Mitral valve disruption following percutaneous balloon valvuloplasty. Two cases of massive mitral regurgitation due to mitral valve disruption following percutaneous balloon valvuloplasty are reported. This severe complication occurred in two elderly women with recurrent mitral stenosis after previous surgical commissurotomy. Due to their unstable hemodynamic and clinical condition, both patients underwent emergency valve replacement. At surgery, the commissures appeared fused and heavily calcified; the chordae tendineae thickened, shortened, and fused; and the leaflets presented a large tear with sheared edges. Because the technical aspects of both procedures were unremarkable, the anatomic features of the mitral valve seemed to affect the occurrence of severe mitral regurgitation. Percutaneous balloon valvuloplasty should be therefore applied carefully to patients with prior surgical valvotomy, in whom the structural alterations of the mitral apparatus may predispose to severe valvular damage. 