- Treated with stable and optimal CHF medications, which includes an ACE inhibitor (ACE-I) or Angiotensin Receptor Blocker (ARB) at therapeutic dose for 1 month prior to enrollment, if tolerated, and a Beta Blocker that is approved and indicated for HF for 3 months prior to enrollment, if tolerated, with a stable dosage for 1 month prior to enrollment. If the patient is intolerant of ACE-I or beta blockers, documented evidence must be available. Eplerenone requires dosage stability for 1 month prior to enrollment. Diuretics may be used as necessary to keep the patient euvolemic. Therapeutic equivalence for ACE-I substitutions is allowed within the enrollment stability timeliness. Stable is defined as no more than a 100% increase or a 50% decrease in dose.