THROMBOCYTOPENIA - A RISK FACTOR FOR ACUTE MYOCARDIAL-INFARCTION DURING THE ACUTE-PHASE OF KAWASAKI-DISEASE

Background: We report on 10 patients with Kawasaki disease and thrombo cytopenia who were found to have a high incidence of coronary artery a neurysm and acute myocardial infarction. The clinical features of thes e patients, the cause of their thrombocytopenia and the relationship b etween cardiovascular pathology and thrombocytopenia were analyzed. Me thods: The clinical features of 10 patients with Kawasaki disease foun d to have thrombocytopenia (group A: mean age 8.0+/-7.0 months) and th ose of 293 patients with Kawasaki disease (group B, controls: mean age 13+/-20 months) were analyzed. Coagulation studies and bone marrow as piration were performed to ascertain the cause of the thrombocytopenia in nine out of 10 subjects in group A. Results: The minimum platelet count was 4-12 x 10(4)/mm(3) (average day of illness, 10.3) and platel et counts were elevated to the baseline value within 1-2 weeks of onse t of the illness. Low fibrinogen concentrations, high levels of fibrin degradation products, and low erythrocyte sedimentation rates with hi gh C-reactive protein levels were observed in seven patients. In two o ther patients, immature megakaryocytes with normal coagulation values were observed. The differences in the incidence of coronary artery ane urysm and acute myocardial infarction between groups A and B were high ly significant (coronary artery aneurysm: 60% in group A, 8.9% in grou p B; acute myocardial infarction: 40% in group A, 0.3% in group B). Co nclusions: In many patients with Kawasaki disease and thrombocytopenia , the thrombocytopenia appears to be a result of intravascular coagula tion, and to be one of the risk factors for acute myocardial infarctio n.