What Is Preserved Ejection Fraction?

Ejection fraction (EF) measures the percentage of blood pumped out of the heart’s left ventricle each time it beats. The left ventricle is a heart muscle that contracts and relaxes with every beat. Each time this happens the heart pumps blood throughout the body. This is the fundamental process of circulation.¹

A normal heart does not completely fill or empty each time it beats. The ejection fraction is expressed as a percentage where the normal range is 55% to 70%.¹ Sometimes people develop heart failure without any significant decrease in their ejection fraction noted. This is referred to as diastolic heart failure.¹

Diastolic heart failure

Also known as heart failure with preserved ejection fraction (HFpEF), diastolic heart failure develops when the left ventricle becomes rigid and cannot relax between beats. Diastole is the medical term for the process where the heart returns to a relaxed state. When it cannot relax, the heart doesn’t properly refill with blood.^2-3

When the heart is relaxed (diastole), changes develop in cardiac pressure and volume relationships that can cause diastolic HF. Monitoring includes measuring ejection fraction and evaluating the functioning of the heart valves and heart muscle rigidity.³ The EF remains in the normal range because the left ventricle is still pumping well, it is just stiff and cannot relax. Diastolic heart failure is most common in older people and in women and represents about half of all people with heart failure.

Causes of preserved ejection fraction

Chronic hypertension, high blood pressure over many years, is the most common cause of diastolic heart failure. High blood pressure over time causes the muscle of the left ventricle to enlarge and become less compliant, also called LV hypertrophy. This causes an increase in fibrosis in the left ventricular muscle leading to a decrease in cardiac compliance. This means that the chamber of the heart cannot expand easily when it is filled with blood. Coronary artery disease and heart valve disease can also lead to diastolic heart failure.²

There are other conditions that can damage the left ventricle of the heart and other organ systems contributing to the development of HFpEF.⁴ Some non-heart based conditions that can cause HFpEF include diabetes, obesity, chronic kidney disease, and chronic obstructive pulmonary disease (COPD). Over time, these diseases can affect the structure and function of the heart. They result in the stiffening of the heart and increased work required of the left ventricle to fill. This causes insufficient filling of the heart and limits the blood pumped out during each beat.³

Symptoms of heart failure

Symptoms of heart failure in a patient with preserved left ventricular function include:²

• Shortness of breath with exertion
• Shortness of breath at rest
• Shortness of breath when lying flat
• Decreased ability to exercise comfortably
• Fatigue
• Chest pain/pressure
• Swelling in the lower feet and legs

The symptoms are caused by fluid accumulation in the tissues of the body. Fluid backs up into these tissues because the heart cannot adequately fill with enough blood during diastole. For example, when fluid accumulates in the lungs it can cause shortness of breath; fluid in the legs can cause edema (swelling).²

Diagnosing preserved ejection fraction

It can be a clinical challenge for doctors to diagnose HFpEF at an early stage because there are no outward signs of heart failure. Even with a physical exam and complete medical history, a diagnosis can be easily overlooked as there are no signs of fluid retention. When the left ventricle stiffens (becomes more rigid) it leads to increased diastolic pressure and symptoms. The diagnosis of diastolic heart failure is best made using echocardiography. There are also cardiac biomarkers such as N-terminal pro-b-type natriuretic peptide (NT-proBNP) that can be evaluated using a blood test. This can be helpful when there are few symptoms.² It is used to help detect, diagnose, and evaluate the severity of heart failure.⁵

Treating preserved ejection fraction

The goal of treatment is largely based on resolving symptoms and treating other underlying conditions, like hypertension, obesity, and diabetes. HFpEF can be treated with a variety of medications used to keep blood pressure under control and decrease fluid retention.^2-3