Intracoronary Physiology refers to the measurement of various parameters within the coronary arteries, the blood vessels that supply blood to the heart muscle using a variety of techniques.
Cardiologists skilled in the use of Intracoronary Physiology techniques, are able to more accurately assess the functional status of the coronary arteries and the heart muscle, and provide important information for the diagnosis and management of cardiovascular diseases, such as CAD (coronary artery disease).
Two of the most commonly used parameters in intracoronary physiology are:
Both FFR and IFR are used to measure the functional severity of stenosis (narrowing) within the coronary arteries and guide the management of CAD.
Fractional Flow Reserve (FFR)
FFR is a widely used measure of the functional severity of narrowing within the coronary arteries. It is measured using a pressure wire, which is a thin wire with a pressure sensor at its tip that is advanced through the coronary arteries to the site of stenosis.
When calculated the FFR ratio is expressed as a value between 0 and 1. An FFR value of less than 0.75 is considered to indicate a significant narrowing that may require intervention, such as percutaneous coronary intervention (PCI) or coronary artery bypass surgery.
Instantaneous Wave-free Ratio (IFR)
IFR is another measure of the functional severity of narrowing within the coronary arteries. Like FFR, IFR is measured using a pressure wire, but the method of calculating the ratio is different. The value is still expressed as a value between 0 and 1. An IFR value of less than 0.89 is considered to indicate a significant narrowing that may require intervention.
Summary – FFR vs IFR
While there are some key differences between FFR and IFR, both measures have been shown to be useful in the diagnosis and management of CAD, and the choice between the two will depend on the specific clinical situation and the preferences of the physician.