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Results of study on stenting chest pain patients misinterpreted: researchers

Dr. Christopher Overgaard, interventional cardiologist at the Peter Munk Cardiac Centre in Toronto is seen in catheterization lab in this undated handout photo. It's hard to believe that a single small study could cause such a hullabaloo, but that's been the case with a research paper that looked at the effectiveness of using stents to open up clogged coronary arteries in patients with chest pain known as angina. THE CANADIAN PRESS/HO, Peter Munk Cardiac Centre *MANDATORY CREDIT*

Dr. Christopher Overgaard, interventional cardiologist at the Peter Munk Cardiac Centre in Toronto is seen in catheterization lab in this undated handout photo. It's hard to believe that a single small study could cause such a hullabaloo, but that's been the case with a research paper that looked at the effectiveness of using stents to open up clogged coronary arteries in patients with chest pain known as angina. THE CANADIAN PRESS/HO, Peter Munk Cardiac Centre *MANDATORY CREDIT*

TORONTO — It's hard to believe that a single small study could cause such a hullabaloo, but that's been the case with a research paper that looked at the effectiveness of using stents to open up clogged coronary arteries in patients with chest pain known as angina.

The U.K.-led study published last week in The Lancet has sparked a heated international debate among doctors about how best to treat such patients — by inserting a mesh tube into their blocked artery to improve blood flow or by prescribing anti-angina pills?

"I think there was a lot of hysteria here," said study co-author Dr. Justin Davies, a professor of cardiology at Imperial College London, pointing to the headline on a New York Times story about the study: "'Unbelievable': Heart stents fail to ease chest pain."

Dr. Rasha Al-Lamee, an Imperial College interventional cardiologist who led the study, was somewhat more circumspect in her reaction to how the findings were interpreted  by some heart disease experts quoted by various media outlets.

"I think that perhaps some of their statements were an overreach of the results," she said from London. "In America, it has been quite incredible."

The 2014-17 ORBITA study enrolled 230 patients with one blocked coronary artery — there are three such major vessels — who were experiencing chest pain and reduced exercise capacity on speed-modified treadmill stress tests.

Patients were treated over six weeks with increasing doses of anti-angina medications, such as heart rate-reducing beta blockers and blood thinners, then randomized half and half to undergo either insertion of a stent or a sham procedure that left their blocked artery as it was. In what's called blinding to prevent biased results, patients were not told which procedure they received.

Despite which group the patients were in — stent or no stent — both reported some improvement. But researchers said the difference between the two groups was not statistically significant.

"We found, to our surprise, that while the stents improved the blood supply to the heart in this population of people with disease in just one artery ... we didn't significantly  improve how they felt in terms of symptoms or how they did in terms of walking on an exercise path, more than a placebo (sham) procedure," said Al-Lamee.

"It probably means that stable angina is quite complex and fixing narrowing you see with stents doesn't probably fix everything, because these people may have disease in the small arteries we don't see (with imaging)," she said.

"They might have chest pain for other reasons, they may be limited because of other factors that are not their heart."

However, some heart specialists interpreted the findings to mean that the long-used practice of stenting — known medically as percutaneous coronary intervention, or PCI — to treat angina should be re-assessed.

Among them were Dr. David L. Brown of the Washington University School of Medicine and Dr. Rita F. Redberg of the University of California-San Francisco, who prepared an editorial review of the study for The Lancet.

"The results of ORBITA show unequivocally that there are no benefits for PCI compared with medical (drug) therapy for stable angina," they wrote. "Based on these data, all cardiology guidelines should be revised to downgrade the recommendation for PCI in patients, despite use of medical therapy."

But Al-Lamee disagreed with that interpretation, saying international practice guidelines recommend first starting patients on a variety of anti-angina drugs, with stenting reserved for those who get minimal or no relief from the medications. But it doesn't mean never using the devices in such patients, she said. 

Stents are widely used internationally. They are considered first-line treatment for people having a heart attack, and an estimated 500,000 PCI procedures are performed each year worldwide for stable angina.

"The results have been a total surprise and they probably need to make us stop and think, but I don't think they need to be used to change all that we do," she said.

Dr. Christopher Overgaard, an interventional cardiologist at the Peter Munk Cardiac Centre in Toronto, said the New York Times headline is what initially "got my blood pressure up," because it reflected what he characterized as an "irresponsible" inference from the study.

Given that the patients were relatively healthy, with only a single blocked artery, and had been on weeks of intensive drug therapy, "it's not really a surprise that the main finding of the study was that their exercise tolerance didn't change," said Overgaard, who was not involved in the study.

"So the interpretation in my opinion should not be stenting doesn't work. The interpretation, I think, should be that medical therapy in healthy (angina) patients that already had a good exercise tolerance is probably sufficient and we may not need to open those arteries in the first place."

Overgaard, director of the catheterization lab at Peter Munk, said Canadian doctors commonly stent patients with chronic coronary disease who have significant chest pain after minimal exertion, such as those who can only walk a couple of minutes before becoming breathless. And he doesn't think the study will change practice in Canada. 

"But I think the message from this study is that if somebody has a blockage, but they're doing really well, it may be sufficient to just treat them with pills."

Still, he agreed with both Davies and Al-Lamee that many patients prefer what they see as a quick fix with a stent over taking medications for life with their attendant side-effects. Beta blockers, for instance, may cause drowsiness and, in men, erectile dysfunction. 

"I see a lot of patients in clinic and it's very common for patients not to take their medications or not to want to take their medications," Overgaard said.

"So that's the caveat. Human nature is to get something treated that will eliminate the need for ongoing pills."

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