Background: Very young infants with Kawasaki disease (KD) often present with atypical features that render diagnosis difficult and the incidence of coronary complications high. Picking up clues at early phase of KD can be critical. Herein we present 3 cases of KD in very young infants who showed mitral regurgitation (MR) around the 7th day from the onset of fever. They received IVIG around 7th fever day. However, the advice for short-term follow up echocardiography (ECHO) was neglected as clinical course thereafter were so unusual. Giant coronary aneurysms developed in all the patients later.
Case 1: A 31-day-old infant got admission care for sepsis. ECHO at the 7th day from the onset of fever showed trivial MR and the patient received IVIG. Follow up ECHO was recommended, but was not conducted as clinical course was ambiguous for KD thereafter. Being treated with steroids due to skin rash and eosinophilia that masked patient’s fever, the infant reappeared to hospital with cardiogenic shock 10 days later. ECHO revealed giant aneurysms in the right coronary artery (RCA) and CT angiography for pulsating axillary masses revealed axillary aneurysms.
Case 2; A 67-day-old infant was admitted with fever and persistent thrombodytopenia. ECHO done at the 5th day from the onset of fever due to red lips showed non-specific findings. Follow up ECHO at the 7th fever day showed newly developed MR. IVIG and steroids was added on for persistent fever, but severe leukocytosis ensued and clinical course was also ambiguous for KD. Defervescence was achieved with infliximab. The infant showed coronary aneurysms.
Case 3; A 80-day-old infant was admitted with fever and seizure, and treated for sepsis. On the 6th day from the onset of fever, MR was shown on ECHO and the patient received IVIG and steroids. However, fever and severe anemia, left shift of leukocytes, and severe thrombocytopenia persisted for two weeks. Giant coronary aneurysms, as large as the ascending aorta, developed in the RCA. Pulsatile masses identified in the axilla were found to be large aneurysms on CT angiography.
Conclusion: A newly developed MR, even trivial, around the 7th day from the onset of fever may be a clue to the diagnosis of KD and short term follow up ECHO is recommended for ongoing febrile infants younger than 3 months.