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What is Fractional Flow Reserve (FFR)?

By Dr. Naveen Bhamri in Cardiac Sciences

May 14 , 2018 | 10 min read

Finding out if you need coronary artery disease treatment is essential to taking action. While coronary artery disease is a complex disease that affects arteries throughout the heart, heart blood flow tests can give you an idea of the risk factors for coronary artery disease (CAD) and help you determine if treatment is needed. One of those tests is coronary artery fractional flow reserve assessment. FFR is a measure of coronary artery blood flow reserve. It helps determine the risk of heart attacks and strokes. A lower rate means a greater risk of heart attack or stroke.

Coronary artery disease, also known as coronary heart disease, is the most common type of heart disease that affects millions of people worldwide. It is caused by a narrowing or blocking of the arteries due to plaque which restricts blood flow and reduces the amount of oxygen to the heart. There are several different tools that aid physicians in the treatment of the disease. One traditional tool is a coronary angiogram, which is an X-ray examination of the blood vessels in the heart.

Other advanced tools that aid physicians in making the best treatment decisions for their patients are a next-generation imaging technology called Optical Coherence Tomography (OCT) and the measurement of Fractional Flow Reserve (FFR), which provides a more detailed, physiological analysis of blood flow blockages in the heart.

Dr. Naveen Bhamri, Head of Department and Associate Director, Interventional Cardiology, Max Super Speciality Hospital, Shalimar Bagh says, An FFR measurement indicates the severity of blood flow blockages in the coronary arteries and allows physicians to identify which specific lesion or lesions (or blockage causing blood flow restriction) are responsible for a patient’s ischemia (a restriction of blood flow to the heart) and warrant stenting.

The landmark FAME family trials are sponsored by St. Jude Medical and include the original FAME Trial, and the FAME II Trial. Both trials have demonstrated that when PressureWire™ measurement technology is used in the treatment of coronary artery disease, patient outcomes are improved.

When Would Fractional Flow Reserve Be Needed?

When someone is having trouble breathing, it's essential to identify and treat the cause quickly. Sometimes, a doctor may suggest using a chest X-ray or ambulance ride to help diagnose a medical condition. These can be effective, but they are only sometimes needed.

In some cases, clinicians may use fractional flow reserve (FFR full form) imaging to diagnose chest pain or other conditions. The imaging is a chest scan that uses contrast to determine how well blood flows through the heart and lungs. This outpatient procedure can take place in a doctor's office or hospital. It should not delay treatment for heart disease or respiratory problems. If you're experiencing chest pain or difficulty breathing, seek medical attention immediately to ensure your health status is stable and safe.

What Are The Drawbacks Of A Fractional Flow Reserve Assessment?

An FFR assessment cannot differentiate between coronary artery stenosis and spasm or coronary artery disease. Another limitation of an assessment is that it can be affected by other factors, such as heart rate and blood pressure. Also, the measurement may need to be more precise for specific individuals or certain patients with coronary artery disease. Moreover, the test is expensive, invasive, and only suitable for some patients.

How Do You Prepare For The Coronary Fractional Flow Reserve Assessment?

Understanding coronary blood flow reserve (CFR) must be understood before assessing the coronary fractional flow reserve. CFR is used to determine heart health and is measured by taking blood flow through the coronary arteries through an angiography procedure. The angiography procedure involves injecting a mixture of x-rays and dye into arteries to create a visual image of the inner structure of arteries.

What To Expect Before The Fractional Flow Reserve Procedure?

A fractional flow reserve procedure is used to measure the blood flow to a specific body area. Before the procedure, patients are given an injection of radioactive material that will be used to image blood flow in a specific area of the body. After imaging, blood flow is obtained, a local anesthetic is administered, and a small incision is made.

What To Expect During The Fractional Flow Reserve Procedure?

During fractional flow reserve (FFR) cardiography, a heart-lung machine helps create a picture of the blood flow through the heart. It is done by putting a coronary catheterization guide tube into one of the coronary arteries.

