We randomly assigned 390 patients with symptomatic, paroxysmal AF to undergo catheter ablation with PVI (PVI group) alone or combined with 6 additional ablation lines extended outside the PVI circumferences at 1, 3 and 6 o'clock of left PV and 6, 9 and 11 o'clock of right PV (PVI+6L group). Patients received monthly 12-lead electrocardiogram, 24-hour Holter at 3, 6 and 9 months and 14-days continuous monitoring at 12 months to detect atrial tachyarrhythmia. The follow-up period was 12 months. The primary end point was freedom from AF recurrence between 91 and 365 days after catheter ablation. The secondary end points included the AF burden, procedural parameters, and complications.

We randomly assigned 390 patients with symptomatic, paroxysmal AF to undergo catheter ablation with PVI (PVI group) alone or combined with 6 additional ablation lines extended outside the PVI circumferences at 1, 3 and 6 o'clock of left PV and 6, 9 and 11 o'clock of right PV (PVI+6L group). Patients received monthly 12-lead electrocardiogram, 24-hour Holter at 3, 6 and 9 months and 14-days continuous monitoring at 12 months to detect atrial tachyarrhythmia. The follow-up period was 12 months. The primary end point was freedom from AF recurrence between 91 and 365 days after catheter ablation. The secondary end points included the AF burden, procedural parameters, and complications.

Inclusion criteria

1. Patients between the ages of 18 and 80 years undergoing their first ablation of atrial fibrillation.
2. Diagnosed with symptomatic paroxysmal atrial fibrillation, defined as an documented episode of atrial fibrillation that lasts more than 30 seconds and terminates in less than 7 days.
3. Resistant or intolerant to at least one class I, II, or III antiarrhythmic drugs.
4. Patients deemed candidates for radiofrequency ablation of atrial fibrillation.
5. Able and willing to comply with pre-, post-, and follow-up requirements.

Exclusion criteria

1. Left atrial thrombus by pre-procedural imaging.
2. Uncontrolled heart failure: New York Heart Association Class III or IV, or left ventricular ejection fraction< 40%
3. Myocardial infarction, unstable angina, coronary stenting within the previous 90 days.
4. Stroke or any thrombo-embolic events within the previous 90 days.
5. Expecting cardiac transplantation or other cardiac surgery within 180 days.
6. History of catheter ablation of atrial fibrillation, atrial flutter or atrial tachycardia.
7. History of blood clotting or bleeding abnormalities.
8. Contraindication to anticoagulation.
9. History of cardiac surgery.
10. Uncontrolled maligment tumor.
11. Patients in dialysis or creatinine > 221 μmol/L.
12. Patients with alanine aminotransferase > 150 U/L or aspartate aminotransferase > 76 U/L
13. Acute illness or active infection at time of index procedure or leukocytosis for which antibiotics have been or will be prescribed.
14. Life expectancy less than 1 year.
15. Women who are pregnant or who plan to become pregnant during the study.
16. Other significant congenital anomaly or medical problem that in the opinion of the investigator would preclude enrollment