Heart failure with preserved ejection fraction is characterized by dynamic impairment of active relaxation and contraction of the left ventricle on exercise and associated with myocardial energy deficiency. - Phan, T; Abozguia, K; Nallur Shivu, G; Mahadevan, G; Ahmed, I; Williams, L; Dwivedi, G; Patel, K; Steendijk, P; Ashrafian, H; Henning, A; Frenneaux, M (Journal of the American College of Cardiology, 2009)