During the second half of the 20th century the improvement in the socio-economic situation and the widespread use of antibiotics led to the eradication of rheumatic fever in developed countries. In contrast, the incidence of this disease has remained extremely high in non-industrialized countries. Today, rheumatic fever still remains the principle cause of valvular heart disease and particularly mitral valve disease worldwide.
As discussed extensively in the historic review section, a history of untreated group A Beta hemolytic streptococcal pharyngitis is the event that may lead to rheumatic fever. In this scenario, the rate of development of rheumatic fever is about 3%.
The two major factors that should be considered regarding the risk of rheumatic fever are: 1) the intensity of the immune response during the episode of streptococcal pharyngitis and 2) the persistence of the organism during the recovery. The strain of Group A streptococcus also plays a role as M-types are associated with strong immune response. These so-called rheumatogenic strains have a cell wall which contains M proteins that are highly antigenic. The immunologic response to M proteins produces antibodies that may cross react with cardiac myosin. They also cross react with perivascular connective tissue leading to the formation of Aschoff bodies. It has also been suggested that cell-mediated immunity plays a definite role in the constitution of acute rheumatic valvular lesions.
Jones Criteria, first described in 1944 and updated in 1992, remain relevant and are used for the diagnosis of initial attacks of rheumatic fever. They are divided into two categories of major and minor criteria.
During the acute phase, carditis is noted in about 50% of patients. As mentioned first by Bouillaud, cardiac involvement is a pancarditis and acute valvulitis involving the left-sided valves is a characteristic feature of this disease. Mitral valve regurgitation due to type I dysfunction with annular dilatation is a hallmark of acute rheumatic carditis. With the resolution of the acute phase, the long-term prognosis is dominated by the extent and the progression of valvular heart disease.
During the chronic phase, in patients with valvular manifestations but with no known history of rheumatic fever or untreated streptococcal pharyngitis, it may be difficult to establish the rheumatic origin of their valve disease. Echocardiography and intraoperative valve analysis may demonstrate characteristic lesions which would confirm this etiology.
World Health Organization. Rheumatic fever and rheumatic heart disease. WHO technical report series 764. Geneva, World Health Organization, 1998
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