In contrast to rheumatic MS, there is no commis- sural fusion, and the leaflet tips are usually unaffected. The progression of calcific MS is variable, ranging from an increase of <1.0 to up to 9 mmHg per year.9,11 The prognosis of this group of patients is poor, with a 5-year survival rate <50%, most likely because of advanced age and other comorbidities.4 Determination of the severity of stenosis is difficult because of extensive calcification, which prevents measurement of an accurate planime- tered area, and the significant abnormalities of LA and LV compliance, which cause a high gradient in the absence of severe obstruction.12 16 These patients are at high risk with any intervention because of the extensive calcifica- tion, as well as advanced age and multiple comorbidi- ties. Thus, in patients with calcific MS, the indications for any intervention differ from those for rheumatic MS, and intervention for calcific MS should be performed only in the highly symptomatic patient. Nonrheumatic MS can also be present after radiation therapy and after a mitral valve repair with a small annuloplasty ring. Recommendation-Specific Supportive Text 1. Indications for intervention in patients with cal- cific MS are different from those for rheumatic MS for the following reasons. First, because calci- fication involves the annulus and base of the leaf- lets without commissural fusion, there is no role CLINICAL STATEMENTS AND GUIDELINES for PMBC or surgical commissurotomy. 