Objective To explore the changes of left atrial (LA) volume and function in coronary heart disease (CHD) patients by four-dimensional (4D) LA quantification. Methods 62 patients ，who were clinically suspected of CHD and without regional wall motion abnormalities (RWMA) under two-dimensional echocardiography (2DE) at rest were enrolled. 41 patients diagnosed with CHD by CAG were categorized as CHD group while 21 patients with negative CAG results served as the control group. LA end-systolic anteroposterior diameter (LAD)，left ventricular ejection fraction (LVEF)，the ratio of early diastolic peak transmitral flow velocities (E) and peak mitral annular displacement velocities (a) (E/e) were acquired by 2DE. LA minimum volume (LAVmin)，LA maximum volume (LAVmax)，LA volume at the onset of atrial contraction (LAVpreA)，LAVmin index (LAVImin)

LAVmax index (LAVImax)

LA ejection volume (LAEV)

LA ejection fraction (LAEF)

LA longitudinal and circumferential strain during reservoir (LASr， LASr_c)， conduit (LAScd

LAScd_c) and contraction phase (LASct，LASct_c) were obtained by 4DE. Then we compared the baseline information and echocardiographic parameters between these two groups. And the receiver operating characteristic curve (ROC) was conducted to evaluate the diagnostic value of 4DE parameters for CHD. The CHD group was furtherly divided into LCX involved and non-LCX involved groups based on CAG results，and then left atrial parameters by 2DE and 4DE between these two groups were compared. The interclass correlation coefficients (ICC) were used to test the reproducibility of echocardiographic parameters. Results There were no significant differences in baseline demographics and 2DE parameters between the CHD and control group，and all P＞0.05. LAVmin，LAVminI were increased and LAEF，LASr，LASr_c，LAScd_c，LASct_c were decreased significantly in the CHD group when compared with those in the control group，and all P＜0.05. LASr_c demonstrates the highest area under the ROC curve ((AUC=0.891，P=0.000) sensitivity 90.2%，specificity 71.4%)

with the cut-off value of 33.5% for predicting CHD patients. There were no significant differences in left atrial echocardiographic parameters between LCX involved and non-LCX involved groups. All echocardiographic parameters documented showed good reproducibility (ICC＞0.640). Conclusions 4D LA quantification can effectively evaluate the changes of LA volume and function. LASr_c showed the best diagnostic capacity for CHD patients

which provides a new method for clinical research on CHD.