Effects of inorganic nitrite on cardiac and skeletal muscle

INTERVENTION: Participants are randomly allocated to one of two groups. Intervention group: Participants asked to take 7mmol inorganic sodium nitrate orally for two months Control group: Participants asked to take an identical placebo orally for two months CONDITION: Topic: Cardiovascular disease; Subtopic: Cardiovascular (all Subtopics); Disease: Heart Failure ; Circulatory System ; Chronic heart failure PRIMARY OUTCOME: Peak VO2O2 consumption/workload relation during submaximal exercise at baseline and 2 months. SECONDARY OUTCOME: 1. Cardiac and skeletal muscle energetic status is measured using an MRI at baseline and 2 months; 2. Change in peak VO2 on exercise testing is measured after 1 week of treatment; 3. Fasting plasma glucose and insulin (HOMA), high sensitivity CRP is measured at baseline, 1 week and 2 months; 4. Quality of life is measured using the Minnesota Living with Heart Failure Questionnaire score at baseline and 2 months; 5. Nitrate/nitrite/nitroso‐species levels, conjugated nitro‐fatty acid levels are measured at baseline, 1 week and 2 months; 6. Oxygen uptake/workload relation on exercise testing is measured at baseline, 1 week and 2 months; 7. Parameters of diastolic and systolic function on transthoracic echocardiogram are measured at baseline and 2 months; 8. Plasma N‐terminal Pro BNP are measured at baseline, 1 week and 2 months; 9. Six minute hall‐walk distance is measured at baseline and 2 months; 10. Skeletal muscle proteomics on skeletal muscle biopsy is measured at baseline and 2 months INCLUSION CRITERIA: 1. Aged 18 years or over 2. Patients who suffer from symptomatic but stable chronic heart failure despite maximal tolerated contemporary medication, of non‐ischaemic aetiology, in sinus rhythm