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ORBITA study: Stents no better than placebo
11/29/2017
 
Leading cardiologists can’t quite believe the results of an influential study reported in the Lancet which concluded stents are no better than a placebo in improving exercise capacity or symptoms, even in patients with severe coronary stenosis.

As the researchers described it, “in patients with medically treated angina and severe coronary stenosis, PCI did not increase exercise time by more than the effect of a placebo procedure.”

ORBITA was a double-blind, randomized controlled trial of percutaneous coronary intervention versus a placebo procedure for angina relief. The recently concluded study, which enrolled 230 patients, was done at five study sites in the UK. It is the first double blind randomized controlled trial to directly compare stenting with placebo in patients with stable angina who are receiving high quality drug treatment. Results were presented on November 2 at the Transcatheter Cardiovascular Therapeutics 2017 conference in Denver, and simultaneously published online by the Lancet.

In a press release, Dr Rasha Al-Lamee, lead author of the study from the National Heart & Lung Institute at Imperial College London, explained “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," she said. “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," she added.

Nevertheless, the study results have caused a stir among cardiologists. Dr. William E. Boden, a cardiologist and professor of medicine at Boston University School of Medicine, told the New York Times the results are “unbelievable.” Dr. Brahmajee Nallamothu, an interventional cardiologist at the University of Michigan, said “it’s a very humbling study for someone who puts in stents.”

In an accompanying editorial in Lancet, Dr. David Brown, of Washington University School of Medicine in St. Louis, and Dr. Rita Redberg, of the University of California San Francisco, said "based on these data, all cardiology guidelines should be revised to downgrade the recommendation for PCI in patients with angina despite use of medical therapy."

The Society for Cardiovascular Angiography and Interventions responded quickly to challenge the study. “The number of patients studied was very small, so the study is far from conclusive,” it said.

“The primary endpoint used, exercise tolerance, is imprecise and very subjective: patient tolerance of exercise normally varies from week to week, so differences of a few seconds in exercise tolerance are hard to interpret," said Dr. Kirk Garratt, president of the society.

The American College of Cardiology also voiced caution, despite lauding the study. “This is clearly a landmark trial, extremely well done,” it said, but “the trial appears to be too small to address a question of this magnitude. These findings need to be validated in a larger randomized controlled trial.”

The ORBITA study is notable because it is the first to compare stents with placebo while keeping patients in the dark about whether they had received a stent. As the Wall Street Journal explains it, all patients in the study had catheters inserted in an artery and were heavily sedated before being taken into the cath lab. But only about half the patients were given stents, while the rest remained on a table in the lab for about 15 minutes and then simply had the catheter removed.

Dr Al-Lamee, the lead researcher, said the safest conclusion from the study is that “the link between opening a narrowing coronary artery and improving symptoms is not as simple as everyone had hoped.”

She cautioned that “to extrapolate the results to patients with high risk would be perhaps an oversimplification of these results. To use this to downgrade guidelines would be an incredibly large overreach.”