ABSTRACT Objective The purpose of this research is to analyze the association between left atrial appendage (LAA) mechanical parameters assessed by two-dimensional speckle tracking technology(2D-STI) and the degree of myocardial fibrosis in patients with rheumatic heart disease (RHD)and atrial fibrillation (AF). Methods The study included 36 patients with RHD and AF who underwent transesophageal echocardiography (TEE). They were scheduled to undergo valve replacement combined with modified radiofrequency maze surgery in Yichang Central people's Hospital from January 2019 to December 2020. The LAA strain rate and the degree of LAA fibrosis of all patients were evaluated. The patients were divided into two group according to the recurrence of AF after 6 months. Results After a follow-up of six months

eight patients had recurrent atrial fibrillation. We found that compared with the non-recurrent group

the LAALSRs、LAALSRs1 and LAALSRs3 in the recurrent group were significantly lower than those in the non-recurrent group (P < 0.05). The degree of fibrosis in the recurrent group was more serious than that in the non-recurrent group (P < 0.05). Correlation analysis showed that the systolic strain rate of left atrial appendage was negatively correlated with the degree of overall fibrosis of left atrial appendage (r = 0.766

P < 0.0l)

and the strain rates of basal

middle and the tip of left atrial appendage were negatively correlated with the degree of fibrosis of corresponding segments (r =-0.752

-0.547

-0.589

P < 0.01). Conclusions The degree of left atrial appendage fibrosis in patients with atrial fibrillation recurrence after ablation is more severe. LAA strain rate is negatively correlated with the degree of myocardial fibrosis in patients with RHD and AF and the r values of the basal segment of the left atrial appendage is higher. The 2D-STI has a certain value in evaluating the degree of myocardial fibrosis.