Rheumatic Fever in Emergency Medicine Workup

Updated: Feb 23, 2023
  • Author: Anne Klimke, MD, MS; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Approach Considerations

The best approach to evaluating and treating the patient with group A streptococcal (GAS) pharyngitis is beyond the scope of this discussion (see Pharyngitis), but since the diagnosis of acute rheumatic fever (ARF) is dependent upon a preceding GAS infection, it warrants discussion. While the need to treat all cases of streptococcal pharyngitis remains controversial, it is clear that antibiotic treatment of GAS does prevent ARF. The number needed to treat to prevent one case of ARF is estimated to be 100. [40, 41]

The diagnosis of GAS pharyngitis can be confirmed with a rapid antigen detection test or a throat culture, with throat culture considered the gold standard during acute infection. Note that the Centers for Disease Control and Prevention (CDC) advises that testing for group A beta-hemolytic Streptococcus (GABHS) pharyngitis is not routinely indicated for children younger than 3 years of age or for adults, since ARF is very rare in those age groups in the United States. In children older than 3 years of age, the CDC recommends confirming the diagnosis of GABHS pharyngitis, which can be done with a positive rapid test. In a child with a negative rapid test, however, a follow-up throat culture should be performed. [1, 42]

Similarly, the Infectious Disease Society of America and the American Heart Association (AHA) recommend that the diagnosis of GABHS infection be confirmed with testing. In children and adolescents, a negative rapid antigen test result should be followed by culture unless the physician has determined that in his or her own practice the rapid antigen test is comparable to a throat culture. [43] A culture positive for GABHS does not definitively prove active infection, however, as some patients are carriers.  

Of course, access to rapid antigen tests, molecular assays, and microbiological cultures is limited in lower socioeconomic areas. They are costly, and storage can be challenging. Increasing accessibility to diagnostic tools as a primary prevention strategy is a cornerstone of the AHA's Call to Action for Reducing the Global Burden of Rheumatic Heart Disease. [44] ​ 

The AHA further suggests that ARF diagnostic criteria may be applied differently, depending on the rate of ARF or RHD in the local population. This can help avoid overdiagnosis in low-incidence populations and underdiagnosis in high-risk ones. The AHA defines low risk as an ARF incidence of < 2 per 100,000 school-aged children (usually 5–14 years old) per year or an all-age prevalence of RHD of ≤1 per 1000 population per year. Children not clearly from a low-risk population are at moderate to high risk, depending on their reference population. [20]

Diagnosis of ARF therefore requires a high index of suspicion. The modified Jones Criteria and clinical guidelines from the AHA include major and minor criteria, which are described in the Presentation/Physical Examination. Laboratory evidence of a preceding GAS infection is preferred whenever possible. Without it, the diagnosis of ARF is in doubt, except in patients with chorea, which may be the sole initial manifestation of ARF, and rarely in patients with indolent rheumatic carditis with insidious onset and slow progression. [20]


Laboratory Studies

No specific confirmatory laboratory tests exist for acute rheumatic fever. However, several laboratory findings indicate continuing rheumatic inflammation, and some are part of the minor Jones criteria. Confirmation of a preceding group A strep infection is strongly preferred, but not always possible.

According to a statement by the American Heart Association, evidence of prior GAS infection can be demostrated by an increased or rising anti-streptolysin O titer or other streptococcal antibodies; a positive throat culture for GABHS, or a positive rapid GAS test in a child with a high pre-test probability of GAS pharyngitis. [43]  Routine testing for streptococcal skin infections is not yet recommened, but may be beneficial in some cases. [17]

Acute-phase reactants (eg, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]) may show an increase, as may serum complement, mucoproteins, alpha-2, and gamma globulins. Anemia is usually caused by suppression of erythropoiesis. [45, 22]

Although there are a few small studies that show the contrary, troponins have not been shown to be helpful in making the diagnosis because ischemia and necrosis are not the major cardiac problems. [46]

In patients with arthritis, synovial fluid analysis may demonstrate an elevated white blood cell count with no crystals or organisms. [47]

Current research is focused on identifying novel biomarker profiles associated with ARF that could become the basis of reliable point-of-care testing in regions with a high disease burden. This research could also yield targets for new immunomodulatory therapies. [2, 44, 48]


Imaging Studies

Echocardiography has shown to be extremely effective in diagnosis carditis and valvular dysfunction in ARF, and it can be used to diagnose latent RHD in asymptomatic children. [49] Its use has revolutionized screening in remote areas with limited healthcare access and will likely contribute to earlier identification and treatment of RHD in high disease burden areas. [20, 2]

Chest radiography should be performed to determine the presence of cardiomegaly and congestive heart failure in ARF. [2, 12]