In time, chronic rheumatic valvulitis may develop by organization of the acute endocardial inflammation along with fibrosis, as shown here affecting the mitral valve. Note the shortened and thickened chordae tendineae.

In places where adequate health care systems provide prompt diagnosis and treatment the prevalence of RHD is decreasing, and strict criteria must be employed to assess whether antibiotic therapy should be given for a 'sore throat'. Without adequate health care systems, the incidence of new rheumatic heart disease cases may be 100/100,000 persons.