Etiology and pathogenesis
The pathological process is initiated by GABHS. This pathogen is highly contagious and contains M-protein, a crucial virulence factor that inhibits bacterial phagocytosis by macrophages. Familial predisposition plays a major role: the risk of disease is higher in carriers of certain histocompatibility antigens (HLA DR5-DR7, CW2-CW3) and the specific B-cell alloantigen D 8/17.
The pathogenesis is based on two mechanisms:
- Direct toxic tissue damage by streptococcal enzymes.
- Immunopathological reactions (the main component). The body produces antibodies against pathogen antigens, but due to the phenomenon of molecular mimicry (antigenic similarity), these antibodies begin to attack the host's own tissues.
Morphologically, systemic connective tissue disorganization proceeds through four stages: reversible mucoid swelling, irreversible fibrinoid changes, granulomatosis (formation of Aschoff bodies), and sclerosis.
Clinical presentation
The first symptoms appear a few weeks after the streptococcal infection. In preschool children, the onset is usually acute (fever, prominent arthritis, pronounced carditis), whereas in adolescents, the process often has a subacute, insidious character.
- Rheumatic carditis. The leading syndrome, occurring in 70–85% of cases. Its key manifestation is valvulitis (inflammation of the valve, most commonly the mitral valve), which auscultically produces a blowing systolic murmur. The insidious nature of carditis is that patients rarely complain of cardiac pain—often only unmotivated lethargy and fatigue are noted.
- Rheumatic polyarthritis. Affects large or medium joints. Characterized by migrating pain and a completely benign course without destruction of articular surfaces. Symptoms rapidly regress with anti-rheumatic therapy.
- Sydenham's chorea (St. Vitus' dance). Specific involvement of subcortical nuclei, typical for girls aged 6–15 years. It begins with emotional lability and tearfulness, deterioration of handwriting. Later, choreic hyperkinesias (chaotic awkward movements that disappear during sleep) and marked muscular hypotonia ("floppy shoulders" sign) appear.
- Skin manifestations. Rare specific signs. They include erythema annulare on the trunk and firm, painless subcutaneous rheumatic nodules over areas of mechanical friction.
Diagnostics and differential search
The diagnostic algorithm for an initial ARF attack is based on the modified Jones criteria (Association of Rheumatologists of Russia, 2003). The diagnosis is valid in the presence of two major criteria or one major and two minor criteria, strictly provided there is laboratory confirmation of a recent streptococcal infection (e.g., high titers of anti-streptolysin O).
Instrumentally (using echocardiography), signs of valvulitis are visualized: thickened, friable valve leaflets with restricted mobility.
What can it be confused with? Newly detected heart murmurs require the exclusion of congenital heart defects and minor cardiac anomalies (e.g., mitral valve prolapse). If the patient shows signs of isolated myocarditis without valve involvement, the diagnosis of ARF is called into question. Joint syndrome is differentiated from juvenile idiopathic arthritis, systemic lupus erythematosus, and reactive arthritidis.
Disease outcomes
In an unfavorable course, the acute phase transitions into chronic rheumatic heart disease (CRHD). This occurs in 20–25% of patients and is accompanied by persistent deformation of the valvular apparatus due to post-inflammatory marginal fibrosis.
Mitral regurgitation develops most frequently, less commonly mitral stenosis or aortic valve involvement. The development of a heart defect leads to severe hemodynamic disturbances, atrial dilatation, atrial arrhythmias, and the risk of thromboembolic complications.
The 4 stages of connective tissue pathomorphology can be remembered as MFGS: Mucoid swelling (the only reversible one) ➔ Fibrinoid changes ➔ Granulomatosis ➔ Sclerosis (scar).
Class and exam questions
At what age do people most frequently develop ARF?
The disease has strict age specificity: the vast majority of cases debut in childhood and adolescence, between 7 and 15 years of age. Primary development of ARF in adults is a rarity.
Does rheumatic polyarthritis lead to disability due to joint destruction?
No. Unlike other rheumatological conditions, arthritis in ARF has a completely benign course, does not cause cartilage or bone destruction, and resolves completely with proper treatment.
Can a diagnosis of ARF be made without confirmation of a preceding infection?
During the initial attack of the disease, the presence of markers of a preceding group A beta-hemolytic streptococcal infection (e.g., ASO or anti-DNase B) is a mandatory condition for making the diagnosis.
What else to study on this topic
- Detailed analysis of major and minor Jones criteria (ARR 2003 modification).
- Hemodynamic disturbances and stages of heart failure in CRHD.
- Features of ECG and echocardiographic patterns in rheumatic valvulitis and carditis.
- Differential diagnosis of joint syndrome in systemic connective tissue diseases.
- Clinical forms and phases of Sydenham's chorea.
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