Energetic Abnormalities in Heart Failure With Preserved Ejection Fraction

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