  • A stent is placed in the coronary artery, and blood flow is measured for several minutes. However, this procedure isn't usually done as part of routine cardiac catheterization. It is mainly performed during diagnostic imaging of coronary arteries to evaluate coronary stenosis and other heart conditions associated with narrowed arteries.
  • The procedure is similar to coronary angiography, except that it allows for measuring fractional flow across the stenosis instead of taking a single image. It provides an estimation of the degree of obstruction within the coronary arteries. 
  • The procedure is painless and can be performed in a hospital or outpatient facility. It can be used with other cardiac diagnostic tests, such as cardiac catheterization and imaging tests, to help provide more comprehensive information about coronary artery disease.

What To Expect After The Fractional Flow Reserve Procedure?

After an FFR procedure, patients are typically admitted to the hospital for observation for several hours. Patients may experience chest pain following the procedure, most likely due to vaso-constriction from using medications during the procedure. Patients should call their doctor if they experience dizziness or fainting after the procedure.

What Are the Side Effects of the Fractional Flow Reserve Procedure?

Fractional flow reserve is a blood flow measurement technique that involves injecting a contrast agent and then taking X-rays of the arteries in the patient's chest. It is done to spot potential blockages in arteries.

A common side effect of FFR is chest pain, which is very likely if a contrast agent is injected through the artery in a way that irritates it. Another possible side effect is mild to moderate pain, swelling, or tingling of the arm or leg after the procedure.  Apart from these effects, there are no known risks associated with using it as a diagnostic tool for CAD.

What Type Of Results Do You Get After The Fractional Flow Reserve Test?

A fractional flow reserve test is a medical test that determines the flow reserve of a blood vessel in the body. It helps diagnose coronary artery disease, heart failure, and stroke. After coronary angiography, the doctor will determine how severe the coronary artery disease is and what treatment is needed. Percutaneous coronary intervention (PCI) may be performed if a stent is needed.

Category Range Treatment
Low blood supply/flow ≥0.80 Medicine
Lower blood supply/flow ("grey zone") 0.75 to 0.80 Angioplasty and stent or Medicine
Lowest blood supply/flow <0.75 Angioplasty and stent

How is FFR measured? 

Interventional cardiologists use FFR measurement systems, such as PressureWire™ Aeris and PressureWire™ Certus to measure pressure inside the coronary arteries. Measurements are taken by placing the PressureWire across the lesion of interest and inducing a state of maximum blood flow, thereby allowing the physician to determine if the narrowing is tight enough to cause ischemia.

FFR is defined as the ratio of maximal blood flow in a stenotic (narrowed) artery to normal maximal flow, expressed as a fraction of the normal blood flow in an artery compared to the maximum achievable blood flow in the same artery.

  •  An FFR measurement of 1.0 indicates an artery with normal blood flow.
  • An FFR measurement above .80 indicates that ischemia is very unlikely, as demonstrated in the FAME study
  • An FFR measurement below .75 is 100 percent specific in identifying that the blood flow blockage caused by the narrowing is responsible for a patient’s ischemia

The Original Fame Trial 

The original FAME (Fractional Flow Reserve (FFR) vs. Angiography in Multivessel Evaluation) Trial compared outcomes of patients whose treatment was guided by FFR to those whose treatment was only guided by angiography using the St. Jude Medical PressureWire Certus technology for FFR measurement.

Results from the landmark trial demonstrated improved clinical outcomes in patients with stable coronary artery disease and two or three-vessel disease. The 12-month results published in the New England Journal of Medicine demonstrated that instances of major adverse cardiac events were reduced by 28 percent for patients whose treatment was guided by FFR rather than by standard angiography alone.

Two-year results demonstrated that patients who received FFR-guided treatment continued to experience improved outcomes over time, including a 34 % risk reduction in death or heart attack.

