Are Stents Really Useful for Stable Angina?

What the ORBITA trial should mean for you

Stent
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In November 2017, the results of a unique clinical trial were reported in the Lancet, immediately throwing the cardiology world into turmoil. The ORBITA trial challenged three decades of cardiology dogma regarding the effectiveness of treating stable angina with stents. Stents, the ORBITA trial concluded, offered no measurable clinical improvement in stable angina when compared to a sham procedure.

Can it be that the benefits cardiologists have attributed to stents all this time are really due to nothing more than a placebo effect? Experts formed into battle lines overnight. One group declared that the ORBITA trial should end the practice of stenting for stable angina. The second group of experts insisted that the ORBITA trial, while interesting, was fatally flawed, and should not change clinical practice at all. 

This gathering war looks like one that won’t be resolved for several years. This, of course, is how clinical science advances. The question for us is: What is a person who is dealing with stable angina today (while the experts are still quarreling) supposed to do now? 

If we step back and take an objective look at the available data, it turns out not to be that difficult to come up with an approach for treating stable angina that makes sense, and also fits the evidence from the clinical trials (including ORBITA) as it exists today.

Stents for Stable Angina

Stents are wire-mesh struts that are expanded within a blocked artery during an angioplasty procedure. In angioplasty, a balloon is inflated at the site of the atherosclerotic plaque to relieve the blockage. The stent is simultaneously deployed to keep the artery propped open.

Angioplasty plus stenting is often referred to by doctors as “percutaneous coronary intervention,” or PCI.

PCI was developed as a less invasive substitute for coronary artery bypass grafting, an open-heart surgery procedure. Since PCI was developed, the proportion of patients with coronary artery disease who are treated with bypass surgery has dropped significantly.

There are times when using PCI is critically important. Immediate PCI significantly improves the outcomes of people suffering from acute coronary syndrome (ACS)—a range of life-threatening problems caused by an acute blockage of a coronary artery. The three clinical syndromes caused by ACS include unstable anginaST-segment elevation myocardial infarction (STEMI), and non-ST-segment elevation myocardial infarction (NSTEMI). For many of these syndromes, rapid PCI has been established, by several clinical trials, as the treatment of choice.

For many years, stenting was also the treatment of choice for most people who had stable angina—angina caused by a more chronic, fixed, partial blockage in a coronary artery. That PCI relieved angina in these people was obvious to all, and it was assumed that they would also have a reduced risk of subsequent heart attacks.

Then, in the late 2000s, the COURAGE trial showed that PCI really didn’t measurably reduce the risk of heart attack or death in people with stable angina, as compared to aggressive medical therapy. Since that time, clinical guidelines have urged cardiologists to use PCI in stable angina only to relieve symptoms of angina, and only in people who could not be treated effectively with medication. 

While it is difficult to document objectively, it appears that many cardiologists (despite what the guidelines say and despite the evidence from clinical trials), have continued to use stenting as first-line therapy for stable angina, and not as second-line therapy in people who fail with drugs.

They do this, they will tell us, because nothing beats a stent for getting rid of angina. 

In fact, virtually everyone has believed that stents are the most effective way to relieve angina, even those who urged cardiologists to try aggressive medical therapy first. It has become virtual dogma: Despite all the its drawbacks, stenting is a highly reliable and effective way to treat stable angina.

But now, the ORBITA trial has thrown this dogma into turmoil.

What the ORBITA Study Did

The ORBITA investigators tested a startling hypothesis. They asked: What if the angina relief experienced by patients after a stent is not due to the opening of the artery but is a placebo effect? To test this hypothesis, they compared actual stenting to a sham stenting procedure.

They enrolled 200 people with stable angina and at least one significant blockage in a coronary artery (more than 70 percent blocked). After a six-week period of optimizing medical treatment, and after extensive baseline testing to measure the extent of their angina and their exercise capacity, subjects were randomized to receive either a stent, or a sham stent procedure. In the sham procedure, subjects received the entire PCI procedure, including inserting a wire across the blockage, except that no angioplasty or stent was actually performed. After the procedure, both groups received the aggressive anti-platelet therapy routinely used after PCI.

After six weeks, all subjects were tested again to measure the extent of their angina and exercise capacity. The investigators found that, while those who actually received stents seemed to have a bit more improvement than those who had the sham procedure, the difference between the two groups was not close to being statistically significant.

Therefore, they concluded, stenting is not measurably better than a sham procedure for treating people with stable angina.

