All patients studied were children who fulfilled the diagnostic criteria for KD and were admitted for IVIG treatment at Chang Gung Memorial Hospital-Kaohsiung Medical Center, from 2002 and 2009. All patients were treated with a single high-dose IVIG (2 g/kg) over a 12hour period [10] [11] [12] . This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital with written consent statement. We excluded patients who did not fit the diagnostic criteria of KD. CAL was defined by the internal diameter of the coronary artery being greater than 3 mm (4 mm, if the subject was over the age of 5 years) or the internal diameter of a segment being at least 1.5 times that of an adjacent segment, as observed in the echocardiogram [13, 14] . KD patients with coronary artery ectasia or dilatation which was disappearing within the initial 6-8 weeks after the onset of illness was defined as transient CAL [3] . The diagnosis of coronary artery fistula (CAF) was made mainly by pulsed Doppler and color flow imaging [15] . IVIG treatment responsiveness was defined as defevrscence 48 hrs after the completion of IVIG treatment and no fever (temperature, >38 • C) recurrence for at least 7 days after the initial IVIG treatment with marked improvement of inflammatory signs [16] . Patients with IVIG resistance received another dose of IVIG (1-2 g/kg) or other anti-inflammatory regiments. Children who were admitted for upper and/or lower respiratory tract infections (including acute bronchiolitis, acute pharyngitis, acute bronchitis, croup, and acute tonsillitis) were also collected as control subjects for comparison during the same study period, as we have previously described [12] .