Do you sometimes get a little chest pain, or feel faint after a little exertion, and wonder, "Is there a blockage in one of my coronary arteries?" When you have such doubts, a doctor may ask you to have a coronary angiogram, which is a test that involves a cardiac catheterization. It can check for any blockages or stenosis in the coronary arteries that supply blood to the heart. But sometimes, even after seeing this blockage, it is difficult to determine exactly whether it is serious enough to need a stent or whether it can be controlled with medication alone. This is where this special test called Fractional Flow Reserve or FFR comes in handy.
Simply put, what is this FFR?
Imagine that there is a water pipe, and there is a small piece of dirt stuck in the middle of the pipe. Now, the pressure of the water flowing through the pipe is slightly different before and after the blockage, right? The FFR test does something similar.
Simply put, FFR is a method of measuring how much blood flow to the heart muscle is being obstructed by a blockage in one of your coronary arteries. In this, blood pressure is measured on both sides of the blockage. By comparing the two pressure values, the doctor determines whether the blockage is actually harmful to the heart muscle or not.
This test is a minimally invasive procedure that is performed during cardiac catheterization.
When is an FFR test needed?
Not everyone needs this test. A doctor will usually decide to perform an FFR test in the following situations:
- Intermediate Blockages: If an angiogram shows a blockage of between 50% and 70% of a vein, it is difficult to say for sure whether a stent is needed. In such cases, the FFR measures exactly how much the blockage is obstructing blood flow.
- When there are multiple blockages: Sometimes a person may have multiple small blockages in their veins. FFR can help pinpoint which blockage is actually affecting blood flow the most, without having to place stents in each one.
- After a stent is placed: Sometimes after a stent is placed, an FFR test may be done to make sure it is working properly and that blood flow has returned to normal.
However, if the blockage in a vein is less than 30% (meaning there is no major blockage) or more than 90% (meaning there is a serious blockage that definitely requires treatment), an FFR test is usually not needed. Because at that time, a decision about treatment can be made from the angiogram itself.
What is the difference between FFR and iFR?
You may have also heard of iFR (instant wave-free ratio). Both of these measure the severity of a blockage in a vein. The main difference is that in the FFR test, a special drug, such as adenosine, is given to maximize blood flow to the heart. In the iFR test, instead of giving such a drug, the pressure is measured at a specific moment in the heartbeat. Your doctor will decide which of these two methods is best for you.
How should you prepare before the test?
Your doctor will give you some special instructions before this test, and it is very important to follow them.
- Medication information: You may be asked to stop taking some medications, especially blood thinners , a few days before the test. Be sure to tell your doctor about all medications you are taking.
- Food and Drink: You will be advised not to eat or drink anything after midnight the night before the test.
- Assistant: Since you will be anesthetized during the test, it is essential that you have someone to take you home after the test.
What happens during the test?
If you only do the FFR test, it takes less than 60 minutes. However, if you decide to place a stent right away based on the results, it will take a little longer. The whole process goes like this:
1. Numbness: First, a small injection of numbing medicine is given into a vein in your arm, groin, or neck where the catheter will be inserted.
2. Catheter insertion: Next, a thin tube (catheter) is inserted through the numb area into one of your blood vessels.
3. Moving to the heart: This catheter is carefully guided to the coronary artery of the heart using X-ray (fluoroscopy) technology.
4. Dye Injection: Next, a special dye (contrast media) is injected into the veins through this tube. The inside of the veins can then be clearly seen on the X-ray.
5. Pressure Wire: This is where the real work begins. A very thin wire with sensors is passed through the catheter and inserted into the blocked vein.
6. Pressure measurement: This pressure wire is used to measure blood pressure before and after the vein is blocked.
7. Administering medication: To get the exact reading, you need to maximize the blood flow to the heart. For this, you will be given a medication like adenosine. When this medication is given, you may experience a slight chest pain and difficulty breathing for about a minute. This is normal, don't worry. This means that the medication is working and now is the right time to take the reading.
8. Treatment Decision: After receiving the FFR value, the doctor will decide whether or not you need to have a stent placed. If necessary, the stent can be placed immediately after performing angioplasty.
9. End: When the work is finished, the catheter is removed, pressure is applied to the insertion site, and a plaster is applied.
How to understand the results?
The result of the FFR test comes in a number. This number is very easy to understand.
| FFR Result | What does it mean? |
|---|---|
| 0.94 to 1.0 (normal) | Great! Your heart's blood flow is very good. The visible blockage in the artery is not causing any major disruption to the blood flow. A stent is usually not needed, and this condition can be managed with medication. |
| If less than 0.80 | In this case, the amount of blood flowing to the heart muscle has been significantly reduced due to the narrowing of the artery. The doctor is more likely to decide to perform a treatment such as placing a stent (angioplasty). |
| Example: What if the FFR value is 0.75? | This means that the blood pressure has decreased by 25% due to the narrowing of the artery. This means that there is a 25% obstruction to the flow of blood to the heart muscle. |
What to expect after the test?
Major complications rarely occur after an FFR test.
- Going home: If you don't have a stent, you can go home after a few hours of observation. If you do have a stent, you may need to stay in the hospital overnight.
- Rest: It's best to rest for a day or two after you go home. There may be some bruising and soreness where the catheter was inserted.
- Side effects: Things like chest pain caused by the adenosine medication will completely disappear within a few minutes.
If you experience these symptoms, call your doctor immediately.
If you experience any of the following symptoms after going home from the test, notify your doctor immediately. If necessary, go to the Emergency Department (ETU) of the nearest hospital.
- Severe chest pain
- Difficulty breathing
- Fever
- Bleeding, swelling, or severe pain at the catheter insertion site
- Dizziness
- Abnormal changes in heart rate (palpitations)
FFR is a very important test in the treatment of heart disease. It helps doctors determine the severity of a blockage in a vein, avoid unnecessary stent placement, and choose the best treatment for you, rather than relying solely on what is seen on an angiogram. So, if your doctor suggests this test, don't be afraid to ask any questions you may have.
Take-Home Message
- FFR (Fractional Flow Reserve) is a special test that measures the severity of a blockage in a heart artery.
- This is very important in determining whether or not a stent is necessary for an intermediate level (50%-70%) blockage seen on an angiogram.
- This test is performed during cardiac catheterization.
- If the result is less than 0.80, it indicates that the blockage is causing significant obstruction to blood flow and may require treatment.
- This test allows doctors to minimize unnecessary stent placement and provide the most appropriate treatment for the patient.
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