Objective To explore left ventricular longitudinal systolic function changes during perioperative period of coronary artery bypass graft(CABG).Methods Totally 41 patients with confirmed coronary artery disease(CAD)who underwent CABG were prospectively enrolled.The preoperative left ventricular global longitudinal strain(GLS),as well as GLS on the day of CABG,on the 3rd and 7th day postoperation were measured.According to preoperative left ventricular GLS,the patients were divided into 3 groups,i.e.normal group(group A,GLS≤-18.1％,n=6),mildly decreased group(group B,-18.1％＜GLS≤-14.0％,n=22)and severely decreased group(group C,GLS＞-14.0％,n=13).Repeated measures analysis of variance,generalized estimating equation and multiple comparisons were used to analyze left ventricular systolic function in different perioperative time points.Results No significant difference of GLS was found among different time points during perioperative period of CABG in group A and C(all adjusted P＞0.05).In group B,GLS on postoperative days were lower than that before CABG(all adjusted P＜0.001),and the lowest value was observed on the day of CABG postoperatively,while no significant difference of GLS was found between the 3rd and 7th day postoperation(adjusted P=1.00).Compared with those before CABG,the longitudinal strain(LS)of basal segment on the day of CABG postoperatively and 3rd day postoperation,of middle segment and apical segment at all postoperative time points were lower(all adjusted P＜0.05),while of the apical segment on the day of CABG postoperatively decreased most obviously.No significant difference of LS of each ventricular segment was found between the 3rd nor the 7th day postoperation(all adjusted P＞0.05).Conclusion GLS decreased significantly on the day of CABG postoperatively but partially recovered within the following week in CAD patients with mildly decreased preoperative GLS.CABG had the most pronounced effect on LS of apical segment in left ventricle.