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I enjoyed reading the recent article on the worldwide perspective of valve disease by Soler-Soler and Galve from Barcelona, Spain. But I was surprised that no mention was made of mitral valve prolapse (MVP) anywhere in their article.
MVP is the commonest valve disorder in the United States as well as in many parts of the world. It also has a prevalence of 4.3% in Spain (see table).
Prevalence (%) of mitral valve prolapse
Modified from reference 2.
*Echocardiographic study; **Necropsy study; ***Expressed as a ratio.
MVP is the commonest cause of mitral regurgitation in the United States and other developed countries  as well as in the developing countries such as China.  One of the serious complications of mitral regurgitation is atrial fibrillation which usually persists even after successful corrective surgery of the mitral valve and often recurs after pharmacologic or electric cardioversion. Although postoperative atrial fibrillation can be successfully managed by antiarrhythmic drugs and long-term anticoagulant therapy to prevent thromboembolism, these therapeutic modalities are not without side-effects, torsades de pointes and bleeding, respectively. However, it was gratifying that the adjunctive use of the Cox maze procedure reported recently from the Mayo clinic increased the restoration of sinus rhythm to 82% of their patients.
MVP is also the commonest cause of infective endocarditis. The microbial agents causing infective endocarditis on prolapsing mitral valve are similar to those that infect valves deformed by congenital or rheumatic processes. Although streptococci viridans are the most common organisms, coagulase-negative staphylococcal endocarditis is not an infrequent occurrence in patients with MVP. Recognition of the occurrence of endocarditis due to coagulase-negative staphylococci in patients with MVP is important for several reasons. First, blood cultures positive for these organisms are frequently disregarded in patients without prosthetic heart valves or intravascular catheters. Second, the indolent course of some coagulase-negative staphylococcal endocarditis may delay consideration of the correct diagnosis, particularly in patients without congenital or rheumatic heart disease. Finally, even with effective antimicrobial therapy on the basis of in vitro studies, the clinical course may be prolonged and characterized by multiple responses to and relapses following drug withdrawal.
Thus it was most unfortunate that such an important valve disease as MVP was inadvertently omitted from discussion in this otherwise comprehensive review of the subject.
Tsung O. Cheng, M.D.
Professor of MedicineDivision of Cardiology
The George Washington University Medical Center2150 Pennsylvania Avenue, N.W.Washington, DC 20037, USA
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2. Cheng TO, Barlow JB: Mitral leaflet billowing and prolapse. Its prevalence around the world. Angiology 1989;40:77-87.
3. Cheng TO: Mitral valve prolapse: an overview. J Cardiol 1989;19 (Suppl 21):3-20.
4. Danielsen R, Nordrehaug JE, Vik-Mo H: High occurrence of mitral valve prolapse in cardiac catheterization patients with pure isolated mitral regurgitation. Acta Med Scand 1987;221:33-38.
5. Zhou LY, Hu RD: Floppy valve syndrome: a clinicopathological analysis of 16 cases. Chin J Intern Med 1986;25:149-151.
6. Cheng TO: Mitral valve prolapse. A review. Chin J Intern Med 1988;27:56-60, 126-129.
7. Cheng TO: Combined mitral valve repair and the Cox maze procedure for mitral valve prolapse and regurgitation and associated atrial fibrillation. J Thorac Cardiovasc Surg 2000;119:634.
8. Handa N, Schaff HV, Morris JJ, Anderson BJ, Kopecky SL, Enriquez-Sarano M: Outcome of valve repair and the Cox maze procedure for mitral regurgitation and associated atrial fibrillation. J Thorac Cardiovasc Surg 1999;118:628-635.
9. McKinsey DS, Ratts TE, Bisno AL: Underlying cardiac lesions in adults with infective endocarditis. The changing spectrum. Am J Med 1987;82:681-688.
10. Atkinson JB, Virmani R: Infective endocarditis: changing trends and general approach for examination. Hum Pathol 1987;18:603-608.
11. Baddour LM, Bisno AL: Infective endocarditis complicating mitral valve prolapse: epidemiologic, clinical, and microbiologic aspects. Rev Infect Dis 1986;8:117-137.
12. Barlow JB, Cheng TO: Mitral valve billowing and prolapse. In: Cheng TO: The International Textbook of Cardiology. New York: Pergamon Press, 1987:497-524.