Abstract: Objective: To observe the changes of structure and function of left atrium before and after transcatheter radiofrequency ablation by two-dimensional speckle tracking imaging (STI) technology in paroxysmal atrial fibrillation(AF)patients,so as to evaluate the clinical efficacy of radiofrequency ablation in paroxysmal AF. Methods: A total of 33 patients undergoing transcatheter radiofrequency ablation for paroxysmal AF were selected and divided into the sinus rhythm group (n=25) and recurrence group (n=8) according to whether sinus rhythm was restored after surgery.Cardiac color-ultrasound examination was performed to measure left atrial diameter (LAD),left atrial anteroposterior diameter (LAAPD),left atrial upper and lower diameter (LAUDD),left atrial left and right diameter (LALRD),end diastolic left atrial volume (EDLAV),end systolic left atrial volume (ESLAV),and left atrial ejection fraction (LAEF) before surgery,3 days after surgery,and 3 months after surgery.STI was applied to measure the left atrium global longitudinal strain(LAGLS) and left atrium global longitudinal strain(LAGLSR),as well as the strains and strain rates of left wall,roof and right wall of left atrium. Results: At 3 days after surgery,there was no statistically significant difference in all left atrium structure and function indicators of patients between the two groups compared with before surgery (P>0.05).At 3 months after surgery,in the sinus rhythm group,LAD,LAAPD,LALRD,LAUDD,EDLAV,ESLAV decreased compared with before surgery and 3 days after surgery (P<0.05),LAEF increased compared with before surgery and 3 days after surgery (P<0.05),LAGLS,LAGLSR,and strains and strain rates of left wall,roof and right wall of left atrium increased compared with before surgery and 3 days after surgery (P<0.05).At 3 months after surgery,in the recurrence group,the LAUDD,LAD,EDLAV,ESLAV increased compared with before surgery and 3 days after surgery(P<0.05),LAEF decreased compared with before surgery and 3 days after surgery (P<0.05),while there was no statistically significant difference in LAAPD,LALRD compared with 3 days after surgery (P>0.05);LAGLS and strains of left wall,roof and right wall of left atrium decreased compared with before surgery and 3 days after surgery (P<0.05),LAGLSR and strain rates of left wall,roof and right wall of left atrium slightly decreased compared with before surgery and 3 days after surgery,but the difference of which was not statistically significant (P>0.05).At 3 days and 3 months after surgery,the LAD,LAAPD,LALRD,LAUDD,EDLAV,and ESLAV of patients in the sinus rhythm group were lower than those in the recurrence group (P<0.05 to P<0.01),while LAEF was significantly higher than that in the recurrence group (P<0.01).At 3 months after surgery,LAGLS,LAGLSR,strains and strain rates of left wall,roof and right wall of left atrium of patients in the sinus rhythm group were significantly higher than those in the recurrence group(P<0.01). Conclusions: The left atrium function and structure of patients with paroxysmal AF gradually improve after the restoration of sinus rhythm after radiofrequency ablation,while the left atrium function and structure of patients with recurrence do not significantly improve,and may even get worse.