Objective:To quantitatively evaluate the left ventricular myocardial strains and global myocardial work indices in severe aortic stenosis(AS) patients with preserved left ventricular ejection fraction (LVEF) undergoing transcatheter aortic valve implantation (TAVI) by using two-dimensional speckle tracking imaging (2D-STI) technology and pressure-strain loop (PSL).Methods:Twenty patients undergoing TAVI from January to November 2020 in Cardiovascular Hospital of Xiamen University were selected as the TAVI group, and 20 healthy volunteers (with the matched gender, age) were selected as the control group at the same period. Left ventricular global longitudinal strain (GLS), endocardial, middle, epicardial myocardial longitudinal strain (LSendo, LSmid, LSepi) were measured by 2D-STI. The correlation between aortic pressure and the left ventricular systolic pressure invasively measured by cardiac catheterization, and blood pressure and the left ventricular systolic pressure non-invasively measured by peripheral brachial artery systolic blood pressure combined with Doppler-derived mean aortic gradient was separately compared. The non-invasive PSL was used to evaluate the global work index (GWI), global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE). The differences of the myocardial strains and myocardial work indices between the two groups, including controls, patients with preoperation, 1 week and 3 months after TAVI, were compared.Results:Compared with the control group, GLS, LSendo, LSmid and LSepi of the left ventricle in the TAVI preoperation group were decreased (all P<0.05), LSendo increased at 1 week after TAVI, and GLS, LSendo, LSmid, and LSepi increased at 3 months after TAVI (all P<0.05). In the TAVI preoperative, invasive aortic pressure was positively correlated with peripheral brachial artery systolic blood pressure, invasive left ventricular systolic pressure was positively correlated with non-invasive left ventricular systolic pressure ( r=0.658, 0.565; all P<0.01). Compared with the control group, the preoperative the GWE decreased and the GWW increased in the TAVI group (all P<0.05). Compared with the preoperation, the GWI and GCW decreased at 1 week after TAVI (all P<0.05). Compared with 1 week after TAVI, GWI, GCW, GWE increased and GWW decreased at 3 months after TAVI (all P<0.05). Conclusions:The application of 2D-STI and PSL can quantitatively evaluate the left ventricular myocardial systolic function before and after TAVI in AS patients, which can provide a more objective reference index for clinical evaluation of the efficacy of TAVI.