual MR 2+.