Congenital mitral valve insufficiency is now rare and is mostly secondary to mitral valve insufficiency, with rheumatic simple mitral valve insufficiency accounting for a decreasing percentage of all mitral valve insufficiencies. The most common cause of non-rheumatic simple mitral insufficiency is tendon rupture, followed by infective endocarditis, mitral mucus-like degeneration, and ischaemic heart disease, so the question of whether mitral insufficiency is hereditary is no longer discussed.