Abstract
Pure or predominant mitral insufficiency is nonrheumatic in origin in about half the cases, and some forms have distinctive clinical features that might be called syndromes. Most patients treated surgically require valve replacement; valvuloplasty has limited application. Consideration of possible surgical treatment must take into account the relatively high risk and the uncertainty about the long-range fate of the implanted valve. In addition, clinical disability in these cases is not necessarily progressive.