Recurrent incompetence of repaired floppy mitral valves and the severity of myxomatous degeneration.

The purpose of this study was to clarify whether or not severe myxomatous degeneration impairs the stability of a repaired mitral valve after valve-conservative surgery. A total of 21 patients who underwent successful valve-conservative surgery for pure isolated mitral incompetence were classified into two groups, one comprising those with stable mitral valve function and the other comprising those who developed recurrent incompetence within 1 year after surgery. The histological severity of myxomatous degeneration of the mitral leaflet was compared between the two groups, based upon microscopic observation and quantification of the myxomatous area in the fragment that had been surgically excised from the floppy mitral leaflet during valve-conservative surgery. The degree of myxomatous degeneration of the surgically excised fragment was significantly higher in the "recurrent" group than in the "stable" group (P = 0.02). As a microscopically confirmed severely degenerative myxomatous mitral valve may develop recurrent incompetence after valve-conservative surgery within a relatively short period, careful and regular follow-up is required.