Safety and Efficacy Study of Once and Twice Daily Doses of MCC-135 in Subjects With Congestive Heart Failure.

Inclusion: * Females of childbearing potential who are sexually active must agree to use adequate contraception, and can neither be pregnant nor lactating from Screening throughout the duration of the study. * Having a clinical diagnosis consistent with congestive heart failure, of at least 6 months duration and clinically stable for the last month. * Has a left ventricular ejection fraction less than or equal to 40%. * Has Plasma b-type (brain) natriuretic peptide levels greater than or equal to 200 pg/ml at screening. * Meeting the following requirements for current concomitant medication: * Must be using an angiotensin converting enzyme inhibitor or Angiotensin II receptor antagonists therapy for at least 1 month prior to the screening visit. * If using beta-blockers, must have commenced treatment at least 4 months prior to the screening visit. * All other cardiac medications must have been introduced at least one month prior to the screening visit. Exclusion: * Heart failure primarily due to: * Obstructive valvular disease * Malfunctioning artificial heart valve * Congenital heart disease * Pericardial disease * Uncontrolled thyroid disease * Amyloidosis * Severe pulmonary disease * Restrictive or obstructive cardiomyopathy * Known active myocarditis * Terminal heart failure or on waiting list for transplant. * Atrio-ventricular block except for first-degree atrio-ventricular block. * A history of or currently sustained ventricular tachycardia. * Subjects with atrial fibrillation and/or requiring pacemakers (including bi-ventricular pacing). * Presence of pulmonary embolism. * Acute myocardial infarction, unstable angina, coronary revascularization or major surgery during the last 6 weeks prior to screening. * Episode of syncope or cardiac arrest during the last 6 weeks prior to screening. * Requiring treatment with the following therapies: * Anti-arrhythmics (Amiodarone/beta-blockers are permitted) * Calcium sensitizers * Catecholamines * Phosphodiesterase inhibitors * Is currently participating in another investigational study or who have participated in an investigational study (including MCC-135) during the 2 months prior to the screening visit * Has a history of drug or alcohol abuse, as defined by Diagnostic and Statistical Manual of Mental Disorders-4th edition criteria, within the past two years. * Has significant, moderate-severe renal dysfunction or disease, confirmed by serum creatinine of greater than 2mg/dl (180 micromol/L). * Serum potassium levels at entry confirmed below 3.5mmol/L. * Known severe symptomatic primary pulmonary disease in the last 5 years e.g. asthma, chronic obstructive pulmonary disease. * Concurrent severe disease (including significant hepatic, metabolic or other systemic disease) or any medical condition that, in the opinion of the investigator, would compromise the subject's safety or their successful participation in the study. * History of multiple drug allergies or with a known allergy to the study drug or any medicine chemically related to the study drug. * Individuals who are morbidly obese. * Is required to take or intends to continue taking any disallowed medication, any prescription medication, herbal treatment or over-the counter medication that may interfere with evaluation of the study medication, including: * Anti-arrhythmics (Amiodarone/beta-blockers are permitted) * Calcium sensitizers * Catecholamines * Phosphodiesterase inhibitors