[Mitral valve prolapse: a severe abnormality?].

The reputation of mitral valve prolapse being a benign condition is based to a great extent on the fact that complications are rare in minor forms, but also because a number of studies of the condition included normal subjects, especially of the female sex. The prevalence of mitral valve prolapse in the general population is 4 to 5%. Approximately 20% of these patients have marked redundancy of valve tissue and are particularly exposed to complications. The incidence of infective endocarditis in cases with an audible murmur is 0.05% per year. The incidence of mitral regurgitation increases with age, so that the annual probability of surgical correction is 0.03%. The risk of sudden death in cases without mitral regurgitation is low (2/10,000 per year) but it is 50 to 100 times greater when mitral regurgitation is present. The frequency of arrhythmias is also higher in cases with mitral regurgitation and that of cerebro-retinian ischemia is estimated to be 0.02% per year. Therefore, a serious complication (endocarditis, sudden death, surgical mitral regurgitation, cerebral or retinian ischemia) occurs each year for every 1,000 mitral valve prolapses, or for a population of 25,000 inhabitants.