Abstract:Objective To evaluate the ventricular systolic function of Sichuan plateau settlers after returning to the plain by three-dimensional speckle tracking echocardiography. Methods From January 2016 to February 2019, 400 Han people who migrated to the western plateau of Sichuan Province (over 4 000 meters above the sea level, migrated to the plateau for more than 3 months) and returned to the Sichuan plain area after living and working were selected as the observation group, and 400 healthy and normal Han people who never lived in the high altitude area for a long time (less than 3 months) were selected as the control group. After three-dimensional speckle tracking echocardiography was performed in all subjects, the left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and stroke volume(SV), cardiac output (CO), ejection fraction (EF), left ventricular end-systolic spherical index (LVSI), left atrial anterior-posterior diameter (LAAP), left atrial maximal volume (LAV^max), left atrial pre-systolic volume(LAV^olp), left atrial minimalm volume(LAV^min), left atrial active emptying fraction(LAAEF), left atrial passive emptying fraction(LAPEF), left atrial positive strain(LAPS)and left atrial negative strain(LANS)were observed and compared between two groups. Results There were no significant differences in LVEDV, LVESV, SV, CO, EF, LAAEF and LAPEF between two groups (all P>0. 05). Compared with control group, LAAP, LAV^max, LAV^olp, LAV^min and LANS increased, and the absolute value of LAPS decreased in observation group (all P>0. 05). Conclusion For Sichuan plateau settlers with a series of changes in heart during the period of de-adaptation after returning to the plain, the recovery of cardiac function is earlier than the improvement of cardiac movement and morphology. The three-dimensional speckle tracking technology can evaluate the ventricular function and morphological changes so as to provide guidance for clinical intervention.