Abstract:ObjectiveTo investigate the factors affecting the retraction of medium large coronary artery aneurysm(CAA) in children with Kawasaki disease(KD). Methods A retrospective analysis was performed on the clinical data of 43 KD children complicated with medium large CAA diagnosed in Childrens Hospital of Soochow University from January 1, 2018 to August 31, 2021, including 33 males and 10 females. According to the retraction of coronary aneurysm after 6 months of follow up, the patients were divided into CAA retraction group(n=22) and CAA non retraction group(n=21).The results of blood routine examination, blood biochemical measurements at admission and cardiac color Doppler ultrasound during acute stage and after 6 month follow up were collected and statistically analyzed. Results Among the 43 children, a total of 89 coronary vessels were involved, including 13 left main coronary artery(LMCA), 24 left anterior descending artery(LAD), 5 left circumflex artery(LCX), 6 proximal right coronary artery(RCA), 20 middle RCA, and 21 distal RCA. After six months of follow up, the diameter of all involved coronary branches had a tendency to decrease, of which 61 involved coronary arteries had no residual medium large CAA. The remaining 28 coronary arteries were still with residual CAA, including 3 LMCA, 8 LAD, 8 middle RCA and 9 distal RCA. At the end of follow up, the coronary arteries of 2 children in retraction group had completely recovered to normal, and the remaining 20 affected coronary arteries had no medium large CAA residue. The level of hemoglobin and the ratio of alanine aminotransferase/ aspartate aminotransferase(ALT/AST) in retraction group were significantly lower than those in non retraction group, while the platelet count was higher than that in non retraction group(P＜0.05). Regression analysis showed that the maximum inner diameter Z value of dilated coronary artery lesion(CAL Zmax) and ALT/AST ratio increasing in the acute phase were the risk factors influencing recovery of coronary artery（P＜0.01）. The cut off value of CAL Zmax for predicting coronary artery retraction was 10.84, with an AUC of 0.721. The cut off value of the ALT/AST ratio for predicting coronary artery retraction was 1.16, and AUC was 0.775. Conclusion Medium large CAA in Kawasaki disease is mainly seen in LAD and the middle and distal segment of RCA, and about 1/3 of the affected vessels in LAD and the middle and distal segments of RCA still have medium to large CAA after 6 months of follow up. The severity of coronary dilatation and the high ALT/AST ratio in the acute phase are the risk factors affecting the recovery of CAA in children with Kawasaki disease.