Fractional Flow Reserve (FFR) Explained: What It Is and Why It Matters for Heart

Coronary artery disease (CAD) is a leading cause of illness and death globally. Improving its diagnosis and treatment can reduce both the health effects and economic burden of this condition.

FFR is a pressure-based index that reflects the maximum possible blood flow in a coronary artery with stenosis. It is expressed as a ratio, comparing the achievable blood flow in the narrowed artery to the flow that would occur if the artery were normal.

Why is FFR done?

Your healthcare providers perform the FFR test during cardiac catheterisation of the left side of your heart or as part of a coronary angiogram. The results assist them in determining the appropriate treatment for your condition.

Need of an FFR test

You may need this test if your healthcare provider is determining whether you require angioplasty and a stent in one of your coronary arteries, which supply oxygen-rich blood to your heart muscle. Typically, this cost-effective, straightforward test is conducted when imaging reveals a 50% to 70% narrowing (stenosis) of the artery. In some cases, FFR may also be checked in individuals with up to 90% narrowing. If your stenosis is less than 30% or greater than 70%, you likely won’t need this test. Minimal stenosis indicates that angioplasty is not necessary, while severe narrowing requires treatment.

After undergoing angioplasty and stent placement, FFR can help predict the likelihood of major heart issues in the future.

Who performs the FFR test?

A cardiologist performs an FFR test.

How does the FFR test work?

Your healthcare provider uses a device to measure blood pressure on both sides of a blockage in your coronary artery. These readings are then used to calculate your FFR.

How do you prepare for an FFR test?

Your healthcare provider may ask you to discontinue certain medications, particularly blood thinners, a few days before your test. Additionally, you should avoid eating or drinking anything after midnight on the night before the procedure.

What should you expect on the day of an FFR test?

Patients receive an injection of a radioactive substance, which is used to create images of blood flow in a specific area of the body. This procedure can take less than half an hour, but if your healthcare provider decides to perform an FFR cardiology procedure like angioplasty and place a stent, it will require additional time.

What happens during an FFR test?

Your provider will start by injecting a local anaesthetic to numb the area and then insert a needle into your arm, neck or groin to thread a catheter into your artery. The catheter is guided through the arteries to your aorta and coronary arteries using X-ray imaging. A contrast dye is injected to help visualise the arteries. Your provider will check for blockages and use an ultrasound on the catheter to assess blood flow. Before measuring pressure in the narrowed area, they will give you heparin and nitroglycerin. Pressure readings are taken when blood flow is highest, with medicine given to boost flow. If needed, an angioplasty and stent will be performed. Afterwards, your FFR will be checked again, and the catheter will be removed, with pressure applied to the access site.

What to expect after the FFR test?

Most people experience minimal discomfort during an FFR test and rarely have complications. Typically, patients can go home a few hours after the procedure. However, if you undergo angioplasty and stent placement, you may need to stay in the hospital overnight.

How do we interpret the results of an FFR test?

During your procedure, your healthcare provider will monitor your pressure measurements along with the FFR on their equipment console. They may provide you with your FFR results either during or after the procedure.

You will receive a numerical result. A normal range is between 0.94 and 1. Any value below that indicates a need for treatment, as it suggests that your blood flow is insufficient.

If your FFR indicates that your coronary artery blockage is not severe, you won’t need angioplasty or a stent. Medication can be used as an alternative treatment.

Are there any side effects of the FFR procedure?

You may experience chest pain and/or shortness of breath about a minute after your healthcare provider administers adenosine through your IV or directly into your coronary artery. This is a normal reaction and indicates to your healthcare provider that it is the right time to take the readings, as your blood flow is at its peak.

The drawbacks of FFR

Your healthcare provider may receive a falsely normal result if the coronary arterioles (the smallest arteries) do not respond to the medication used to increase blood flow during the FFR procedure. Additionally, the length of the narrowed area can also impact your FFR results.

Conclusion

An FFR assessment can assist your healthcare provider in determining the most appropriate treatment for your coronary artery disease. They will ensure you are as comfortable as possible during the procedure. If you have any questions about the test, do not hesitate to ask your healthcare provider. It can be helpful to mentally prepare yourself if you require angioplasty and a stent immediately after the FFR calculation.