Heart failure is a rare cause of wheezing and may develop into a critical condition in children. Few cases report patients with heart failure, secondary to dilated cardiomyopathy, with high fever. A 23-month-old girl visited the emergency department with high fever, cough, first wheezing episode, chest retraction and tachycardia. The chest X-ray revealed consolidation on the left lower lung field; the cardiothoracic ratio was 60%. She was diagnosed with bronchial asthma triggered by pneumonia, which remained unchanged during four visits. Subsequently, she was diagnosed with heart failure in idiopathic dilated cardiomyopathy and discharged without sequelae. During the first wheezing episode in children with abnormal vital signs, heart failure should be considered in the differential diagnosis, and a chest X-ray should be performed. Additionally, when the cardiothoracic ratio is greater than 50%, 12-lead ECG and echocardiography should be performed. Moreover, cognitive bias should be considered in all emergency care unit situations.