Understanding ejection fraction in heart failure
When you receive a diagnosis of heart failure, all the new information and medical jargon you are faced with can quickly become overwhelming.
Here we take a look at the term ‘ejection fraction’ which you might come across when talking to your care team about the severity or type of your heart failure.
Ejection fraction (or EF) is a medical measure of the proportion of blood being pumped out of the heart each time it contracts.1
Your doctors will determine your ejection fraction by performing a scan. Generally, this will be an echocardiogram (echo) which uses soundwaves to create a picture of the heart, but there are several other types of scanning technology that may be used (e.g. an MRI scan).1 Your doctor should explain to you which type of test they are performing and the procedure for this.
Your ejection fraction is calculated using the volume of blood in one of the chambers, or ‘ventricles’, of the heart when it is ‘full’ (i.e. before a heartbeat) and the volume of blood in the ventricle after it beats.1
The ratio of these numbers then gives us an EF value. EF values are always percentages so, for example, an ejection fraction of 50 means that 50% of blood is being pumped from the heart with each beat.1
In a healthy heart, the walls of the ventricles are flexible, allowing blood to fill the ventricles properly before being pumped out. The chamber walls are also strong, so the right amount of blood can be pumped around the body.1
A normal EF is generally considered to be between 50 and 70%.1
A rapid or recent reduction in EF, or a lower percentage of blood being pumped out, can be an indicator of new or worsening heart failure. This is also known as Heart Failure with Reduced Ejection Fraction (HFrEF).
In heart failure with reduced ejection fraction the ventricles are unable to contract normally because they are enlarged and ‘flabby’ – this means the heart struggles to pump enough blood around the body. Patients with this form of heart failure will have a lower-than-normal EF.1
This is generally indicated by an EF of less than 40%.1
It is however possible to have a normal EF value and still receive a diagnosis of heart failure. This is also called heart failure with normal ejection fraction or Heart Failure with Preserved Ejection Fraction (HFpEF).
In heart failure with preserved ejection fraction, the heart contracts normally. However, the ventricles become stiff and are unable to fill properly.1 People with this type of heart failure will have a normal (or preserved) EF, but less blood is pumped out because not enough blood can enter the heart chambers first.1
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