Jose Zamorano - Heart Valve Disease: State of the Art

The etiology of valve heart diseases has slightly changed during the last half of the twentieth century, as rheumatic fevers incidence has declined in developed countries []. However, it is still the most common cause of valve disease in the young and in developing countries including Africa, Middle East, Indochina, South America and some parts of Australia. The decline in the prevalence of rheumatic fever is related to sociosanitary evolution, which has led to an improvement in living conditions and in the access to health care.

It is also due to the improvement of life expectancy that valve diseases tend to be much more prevalent in the elderly []: an U.S. registry showed how global prevalence is around 2.5%; however, the prevalence amongst patients older than 75 years increased to 13%. Between elderly patients, the most common diseases are calcific aortic stenosis, aortic regurgitation due to aortic root dilation and secondary mitral regurgitation.

Nevertheless, an unknown but probably significant percentage of patients with valve disease remains undiagnosed [].

Rheumatic fever is the consequence of an impaired immune response against group A beta-hemolytic Streptococcus (also known as Streptococcus Pyogenes). After the initial infection, which usually takes place during childhood []. Although the initial damage can cause severe valve lesions, rheumatic valve disease is more often based on cumulative damage due to either recurrent episodes of acute rheumatic fever or chronic degeneration cause by an impaired valve function.

The mechanism of the immune response relies on molecular mimicries between several streptococcal and human proteins. Although the exact pathophysiology remains obscure, some advances have been made in this field. The abnormal immune response is based on the streptococcal strain, the presence of genetic susceptibility and an aberrant host-bacteria interaction.