Abstract： Objective:To evaluate the left atrial function and recent postoperative functional changes after removal surgery of left atrial myxoma(LAM) by automatic strain without electrical synchronization.Methods:This study was a case-control study, a total of 25 patients were selected from the department of Cardiovascular Surgery of General Hospital of Northern Theater Command from February 2023 to October 2023, including 9 males and 16 females, aged(56.3±13.9) years old, the age ranging from 32 to 76 years old.Grouped based on whether LAM causeed mitral valve obstruction, patients without mitral valve obstruction as A group( n=15) and patients with mitral valve obstruction as B group( n=10).Another 25 healthy examiners with no abnormalities in echocardiography and electrocardiogram and no clinical symptoms during the same period were selected as C group, including 10 males and 15 females, aged(52.2±16.5) years old, the age ranging from 30 to 75 years old.All participants underwent transthoracic echocardiography without electrical synchronization.A group and B group underwent transthoracic echocardiography 1 to 5 d before surgery and 3 to 7 d after surgery, and measured the longest diameter, widest diameter, and pedicle width of the LAM.All participants measured left atrium diameter(LAD), mitral transmitral pressure gradient(MVPG), and measured the left atrial strain during reservoir phase(LASr), left atrial strain rate during conduit phase(LAScd) and left atrial strain rate during contraction phase(LASct) through automatic strain.Compared the above values between groups and conducted Pearson correlation analysis. Results:Before surgery, the LAD[(43.96±5.43) mm], MVPG[(10.08±4.07)mmHg, 1 mmHg=0.133 kPa]of B group patients were higher than those of C group patients[(32.13±4.73)mm, (1.75±0.82)mmHg].The absolute values of LASr[(20.54±5.91)%, (10.49±5.03)%], LAScd[(-10.31±4.09)%, (-5.49±4.01)%], LASct[(-10.24±4.37)%, (-4.89±2.12)%]in A group and B group were lower than those in C group[(33.55±7.89)%, (-18.63±6.84)%, (-15.07±6.11)%], and the differences were statistically significant( P<0.05).The longest diameter[(54.9±18.24)mm], widest diameter[(31.08±8.45)mm], LAD and MVPG of B group were all higher than those in A group, the absolute values of LASr, LAScd and LASct were lower than those in A group, and the differences were statistically significant( P<0.05).Correlation analysis showed that LASr was moderately negatively correlated with LAD( r=-0.61), MVPG( r=-0.59), longest diameter( r=-0.54) and widest diameter( r=-0.56), LAScd was moderately negatively correlated with LAD( r=-0.51), and LASct was moderately negatively correlated with LAD( r=-0.54), MVPG( r=-0.56) and longest diameter( r=-0.53).After surgery, the LAD[(36.03±6.14)mm], MVPG[(2.76±2.21)mmHg]of B group were higher than those in C group[(32.77±4.60)mm, (1.79±0.71)mmHg], the the LAD was higher than A group[(33.41±4.58)mm].The absolute values of LASr[(16.13±3.07)%, (14.52±2.78)%], LAScd[(-8.34±6.78)%, (-8.46±2.55)%], LASct[(-6.24±3.91)%, (-6.04±2.37)%]in A group and B group were lower than those in C group[(33.54±7.92)%, (-18.25±6.36)%, (-15.35±5.98)%], and the differences were statistically significant( P<0.05). Conclusions:LAM caused the morphological expansion of left atria and reduced the function of blood storage, pipeline and auxiliary pump in left atria, the larger the tumor body, the more obvious the morphological change and function decreased.After myxoma enucleation, the left atrial morphology, blood storage and auxiliary pump function were further reduced; the left atrial morphology returned to normal, and the left atrial blood storage function improved compared with the preoperative operation, but the functions were still lower than normal.