Etiology and prevalence
Acute rheumatic fever is triggered by infection with specific strains of group A streptococci which possess antigens that cross-react with human connective tissue. particularly heart valve glycoprotein.

The condition usually affects children or young adults and there is a familial variation in susceptibility. Its prevalence in Western Europe and North America has progressively declined to very low levels, but it remains common in parts of Asia, Africa and South America, where it is still the most common cause of acquired heart disease in childhood and adolescence.

Clinical features
Rheumatic fever is a systemic illness typically presenting with fever, anorexia, lethargy and joint pains. Arthritis occurs in approximately 75% of patients and other features include skin rashes, carditis and neurological features. The diagnosis according to the revised Jones criteria is based upon two or more major manifestations or one major and two or more minor manifestations. In both cases evidence of preceding streptococcal infection is required (antistreptococcal antibody: antistreptolysin antibody: positive culture for group A streptococcus; recent scarlet fever).

Carditis
This is the most important manifestation of rheumatic fever. Carditis presents as breathlessness (due to heart failure or pericardial effusion), palpitations or chest pain (usually due to peri- or pancarditis). Other features consist of tachycardia, cardiac enlargement and new or changed cardiac murmurs. A soft systolic murmur is common but non-specific. A soft mid-diastolic murmur (Carey Coombs murmur) is often due to valvulitis, with nodules forming on the mitral valve leaflets. There may be a pericardial friction rub which is often intermittent. Cardiac failure may result either from impaired function of ventricular muscle or from mitral or aortic incompetence and tends to occur in a 'fulminant' form of rheumatic fever that is more common in developing countries. Electrocardiographic changes include ST or T wave changes: conduction defects sometimes occur and may cause syncope.

Sydenham's chorea (St Vitus dance)
Central nervous system involvement may manifest late after the initial infection (6 months or more), with those affected exhibiting spasmodic unintentional movements and possibly altered speech. Spontaneous recovery is usual, though it may be followed by chronic cardiac disease.

Arthritis
The arthritis of rheumatic fever is often symmetrical, affecting large joints with acute painful inflammation which characteristically 'flits' from joint to joint (i.e. a migratory polyarthralgia). The joints affected include those of the limbs, spine, and sometimes the temporomandibular and costoclavicular joints. There is commonly, but not invariably, a history of sore throat 2-4 weeks before the onset of joint symptoms. In adults, joint symptoms tend to be more prominent than carditis: in children under 6 years old the converse may be true.

Skin lesions
The following may be present:

-Erythema marginatum, which occurs in 10-20% of children with rheumatic fever. It starts as red macules (blotches) which fade in the centre but remain red at the edges. The resulting red rings or 'margins' may coalesce or overlap.

-Subcutaneous nodules, which are uncommon, but associated with more severe carditis. They are small ( < 0.5 cm), firm, painless, and best felt over bone or tendons. Typically the nodules are much smaller than those of rheumatoid arthritis.

Other systemic manifestations are rare, but include pleurisy, pleural effusion and pneumonia.

Investigations
It is important to note that while the systemic markers are non-specific, they may be useful in following progress of the disease. Furthermore, positive throat cultures are present only in a minority of patients at the time of clinical presentation and ASO titers are normal in about one-fifth of adult cases of rheumatic fever and most cases of chorea.

Management
Treatment for acute rheumatic fever is directed towards limiting cardiac damage, relieving symptoms and eliminating the streptococcal infection.

Bed rest and supportive therapy
During the acute phase of rheumatic fever or during active carditis the patient should be rested in bed, as otherwise there is a risk of recurrence of signs and symptoms. Later, the patient may feel well, although temperature, leucocyte count and erythrocyte sedimentation rate (ESR) remain elevated. Bed rest must be continued until these indices of continuing disease activity have settled. In patients who have had carditis, it is conventional to continue bed rest for 2-6 weeks after the ESR and temperature have returned to normal. Prolonged bed rest, particularly in children or adolescents produces problems of boredom and depression that need to be anticipated and managed.

Cardiac failure should be treated as necessary. Valve replacement may be required for severe mitral or aortic incompetence. Heart block is seldom progressive. and pacemaker therapy is rarely needed.

Aspirin
Aspirin will usually relieve the symptoms of arthritis rapidly and a prompt response (within 24 hours) helps to confirm the diagnosis. A reasonable starting dose is 60 mg/kg body weight per day, divided into six doses. In adults, 120 mg/kg per day may be needed up to the limits of tolerance or a maximum of 8 g per day. Mild toxic effects include nausea, tinnitus and deafness: more serious ones are vomiting, tachypnea and acidosis. Aspirin should be continued until the ESR has fallen and then gradually tailed off.

Corticosteroids
These produce more rapid symptomatic relief than aspirin and are indicated in cases with carditis or severe arthritis. There is no evidence that long-term steroids are beneficial. Prednisolone or prednisone 1.0-2.0 mg/kg per day in divided doses should be continued until the ESR is normal, then gradually tailed off.

Antistreptococcal therapy
Eradication of streptococcal infections and prevention of recurrence are important. Benzathine penicillin 1.2 million units i.m. should be given on diagnosis, followed by oral phenoxymethyl-penicillin 500 mg 12-hourly for 10 days. Subsequent prophylaxis may be with oral phenoxymethylpenicillin 500 mg continued for at least 5 years after the last attack and until the patient reaches at least 20 years of age. If compliance with an oral regimen is in doubt. then i.m. administration may be employed.

Recurrences are more common when cardiac disease is present and, if so, prophylaxis should continue until age 30. A sulphonamide or erythromycin, may be used if the patient is allergic to penicillin.

Follow-up
Carditis most frequently occurs within 2 weeks of the onset of arthritis. Chronic rheumatic heart disease is much more common in patients who have carditis during the initial attack or during a recurrence. It is important to prevent recurrence by continuing antistreptococcal prophylaxis and to recognize and follow up chronic valve lesions, but at the same time it is important not to induce a cardiac neurosis. Echocardiography is valuable in assessing valve problems. If it remains normal, follow-up can be discontinued 10 years after the initial attack.

CHRONIC RHEUMATIC HEART DISEASE

Chronic valvular heart disease develops subsequently in at least half of those affected by rheumatic fever with carditis. The predominantly affected valve is the mitral (in > 90%) and then less commonly the aortic, tricuspid and pulmonary. The lesions develop after 10-20 years in 'Western' countries but much earlier in developing countries.

Pathology
The main pathological process in chronic rheumatic heart disease is a progressive fibrosis particularly affecting the heart valves. This is in contrast to the destructive lytic process of acute rheumatic fever. The condition also affects the pericardium and myocardium and may contribute to heart failure and conduction disorders. For the mitral valve the result is shortening of the chordae tendineae, fusion of the commissures and a reduction in size of the valve orifice. The hemodynamic result is mitral stenosis with or without regurgitation. Similar disorders of the aortic and tricuspid valves produce distortion and rigidity of the cusps and in consequence, stenosis and incompetence. Once damage has developed on a valve, the altered hemodynamic stresses on the valve perpetuate and extend the damage, even in the absence of a continuing rheumatic process.

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