[Syndrome of mitral valve prolapse: past, present and prospects].

A short history of mitral valve prolapse was reviewed to learn what was the knowledge we have and to recognize what should be resolved at the present time and in the near future. Particular emphasis was placed on the detailed studies performed in Japan as compared to those of occidental countries. Prevalence of mitral valve prolapse largely depends on the methods of investigation and is definitely related to the diagnostic criteria. Among those, the echocardiographic criteria are particularly important, but there are pitfalls which cause over- or underdiagnosis. Auscultatory criteria, which should be confirmed by phonocardiography, are not sensitive enough because of the presence of "silent" prolapse, though the auscultatory acumen of the averaged doctors is quite often unexpected. DaCosta syndrome and the related conditions have some connections with mitral valve prolapse syndrome. The relation should extensively be studied, because somatic and mental signs are not conclusively related to the anatomical abnormalities and the cases with borderline prolapse tend to have definite signs and symptoms. Natural course of mitral valve prolapse based on the long follow-up study is far from the conclusion. So far, no comprehensive cases with well-known natural history of this entity. Prognosis should be carefully evaluated, because most of the patients are doing well and several ominous prognostic signs, such as sudden deaths, are thought to be overemphasized.