A 3-year-old child presented to the OPD with chief complaints of high-grade fever for 15 days along with a polymorphous exanthem all over the body, rhinorrhea, multiple episodes of vomiting, diarrhea and abdominal pain. O/E: - B/L conjunctival injection with limbal sparing Erythema of oral and pharyngeal mucosa Edema of hands and feet* Mild cervical lymphadenopathy at III and IV levels Lab findings: - Leucocytosis with neutrophilia and immature forms Elevated erythrocyte sedimentation rate* Elevated c-reactive protein Anemia Abnormal plasma lipids Hypoalbuminemia Hyponatremia. Coronary angiogram What should be the most impoant next step in the management of the child: -