Objective To evaluate the role of left ventricular morphology combined with ST segment depression in predicting cardiac dysfunction in infants after patent ductus arteriosus （PDA）. Methods This study is designed as a retrospective study. From January 2016 to December 2022， 445 infants with PDA were treated in our hospital. Preoperative electrocardiogram examination and echocardiographic measurements were performed for recording the ST segment depression， left atrial diameter （LAD）， left ventricular end diastolic diameter （LVEDD）， left ventricular end systolic diameter （LVESD）， aortic diameter （AOD）， pulmonary artery diameter （PAD）， pulmonary artery systolic pressure （PASP）， left ventricular ejection fraction （LVEF） and left ventricular fractional shortening （LVFS）. According to the postoperative left ventricular function， the above indexes were divided into groups and compared. Binary logistic regression analysis was done to investigate potential influences on cardiac function， and a ROC curve was plotted to assess the predictive significance of combining left ventricular morphology with ST segment depression. Results The left ventricular dysfunction occurred in 42 cases （9.23%）， with an average LVEF of （54.83 ± 3.37）%. Compared with the children with normal LVEF， there was no significant difference in age， weight， BSA， PDA diameter， LAD， AOD， PAD， LVEF and PASP （P > 0.05）. The preoperative levels of LVEDD， LVESD and ST segment depression were significantly higher in the children with left ventricular dysfunction （P < 0.05）. Binary logistic regression analysis showed that ST depression was an independent risk factor for predicting postoperative cardiac insufficiency in the children with PDA. The area under the curve of ROC analysis was 0.785， the sensitivity was 85.4%， and the specificity was 54.0%. Compared with pre-operative conditions， the levels of LAD， LVEDD， LVESD， AOD， PAD and LVFS were significantly decreased 6 months after operation （P < 0.05）. Conclusion Attention should be paid to left ventricular systolic dysfunction after closure of different PDA procedures， which is related to the rapid decrease of left ventricular preload and increase of after load. Preoperative left ventricular morphology combined with ST segment depression can be used as an important index to predict postoperative cardiac insufficiency in children with PDA.