Criteria

American Heart Association (AHA) diagnostic criteria[1][28]

Diagnosis is based on clinical signs and symptoms. There are no unique laboratory diagnostic tests for the disease. The principal signs were recognised and reported in 1974, and these criteria have been updated by the AHA (Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease; the Council on Cardiovascular Disease in the Young) and endorsed by the American Academy of Pediatrics.[1][28]​​[30]

Patients with classic KD must have 4 days of fever that is refractory to antibiotic therapy (if given) and at least four of the following five signs and symptoms:

  • Bilateral conjunctival injection without exudate

  • Polymorphous rash

  • At least one of the following mucous-membrane changes:

    • Injected lips (and/or dryness, fissuring, peeling, cracking, and bleeding of the lips)

    • Injected pharynx

    • Strawberry tongue (with erythema and prominent fungiform papillae)

  • At least one of the following extremity changes:

    • Erythema of the palms or soles (painful induration is common)

    • Periungual desquamation of the fingers and toes (2-3 weeks following the onset of fever)

  • Cervical lymphadenopathy (at least one lymph node >1.5 cm in diameter), usually unilateral.

Risk stratification for relative risk of future myocardial ischaemia has also been proposed:[1]

  • Low-risk level: patients without detectable coronary artery aneurysms (CAAs)

  • Low-moderate-risk level: patients with regressed CAAs

  • High-risk level: patients with angiographical evidence of large or giant aneurysms, or coronary obstruction.

Although not part of the formal diagnostic criteria, AHA guidelines emphasise the utility of Z scores to reflect standardised dimensions of coronary arteries normalised for body surface area (BSA) to allow for classification and comparisons across time and populations.[1][28][49] The guidelines suggest using maximal past and current Z scores and any other additional clinical features when deciding on risk stratification for long-term management.[1][28]

Z-score classification[1][28]

  1. No involvement: always <2

  2. Dilation only: 2.0 to <2.5

  3. Small aneurysm: ≥2.5 to <5.0

  4. Medium aneurysm: ≥5 to <10, and absolute dimension <8 mm

  5. Large or giant aneurysm: ≥10, or absolute dimension ≥8 mm.

Additional clinical features indicating risk of myocardial ischaemia include greater total number, length, number of branches, and distal location of aneurysms; structural and functional vessel wall abnormalities; poor collateral vessels; previous revascularisation, coronary artery thrombosis, or myocardial infarction; and ventricular dysfunction.[1]

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