QFR (Quantitative Flow Ratio)

The blood vessels that supply blood to the heart (coronary arteries) can become narrowed due to atherosclerosis. Traditionally, to determine whether catheter treatment is necessary to widen these lesions (whether a stent should be placed), it was necessary to evaluate by directly inserting a special wire that measures blood flow (pressure) into the coronary artery lesion.

When a coronary artery is narrowed, it becomes problematic if the blood supply to the heart muscle (myocardium) downstream is impaired. If the condition is severe, the need for treatment to improve blood flow increases. However, the body’s mechanism for regulating blood flow to the heart is complex, and it has been found difficult to judge this based solely on the ‘appearance’ in images obtained from catheter examination. For this reason, it is considered appropriate to decide whether to place a stent in a narrowed coronary artery lesion not based on ‘appearance’ but on the ‘rate of blood flow reduction’. However, to measure this blood flow, an additional examination is required in addition to the usual catheter examination (coronary angiography). This additional examination is called FFR testing, which measures the pressure inside the blood vessel before and after the narrowed lesion using a special wire to determine how much the blood flow has decreased due to the lesion.

However, when measuring FFR, the need to administer special drugs and insert a wire into the coronary artery is known to pose a small but existing risk to patients of complications.

As an alternative to this conventional wire-based blood flow measurement, QFR (Quantitative Flow Ratio), a coronary artery blood flow analysis software, has been developed. QFR creates a 3D model of the coronary artery on a computer by combining catheter examination images taken from two directions, enabling highly accurate analysis of how much blood flow is reduced before and after the stenosis.

Numerous studies have been conducted in many countries around the world, and there have been many reports stating that ‘QFR can safely and accurately determine the need for coronary artery treatment.’ It has been in practical use in Europe since 2017, and in Japan, it received insurance approval in January 2024. Our hospital introduced it in February of the same year and welcomed the first patient in Japan.

At our center, we perform QFR on patients who meet multiple conditions, allowing for safer evaluation of coronary artery blood flow. Currently, we are somewhat strict with the conditions for its use, and it cannot be used for all patients, but please ask your attending physician if you are interested.

For those who want to know more about the process of cardiac catheterization and treatment at our hospital, please refer to here.