Atrial fibrillation (AF) has been the most frequently occurring, sustained arrhythmia, which causes significant morbidity and mortality. AF may not always be a totally random process. It can be maintained by stable and rapid reentrant circuits resulting in fibrillary conduction throughout the atria. During mapping of AF, difficulty is frequently encountered during the identification of culprit sites and an analysis of the wave propagation particularly when the electrogram signals demonstrate wide temporal and spatial disparities. Catheter ablation targeting regions with fractionated potentials or high frequencies during AF, has been previously proposed as a treatment strategy. However, the benefit of adjunctive CFAE (complex fractionated atrial electrogram) ablation or linear ablation after successful PVI (pulmonary vein isolation) was controversial based on the recent data from the Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II (STAR AF II) trial. Therefore, the optimal ablation strategy for persistent AF remains undetermined and an alternative approach has to be explored.

In this prospective trial, investigators will investigate the long-term efficacy of catheter ablation of non-paroxysmal AF, based on selective atrial substrate modification (e.g. wavefrom periodicity analysis, similarity, plus phase mapping) (1). The control group would be PV isolation alone. The primary end point is long-term recurrence of atrial arrhythmias. The secondary end points composite procedural termination, the safety of the procedure, recurrence of multiple procedures, and change of atrial and ventricular function after catheter ablation.

The inclusion criteria, exclusion criteria, stepwise catheter ablation procedures (PVI and then substrate modification), and the follow-up procedure are the same as current treatment approaches in patients with non-paroxysmal AF.

Inclusion Criteria:

1. Patents who sign the informed consent forms, and allow to be followed.
2. Symptomatic AF refractory or intolerant to at least one Class 1 or 3 antiarrhythmic medication.
3. Patients with persistent/permanent AF (sustained beyond seven days, or lasting less than seven days but necessitating pharmacologic or electrical cardioversion).
4. Patients with age equal or greater than 20 years old regardless of gender.

Exclusion Criteria:

1. The presence of a atrial or ventricular thrombus.
2. Patients who are allergic to or unsuitable for use with the contrast media.
3. Pregnant patients or patients who are unavailable to receive X-ray.
4. Patients with renal insufficiency.
5. Patients had autonomic nervous system disorder (e.g. respiratory apnea) or previous catheter ablation in the LA or MAZE procedure.
6. Patients who do not need atrial substrate modification (patients with non-paroxysmal AF respond to PVI in terms of procedural termination of AF).
7. Patients with age less than 20 years old or greater than 90 years old regardless of gender.

The patient's data was available to the host of IRB.