| Rheumatic MS | Degenerative MS | Congenital MS |
| The main lesion is “commissural fusion” | The main lesion is “annular calcification”. No commissural fusion | The main lesion is in “subvalvular apparatus”. Commissural fusion is rare |
| Calcification predominates at leaflet tips | At base of leaflets | Chordal fusion with calcification |
| Planimetry is reliable | Not reliable | Large orifice may be present |
| Pressure half-time reliable | Unreliable due to impaired diastolic function and should be avoided | Reliable when diastolic jet occurs |
| Mean Gradient can be used following balloon mitral commissurotomy | Mean Gradient can be used as a marker of severity | Reliable when diastolic jet occurs |
| Central or commissural jet due to valve stiffness. | No particular orientation | Central jet in symmetric type. Eccentric jet in asymmetric type (anteriorily oriented jet in parachute type) |
| Orifice is circular or elliptical in short axis view of planimetry. | Unpredictable | Chordal convergence’ on a single papillary muscle in short axis view at mid-ventricular level in parachute type |
| Manifest in younger age group | Manifest in older age group | Seen from birth |
| Single orifice | Single orifice | May present with “double orifice” type |