ESSENTIAL-"The Studies of Oral Enoximone Therapy in Advanced Heart Failure"

In order to be considered eligible subjects, the following entry criteria must be met: * At least 18 years of age * ischemic or nonischemic cardiomyopathy * NYHA Class III or IV * one hospitalization, or two outpatient visits, for the treatment of worsening heart failure within 12 months requiring the administration of I.V. heart failure therapy * LVEDD \>3.2 cm/m2 or \>=6.0 cm * LVEF of less than or equal to 30% * concomitant treatment with optimal conventional heart failure therapy Exclusion Criteria Subjects who meet any one of the following criteria will be deemed ineligible for participation in the study: Subjects on the following concomitant medications: * Calcium antagonists other than amlodipine or felodipine * Flecainide, encainide, propafenone, dofetilide or disopyramide * Subjects receiving I.V. positive inotropic agents within seven days of the Screening Visit or Randomization Visit * Subjects receiving a human B-type natriuretic peptide, including nesiritide, within seven days of the Screening Visit or Randomization Visit * Subjects receiving oral or I.V. phosphodiesterase III inhibitors (PDEI III), including levosimendan and cilostazol, within seven days of the Screening Visit or Randomization Visit * Subjects with active hepatic (screening serum total bilirubin \>= 3.0 mg/dl (\>=51.3 umol/l), renal (screening serum creatinine \>= 2.0 mg/dl (=178.8 umol/l)), hematologic, gastrointestinal, immunologic, endocrine, metabolic, or central nervous system disease * Subjects with a serum potassium \<4.0 mEq/L or \>5.5 mEq/L (\<4.0 mmol/l or \>5.5 mmol/l) at Randomization Visit * Subjects with a magnesium level of \<1.0 mEq/L (\<0.5 mmol/l) at Randomization Visit (Visit 0) * Subjects with a serum digoxin of \>1.2 ng/ml (\>1.5 nmol/l) or a serum digitoxin of \>20 ng/ml (\>26.2 nmol/l) at the Randomization Visit are excluded. A target serum digoxin level of \<=1.0 ng/ml (\<=1.3 nmol/l) is recommended