Study of JK07 in Patients With Chronic Heart Failure

Inclusion Criteria: * Participants with New York Heart Association (NYHA) Class II-III. * Cohort 1 - Left Ventricular Ejection Fraction (LVEF) ≤ 40%. * Cohort 2 - Left Ventricular Ejection Fraction (LVEF) \>40% and ≤ 65%, elevated N-terminal pro B-type natriuretic peptide (NT-proBNP) ≥ 600pg/mL and atrial fibrillation/flutter. * Stable heart failure and on optimal medical therapy. * Screening hemoglobin ≥ 9.0 g/dL. Exclusion Criteria: * Uncontrolled hypertension. * Sustained systolic Blood Pressure (BP) \< 90 mmHg and/or diastolic BP \< 50 mmHg on 2 consecutive (duplicate seated) readings at screening. * Heart failure due to hypertrophic cardiomyopathy, restrictive and/or infiltrative cardiomyopathy, arrhythmogenic right ventricular dysplasia, Fabry disease, or Noonan syndrome with LV hypertrophy or a positive serum immunofixation result. * Diagnosis of stress-induced (Takotsubo) cardiomyopathy, myocarditis, or peripartum cardiomyopathy. * Diagnosis of chemotherapy- or radiation-induced cardiomyopathy. * Diagnosed with stroke or Transient Ischemic Attack (TIA) within 12 weeks of screening. * History of syncope within the last 12 weeks prior to screening or sustained ventricular tachycardia without an implantable cardioverter-defibrillator. * Moderate or severe aortic and/or mitral valve stenosis. * Medically documented unstable angina, acute coronary syndrome (e.g., myocardial infarction, troponin-positive with symptoms of angina or unstable angina) within the last 8 weeks prior to start of screening. * Medically documented ST-elevation myocardial infarction within 12 weeks of screening. * Any tachycardia (inclusive of Atrial Fibrillation (AF) or atrial flutter) with a resting ventricular rate \> 110 beats per minute at screening. * For participants with a history of AF or atrial flutter, not on adequate anticoagulant therapy via non-vitamin K oral anticoagulants or warfarin if the CHA2DS2-VASc score is ≥ 2 in men or ≥ 3 in women or per local guidelines. Percutaneous occlusion of the left atrial appendage alone is not adequate. * AF ablation within the last 12 weeks prior to screening or planned during the study duration. * Symptomatic bradycardia or second (Mobitz Type II)- or third-degree heart block without a pacemaker. * Cardiac surgery, coronary artery revascularization or indication for coronary artery revascularization, percutaneous coronary intervention, valve repair/replacement or valvuloplasty within 12 weeks prior to screening. * Implantation of a Cardiac Resynchronization Therapy (CRT) device within 12 weeks prior to screening, or intent to implant a CRT device during the course of the study. * Previous cardiac transplantation, or any use of mechanical circulatory support or similar device, or implantation expected after randomization. * Receiving mechanical hemodynamic support or invasive mechanical ventilation within the last 8 weeks prior to screening. * Receiving Intravenous (IV) inotropes or IV vasopressors within the last 8 weeks prior to screening. * Receiving IV vasodilators within the last 4 weeks prior to screening. * Receiving noninvasive mechanical ventilation within the last 4 weeks prior to screening. The use of noninvasive ventilation for sleep disordered breathing is permitted.