Maladie de Kawasaki : ce qu’il faut savoir

Abstract

Kawasaki disease (KD) is an acute systemic vasculitis syndrome occurring mostly in children younger than 5 years of age. Especially young infants (<1 year) have an increased risk of coronary artery lesions (CAL). Whereas the etiology of KD is still unknown, progress in treatment during its acute phase has decreased the incidence of CAL from 25-30% to 3-5%. In "atypical KD", the clinical picture is dominated by an unusual symptom as seizure, bloody diarrhea, compressive cervical adenopathy, nephrotic syndrome or hyponatremia. To make a diagnosis in case of "incomplete KD", the supplementary criteria (clinical and biological) suggested by the American Heart Association can be helpful. Once the diagnosis established, the treatment of choice is the intravenous administration of immunoglobulin associated to aspirin at anti-inflammatory dose. However, some patients remain feverish within 36 hours following the end of immunoglobulin administration. This treatment resistance seems increasing in some regions of the globe and can touch up 20% of patients. The unsatisfactory answer to the initial treatment is associated to a higher risk of CAL. Predictive criteria of resistance have been identified and allow to strengthen the medical treatment with a second administration of immunoglobulins. Moreover, methylprednisolone pulse therapy and tumor necrosis factor-alpha blockade (infliximab) appear to be interesting therapeutic options in the future. At last, other treatments have not been the object of controlled studies yet but are alternatives in refractory forms e.g. cytotoxic agents (cyclosporine A, cyclophosphamide, methotrexate), plasmapheresis, plasma exchange or abciximab, especially in patients with aneurysms. Sclerotic vascular changes are often observed in post-Kawasaki disease patients, including those without coronary lesions during the acute phase. Indeed, endothelial dysfunction and risk factors for the development of atherosclerosis, such as dyslipidemia, decreased vascular elasticity, increased C-reactive protein, oxidative stress, and inflammatory cytokines, are known to be present in the late phase of KD. However, it is not clearly established that the survivors of KD carry a higher risk of coronary disease. The epidemiological studies of the next decade should give clearer answers as far as these patients henceforth achieved the age of the atherosclerosis. In conclusion, the diagnosis of KD imposes a strict supervision by a pediatric cardiologist initially. The follow-up is organized according to the existence or non-existence of coronary artery lesions. Late complications as stenosis or coronary thrombosis can occur but remain rare. Thus, it is necessary to be reassuring with the parents, especially for those whose children had no or regressive CAL, while recommending a prevention of the cardiovascular risk factors in the adulthood.