The Inorganic Nitrate and eXercise Performance in Heart Failure (iNIX-HF)

Inclusion Criteria To participate in this study, a patient must meet all of the criteria listed below: * Males and females aged greater than or equal to 18y and less than 80y at time of consent * Diagnosis of heart failure with reduced ejection fraction * New York Heart Association (NYHA) Class II-III at Visit 1 * Ejection fraction less than 45%, as evaluated through transthoracic echocardiography at Visit 1 * Stable medical therapy, defined by no addition or removal (or change of more than 100 percent) of the following for 60 days prior to Visit 1: beta-adrenergic blockade and angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blocker (ARB or aldosterone antagonists) or ARNI (ARB + sacubitril) * Ability and willingness to sign an IRB approved written informed consent form; legally authorized representatives are not allowed in this study Exclusion Criteria To participate in this study, a patient must not meet any of the criteria listed below: * Vulnerable populations as defined by the U.S. Department of Health and Human Services; prisoners and children will be excluded from this study * Pharmacologic, organic nitrate therapy within 3 months prior to Visit 1 * Major orthopedic, psychiatric, neurological, or other conditions that would hinder the ability to complete the exercise tests at the time of Visit 1 * Estimated glomerular filtration rate less than 45 mL/min/1.73m2 on screening clinical laboratories measured at Visit 1 * Systolic blood pressure less than 90mmHg or greater than 180mmHg at Visit 1 * Diastolic blood pressure less than 40mmHg or greater than 100mmHg at Visit 1 * Previous adverse reaction to nitrate prior to Visit 1 * Treatment with phosphodiesterase inhibitors within the last 3 months prior to Visit 1; Patient must also be willing to not take them for the duration of the trial * Diagnosis of primary hypertrophic cardiomyopathy, infiltrative cardiomyopathy (e.g., amyloid), active myocarditis, or complex congenital heart disease prior to Visit 1 * Active collagen vascular disease at time of Visit 1 * Percutaneous coronary intervention, new bi-ventricular pacing, or coronary artery bypass grafting within the 3 months prior to Visit 1 * Valvular heart disease with severe regurgitation or stenosis of any valve, as demonstrated on the echocardiogram at Visit 1 * Known severe liver disease as evidenced by encephalopathy or variceal bleeding; * Terminal disease (other than heart failure) with expected survival less than 1 y at time of Visit 1 * Enrollment in another therapeutic trial at time of Visit 1 * Pregnant and breastfeeding women or postmenopausal women taking exogenous estrogen replacement therapy at time of Visit 1 * To meet this criterion, patients must have a negative urine pregnancy test and provide verbal confirmation that they are not breastfeeding at time of Visit 1. * Note, post-menopausal is defined as last menstrual period occurring greater than or equal to 12 months prior to Visit 1 or confirmation of prior bilateral oophorectomy at least 6 months prior to first dose of study drug. * Women of childbearing potential or men with childbearing potential partners must agree that the participant and/or their partner will use at least two of the following highly effective method of birth control from study entry until 48 hours after completing study therapy, if not abstaining from sexual activity: * Barrier method contraception (e.g., male or female condoms with or without a spermicidal agent, diaphragm, or cervical cap with spermicide) * Stable dose of injectable, depot, oral, implanted, intravaginal, or transdermal hormonal contraception for at least 30 days before sexual activity * Intrauterine device (IUD) with or without hormones * Surgical sterilization * For women, this includes hysterectomy, bilateral oophorectomy with or without hysterectomy, or bilateral tubal ligation, bilateral salpingectomy, completed at least 6 months before first dose of study drug. * For men, this includes vasectomy. * Patients requiring exogenous oxygen at rest or during exercise prior to Visit 1 * Patients with active angina at time of Visit 1 or ischemia due to epicardial coronary disease prior to or at time of Visit 1 * Patients taking xanthine oxidase inhibitors at time of Visit 1 * Individuals taking proton pump inhibitors and/or antacids at time of Visit 1, if unable to stop these medications for the duration of the study. * Note, while patients will be asked to refrain from taking these medications for the duration of the study, they may take tums. However, patients must discontinue Tums for 5 days prior to study visits 2, 3, and 4.