The placebo effect on people who have stents inserted for stable angina may be more significant than previously realised, according to a new analysis.
Researchers in the ORBITA trial, who compared stenting with a simulated procedure, found that the treatment had no significant additional benefit on patient symptoms or quality of life – suggesting that the relief of angina symptoms came from the experience of undergoing treatment.
Researchers said this did not mean that the stents were not effective in treating cardiovascular disease.
The UK trial, which is a randomised, placebo-controlled study of 200 patients with stable angina, provides the first evidence of a direct comparison between stenting for stable angina and placebo.
The findings are published in The Lancet and were presented yesterday (2 November 2017) at the Transcatheter Cardiovascular Therapeutics 2017 conference in Denver, Colorado.
Dr Rasha Al-Lamee, lead author of the study from the National Heart & Lung Institute at Imperial College London, said: “The most important reason we give patients a stent is to unblock an artery when they are having a heart attack. However, we also place stents into patients who are getting pain only on exertion caused by narrowed, but not blocked arteries. It’s this second group that we studied.
"Surprisingly, even though the stents improved blood supply, they didn’t provide more relief of symptoms compared to drug treatments, at least in this patient group.
"While these findings are interesting and deserve more attention, they do not mean that patients should never undergo the procedure for stable angina. It may be that some patients opt to have an invasive procedure over taking long-term medication to control their symptoms.”
Although people with stable angina can manage the condition with beta-blockers or nitro-glycerine, some may undergo angioplasty with stent or percutaneous coronary intervention (PCI).
Since the procedure was introduced, it has been unclear as to whether the relief of symptoms is due to the treatment or to a placebo effect. As part of the multi-centre ORBITA trial, the 200 patients had a six-week phase of intensive medical treatment in which the medications used to treat angina were introduced and increased to maximal doses.
Patients were grouped randomly so that half received a heart stent while the other half had a placebo procedure in which they had an angiogram procedure, but did not receive the stent.
Both before and six weeks after undergoing the procedure, patients had exercise tests to assess how fast they could walk on a treadmill while their heart and lung function were measured. The key outcome was a change in the amount of time they could exercise after the procedure.
Researchers found the average increase in overall exercise time was 28•4 seconds for patients who had PCI and 11•8 seconds for the placebo group, which they said was not statistically significant.
However, the tests did confirm that stenting significantly relieved the narrowing in the coronary artery and improved the blood supply to the heart.
“It seems that the link between opening a narrowing coronary artery and improving symptoms is not as simple as everyone had hoped," said Dr Al-Lamee.
"This is the first trial of its kind and will help us to develop a greater understanding of stable angina, a disease which affects so many of our patients every day."
Al-Lamee R et al. Objective Randomised Blinded Investigation with optimal medical Therapy of Angioplasty in stable angina (ORBITA trial): a randomised double-blind trial. The Lancet 2 November 2017; doi:10.1016/ S0140-6736(17)32714-9
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