New stenting tool could make heart procedures cheaper and less painful

March 20, 2017 by Caroline Brogan
A stent holding open a clogged artery

A new tool for assessing the narrowing of the heart's arteries was found to be as effective as current methods and less painful for patients.

The tool is similar to current techniques in telling surgeons whether a patient needs a stent – a type of mesh tube used to hold open clogged arteries and increase blood flow. However, this new technique, known as instantaneous wave-free ratio (iFR), is much more pleasant for the patient, and could be cheaper and less time-consuming for healthcare providers.

Coronary stenosis occurs when various factors cause narrowing of the coronary arteries, which deliver oxygen-rich blood to the muscle of the .

When these become blocked or are narrowed, this can affect how the heart functions, potentially leading to chest pain, heart attacks and heart failure.

Now, Dr Justin Davies and his team from the National Heart and Lung Institute at Imperial College London have developed iFR to measure the pressure loss caused by the narrowing in these important blood vessels without the need for drugs with sometimes unpleasant side effects. This novel technology was licensed to Volcano-Philips by Imperial Innovations, the College's technology transfer partner.

The technique received FDA approval in 2013 and is already used in 4,500 labs worldwide, but the latest study is the biggest yet to prove its effectiveness compared with the current most widely established technique.

"We have already seen iFR adopted into the latest 2017 appropriate use criteria (AUC) guidelines and expect this will lead to further changes in guidelines, which would have huge implications for cardiologists and their ," said Dr Davies. "iFR technology is already used widely worldwide, and this is the study we've been waiting for to show that our technique is just as accurate as old ones, but far better for patients."

Deciding on stents

Measuring pressure in the is important when deciding whether patients need to have a stent fitted – a procedure known as angioplasty. This helps to improve the blood supply to the heart muscle by widening the narrowed coronary arteries. However, before patients can undergo angioplasty, cardiologists must test the pressure of the artery to make sure it is narrow enough for a stent to be useful.

The first line technique in current guidelines, known as fractional flow reserve (FFR), requires using powerful drugs such as adenosine to open the blood vessels for easier measurement. However, it can cause severe crushing pain, low blood pressure and breathing difficulties, and adds more time and costs on to the procedure.

The latest study has shown that using the new technique (iFR) is just as accurate, causes less discomfort, is less time-consuming, and might be cheaper, than FFR. Click here for a live case demonstration of iFR, courtesy of Imperial College Healthcare NHS Trust.

Like FFR, iFR measures pressure using a thin wire in the coronary artery, but unlike FFR, it uses a mathematical algorithm to take measurements only when the heart is relaxed and the is high, negating the need for adenosine.

In this study, the researchers enrolled 2,492 patients in 17 countries who suffered with chest pain or (heart attack). They randomly assigned participants to undergo iFR or FFR, and either inserted a stent or not, depending on the measurements. Patients were followed up for 12 months after the procedure.

By measuring subsequent heart attack and mortality after FFR and iFR, the researchers were able to tell whether the type of technique used had any association with higher mortality or other outcomes.

Although there were no significant differences in rates of death or subsequent heart attack between the two techniques, patient experience was much improved with the iFR technique.

The researchers found that adverse events occurred in 31 per cent of FFR patients and three per cent of iFR patients overall.

FFR was also associated with a higher rate of shortness of breath (reported in one per cent of iFR patients and 20 per cent of FFR patients); chest pain (nearly two percent in iFR and seven per cent in FFR); heart rhythm disturbances (nearly zero per cent in iFR and nearly five per cent in FFR); abnormally (nearly zero per cent in iFR and one per cent in FFR); and serious adverse events, which included severe shortness of breath or disturbance of normal heart rhythm (nearly zero per cent in iFR and nearly one per cent in FFR).

They also found that iFR reduced the overall length of the procedure, from an average of 45 minutes for FFR to 40 minutes for iFR.

The results from this trial, known as DEFINE-FLAIR, are published in the New England Journal of Medicine, and are presented today at the American College of Cardiology's 66th Annual Scientific Session in Washington.

