Increasing ketone supply to the heart in mice with heart failure with preserved ejection fraction (HFpEF) allowed their hearts to utilize more ketones and produce more energy, according to preliminary research. Heart failure with preserved ejection fraction, a common type of heart failure, occurs when there are signs and symptoms of heart failure with a high left ventricle filling pressure despite normal or a near-normal left ventricle ejection fraction of 50% or higher. Heart failure with reduced ejection fraction is when the heart's pumping power is 40% or less. Healthy hearts require a high rate of adenosine triphosphate (ATP) production...