Background The purpose of the study was to determine the association between vena contracta area (VCA) and secondary leaflet tethering among mitral valve prolapse (MVP) patients, and thus to further identify and characterize an MVP with pathological leaflet tethering (MVPt+) phenotype. Methods We prospectively evaluated 94 consecutive MVP patients with significant mitral regurgitation (MR) and 20 healthy controls. MVPt+ group was defined as tenting volume index (TVi) > 0.7 ml/m ². The three-dimensional (3D) geometry of mitral valve apparatus and VCA was measured with dedicated quantification software. Results Of the 94 patients with MVP and significant MR, 31 patients showed a TVi > 0.7 ml/m ² and entered the MVP with leaflet tethering (MVPt+) group. In stepwise multivariate analysis, only prolapse volume index and TVi was independently associated with 3D VCA. Apart from marked left ventricular and annular enlargement, MVPt+ group presented significantly higher frequency of leaflet flail, greater VCA, elevated plasma levels of NT-proBNP and sPAP. ROC curve revealed that occurrence of leaflet tethering is associated with a VCA ≥0.55 cm ² in MVP patients. Conclusions Secondary leaflet tethering is a significant mechanism behind severe degenerative mitral regurgitation, resulting an MVPt+ phenotype featuring more advanced morphological and hemodynamical characteristics .