Inorganic Nitrite to Amplify the Benefits and Tolerability of Exercise Training in Heart Failure With Preserved Ejection Fraction (HFpEF) (INABLE-Training)

Inclusion criteria

• Age ≥ 40 years
• Symptoms of dyspnea (II-IV) without evidence of a non-cardiac or ischemic explanation for dyspnea
• Ejection Fraction (EF) of > or = 50% determined on most recent imaging study within the preceding 5 years, with no change in clinical status suggesting potential for deterioration in systolic function
• One of the following:

• Previous hospitalization for Heart Failure (HF) with radiographic evidence (pulmonary venous hypertension, vascular congestion, interstitial edema, pleural effusion) of pulmonary congestion or
• Catheterization documented elevated filling pressures at rest (Pulmonary Capillary Wedge Pressure (PCWP)= ≥15 or Left Ventricular End-Diastolic Pressure (LVEDP) ≥18) or with exercise (PCWP ≥25) or
• Elevated Natruretic Peptide-proBNP (>400 pg/ml) or B-Type Natriuretic Peptide (BNP)(>200 pg/ml) or
• Echo evidence of diastolic dysfunction/elevated filling pressures manifest by medial E/e' ratio≥15 and/or left atrial enlargement and chronic treatment with a diuretic for signs or symptoms of heart failure
• Heart failure is primary factor limiting activity as indicated by answering # 2 to the following question:

My ability to be active is most limited by:

• Joint, foot, leg, hip or back pain
• Shortness of breath and/or fatigue and/or chest pain
• Unsteadiness or dizziness
• Lifestyle, weather, or I just don't like to be active

• No chronic nitrate therapy or not using intermittent sublingual nitroglycerin (requirement for >1 sublingual nitroglycerin per week).
• No daily use of phosphodiesterase 5 (PDE5) inhibitors or soluble guanylyl cyclase activators and willing to withhold as needed use of PDE5 inhibitors for duration of study
• Ambulatory (not wheelchair / scooter dependent)
• Body size allows wearing of the accelerometer belt as confirmed by ability to comfortably fasten the test belt provided for the screening process.
• Willingness to wear the accelerometer belt for the duration of the trial

Exclusion criteria

• Recent (< 1 month) hospitalization for heart failure
• Ongoing requirement for PDE5 inhibitor, organic nitrate or soluble guanylyl cyclase activators
• Hemoglobin (Hgb) < 8.0 g/dl within 30 days prior to randomization
• Glomerular Filtration Rate (GFR) < 20 ml/min/1.73 m2 within 30 days prior to randomization
• Systolic blood pressure < 115 mmHg seated or < 90 mmHg standing
• Resting Heart Rate > 110
• Previous adverse reaction to the study drug which necessitated withdrawal of therapy
• Significant chronic obstructive pulmonary disease that is a primary contributor to symptoms, in the opinion of the Investigator.
• Ischemia thought to contribute to dyspnea, in the opinion of the Investigator.
• Documentation of previous Ejection Fraction < 40%
• Acute coronary syndrome within 3 months defined by electrocardiographic (ECG) changes and biomarkers of myocardial necrosis (e.g., troponin) in an appropriate clinical setting (chest discomfort or anginal equivalent)
• Percutaneous Coronary Intervention, coronary artery bypass grafting, or new biventricular pacing within past 3 months
• Obstructive hypertrophic cardiomyopathy
• Known infiltrative cardiomyopathy (amyloid)
• Constrictive pericarditis or tamponade
• Active myocarditis
• Complex congenital heart disease
• Active collagen vascular disease
• More than mild aortic or mitral stenosis
• Intrinsic (prolapse, rheumatic) valve disease with more than moderate mitral, tricuspid or aortic regurgitation
• Acute or chronic severe liver disease as evidenced by any of the following: encephalopathy, variceal bleeding, International Normalized Ratio (INR) > 1.7 in the absence of anticoagulation treatment
• Terminal illness (other than HF) with expected survival of less than 1 year
• Enrollment or planned enrollment in another therapeutic clinical trial in next 3 months.
• Inability to comply with planned study procedures
• Pregnancy or breastfeeding mothers