The RALES study has shown that spironolactone reduces the risk of morbidity and mortality both from progressive heart failure and sudden death, in patients with NYHA III or IV heart failure. This favourable effect was clearly independent from a diuretic effect. Antialdosterone drugs may be effective because they opposes the effects of aldosterone on sodium retention, loss of magnesium and potassium, sympathetic activation, baroreceptor function and vascular compliance. Antialdosterone treatment may also antagonize the effect of aldosterone in promoting cardiac fibrosis. In a RALES substudy baseline serum PIIINP, a marker of cardiac fibrosis synthesis showed an independent negative correlation with survival and CHF hospitalizations in the placebo group. Therefore it seems interesting to evaluate the effect of an Aldosterone receptor blocker on progression of left ventricular dysfunction in patients with mild heart failure assuming standard therapy.

The protocol is sponsored by and independent organization and partially supported by Therabel

Inclusion Criteria:

• Established diagnosis of congestive heart failure in NYHA class II
• Left ventricular ejection fraction <= 45% measured within 6 months from enrolment
• Stable standard heart failure therapy (if patients are on beta blocker drugs, treatment must have been started at least three months before enrolment)
• Informed consent (obtained prior of any study procedures)

Exclusion Criteria:

• Age <18 and >80
• Serum creatinine level > 2.5 mg per deciliter
• Serum potassium level > 5.0 mmol per liter
• Valvular heart disease amenable to surgical treatment
• Congenital heart disease
• Unstable angina and/or acute myocardial infarction and/or coronary revascularization procedure within three months before enrolment
• Intravenous therapy with inotropic drugs within three months before enrolment
• History of resuscitated ventricular fibrillation or tachycardia, unless these occurred within 24 hours of an acute myocardial infarction or the subject has an implanted an automatic cardioverter defibrillator
• Chronic active hepatitis or cirrhosis
• Malignant neoplasm or any life threatening non cardiac disease
• History of hypersensitivity to study drug
• Pregnancy or lactating or childbearing age women who are not protected by an accepted method of contraception
• History of drug or alcohol abuse
• Legal incapacity and/or other circumstances rending the patient unable to understand the nature, scope and possible consequences of the study.
• Evidence of uncooperative attitude
• Any condition other than heart failure that does not permit an optimal participation to the trial
• Participation to other RCTs during the last 3 months
• Treatment with: Lithium salts, Potassium sparing diuretics, oral positive inotropic drugs or any investigational drug