Inclusion Criteria:

• Patients hospitalized with symptomatic CHF, current New York Heart Association (NYHA) class II-IV requiring treatment with a diuretic, who had had within the last month at least 1 episode of dyspnea or fatigue at rest, or on slight exertion corresponding to NYHA class III or IV
• Wall motion index (WMI) ≤1.2 determined by a blinded central evaluation of a recorded standard echocardiography, equivalent to a left ventricular ejection fraction (LVEF) ≤35%.

Exclusion Criteria:

• acute pulmonary edema within 12 hours prior to start of study medication
• various heart conditions (cardiogenic shock, obstructive valvular disease, obstructive cardiomyopathy; acute myocardial infarction, cardiac surgery, acute myocarditis or constrictive pericarditis, history of torsades de pointes, bradycardia <50 bpm and/or PR-interval ≥280 ms, QTc-interval >500 ms, significant sinus node disease)
• any illness or disorder other than CHF (cancer with metastasis, organ transplantation)
• current participation in another clinical study or currently taking an investigational drug including dronedarone or concomitant prohibited medication or treatment with other class I or III anti-arrhythmic drugs
• pregnant and/or breastfeeding women or women of child-bearing potential without adequate birth control
• serum potassium <3.5 mmol/L.

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