Rheumatic heart disease (RHD) has traditionally been considered the most common underlying condition predisoposing to infective endocarditis. While RHD is still common in developing countries, its prevalence has declined and "mitral valve prolapse is now the most common underlying condition in patients with infective endocarditis."
(from AHA Guideline on Prevention of Infective Endocarditis, Circulation, October 9, 2007)
