A new tool for assessing the narrowing of the heart’s arteries, developed by clinicians working at the Imperial Biomedical Research Centre, part of Imperial College Healthcare NHS Trust, is set to be adopted internationally as the new global standard in evaluating patients’ suitability for a stent.

Coronary stenosis occurs when there is a narrowing of the coronary arteries which deliver oxygen-rich blood to the muscle of the heart. When these blood vessels become blocked or are narrowed, it can affect how the heart functions, potentially leading to chest pain, heart attacks and heart failure.The new technique, known as instantaneous wave-free ratio (iFR), allows clinicians to measure the pressure loss caused by the narrowing in these blood vessels to see whether the patient is suitable for a stent – a type of mesh tube used to hold open clogged arteries and increase blood flow.

Like the current technique for measuring pressure loss, known as fractional flow reserve (FFR), iFR measures pressure using a thin wire in the coronary artery, but unlike FFR it does not require powerful drugs to open the blood vessels – which can cause patients severe crushing pain, low blood pressure and breathing difficulties. Instead iFR uses a mathematical algorithm to take measurements when the heart is relaxed and the coronary blood flow is high.

The technique has been found to be a much more comfortable procedure for patients, taking less time and being more cost effective than the current clinical standard FFR, potentially making it cheaper for healthcare providers.

Dr Justin Davies from Imperial College, Imperial BRC and Hammersmith Hospital, who developed the iFR and led the research, said:

“We have been using the iFR technique on suitable patients at Imperial College Healthcare NHS Trust for a number of years and it has also been adopted by another 4,500 cardiology centres around the world.

“With our research demonstrating the benefits for patients, as well as iFR’s recent entry in the 2017 advanced diagnostic imaging services guidelines, we expect iFR will have huge implications internationally, for cardiologists and their patients over the coming years.”

A live case demonstration of iFR is available here.

Notes to editors

1. The iFR is licensed to Volcano-Philips by Imperial Innovations, Imperial College’s technology transfer partner.
2. Pressure is measured in the coronary artery before a stent is fitted to ensure the artery is narrow enough for a stent to be useful.
3. iFR received Food and Drug Administration approval in the United States in 2013 leading to its adoption by 4500 cardiology labs worldwide.
4.“Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI” J.E. Davies et al., published Saturday 18 March 2017 in the New England Journal of Medicine.
5.The NIHR Imperial Biomedical Research Centre (BRC) is a partnership between Imperial College Healthcare NHS Trust and Imperial College London. It undertakes translational, experimental medicine research – taking discoveries from basic laboratory science and facilitating their translation quickly and efficiently into clinical settings, delivering improved health outcomes for patients.