Primary Objective:

- To assess the efficacy of dronedarone versus placebo for the control of ventricular rate in patients with permanent Atrial Fibrillation (AF).

Secondary Objective:

• To assess the safety and tolerability of dronedarone after repeated oral doses of 300 mg, 400 mg, or 600 mg twice daily in the selected population.
• To document SR33589 and SR35021 trough plasma levels at steady state.

The study period per patient is approximatively 1 month broken down as follows:

• Screening period up to 7 days,
• Treatment period of 14 days,
• Follow-up period of 10 days.

Inclusion criteria:

• Patients of aged 20 years or more.
• Permanent Atrial Fibrillation [AF] (defined as duration of AF > 6 months) for which cardioversion is not considered and with resting ventricular heart rate ≥ 80 bpm at screening.

Exclusion criteria:

• Unstable angina pectoris.
• History of torsades de pointes.
• Prolonged QT corrected interval (≥ 500 ms).
• Third degree atrioventricular block (AVB) on the screening ECG while in AF or, documentation on previous ECGs while in sinus rhythm of PR-interval > 0.28 sec or high degree AVB (2nd degree or higher) or, significant sinus node disease (documented pause ≥ 3 sec) - without a permanent pacemaker implanted.
• Congestive Heart Failure (CHF) of New York Heart Association classification (NYHA) class IV or recent (within 1 month prior to randomization) unstable NYHA class III.
• Treatment with other class I or III anti-arrhythmic drugs.
• Patients treated with amiodarone during the 4 weeks preceding randomization.
• Clinically relevant haematologic, hepatic, gastro-intestinal, renal, pulmonary, endocrinologic (in particular thyroid) or psychiatric disease.
• Hypokalemia and hypomagnesemia must be corrected before randomization.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.