Coronary artery disease (CAD) is the most common form of heart disease and impacts millions of lives worldwide. CAD is a condition in which unhealthy fat deposit buildup causes narrowing or blockage of coronary blood vessels that supply blood to the heart muscles. This restricts the flow of blood to the heart. Aggravated CAD may further lead to other forms of heart diseases like heart attack, heart failure, and arrhythmia.
A patient suffering from CAD may benefit from angioplasty (also known as percutaneous coronary intervention) or bypass surgery (Coronary Artery Bypass Grafting or CABG). While, angioplasty is a minimally invasive procedure, where a mesh-like device called a 'stent' is used to open blocked blood vessels, bypass surgery is a surgical procedure which creates a bypass for the blocked vessels.
Treatment for CAD is predominantly determined by a test called - the angiogram or angiography. (See Fig.1)
Angiogram is an x-ray image of the blood vessels in the heart and has been widely used for several decades to identify blocked vessels. However, angiogram being only a visual assessment has the margin of under or overestimating the severity of blockage.
To overcome this limitation, a new diagnostic modality called the FFR (or Fractional Flow Reserve) can be done after an angiogram to objectively determine the severity of blockage. FFR measurement aids the treating cardiologists in deciding whether or not to perform angioplasty on the blocked vessels.
Clinical studies have shown that patients who have suffered a heart attack or have unstable angina (also called acute coronary syndrome) are likely to benefit from angioplasty, however, similar effect in patients with stable CAD was debatable. In 2007, a study called "COURAGE trial" investigated the necessity of angioplasty in patients with stable CAD, the trial showed that angioplasty did not reduce the risk of death, heart attack, or other major cardiovascular events when added to medication.
In 2009, the result of another study called "FAME" showed that patients with multivessel disease (i.e. patients with 2-3 blocked coronary vessels) have better outcomes with FFR-guided angioplasty compared to angioplasty guided only by angiogram. Furthermore, in 2012 results from "FAME-2" demonstrated that in patients with stable CAD, FFR-guided angioplasty had improved clinical outcomes and reduced need for urgent treatment (repeat angioplasty or bypass surgery) compared to medication alone.
These landmark studies (COURAGE, FAME, and FAME-2) have demonstrated that the angiography alone is inadequate to determine the severity of vessel blockages and angioplasty may not be necessary for all patients with CAD, and therefore, it is important to examine patients with the FFR test prior to determine treatment as advised in global clinical guidelines.
How is the FFR test performed?
FFR test is performed by guiding a thin wire (with a pressure sensor at the tip) into the blocked blood vessel(s) through a catheter (thin hollow tube) and a measurement is made. (See Fig.2)
How to interpret the FFR measurement?
In a normal blood vessel, FFR value equals 1. When the FFR value is greater than 0.80, it indicates a non-significant blockage and that patient may not benefit from angioplasty, and hence could be managed on medication alone. In contrast, if the FFR value is less than 0.80, it indicates a significant blockage and the patient is likely to benefit from intervention, hence angioplasty may be performed. (See Fig.3)
How FFR technology helps CAD patients?
The course of treatment for patients with CAD depends on disease severity (i.e. blood flow in the blood vessel). FFR helps the treating cardiologist in treatment decision-making that improves patient outcomes and helps to avoid unnecessary procedures. FFR-guided treatment has been proven to reduce the incidences of adverse events such as heart attacks, repeat angioplasty (or bypass surgery), and repeated hospitalizations.
Is the FFR test approved and recommended in guidelines?
The FFR technology is a safe and established procedure. The European Society of Cardiology and European Association for Cardio-Thoracic Surgery and the American College of Cardiology Foundation / American Heart Association / Society for Cardiovascular Angiography and Interventions clinical guidelines recommend FFR- guided treatment in specified populations.
Does FFR test require additional hospitalization?
FFR test can be performed at the time of an angiogram. No additional hospitalization is required to perform an FFR test. Most of the leading hospitals in India have the facility for FFR test. The patient may consult his/her treating doctor for advice.
Dr. Praveen Chandra, Indian Cardiologist and Chairman of Interventional Cardiology at Medanta Medicity, Gurgaon, India. He is recognized as one of the leaders in Angioplasty in the country. He has been awarded for success and achievement in the field of medicine with "Padma Shri" in 2016 by the President of India.