Objective To assess left ventricular（LV） torsional mechanics in patients with chronic severe aortic regurgitation（AR） by three-dimensional speckls tracking imaging（3D-STI）

and to assess the effect of aortic valve replacement（AVR） on LV twist function.Methods A total of 76 patients with chronic severe aortic regurgitation were divided into 40 patients in AR-A group（LVEF≥55%） and 36 patients in AR-B group（LVEF<55%）

and 30 healthy controls were selected（healthy control group）.LV basal rotation（Basal-Rot）

apical rotation（Api-Rot） and time to peak rotation（Basal-Rot TR

ApiRot TP）

LV Torsion（Torsion） and time to peak twist（Twist TP） by 3D-STI were analyzed and compared among subgroups.31 patients who underwent AVR were re-examined 2 weeks after operation

and the above parameters were measured.Results①Both Api-Rot and Torsion in AR-A group were reduced compared with those of healthy control group（both P<0.05）

there was no statistical difference of Basal-Rot between AR-A group and healthy control group.In AR-B group

Api-Rot

Basal-Rot and Torsion were all lower than those in healthy control group（all P<0.05）.Basal-Rot and Torsion were lower than those in AR-A group（both P<0.05）

and there was no statistically significant difference of AR between AR-B group and AR-A group.② Compared with healthy control group

Basal-Rot TP and Twist TP were longer in AR-A group（both P<0.05）

Twist TP

Api-Rot TP and Basal-Rot TP were shortened in AR-B group（all P<0.05）.③2 weeks after AVR

Torsion and Api-Rot in 31 patients were significantly increased（both P<0.05）.④ Pearson correlation analysis revealed that Torsion

Api-Rot

Basal-Rot were associated with LVEF（r=0.591

0.327

0.369

all P<0.05）.Torsion and Api-Rot were correlated with LV-SpI（r=-0.506

-0.320

both P<0.05）.Conclusion 3D-STI could quantitatively assess the LV torsional dynamics in chronic severe AR patients and contribute to a deeper understanding of LV subtle mechanic changes.Parameters of torsional dynamics can sensitively reflect the improvement of LV myocardial function after operation.