iNIX-HF Study: KNO3 for Heart Failure
This study, called iNIX-HF, is looking at whether a substance called KNO3 (potassium nitrate) can help people with heart failure improve their exercise performance. You might be able to join if you are between 19 and 79 years old and have heart failure with reduced ejection fraction (meaning your heart doesn't pump as much blood as it should). Participants will receive either KNO3 or a placebo (an inactive substance) in a capsule once a day for 6 weeks. Researchers will measure your peak oxygen uptake (VO2 Peak Testing) and muscle power to see if KNO3 helps you exercise better. The study aims to enroll about 75 people.
- Study design
- This is a randomized, double-blind, placebo-controlled study, meaning participants are randomly assigned to receive either KNO3 or a placebo, and neither you nor the researchers will know which you are receiving. Approximately 75 participants will be enrolled.
- What's involved
- You would have a screening visit lasting about 1.5 to 2 hours, followed by a baseline visit lasting 4 to 5 hours. You would take a capsule once a day for 6 weeks, and have additional visits throughout an 8-week period for testing.
- Compensation
- Not stated in the trial record.
- Follow-up
- Your exercise performance and muscle power will be measured at baseline, after an acute dose, and after 6 weeks of chronic dosing, which will be scheduled throughout 8 weeks.
AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.
NCT05562167
The Inorganic Nitrate and eXercise Performance in Heart Failure (iNIX-HF)
Recruiting
PHASE2Ages 19–79InterventionalTreatmentWashington University School of MedicineInvestigator-initiated
~75 participants
Updated 2026-05-06 on ClinicalTrials.gov
What's tested:KNO3Placebo
At a glance
Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
VO2 Peak Testing
Measured over Determined at Baseline visit, Acute Dose Visit, and Chronic Dose Visit, which will be scheduled throughout 8 weeks.
+1 more outcome measured
Conditions
NCT05562167
Where you'd take part
This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.
Washington University School of Medicine
St Louis, Missouristudy coordinator listed
Recruiting
Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.
Study leadership
- Linda R Peterson, MD · PRINCIPAL_INVESTIGATOR · Washington University School of Medicine
Who to contact
Opens a ready-to-send draft in your own email app — review before sending.
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Eligibility criteria
Inclusion
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
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.
What this trial measures
- VO2 Peak TestingDetermined at Baseline visit, Acute Dose Visit, and Chronic Dose Visit, which will be scheduled throughout 8 weeks.
peak oxygen consumption during treadmill exercise
- Maximal muscle powerDetermined at Baseline visit, Acute Dose Visit, and Chronic Dose Visit, which will be scheduled throughout 8 weeks.
assessment of quadriceps power