Principal Inclusion Criteria:
- Male or female > or = 18 years old.
- Symptomatic CHF corresponding to NYHA class II-IV symptoms for at least 4 weeks prior randomization.
- LVEF < or = 40%
- Treatment with an optimal and stable dose of ACE inhibitor for at least 4 weeks prior to enrolment in the study.
Principal Exclusion Criteria:
- Treatment with an ARB within 8 weeks prior to randomization.
- Known hypersensitivity to ARBs or ACE inhibitors.
- Creatinine clearance < 30 ml/min or serum creatinine > 221
- Current serum potassium > or = 5.0 mmol/L or a history of marked ACE inhibitor or ARB induced hyperkalemia.
- Known bilateral renal artery stenosis.
- Current symptomatic hypotension and/or systolic B.P. < 90 mmHg.
- Decompensated heart failure described as hospitalization or I.V. administration of medication in emergency room or heart failure clinic within 4 weeks
- Stroke, acute coronary syndrome, PCI within the last 4 weeks before randomization.
- Connective tissue disease or chronic inflammatory condition
- Acute inflammatory process such as an infection or gout attack in the last 2 weeks.
- Pregnant or lactating women or women of childbearing potential who are not protected from pregnancy by an accepted method of contraception.