Linear ablation is frequently used in the procedure for persistent atrial fibrillation. However, it has a limitation because of technical difficulty. Incomplete block is common and an important cause of atrial tachycardia.

The association between contact force values and successful linear block has not been revealed yet. We aim to the effectiveness and safety of linear ablation by using CF sensing catheter.

Catheter ablation is currently accepted as a treatment option for symptomatic atrial fibrillation. Linear ablation is frequently used in the procedure for persistent atrial fibrillation. Multiple studies have shown benefit of linear ablation. However, it has a limitation because of technical difficulty. Incomplete block is common and an important cause of atrial tachycardia.

Contact-force (CF) monitoring during procedure has recently been available. This technology appears to significantly decrease procedure time and short term reconnection incidence in pulmonary vein (PV) isolation. It also helped to resolve the cause of PV reconnection. Some reports demonstrated that the association between reconnection and lower CF value.

Linear ablation has more variation to interrupt block and reconnection was more often than PV isolation. The association between CF values and successful linear block has not been revealed yet. In addition, the investigators aim to the effectiveness and safety of linear ablation by using CF sensing catheter.

Inclusion Criteria:

• Patients age is18 years or greater
• Patients with persistent AF (AF episode lasting > 7 days)
• Patients with symptomatic AF that is refractory to at least one antiarrhythmic medication
• Patients with recurrent or sustained arrhythmia after pulmonary vein isolation
• Patients undergoing a first-time ablation procedure for AF
• At least one episode of AF must have been documented by ECG, Holter, loop recorder, telemetry, trans telephonic monitoring (TTM), or implantable device within last 2 years of enrollment in this investigation
• Patients must be able and willing to provide written informed consent to participate in this investigation

Exclusion Criteria:

• Patients with long-standing persistent AF;
• Long-standing persistent AF will be defined as a sustained episode lasting more than 3 years.
• Patients for whom cardioversion or sinus rhythm will never be attempted/pursued;
• Patients with AF felt to be secondary to an obvious reversible cause
• Patients with contraindications to systemic anticoagulation with heparin or warfarin or a direct thrombin inhibitor;
• Patients with left atrial size ≥ 60 mm (2D echocardiography, parasternal long axis view)
• Moderate to severe valvular disease
• Reduced left ventricular function (ejection fraction <40%)
• Patients who are pregnant. Pregnancy will be assessed by patients informing the physicians.