The purpose of this study is to evaluate the feasibility of permanent biventricular pacing using three ventricular leads, and its efficacy in terms of inter and intra-ventricular resynchronization, in patients with congestive heart failure and a non-functional atrium (chronic AF).

Inclusion Criteria:

• NYHA class III-IV congestive heart failure, in spite of optimal medical treatment for their congestive heart failure for 1 month.

The medical treatment must include a 40 mg/day minimum dose of furosemide (or equivalent);

• Permanent atrial fibrillation (AF);
• Left ventricular ejection fraction (LVEF) ≤ 35%;
• Indication for a pacemaker implantation for a permanent and symptomatic bradycardia, or already implanted pacemaker under the condition that leads positioning corresponds to the criteria described in the protocol;
• Aortic pre-ejection delay at least equal to 140 ms.

Exclusion Criteria:

• Indication for a cardiac defibrillator;
• Having presented a myocardial infarct within the previous 3 months;
• Having undergone cardiac surgery or coronary revascularization procedure within the previous 3 months, or being scheduled for such procedures;
• Presenting chronic pulmonary insufficiency;
• Patients whose congestive heart failure requires the use of an intravenous inotropic support;
• Presenting a dysthyreosis;
• Having a life expectancy of less than one year, for other reasons than the congestive heart failure;
• Unable to be followed-up in the scope of the study for geographical reasons;
• Having refused to give their consent;
• Minors (age < 18 years) and pregnant women.