Abnormal myocardial mechanics in Kawasaki disease: Rapid response to γ- globulin

Background: The time course and rate of recovery of myocardial dysfunction in association with Kawasaki disease in response to intravenous γ-globulin is unknown and may provide mechanistic clues. Methods and Results: The acute changes in myocardial contractility in 25 patients with Kawasaki disease were evaluated by noninvasive stress-shortening and stress- velocity analysis. Echocardiograms were performed before and then daily for 4 days during which the patients received γ-globulin 1.6 to 2 g/kg. Before treatment, contractility was abnormally low (<2 SD) in 14 patients (56%). Contractility increased significantly (2 SD increase) in 17 (68%), including 13 of 14 with depressed contractility and 4 whose initial contractility fell within normal limits. Of the 14 patients with de pressed contractility, 8 (57%) normalized within 24 hours and a further 5 (35.7%) normalized within 6 months. A clinical response to treatment (fall in C-reactive protein by 50% and/or resolution of fever within 4 days) was seen in 22 patients (88%). Contractility increased in 17 of the 22 clinical responders and was normal before therapy in the other 5. The 3 patients who did not respond clinically also had no change in contractility with γ-globulin therapy. Long-term (more than 12 months) follow-up was available in 19 patients. All patients had normal contractility at late follow-up. Conclusions: More than half the patients with Kawasaki disease have abnormal contractility at presentation. Myocardial response to γ-globulin therapy is associated with rapid improvement in myocardial mechanics, with a high concordance between the clinical and myocardial response to therapy. The speed of recovery suggests that de pressed contractility in patients with Kawasaki disease is caused by a rapidly reversible process such as circulating toxins or activated cytokines. Long-term outcome is good even in those patients with slow recovery of myocardial function.