Use of catheter ablation for persistent atrial fibrillation (PerAF) remains controversial due to unsatisfactory long-term success rates (15% - 28.4%). The investigators' previous study indicated that the upper area of the left atrium (LA) plays an important role in PerAF, with the LA roof and mitral isthmus appearing to serve as main substrate in progression from PAF to PerAF and maintenance of fibrillatory activities. The investigators therefore hypothesized that AF should not be initiated or sustained if the latter crucial regions for AF maintenance are abolished. This study aimed to describe the efficacy and safety of additional linear ablation on the left atrial anterior wall for PerAF.

Although studies and guidelines have helped establish catheter ablation as preferred treatment for patients suffering from paroxysmal atrial fibrillation (PAF), use of catheter ablation for persistent atrial fibrillation (PerAF) remains controversial due to unsatisfactory long-term success rates (15% - 28.4%).

The investigators' study indicated that the upper area of the left atrium (LA) plays an important role in PerAF, with the LA roof and mitral isthmus appearing to serve as main substrate in progression from PAF to PerAF and maintenance of fibrillatory activities. The investigators therefore hypothesized that AF should not be initiated or sustained if the latter crucial regions for AF maintenance are abolished. This was confirmed using a stepwise pure linear ablation protocol, consisting of a line across the LA roof and extending along the anterior wall of pulmonary veins (PV) antrum to mitral valve annulus (MVA) without PV isolation; the approach appeared safe and effective with long-term (5.2 years) follow-up success rate of 40% for PerAF.

This study will evaluate efficacy and safety of circumferential pulmonary vein isolation (CPVI) + LA roof linear ablation + LA anterior wall (LAAW) linear ablation combined with high density mapping and contact force sensing techniques for perAF. This study is expected to provide a practical and guided catheter ablation strategy with maximized safety and efficacy through use of contact force sensing technique, which will be accepted by other qualified electrophysiology laboratories.

Inclusion Criteria:

- The main inclusion criterion is patients suffering from drug refractory persistent atrial fibrillation and referred to catheter ablation therapy. Persistent AF is defined as continuous AF for over 7 days, or lasting no more than 7 days but requiring pharmacological or electrical cardioversion.

Exclusion Criteria:

1. Patients without spontaneous ongoing AF at the beginning of the procedure;
2. Age: <18 years or >70 years;
3. LA size > 55mm measured on echocardiogram;
4. Previous AF ablation history including surgical ablation;
5. Documented LA thrombus;
6. Severe pulmonary diseases;
7. Previous cardiac surgical history.