Inclusion Criteria:  Signed and dated informed consent form; Male or non-pregnant female, 21 years or older; Diagnosed with symptomatic heart failure; LVEF ≥40 and ≤60%;  One or more of the following:  Heart failure hospitalization; Urgent heart failure visit; Elevated NT-proBNP levels; Elevated BNP levels; Subjects receiving stable treatment for HF and comorbid conditions; Subjects on a scheduled oral loop diuretic treatment.  Exclusion Criteria:  Resting heart rate <50 or >110 bpm; Resting systolic blood pressure <110 or >160 mmHg; BMI greater than 40 Any moderate or severe valvular stenotic disease or any severe valvular regurgitation; Mechanical tricuspid valve; Complex congenital heart disease; Exercise tolerance limited by a condition other than heart failure that, in the opinion of the investigator, contributes significantly to the primary symptoms of shortness of breath and/or exercise intolerance; Unable to walk at least 100 meters during a 6MWT; A KCCQ CCS score higher than 85; Hypertrophic, infiltrative/restrictive or inflammatory cardiomyopathy; Unstable angina pectoris within 30 days prior to study consent; Acute, decompensated heart failure requiring IV therapy or ultrafiltration within 30 days prior to consent, in the hospital or an outpatient setting; Receiving cardiac resynchronization therapy (CRT); Scheduled for a cardiac surgery or a percutaneous cardiac intervention (PCI) or have undergone cardiac surgery within 90 days or a PCI procedure within 30 days prior to study consent; Myocardial infarction within 90 days prior to study consent; Prior heart transplant or ventricular assist device; Planning to become pregnant during the study; Dialysis (permanent) or GFR <30 ml/min/1.73m2; Participating in another investigational study; Currently undergoing active chemotherapeutic and/or radiation treatment for cancer or has a history of chemotherapy during the 2-year period prior to study consent; Expected lifespan of less than 18 months from time of study consent;