A total of 105 patients with persistent atrial fibrillation(AF), that lasting longer than one year and planned to undergo surgical treatment, will be allocated into three groups. These patients will receive left atrial appendage closure(LAAC), radiofrequency ablation under the guidance of 3D mapping and LAAC combined with radiofrequency ablation, respectively (allocation ratio, 1:1:1). Real-time 3D ultrasound and 2D ultrasound examinations and measurement of left ventricle(LV) and left atrial(LA) function are carried out for all patients before the operation, and at 1, 2, 3 and 4 weeks and 2, 3, 6, 9 and 12 months after the operation. All ultrasound data will be stored and a professional director from the ultrasound room will be invited for quantitative analysis. Indicators for ultrasonography include: LV ejection fraction(LVEF), LV end-diastolic volume, Stroke volume, left atrial anterior and posterior diameter, left atrial volume, left atrial volume index, mitral e ", E peak, A peak, velocity time integral (VTI), left atrial ejection fraction, left atrial strain, and strain rate. Blood samples are extracted in all patients to detect type B natriuretic peptide before the operation and at 1, 2, 3 days and 1,3,6,12 months after the operation. Blood samples are extracted in all patients to detect routine blood, coagulation, D-D dimmer,Inflammatory markers (hsCRP） and other biochemical parameters before the operation and at 1, 2, 3 and 4 weeks and 1, 2, 3,6and 12 months after the operation. At the same time in operation LA pressure in all patients will be measured preoperatively and postoperatively. This study will clarify the short-term and long-term changes of LA pressure and function of patients with persistent AF after LAAC, and whether changes in left atrial pressure and function are related to inflammation indicators. This study will also to observe whether the coagulation indexes changed after LAAC that can be used to know whether the LAAC activates the coagulation system. In addition, this study to investigate the effects of radiofrequency ablation combined with LAAC on left atrial pressure and function, changes of blood coagulation and inflammatory markers, and to analyze the above findings. At an average follow-up of one year, changes in left atrial function, inflammation, coagulation, and embolic events were analyzed early (3 months after surgery) and late (1 years after surgery).

Inclusion Criteria:

• persistent atrial fibrillation episode occurs in the patient that lasting longer than one year,
• atrial fibrillation cannot be prevented in patients who orally take class I and III antiarrhythmic drugs,
• and patient age is <80 years.

Exclusion Criteria:

• patients with previous history of atrial fibrillation ablation, atrial thrombosis, or valvular heart disease (moderate and severe valvular stenosis, severe valvular regurgitation),
• patients who underwent prosthetic heart valve replacement,
• pregnant women,
• patients with existing liver and kidney disease, malignant tumors or hematological system diseases.

The researchers will participate in the operation to record operative parameters such as LA pressure. Other researchers including follow-up personnel and the ultrasonic data analyst are uninformed about the random situation of the patients (patient information is recorded according to the random number. Random numbers corresponding to the random allocation list are stored in the research center. After follow-up of the last patient is completed, the random allocation list is published by the random number designer; and the designer does not participate in the data collection and statistics.)