Up to half of all patients with heart failure are found to have normal pumping function of the heart muscle, but show abnormalities in the way the heart muscle relaxes and fills with blood. These patients often have high blood pressure, and tend to have stiff arteries and stiff heart muscle. We wish to test the hypothesis that these patients have abnormal energy stores in their heart muscle.

Inclusion Criteria:

• Clinical features consistent with heart failure
• LVEF ≥ 50%, with no evidence of significant valvular disease, no hypertrophic cardiomyopathy, and no evidence of pericardial constriction
• A peak VO2 < 80% predicted, with a pattern of gas exchange on metabolic exercise testing indicating a cardiac cause for limitation

Exclusion Criteria:

• Objective evidence of lung disease on formal lung function testing
• Reversible myocardial ischaemia on contrast-enhanced myocardial stress
• Echocardiography, and evidence of exercise-induced mitral regurgitation
• Obesity (BMI >35) or a locomotor cause for exercise limitation

Heart Failure Clinic