A Boston Medical Center cardiologist explains what that ‘unbelievable’ heart stent study means

We asked a Boston cardiologist to break down the recent study of the heart stent procedure that has stunned some doctors.

A Doctor Holds a Heart Stent
A detail photo of a stent held by a cardiologist. –David L Ryan / The BostonGlobe

Prominent cardiologists reacted with shock Thursday when a new study found that a common procedure used to relieve chest pain may not be effective at relieving the discomfort.

The study, published in the Lancet, examined the use of stents — wire mesh tubes used to open blocked arteries — in patients who were experiencing a single blockage restricting blood flow to the heart, causing the patient to experience chest pain. The New York Times reports the results of the study are raising questions whether stents should be used so often to treat chest pain, with some doctors telling the newspaper the results were  “humbling” and “unbelievable.”

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We turned to Dr. Ashvin Pande, director of invasive cardiology at Boston Medical Center, to learn more about the study, its results, and the reaction from the medical community.

“I think it’s going to raise a lot of questions for patients and doctors,” Pande told Boston.com. “And I think that the best thing we can do is make sure that we individualize these discussions and solutions based on patients.”

Ahead, Pande, who was not associated with the study in any capacity, breaks down what researchers looked at in the new study and what questions are being raised as a result.

This interview has been lightly edited and condensed for length and clarity.

Boston.com: What were the parameters of the study?

Ashvin Pande: The study was relatively small in terms of cardiology studies. They took 200 patients who had blockages in what they call single vessels, so only one of three major blood vessels was blocked. So for people who had multiple blockages, this didn’t apply. They restricted it to patients who had [blockages] in a single blood vessel.

What they did is randomly assigned half of them to get a stent in a procedure to open up blood flow, and the other half they did what was a sham. So … the patient wouldn’t know if they got the procedure or not, and that was to eliminate the possibility of a placebo effect.

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It’s important to also note that before they got the stent, or procedure, they were all on medical therapy. So [they were taking] medicines for anti-angina to relieve angina before they even started, and they did that for six weeks.

Can you explain what angina is?

Angina is the symptom that people feel — whether it be chest pain, chest tightness, chest heaviness — that is a reflection of portions of heart muscle not getting enough blood flow. So when people come in describing, ‘I get chest pain when I walk or climb stairs,’ that’s the angina we’re talking about.

What did the researchers find?

After they randomized these people, they followed them for another six weeks. They did a number of tests — put them back on a treadmill to see if they could exercise for as long a period — and then they asked how many symptoms they had, how it affected their quality of life and so on.

The bottom line was that there wasn’t a significant difference in whether you had the actual stent procedure or the sham.

What is your reaction to the study’s results?

One key feature is this doesn’t apply to patients who come in with unstable angina. That is to say, they hadn’t had heart attacks or anything similar to that. Those come under a very different category, and I think it has been shown that there’s much less question as to the value of stents for that.

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These are people who had what we call stable angina, so this develops slowly over a period of time. When they do activity they feel it, but when they stop, they get better. We would consider those stable angina patients. They’re not urgent or emergent.

These questions were put in the forefront of international cardiology in general about 10 years ago. There was a large trial called COURAGE where they also saw that aggressive medical therapy can achieve very similar benefits to stenting procedures. At that time also there was a big reaction: Is this true? Is this not true? And so on and so on.

So my initial reaction here is that this is probably not as surprising as it seems because we’ve known for 10 years based on the results of [COURAGE] that medical therapy can do very well for patients with stable angina. What is interesting is that it was felt, even back then, that putting in a stent may get you that angina relief faster, and this challenges that thesis.

What other questions are being raised with the study’s results?

It seems very intuitive for us as cardiologists, but anybody to say, look you have a blockage, so it should be opened. Anybody would make that claim — that if something is closed, opening it would make it better. And we’ve operated under that idea for a long time time. I think this is going to challenge whether opening a blockage mechanically does yield as much as we think it does. It’s counterintuitive in the simplest ways, whether you’re a doctor or not.

Are there risks associated with the stent procedure in general that might push people to one or the other side of this question?

The procedure itself does have some risks. It has become much safer over time, but there’s always a very small risk of bleeding, damaging blood vessels — a very, very small risk of stroke. For patients who we think are less likely to benefit from an invasive procedure, we may be more conservative than may have been before.

I think that ultimately a lot of this is for patients and doctors to discuss. It’s the doctor’s responsibility to say, ‘Look, these are the risks for doing it, these are the risks of doing the stent, these are the risks of not doing the stent, these are the benefits of medicines.’ Patients may decide they can’t tolerate the medicines. But there are patients who have more significant symptoms who may benefit more from a stent procedure.

I think a lot of the things that we considered sort of the straightforward answers — such as the things that are blocked should be opened — are now open to question. That’s going to have to be something that we take into account.

How should patients take in this information?

One of the first things I just want to re-emphasize is that this is only stable angina. So for people who have more concerning symptoms — unstable angina, heart attacks — those are different questions.

Second, ultimately this only furthers the idea that the patient and doctor need to individualize these discussions and the solutions. I think for patients who are having this kind of problem with similar symptoms, this is all the more reason to discuss it with your doctor and make sure all the options are explored. And that you understand that for at least this specific type, medical therapy may be a certainly valid option to pursue instead of the procedure.

Has this study changed anything in your thinking? In the way you approach your day-to-day?

I think we saw a cultural shift after COURAGE, the trial from 10 years ago, which had already tilted some of these types of patients into more conservative arms of medical therapy. I think this will probably tilt it even further, unless there’s conflicting evidence that comes in the future.

If I saw a patient tomorrow, would I do anything differently? I don’t know that yet. I think it’s a bit early to have this represent a sea-change, before we have longer-term data and more patients who are studied. But I do think that it will continue the trend of more conservative type treatments for stable angina.