Reactions to the ORBITA Study

An editorial in Lancet that accompanied the publication of the ORBITA trial declared this study to be “profound and far-reaching,” and called for formal treatment guidelines to be revised in order to “downgrade” the use of PCI in patients with stable angina.

Interventional cardiologists (those who perform PCI), through their organization (the Society for Cardiovascular Angiography and Interventions, SCAI), quickly released an extensive critique of ORBITA. The SCAI pointed out, among other things, that the patients enrolled had relatively low-level angina (that is, many should not have been candidates for PCI in the first place); the main end point of the trial (exercise time) is notoriously subjective and subject to major variability; the study is small and of short duration; and the one really objective measure of ischemia performed in the trial (a measure called the “peak stress wall motion score index”) showed significant improvement with PCI. Therefore, they conclude, the results of ORBITA, while interesting, should not be used to change clinical practice.

So, as you can see, the battle lines have been drawn, and we should prepare for several years of trench warfare.

What Should We Make of All This?

The ORBITA trial does indeed call into question just how effective PCI is at treating the symptoms of stable angina. Cardiologists should not assume, as they have done, that relieving even high-grade blockages in a coronary artery will magically make symptoms disappear. 

Nonetheless, the interventional cardiologists raise many legitimate problems with the ORBITA study. The one that ought to strike us as the biggest problem is this: The patients randomized in this trial had relatively low-grade angina, and under current guidelines many of them should never have been candidates for PCI in the first place. In other words, we should not expect that stenting would have much of an effect in such patients. The fact that it did not have much effect should have been predictable from the outset.

At the same time, interventionalists should not take too much comfort in their critique of the trial. The ORBITA study in fact does demonstrate that, in a large category of patients who are today routinely receiving PCI in the real world (that is, people with “significant” blockages whose symptoms are minimal to moderate), stenting really doesn’t do any measurable good. 

So, even if ORBITA does not justify changing current formal guidelines, it does indeed justify changing widespread current medical practice.

If You Have Stable Angina Today

Stents have revolutionized the treatment of coronary artery disease. For people who have one of the acute coronary syndromes, PCI has resulted in significant reductions in early death and disability. And in many people with severe, debilitating stable angina (a group that was not tested in the ORIBTA trial), PCI has led to a major improvement in symptoms.

However, stents should be avoided whenever possible. In addition to the risk involved with the performance of the PCI procedure itself, the presence of a stent creates a long-term management problem, for both the doctor and the patient, whose ultimate resolution remains unclear. Namely, is it ever safe to stop the powerful anti-platelet drugs needed after PCI? (Notably, several patients in the ORIBTA trial who had the sham procedure suffered major bleeding episodes during follow-up.) Read more about the ongoing problem with stents.

If you have stable angina today, your cardiologist should not be enthusiastic about performing PCI. Stenting will not entirely relieve your medical problem (even if it does successfully treat your angina); rather, stenting will trade one chronic management problem for another.

Instead of jumping right to PCI, in most cases the cardiologist should encourage an aggressive, step-wise trial of anti-anginal medical treatment, and the person with stable angina should welcome the idea of beginning with medical treatment. Both parties should be patient, because achieving optimal medical therapy can take several weeks or even months.

If significant angina remains an issue even after an aggressive trial of medical therapy, that is when serious consideration should be given to a stent. Read more about whether you really need a stent.

A Word From Verywell

The ORBITA trial is creating significant turmoil within the world of cardiology regarding the treatment of stable angina.

However, if you have stable angina, the results of this trial really should not complicate your treatment very much, as long as you and your doctor take an objective look at the evidence.

While the ORBITA trial does not appear to justify a change in how stable angina ought to be treated, it does justify a change in how it has often been treated by actual cardiologists.

Sources:

Al-Lamee R, Thompson D, Dehbi HM, et al. Percutaneous Coronary Intervention In Stable Angina (Orbita): A Double-Blind, Randomized Controlled Trial. Lancet 2017; DOI:10.1016/S0140-6736(17)32714-9. Abstract

Brown DL, Redberg RF. Last Nail In The Coffin For Pci In Stable Angina? Lancet 2017; DOI:10.1016/S01406736(17)32757-5. Editorial

Society for Cardiovascular Angiography and Interventions. SCAI Examines Strengths And Weaknesses Of Sham PCI Trial. November 2, 2017. https://medicalxpress.com/news/2017-11-scai-strengths-weaknesses-sham-pci.html

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