Effect of KNO3 Compared to KCl on Oxygen UpTake in Heart Failure With Preserved Ejection Fraction (KNO3CK OUT HFPEF)
Condition: Heart Failure
MeSH terms: Heart Failure
Intervention: Potassium Nitrate (KNO3); Potassium Chloride (KCl)
Intervention description: The effect of potassium nitrate (KNO3) supplementation on exercise capacity and peak oxygen consumption in HFpEF will be assessed.; Potassium Chloride (KCl) is the matching placebo control drug in this trial.
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Enrollment: 84.0
Sex: All
Minimum age: 18 Years
Maximum age: 90 Years
Healthy volunteers: No
Keywords: Heart Failure; Exercise Intolerance; Ejection Fraction

Summary:

      This trial seeks to assess if potassium nitrate (KNO3) therapy improves exercise capacity and
      oxygen uptake in heart failure patients with preserved ejection fraction (HFpEF).
    

Eligibility criteria:

        Inclusion Criteria:

          1. Adults aged 18-90 years of age

          2. A diagnosis of heart failure with NYHA Class II-III symptoms

          3. LV ejection fraction >50% during baseline echocardiography

          4. Stable medical therapy: no addition/removal/changes in antihypertensive medications,
             or beta-blockers in the preceding 30 days

          5. Elevated filling pressures as evidenced by at least 1 of the following:

               1. Mitral E/e' ratio > 8 (either lateral or septal), with low e' velocity (septal
                  e'<7 cm/sec or lateral e'< 10 cm/sec), in addition to one of the following:

                  i Enlarged left atrium (LA volume index >34 ml/m2) ii Chronic loop diuretic use
                  for control of symptoms iii Elevated natriuretic peptides (BNP levels >100 ng/L
                  or NT-proBNP levels >300 ng/L)

               2. Mitral E/e' ratio > 14 (either lateral or septal)

               3. Elevated invasively-determined filling pressures previously (resting LVEDP>16
                  mmHg or mean pulmonary capillary wedge pressure [PCWP] > 12 mmHg; or
                  PCWP/LVEDP≥25 mmHg with exercise)

               4. Acute heart failure decompensation requiring IV diuretics

        Exclusion Criteria:

          1. Supine systolic blood pressure <100 mm Hg

          2. Pregnancy: Women of childbearing potential will undergo a pregnancy test during the
             screening visit

          3. Orthostatic hypotension defined as >20 mm Hg decrease in systolic blood pressure 3-5
             minutes following the transition from the supine to standing position

          4. Uncontrolled atrial fibrillation, as defined by a resting heart rate>100 beats per
             minute

          5. Hemoglobin < 10 g/dL

          6. Inability/unwillingness to exercise

          7. Moderate or greater left sided valvular disease (mitral regurgitation, aortic
             stenosis, aortic regurgitation), any degree of mitral stenosis, severe right-sided
             valvular disease, or presence of a prosthetic valve in the mitral position

          8. Hypertrophic, infiltrative, or inflammatory cardiomyopathy

          9. Clinically significant pericardial disease, as per investigator judgement.

         10. Current angina

         11. Acute coronary syndrome or coronary intervention within the past 2 months

         12. Primary pulmonary arteriopathy

         13. Clinically significant lung disease as defined by: Chronic Obstructive Pulmonary
             Disease meeting Stage III or greater GOLD criteria, treatment with oral steroids
             within the past 6 months for an exacerbation of obstructive lung disease, or the use
             of daytime supplemental oxygen

         14. Ischemia on stress testing without either (1) subsequent revascularization, or; (2) a
             subsequent angiogram demonstrating the absence of clinically significant epicardial
             coronary artery disease, as per investigator judgement.

         15. Left ventricular ejection fraction <45% in any prior echocardiogram or cardiac MRI,
             unless this was in the setting of uncontrolled atrial fibrillation.

         16. Treatment with phosphodiesterase inhibitors that cannot be withheld

         17. Treatment with organic nitrates

         18. Significant liver disease impacting synthetic function or volume control (ALT/AST > 3x
             ULN, Albumin <3.0 g/dL)

         19. eGFR < 30 mL/min/1.73m2

         20. G6PD deficiency. In males of African, Asian or Mediterranean decent, this will be
             formally evaluated by enzyme testing prior to drug administration. A negative
             screening test for G6PD will be required in these subjects for inclusion in the study.
             If a quantitative test is being performed, a clinically significant reduction in G6PD
             activity (<60% of normal) will exclude subjects.

         21. Methemoglobinemia - baseline methemoglobin level >5%

         22. Serum K>5.0 mEq/L

         23. Severe right ventricular dysfunction

         24. Any medical condition that, in the opinion of the investigator, will interfere with
             the safe completion of the study.

         25. Contraindications to MRI (except as noted below), including the presence of a
             pacemaker, metal implants, claustrophobia, or that have known medical conditions which
             can be exacerbated by stress such as anxiety or panic attacks. Inability to lie flat
             in the MRI scanner for 90 minutes is also an exclusion criterion.