Checkout: Difference between Angioplasty and Angiography


The FAME II (FFR Guided Percutaneous Coronary Intervention (PCI) Plus Optimal Medical Treatment vs. Optimal Medical Treatment Alone in Patients with Stable Coronary Artery Disease) Trial examined the role of FFR in the treatment of stable coronary artery disease in one or more vessels. The trial compared clinical outcomes, safety, and cost-effectiveness of percutaneous coronary intervention (PCI) guided by FFR plus the best available medical therapy (MT) to MT alone.

Trial results published in the New England Journal of Medicine revealed that patients with FFR-guided treatment plus medical therapy experienced superior outcomes to those treated with medical treatment alone. Further, use of the PressureWire technology helped reduce the relative risk of hospital re-admission with urgent revascularization by 86%.

In January 2012, enrollment in the St. Jude Medical-sponsored FAME II Trial was halted after an Independent Data Safety Monitoring Board (DSMB) found a highly statistically significant reduction in unplanned hospitalizations and urgent revascularizations in patients enrolled in the PCI plus MT arm of the trial.

The DSMB therefore deemed it unethical to continue to randomize patients into the arm of the trial receiving MT alone. Patients already enrolled in the trial continue to be followed, but no additional patients were added.

Importance of PressureWire Technologies

Designed to replicate the performance of standard PCI guidewires, the PressureWire technology is available in both the Aeris and Certus models. In 2012, the next generation of FFR measurement technology, the PressureWire™ Agile Tip, entered the market offering improved responsiveness and steerability for easy handling in difficult anatomies.

The PressureWire Agile tip technology also includes a new proprietary hydrophilic coating to reduce friction; making it easier for doctors to deploy stents and coronary balloons. The PressureWire Aeris is a first-of-its-kind wireless FFR system that doesn’t require additional equipment or cabling in the cardiac catheterization laboratory. The system integrates FFR technology directly into a wide array of recording systems to immediately and securely display, measure, and save FFR data.

PressureWire Aeris also integrates FFR results into a patient’s existing record, allowing the severity of coronary lesions to be documented together with other procedural data and angiographic imagery. The market-leading PressureWire Certus provides an FFR measurement without increasing procedural time.

It is the only guidewire on the market to provide a combined measurement of pressure and temperature, which enables calculations of FFR, Coronary Flow Reserve (CFR), and an Index of Microcirculatory Resistance (IMR).

FFR as Standard of Care 

The positive outcomes of the original FAME trial resulted in the level of evidence for FFR to be upgraded to an “A” from a “B” by the American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions. Level of evidence “A” is the highest level available, requiring the most clinical evidence, and is awarded only when data is derived from multiple populations and multiple randomized clinical studies or meta-analyses.

The benefits of the PressureWire technology were also recognized in guidelines from the European Society of Cardiology/European Association for Cardio-Thoracic Surgery (ESC/EACTS) which included recommendations for the treatment of coronary artery disease that support measuring FFR before deciding to perform PCI or send the patient to surgery.

The ESC guidelines gave FFR the highest recommendation possible: 1A. FFR technologies have demonstrated significant cost savings in various healthcare systems. In each country where an economic analysis was conducted, the PressureWire technology was found to save resources while also improving clinical outcomes by increasing quality-adjusted life years and reducing the number of cardiac events.

In the U.S. healthcare system, there was a difference of about $2,000, or 14 percent, between total healthcare costs for the FFR-guided cohort and the group treated by angiography alone after one year. In Europe, the savings ranged from between 500€ and 900€ per patient. These lower healthcare costs were a result of reduced procedural costs, reduced follow-up costs for major adverse cardiac events, and shorter hospital stays.

When Should I Call My Doctor?

You must call your doctor if you are experiencing the following: 

  • Chest pain, 
  • Fainting, 
  • Shortness of breath. 

These could be symptoms of coronary artery disease, a condition in which arteries to the heart become blocked.


An FFR is a noninvasive procedure to assess coronary artery disease (CAD) in patients with coronary artery stenosis. The fractional flow reserve test is a blood test that measures the pressure in your arteries. If you have any concerns regarding this procedure, it is best to consult your cardiologist.

For more information on treatment, you can visit the heart hospital in Delhi.