Pathogenesis of rheumatic mitral valve disease

This figure depicts the theoretical pathway for the various phenotypic manifestations of rheumatic MV disease. The initial inflammatory response following the first episode of ARC determines the degree and extent of structural involvement of the MV apparatus. Severe inflammation of the chordal structures and MV leaflets often lead to severe MR in the very young, whereas moderate inflammation followed by repeated bouts of ARC is more likely to cause mixed MV disease (MR and MS) later in life. Isolated MS is usually the consequence of milder or even subclinical forms of ARC followed by episodes of recurrent carditis. In developing countries where the risk of recurrent ARC is high, MS presents at a younger age and the valve leaflets are more likely to be pliable and not calcified. In Western societies where the risk of recurrent ARC is low, MS presents later in life, and the MV leaflets are more likely to be rigid and calcified.