Kawasaki disease is a generalized vasculitis of unknown etiology that occurs predominantly in infants and young children. It is very important to prevent its cardiovascular manifestations, especially coronary artery lesions. Early treatment with intravenous immunoglobulin reduces cardiovascular sequelae, but some patients do not respond to this treatment, and they have a high incidence of coronary artery lesions. On the other hand, acute heart failure is rare in Kawasaki disease. We report on the cases of two patients with persistent fever and shock even after intravenous immunoglobulin therapy. In both cases, plasma exchange may have reduced the risk of coronary artery lesions and proved effective against acute heart failure with catecholamine-refractory shock; yet the mechanism of this improvement remains unclear.