Angina patients who receive an arterial stent are more likely to be free from symptoms compared to those who receive a placebo treatment.

The findings come from the ORBITA trial; a blinded, randomised, placebo-controlled study of 200 patients with stable angina, in which researchers compared the artery-widening technique (stenting) with a simulated procedure – where a stent was not implanted – for the first time.

Stable angina is a common condition in adults in which patients feel chest pain as a result of over-exertion due to restricted blood flow to the heart. It is typically caused by the build-up of fatty plaques in the arteries and a hardening of the blood vessel walls, which makes them narrower and less flexible.

For our patients, this is one of the most important things we can tell them, that they are more likely to become symptom free. Dr Rasha Al-Lamee Principal Investigator of the study

Patients can manage the condition with drugs such as beta-blockers or nitro-glycerine, however, some may undergo an invasive procedure, known as angioplasty with stent or Percutaneous Coronary Intervention (PCI).

During the ORBITA trial, half of the patients received the stent and half had the placebo procedure. For the next six weeks the patients and their doctors did not know which one they had had.

The primary results of the study were published in The Lancet last year, and showed no difference between the patients who received a stent or placebo treatment, in terms of the change to the length of time they could exercise on a treadmill before and after the treatment. Additionally, the researchers –led by cardiologists at Imperial College London – found no statistical difference in angina symptoms.

In this latest analysis, the ORBITA team were able to look at the number of patients who reported being free from symptoms. They were able to show a benefit of stenting compared to placebo, with more patients who received a stent reporting that they had no angina symptoms at follow-up.

Predicting patient outcomes

They also assessed which patients might gain the greatest benefit from angioplasty and found that those patients who had the greatest narrowing of their coronary arteries, causing the greatest reduction in blood flow, had the greatest benefit from stenting in terms of improvement in their heart function, as shown by ultrasound scans.

The results, presented at the annual meeting of the European Society of Cardiology in Paris and published in the journal Circulation, show that for every 100 angina patients treated, almost 20 more patients who received a stent were symptom free compared to those who received the placebo treatment.

Dr Rasha Al-Lamee, from Imperial’s National Heart and Lung Institute and Principal Investigator of the study, said: “From this additional secondary analysis we have some interesting new data. For physicians, this means that one in five patients that we treat with angioplasty versus placebo will be more likely to be free from angina. For our patients, this is one of the most important things we can tell them, that they are more likely to become symptom free.”

In addition to the main findings, the investigators also showed that two invasive techniques used to measure blood flow were important in predicting how patients would respond to the stenting treatment.

The two techniques, fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR), were used to show the degree of ischaemia – how much the blood flow was restricted in the artery.

“This is the first placebo-controlled evidence we have had of this kind, as we can now predict the benefit in myocardial function we might expect from stenting based on how significant the coronary narrowing is using FFR and iFR ” added Al-Lamee.

“In order to build on some of the questions answered in ORBITA as well as being able to apply ORBITA to a wider patient base, we are also preparing for ORBITA 2 which will be a larger trial, with wider inclusion criteria for patients with stable angina”.

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'Fractional Flow Reserve and Instantaneous Wave-Free Ratio as Predictors of the Placebo-Controlled Response to Percutaneous Coronary Intervention in Stable Single-Vessel Coronary Artery Disease: Physiology-Stratified Analysis of ORBITA' by Rasha Al-Lamee et al. is published in Circulation.