Introduction:In the early days of mitral valve replacement (MVR), there was an increased rate of mortality associated with low cardiac output syndrome (LCOS). Excision of the sub valvular apparatus (SVA) was one of the reasons for LCOS, as MVR at that time included complete excision of mitral leaflets and SVA that is, chordae tendinae and papillary muscles. Left ventricular function and geometry depend on dynamic interaction between left ventricular wall and mitral annulus which is bridged by SVA. Papillary muscle and chordae moderates wall tension during systole and optimize left ventricular distension during diastole. Interruption of ventricular-papillary-annular complex by excision of SVA during MVR thus causes impairment of normal ventricular stress-strain pattern and thus eventually leads to impaired left ventricular function and low cardiac output. In the early sixties Lillehei and his collegues capitalized on the fact and suggested that the high mortality rate associated with MVR could be reduced by preserving the papillary muscles and chorda tendenae. He preserved the posterior leaflet during MVR and noted a decreased incidence of post operative low output syndrome 1 . Short Term Clinical Outcome in Patients with Abstract:Background: Preservation of subvalvular apparatus (SAP) during mitral valve replacement (MVR) was introduced about forty years back, but the outcome of this procedure is not well studied yet. Our study aimed to measure the in-hospital outcome of this procedure in rheumatic patients.