Inclusion Criteria:

1. Patients with CHF who exhibit edema, jugular venous distention, hepatomegaly, pulmonary congestion, or 3rd sound due to extracellular volume expansion
2. Hospitalized patients or patients who can be hospitalized for the study from the commencement of the observation period to the end-of-study examination
3. Men and women between the ages of 20 and 80 (non-inclusive) at the time of giving consent
4. Patients who have taken furosemide at 40 mg/d or more (oral dosing) without alteration of dosage for the 3 days of the observation period
5. Patients whose body weight has been stable (±1.0 kg) for 2 days prior to commencement of study drug administration

Exclusion Criteria:

1. Patients with unstable heart failure (acute heart failure, acute exacerbation of chronic heart failure, etc)
2. Patients with an implanted ventricular assist device

3. Patients who have undergone or are scheduled to undergo any of the following procedures

   • Heart surgery involving thoracotomy within 60 days prior to the screening examination
   • Pacemaker implant surgery involving bilateral pacing within 60 days prior to the screening examination
   • Angioplasty, electrophysiologic device implantation, ventricular assist device implantation, heart transplant, or other cardiac surgery scheduled within 30 days after the screening examination

4. Patients with any of the following diseases, complications, or symptoms

   • Suspected hypovolemia
   • Onset of acute myocardial infarction within 30 days prior to the screening examination
   • Hypertrophic cardiomyopathy (excluding diastolic phase)
   • Definitively diagnosed active myocarditis or amyloid cardiomyopathy
   • Valvular heart disease with significant stenosis
   • Untreated thyroid disease
   • Progressive neurological disease (Alzheimer's disease, Parkinson's disease, multiple sclerosis, etc) or severe episodic neurological disease (epilepsy, Guillain-Barre syndrome, etc)
   • Diabetes with poor glycemic control
   • Anuria
   • Hepatic coma
   • Hyponatremia of moderate or greater severity (serum Na < 120 mEq/L)

5. Patients with a history of the following conditions

   • Occurrence of sustained ventricular tachycardia or ventricular fibrillation within 30 days prior to the screening examination (except for patients using an implantable cardioverter-defibrillator)
   • Evident cerebral infarction
   • Multiple stroke
   • Occurrence of a cerebrovascular accident within 30 days prior to the screening examination
   • Hypersensitivity or idiosyncratic reaction to benzazepine derivatives, such as benazapril
6. Patients with a history of drug abuse or alcoholism in the past year
7. Patients in a state of morbid obesity with a body mass index (weight[kg] ÷ height [m]2) over 35
8. Patients with a supine systolic arterial blood pressure of less than 90 mmHg
9. Patients with any of the following abnormal laboratory values: Hemoglobin <9 g/dL, total bilirubin >3.0 mg/dL, serum creatine >3.0 mg/dL, serum Na >147 mEq/L, or serum K >5.5 mEq/L
10. Patients not capable of taking oral medication
11. Patients who are nursing, pregnant, capable of pregnancy, or intending to become pregnant during or shortly after the study period　
12. Patients who have taken a study drug other than OPC-41061 within 30 days prior to screening
13. Patients who have previously taken OPC-41061 in this study or another study of OPC-41061
14. Patients otherwise judged by the principal investigator or attending investigator to be inappropriate for inclusion in the study (eg, patients with hepatic cirrhosis, renal disease, etc.)