What characterizes heart failure with preserved ejection fraction (HFpEF)?

Heart failure with preserved ejection fraction (HFpEF) is primarily characterized by the stiffening of the left ventricle, which results in impaired diastolic filling of the heart. In HFpEF, while the ejection fraction (the percentage of blood the left ventricle pumps out with each contraction) remains normal, the heart's ability to relax and fill properly is compromised due to the rigidity of the ventricular myocardium. This stiffness leads to increased pressures in the heart and can contribute to symptoms of heart failure, such as difficulty breathing with exertion, fluid retention, and fatigue.

The other options do not accurately reflect the primary characteristics of HFpEF. For example, reduced left ventricular size is not a typical feature of HFpEF; in fact, the size may be normal or even enlarged due to hypertrophy. A decreased heart rate is also not a defining characteristic, as patients with HFpEF can present with normal or elevated heart rates depending on their clinical status and other factors. Lastly, fluid overload in the right ventricle may occur in heart failure but it does not characterize HFpEF specifically, as the condition is primarily focused on the left ventricular function.

Understanding the definition and mechanisms behind HFpEF is