Study to Demonstrate the Non-inferiority of Olmesartan Medoxomil Versus Candesartan Cilexetil in Reducing Blood B-type (or Brain) Natriuretic Peptide Levels at Week 24

Inclusion Criteria: * Male or female, adult, out-patients aged between 18 and 85 years * Patients with documented hospital admission within the previous 3 months before randomization with discharge diagnosis of CHF * Patients with functional NYHA class II-IV with LVEF \< 40% assessed within the last 3 months * Patients with blood BNP levels \> 400 pg/ml or NT-ProBNP levels \> 1500 pg/ml * Patients with CHF due to ischemic heart disease, idiopathic dilated cardiomyopathy (IDC), mitral or aortic insufficiency or hypertension * Patients with stable conventional treatment with diuretics, ACEI and/or beta-blockers and/or aldosterone antagonists for at least 2 months prior to randomisation, unless documented contraindication or intolerance Exclusion Criteria: * Females who are pregnant or plan a pregnancy during the time of the trial, are nursing or are of childbearing potential and not using acceptable methods of contraception. If a female becomes pregnant during the study, she has to be withdrawn immediately * Patients with current hospitalisation due to heart failure * Patients with stroke or transient ischemic attack (TIA) within the last 3 months * Patients with acute coronary syndrome, myocardial infarction, coronary artery bypass or angioplasty within 3 months * Planned cardiac surgery, revascularization or resynchronization within the study period * Patients with operable valvular disease or significant obstructive cardiomyopathy * Patients with bradycardia \[heart rate (HR) \< 50 bpm\] * Patients with hypotension \[systolic blood pressure (SBP) \< 90 mmHg\] * Patients with obstructive pneumopathy * Patients with clinical significant renal failure (creatininemia \> 200 micromol/l)