The purpose of this trial is to explore the optimal AI value for isolating the pulmonary veins and achieving left ventricular apex and mitral isthmus block. Patients with atrial fibrillation who are scheduled to undergo catheter ablation will be randomized to different groups, then every group receive circumferential pulmonary vein isolation with different AI values. The relevant indicators such as the proportion of pulmonary vein single-circle isolation, operation time, the incidence of complications, and the proportion of recurrence of atrial fibrillation and other atrial arrhythmias after 1 year were collected.

This is a prospective, single-center, randomized controlled trial. In this part,a total of 90 patients with paroxysmal atrial fibrillation who are scheduled for catheter ablation were randomly divided into 3 groups, 30 patients in each group. For the first group, the AI target value for the front wall and the top wall is 550, and the rear wall and the lower wall are 400. For the second group, the AI target values for the front wall and the top wall are 500, the rear wall and the lower wall are 350. For the third group, the AI target values for the front wall and top wall are 450, the rear wall and the lower wall are 300. The pressure value at each point is 5-15 g, and the distance between adjacent ablation points is less than 5 mm. The relevant indicators such as single-circle isolation rate of the pulmonary vein, operation time, the left atrial operation time, and the supplemental ablation site are recoded. The incidence of intraoperative and postoperative complications such as stroke, pericardial tamponade and steam pop during ablation are observed. Dynamic electrocardiography is performed during the follow-up period to evaluate the proportion of sinus rhythm within 1 year.

Inclusion Criteria:

1. Male and non-pregnant female subjects, 18≤age≤80.
2. Receiving or able to tolerate anticoagulant therapy.
3. Diagnosis of atrial fibrillation using an electrocardiogram or a dynamic electrocardiogram
4. The longest duration of atrial fibrillation episode is less than 7 days
5. Patient is compliant and willing to complete clinical follow-up.

Exclusion Criteria:

1. Patients who have previously undergone catheter ablation of atrial fibrillation;
2. Left ventricular ejection fraction <35%;
3. Pregnancy, planned pregnancy or lactating women;
4. Left atrial appendage thrombosis was detected by transesophageal ultrasound or intracardiac ultrasound;
5. Abnormal blood system or liver and kidney function;
6. Combined with severe organic heart disease (including congenital heart disease, valvular heart disease, dilated cardiomyopathy, hypertrophic cardiomyopathy, and patients with myocardial infarction or coronary artery bypass grafting);
7. Patients who are considered unsuitable for inclusion by the investigator.

Patients enrolled in the study were randomly assigned to different surgical groups using random envelopes. All study personnel were blind to treatment allocation and had no way of influencing whether a participant would receive high or low AI ablation.