Abstract: Background：Severe coronary artery lesions (CAL) caused by Kawasaki disease (KD) can lead to coronary events or death in children and has an important impact on long-term prognosis and quality of life. Objective：To summarize and analyze the medium-term and long-term clinical outcomes of KD children with severe CAL and provide the basis for long-term follow-up management and prognosis evaluation of KD children. Design：Cohort study. Methods：The HIS system of Children's Hospital of Fudan University was searched to include children < 18 years of age who were discharged from the hospital from January 2008 to December 2019 with a diagnosis of KD and were diagnosed with severe CAL due to KD by coronary angiography (CAG) in our hospital. Patients with other diseases causing severe CAL and affecting the prognosis of severe CAL were excluded. All children were followed up by senior cardiovascular specialists in the outpatient clinic and ward, and were given medical treatment. Children with severe coronary artery stenosis and myocardial ischemia were treated surgically after multidisciplinary discussion. Children with myocardial ischemia, myocardial infarction or death during diagnosis and follow-up were taken as the poor prognosis group, and the opposite was the good prognosis group. The poor prognosis and the evolution of CAL were observed, and the influencing factors of poor prognosis were analyzed. Main outcome measures：Poor prognosis and improvement of CAL. Results：A total of 144 children with severe CAL due to KD were included in this analysis. Among them, 117(81.2%) were males and 27 were females with a median KD onset age of 2.2(1.0, 4.5) years, a median follow-up time of 1.6(0, 3.4) years, and a disease duration of 5.0(3.0, 21.3) months at the diagnosis of severe CAL. A total of 276 coronary arteries were involved in 144 children with KD and severe CAL. Single coronary arteries and ≥2 coronary arteries were involved in 56 cases(38.9%) and 88 cases(61.1%) respectively. There were 122 cases of giant coronary artery aneurysm(GCAA), 8 cases of multiple small and medium-sized coronary artery aneurysms(CAA) in the single coronary artery, 6 cases of GCAA with multiple small and medium-sized CAA in the single coronary artery, and 8 cases of stenosis in all affected coronary arteries. Sixty-two cases developed coronary artery stenosis, including 31 cases of coronary artery occlusion. Fifty-four of 144 children(37.5%) developed poor prognosis, and myocardial ischemia was present in all 54 cases, 14 of which had developed recorded acute myocardial infarction at the ischemic myocardium, and one child died of severe heart failure due to myocardial infarction. The results of multivariate analysis showed that the risk of poor prognosis was 2.6 times higher in children with ≥2 coronary artery involvement than in those with only 1 coronary artery involvement(OR=2.602, 95% CI: 1.201 to 5.634), and 3 times higher in children with coronary artery stenosis than in those without coronary artery stenosis(OR=3.055, 95% CI: 1.450 to 6.437). Among 179 CAG, 114 patients(208 affected coronary arteries) underwent one CAG, and 30 patients(68 affected coronary arteries) underwent≥2 CAG. When 68 affected coronary arteries were first diagnosed, 51 of them were GCAA and the improvement rate was 4.0% at the last follow-up; 3 of them were multiple small and medium-sized CAAs and the improvement rate was 66.6% at the last follow-up; 2 were single small and medium-sized CAAs and developed stenosis(stenosis degree about 50%) until the last follow-up; and 12 were stenosis and did not improve until the last follow-up. Conclusions：GCAA is the main type of KD with severe CAL, and it is difficult to recover. The improvement rate of multiple small and medium-sized CAAs in the single coronary artery is high. Coronary artery stenosis and multivessel coronary artery involvement are factors leading to the poor prognosis of children with severe CAL caused by KD.

Key words: Kawasaki disease, Coronary artery lesions, Coronary artery aneurysms