Using a stent to reopen a blocked artery in or around the heart can be lifesaving for those having heart attacks or who have developed blocked arteries, called atherosclerosis. They’re also commonly used in those who have chest pain known as angina. But new research suggests stents may be more placebo than panacea for some of those patients.

The study looked at a group of 200 patients with “stable angina,” meaning they had heart arteries that had been blocked by fatty plaque that led to intense chest pain during physical exertion.

Researchers at Imperial College London placed the group on several weeks’ medication to help their condition and then broke them into two groups. The first group underwent angioplasty to insert a stent into their blocked artery. The other group underwent a fake stent procedure. The study was double-blinded, so that neither the patients nor their doctors knew who had received what.

When the patients were asked how they were feeling six weeks later, the researchers found no difference between the two groups. Both still had trouble with exertion and there were no significant differences in patient-reported improvement of symptoms.

For those who did receive a stent, tests confirmed that the procedure did significantly improve the blood supply to their hearts, which left the researchers puzzled as to why the increased blood flow didn’t improve symptoms or the ability of the patients to exercise for longer.

The full results appear in The Lancet.

The lead author of the study, Dr Rasha Al-Lamee, a cardiologist from the National Heart and Lung Institute at Imperial College London, says it’s important not to assume that the study’s findings mean that stents are useless for angina, particularly those who are at high risk of a heart attack.

“We found that stents definitely increased the blood supply to the heart in these patients. So for those patients, that might have massive implications in terms of reducing the risk of heart attack or death,” she told CTV News Channel.

“But we did find that their symptoms didn’t improve much more than a placebo or sham procedure and that was very surprising to us.”

Her team notes the study looked only at patients with one blocked coronary artery; patients with multi-vessel blockages may get more symptom relief from stenting.

Dr. Al-Lamee added that stents may be more effective than long-term use of medications since many patients fail to take the prescription drugs they need once they leave hospital.

“Those tablets have side effects and it’s very hard to ensure that patients remain on those tablets,” she said.

Dr. Al-Lamee says her team’s study shows that the link between opening a narrowed coronary artery and improving symptoms is not as simple as most would hope. But she says further research should help lead to a greater understanding of stable angina.