A Study of Ivabradine in African-American/ Black Subjects With Heart Failure and Left Ventricular Systolic Dysfunction.

Inclusion Criteria

• Subject has provided informed consent/assent prior to initiation of any study specific activities/ procedures
• Male or female subject ≥ 18 years of age, describing self as African American/Black
• Must have a diagnosis of heart failure (HF) confirmed by medical records, be in stable condition, and treated with stable optimal pharmacological therapy as per their personal physician's care.
• Left ventricular ejection fraction (LVEF) ≤ 35% confirmed by investigator
• New York Heart Association (NYHA) class II to IV assessed at the time of screening
• Electrocardiogram (ECG) documentation at the time of screening of sinus rhythm with resting heart rate (HR) ≥ 70 bpm by local ECG reading
• Must be able to complete a 6-minute walk test (6MWT) and wear an accelerometer

Exclusion Criteria

• Recent myocardial infarction (≤ 2 months) or stroke (≤ 1 month) prior to enrollment
• If the subject received within 3 months before or is scheduled to receive within 42 days after enrollment any of the following: revascularization, ventricular assist device, continuous or intermittent inotropic therapy, hospice care, major organ transplant, or is receiving renal replacement therapy by dialysis
• If the subject received implantation of a cardioverter defibrillator or cardiac resynchronization therapy within 42 days before or is scheduled to receive implantation of a cardioverter defibrillator or cardiac resynchronization therapy within 42 days after enrollment
• Severe primary valve disease or scheduled for surgery for valvular heart disease
• Pacemaker with atrial or ventricular pacing (except bi-ventricular pacing) >40% of the time, or with a stimulation threshold at the atrial or ventricular level ≥ 60 bpm
• Permanent atrial fibrillation or flutter
• Sick sinus syndrome, sinoatrial block, or second and third degree atrio-ventricular block
• History of symptomatic or sustained (≥ 30 sec) ventricular arrhythmia unless a cardioverter defibrillator was implanted
• History of congenital QT syndrome
• Any cardioverter defibrillator shock experienced within 1 month of enrollment
• Hypertrophic obstructive cardiomyopathy, active myocarditis or constrictive pericarditis, or clinically significant congenital heart disease
• Chronic antiarrhythmic therapy (except digitalis)
• Scheduled outpatient intravenous (IV) infusions for HF (eg, inotropes,vasodilators [eg, nesiritide], diuretics) or routinely scheduled ultrafiltration
• Evidence of digitalis intoxication within 7 days prior to screening
• Systolic blood pressure > 180 mm Hg or 110 mm Hg or < 50 mm Hg at any time during the screening phase
• Known untreated hypothyroidism or hyperthyroidism, adrenal insufficiency, active vasculitis due to collagen vascular disease
• Have known acute or serious co-morbid condition (e.g, major infection or hematologic, renal, hepatic, metabolic, gastrointestinal or endocrine dysfunction) that may interfere with the study, or severe concomitant non-cardiovascular disease that is expected to reduce life expectancy to less than 1 year or malignancy within 5 years prior to enrollment with the following exceptions: localized basal or squamous cell carcinoma of the skin or cervical intraepithelial neoplasia
• Subjects taking QT prolonging medicinal products for cardiovascular (e.g, but not limited to, quinidine, disopyramide, bepridil, sotalol, ibutilide, amiodarone) or non-cardiovascular disease (e.g, but not limited to, pimozide, ziprasidone, sertindole, mefloquine, halofantrine, pentamidine, cisapride, IV erythromycin).
• Subjects exposed to a strong CYP3A4 inhibitor (examples of strong CYP3A4 inhibitors include; azole antifungals [eg, itraconazole], macrolide antibiotics [e.g, clarithromycin, telithromycin], human immunodeficiency virus (HIV) protease inhibitors, [eg, nelfinavir], and nefazodone]) within 14 days prior to enrollment, or to a strong CYP3A4 inducer (examples of CYP3A4 inducers include; St. John's wort, rifampicin, barbiturates, and