To quantitatively evaluate the left atrial (LA) phasic function by two-dimensional speckle tracing imaging (2D-STI) and three-dimensional volume (3D-EV).

A total of 118 patients were selected, including 89 patients diagnosed with LA enlargement by chest echocardiography at Beijing Chaoyang Hospital Affiliated to Capital Medical University from October 2018 to October 2019, and 29 patients with normal LA size. According to the left atrial maximum volume index (LAVImax), the patients were divided into a normal LA group (29 cases), a slightly increased LA group (41 cases), a moderately increased LA group (27 cases), and a severely increased LA group (21 cases). Left atrial storage function (LARS), left atrial duct function (LACD), and left atrial pump function (LACT) were obtained by 3D-EV. Left atrial storage strain (LASr), left atrial duct strain (LAScd), and left atrial systolic strain (LASct) were obtained using 2D-STI.

LARS, LACD, and LACT were negatively correlated with LAVImax (r=-0.772, -0.645, and -0.735, respectively; P＜0.01). LARS, LACD, and LACT differed significantly among the four groups (P＜0.01 for all) .Further pair-wise comparison showed that there were no significant differences in LARS (P=0.078, 0.101), LACD (P=0.112, 0.483), or LACT (P=0.299, 0.066) between the normal LA size group and the slightly increased LA group, and between the moderately increased LA group and the severely increased LA group. LASr, LAScd, and LASct were negatively correlated with LAVImax (r=-0.797, -0.703, and -0.698, respectively; P＜0.01). Further pairwise comparison showed that there were statistically significant differences in LASr and LASct between the four groups (P＜0.05 for all). There were statistically significant differences in LAScd between the normal LA size group and the slightly increased LA group, the moderately increased LA group, and the severely increased LA group, as well as between the slightly increased LA group and the severely increased LA group (P＜0.05 for all).

Both 2D-STI and 3D-EV evaluations showed that the time phase function of the LA decreases with the increase of LA. 2D-STI can detect abnormal LA phase function earlier and may be more sensitive than 3D-EV in evaluating LA phase function.