The objective of the study is to evaluate the efficacy of the epicardial or endocardial radiofrequency ablation in the treatment of atrial fibrillation.

It is a multicentric, prospective, randomized, parallel, comparative, double blind study. The study principal objective is to evaluate the absence of atrial fibrillation after 3 months. The secondary objectives consist in the evaluation of the maintenance of the sinusal heart rate at one year and of the quality of life improvement

Principal objective:

To evaluate the efficacy at 3 months of combined ablation technique in the treatment of chronic atrial fibrillation during cardiac surgery in order to obtain a sinusal heart rate.

A sequential statistical analysis of the results will be performed every 10 patients.

In case of validation of the principal objective by a sequential method i.e. proving the superiority of the treatment by ablation, ,the study would then be opened and pursued by using the ablation technique for all subsequent patients in order to validate the secondary study objectives

Secondary objectives:

• To evaluate the quality of life of the patients at one year and the absence of atrial fibrillation relapse.
• 6 and 12 months clinical follow-up
• To evaluate the left atrial function at 6 months by trans-oesophagus echocardiography

Inclusion Criteria:

• Adult patients with no age limit, presenting a chronic atrial fibrillation and planned to undergo a surgical intervention on mitral valve (valve replacement or plasty) associated or not with myocardial revascularization or replacement/plasty of another valve (aortic, tricuspid)
• The chronic atrial fibrillation is defined as a continuous atrial fibrillation more than 1 month before the surgery despite all anti-arrhythmia treatments including cardioversion ; the atrial fibrillation can be associated to another rhythm trouble except the severe ventricular rhythm troubles.
• The indication for surgery is performed using the clinical evaluation : NYHA >2 and the usual echocardiography criteria (mitral regurgitation > grade 3, mitral gradient >10 mm Hg or valve surface < 1,5 cm2)
• Patients with a vital prognosis not compromised by comorbidity in the next 2 years and with a mental state enabling to give informed consent
• Patients agreeing to take part in the study and having signed the informed consent form.

For the part of the study pursued in open independent to the actual protocol, patients having signed the modified informed consent with approval of the new study procedure not yet published.

Exclusion Criteria:

• Paroxystic atrial fibrillation or atrial fibrillation for less than 1 month
• Atrial fibrillation never treated by cardioversion or pharmacology before surgery.
• Contra-indication to surgery, i.e. severe respiratory failures, multivisceral deficiencies (renal, cardiac or hepatic), rapidly evolutive or metastatic cancers, malignant hemopathies not stabilized by chemotherapy
• Contra-indication to the following arrhythmia treatments: class III (amiodarone) associated to contra-indication to class II (beta blockers) or to class Ic (flecainide, propafenone, cibenzoline).
• Severe decompensated heart failure.
• Uncontrolled, repetitive, severe documented ventricular arrhythmia (ventricular tachycardia, ventricular fibrillation episodes)
• Contra indication to epicardic ablation procedure (pericardic adhesions, intra-atrial thrombus) In these cases the ablation could be only an endocardic ablation but it does not necessarily exclude the patient.
• Ventricular "ejection fraction " < 40%
• Impossibility to follow the pre-inclusion phases i.e. emergency surgery for mitral break or evolutive endocarditis.
• Patients with disabled mental status
• Patient participating in another clinical study