Rheumatic fever – diagnostic criteria
Acute rheumatic fever is an immunologically mediated disease which occurs about three weeks after a streptococcal sore throat caused by Group A beta hemolytic streptococci. Antibodies to streptococci cross react with various tissues in the body to produce the various manifestations of acute rheumatic fever. The diagnostic criteria initially proposed by Duckett Jones in 1944 has been modified and revised several times. Latest revision was by the American Heart Association.
The manifestations of rheumatic fever has been classically divided into major manifestations and minor manifestations. The major manifestations of rheumatic fever are:
- Polyarthritis: Usually migratory, fleeting and flitting type of arthritis; fleeting means transient; flitting means jumping from one joint to another. Monoarthritis and polyarthralgia are also considered in moderate – high risk populations.
- Carditis: Though it is a pancarditis with endocardial, myocardial and pericardial involvement, predominant manifestation is valvular regurgitation due to endocardial involvement. Subclinical carditis with echocardiographic evidence is also considered in the latest revision.
- Chorea – Sydenham’s chorea: Chorea being a late manifestation, is seldom associated with arthritis, which is an early manifestation. (Imagine the trouble for a patient with acute arthritis and chorea!). Sydenham’s chorea was also known as Vitus’ dance. Chorea is often associated with muscle weakness and emotional lability.
- Erythema marginatum: It is an evanescent pink rash with pale center and serpiginous margins, usually present on the trunk and proximal extremities.
- Subcutaneous nodules: Usually seen over the extensor aspect, around the elbow, knee and over the scalp. Subcutaneous nodules are usually associated with carditis – ‘nodules under the skin, nodules in the heart’ (Aschoff nodules – a pathological finding in rheumatic fever). Subcutaneous nodules in rheumatic fever are painless and freely mobile.
Minor manifestations of rheumatic fever are:
- Raised C-reactive protein
- Raised erythrocyte sedimentation rate
- Prolonged PR interval on ECG
- Past history of rheumatic fever or rheumatic heart disease
Polyarthralgia: Since there are various other causes for polyarthralgia, the 2015 revised criteria specifies that it can be considered as major manifestation only in moderate or high risk populations after exclusion of other causes. Earlier polyarthralgia included among minor manifestations. Monoarthralgia is also considered as a minor manifestation in moderate or high risk populations.
For the diagnosis of initial episode of acute rheumatic fever, either 2 major manifestations or 1 major plus 2 minor manifestations are needed.
Recurrent rheumatic fever needs either 2 major or 1 major and 2 minor or 3 minor manifestations.
Evidence of preceding streptococcal infection: Evidence of recent streptococcal infection is rather a mandatory criteria along with the above mentioned criteria. Exceptions to this rule include chorea which may be the only manifestation of rheumatic fever and in chronic indolent carditis. Chronic rheumatic carditis has an insidious onset and slow progression. Criteria for confirmation of recent streptococcal infection are:
- Increased or rising anti-streptolysin O titer or other streptococcal antibodies (anti-DNASE B). A rise in titer is better evidence than an a single report.
- Positive throat culture for group A β-hemolytic streptococci.
- Positive rapid group A streptococcal carbohydrate antigen test in a child whose clinical presentation suggests a high pretest probability of streptococcal pharyngitis.
Clinical findings in acute rheumatic carditis
Carditis manifests predominantly with valvular lesions. Mitral regurgitation with a pansystolic murmur is the commonest valvular lesion in acute rheumatic fever. Aortic regurgitation with an early diastolic murmur can also occur in the acute phase. Left ventricular third heart sound can be heard in severe mitral regurgitation as well as in those who go for heart failure. Carey Coombs murmur is the typical murmur of acute rheumatic valvulitis. It is a short mid diastolic murmur without any opening snap or presystolic accentuation. The Carey Coombs murmur is best heard at the apex and disappears when the valvulitis resolves. There may be an S3 gallop during the acute phase, especially when there is cardiac failure.