Lead author Dr Davies said: "As our technique eliminates the need for adenosine and reduces the length of the procedure, it could mean that iFR saves healthcare providers money. The study also provides a very good, real-world snapshot of the time it takes to actually get a patient in, do the physiological assessment, do the stenting if necessary, and finish."

Co-author of the study, Dr Sayan Sen, said: "'Cardiologists have been waiting for someone to prove that this is just as effective as the current one."

"Many of our physician colleagues have been waiting for these results, and for them to be incorporated fully into the guidelines they use. DEFINE-FLAIR gives guideline makers the evidence they need to go ahead and suggest the that's better tolerated by patients, and more cost effective for the health service."

Next, Dr Davies and co-investigator Professor Javier Escaned will further analyse this data to fully compare the costs of iFR and FFR. They will also work to combine data from another study testing iFR outcomes, SWEDEHEART, with their own. The two groups of researchers will work together to conduct a follow-up analysis combining the data from the two studies in a meta-analysis of primary outcomes that will include approximately 4,500 patients.

Explore further: Improved technology may obviate need for drug when assessing patients for a coronary stent

More information: Justin E. Davies et al. Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI, New England Journal of Medicine (2017). DOI: 10.1056/NEJMoa1700445

Related Stories

Improved technology may obviate need for drug when assessing patients for a coronary stent

December 7, 2011
A new method for measuring narrowing in the arteries of the heart may allow patients to be assessed for a stent without having to take a drug with unpleasant side effects.

PCI, drugs equally beneficial for treating fully blocked arteries

March 20, 2017
In patients with a complete blockage in the heart's arteries that persists over time, treatment with medications alone was found to be equal to percutaneous coronary intervention (PCI), a procedure to open blocked arteries, ...

Study reveals ways to improve outcomes, reduce costs for common heart procedure

February 21, 2017
Hospitals can improve patient care and reduce costs associated with coronary angioplasty if cardiologists perform more of these procedures through an artery in the wrist and if they take steps to discharge such patients on ...

Heart bypass surgery outperforms new generation stents

March 16, 2015
Despite the advent of a new generation of stents, patients with multiple narrowed arteries in the heart who received coronary artery bypass grafting fared better than those whose arteries were opened with balloon angioplasty ...

Preventative angioplasty could save thousands of lives

September 12, 2013
Preventive angioplasty in heart attack patients cuts the risk of death and other serious complications, according to research by cardiologists.

Recommended for you

Could this protein protect people against coronary artery disease?

November 17, 2017
The buildup of plaque in the heart's arteries is an unfortunate part of aging. But by studying the genetic makeup of people who maintain clear arteries into old age, researchers led by UNC's Jonathan Schisler, PhD, have identified ...

New model estimates odds of events that trigger sudden cardiac death

November 16, 2017
A new computational model of heart tissue allows researchers to estimate the probability of rare heartbeat irregularities that can cause sudden cardiac death. The model, developed by Mark Walker and colleagues from Johns ...

Popular e-cigarette liquid flavorings may change, damage heart muscle cells

November 16, 2017
Chemicals used to make some popular e-cigarette liquid flavorings—including cinnamon, clove, citrus and floral—may cause changes or damage to heart muscle cells, new research indicates.

Possible use for botulinum toxin to treat atrial fibrillation

November 16, 2017
From temporarily softening wrinkles to easing migraines, botulinum toxin has become a versatile medical remedy because of its ability to block nerve signals that can become bothersome or risky.

Proteome of the human heart mapped for the first time

November 15, 2017
A healthy heart beats about two billion times during a lifetime, thanks to the interplay of more than 10,000 proteins. Researchers from the Max Planck Institute of Biochemistry (MPIB) and the German Heart Centre at the Technical ...

First transcatheter implant for diastolic heart failure successful

November 15, 2017
Results presented today at the American Heart Association Scientific Sessions and published in Circulation show that a new device designed to treat diastolic heart failure is safe and effective. The first patient in the randomized, ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.