Resolution of congestive heart failure and reverse remodeling in two Chihuahuas with flail mitral valve leaflets.

Development of a flail mitral valve (MV) leaflet secondary to ruptured chordae tendineae in the setting of myxomatous mitral valve disease is a known complication of the disease that often results in severe mitral regurgitation. Two cases are presented in which a flail anterior MV leaflet caused severe mitral regurgitation and led to the development of congestive heart failure in male castrated Chihuahuas. Over variable periods of time, repeat cardiac evaluation disclosed reverse left-sided cardiac remodeling and lessened mitral regurgitation that allowed for withdrawal of furosemide in both dogs. While rare, improvement in mitral regurgitation severity may occur without surgical intervention, allowing for reverse left-sided cardiac remodeling and discontinuation of furosemide.