Kawasaki Disease: Updated AHA Guidelines

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While these guidelines may help clinicians better care for patients with Kawasaki disease, more research is needed.
While these guidelines may help clinicians better care for patients with Kawasaki disease, more research is needed.

A new scientific statement by the American Heart Association is the first update regarding the diagnosis and management of Kawasaki disease (KD) since 2004.1 A multidisciplinary expert panel revised recommendations from the previous guidelines based on their examination of recent evidence and clinical opinion.

KD results in coronary artery aneurysms in approximately one-quarter of untreated cases, and it is the top cause of acquired heart disease in children in the United States.2 While the etiology of KD is unknown, the revised guidelines integrate new findings on the epidemiology, genetics, pathogenesis, and long-term outcomes of the disease. 

Pathogenesis

A newer model of vasculopathy in KD proposes that there are 3 linked pathological processes:

  1. Necrotizing arteritis, which, as the investigators explain, “destroys the arterial wall into the adventitia, causing aneurysms”
  2. Subacute/chronic vasculitis “characterized by an asynchronous infiltration of lymphocytes, plasma cells, and eosinophils with fewer macrophages that begins in the first 2 weeks after fever onset but can continue for months to years in a small subset of patients and is closely linked to the third process” as stated in the guideline
  3. Myofibroblastic proliferation (LMP), which involves a unique medial smooth muscle cell-derived myofibroblastic process that can cause progressive arterial stenosis

Diagnosis

The criteria for KD diagnosis include ≥5 days of fever and the presence of ≥4 of the 5 principal clinical features: bilateral nonpurulent conjunctivitis, oral mucosal changes such as strawberry tongue and cracked lips, peripheral extremity changes, rash, and cervical lymphadenopathy of >1.5 cm. However, patients may not exhibit 4 or more clinical features at once, rendering diagnosis difficult. For example, some patients may present with fever and meet 2 or 3 of the classic criteria. These patients are considered to have suspected incomplete KD vs complete KD.

Noting the critical importance of prompt diagnosis, the guidelines include an updated algorithm outlining supplemental information that may facilitate the diagnostic process in cases lacking complete classic clinical criteria. The investigators noted that in “the absence of a ‘gold standard' for diagnosis, this algorithm cannot be evidence based but rather represents the informed opinion of the expert committee.”

Treatment

Prompt treatment with intravenous immunoglobulin (IVIG) has reduced the incidence of coronary artery aneurysms from approximately 25% to 4%. IVIG should be administered as soon as possible within 10 days of fever onset.

The guidelines highlight other situations in which IVIG may also be appropriate for patients who are beyond the 10-day window, and it is recommended for children who present after the 10th day with “ongoing systemic inflammation as manifested by elevation of ESR [erythrocyte sedimentation rate] or CRP [C-reactive protein] (CRP >3.0 mg/dL) together with either persistent fever without other explanation or coronary artery aneurysms (luminal dimension Z score >2.5).”

There are also recommendations for additional therapies, including corticosteroids, infliximab, and cyclosporine, in patients who are IVIG-resistant, as well as detailed recommendations for KD management based on coronary artery involvement.

Risk Classification

A new classification of coronary artery abnormalities is based on z-scores as follows, with certain caveats noted in the paper:

  • No involvement: always <2
  • Dilation only: 2 to <2.5, a decrease in Z score during follow-up ≥1
  • Small aneurysm: ≥2.5 to <5
  • Medium aneurysm: ≥5 to <10, and absolute dimension <8 mm
  • Large or giant aneurysm: ≥10, or absolute dimension ≥8 mm

Although these guidelines can assist clinicians in the care of patients with KD, important gaps in the evidence remain. “Until the cause and pathogenesis are defined, an exact diagnostic test remains elusive, and acute treatment remains somewhat empirical,” the researchers concluded.

Disclosures: A few of the authors list various disclosures within the paper, available online.

References

  1. McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: a scientific statement for health professionals from the American Heart Association [published online March 29, 2017]. Circulation.doi:10.1161/CIR.0000000000000484
  2. American Heart Association. Kawasaki Disease. http://www.heart.org/HEARTORG/Conditions/More/CardiovascularConditionsof
    Childhood/Kawasaki-Disease_UCM_308777_Article.jsp#.WRMzdFXytaS
    . Accessed May 9, 2017. Last reviewed May 2017.
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