Are Stents Really Useful for Stable Angina?

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. 

As time went by, it became clear that the results of the ORBITA trial, while not definitive, added to the growing evidence that angioplasty and stenting should not be routinely offered as early therapy for most patients with stable angina.

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 healthcare providers 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 angina, ST-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. It was thought 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 its drawbacks, stenting is a highly reliable and effective way to treat stable angina.

The main effect of the ORBITA trial was to question this widely-held dogma.

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% 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 underwent 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 The 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 endpoint 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.

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.

he ORBITA study in fact did demonstrate that, in a large category of patients who in the recent past routinely received PCI (that is, people with “significant” blockages whose symptoms are minimal to moderate), stenting likely did not do much measurable good.

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 healthcare provider 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.)

The verdict is out: Several studies have shown that it is safe to stop dual anti-platelet therapy 12 months after PCI; while other studies and national specialty-society recommendations have suggested that six months of anti-platelet therapy may be enough, particularly with the newer agents available such as Brilinta (ticagrelor).

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.

A Word From Verywell

Studies like the ORBITA trial have significantly tempered what used to be over-enthusiasm on the part of cardiologists in applying stent therapy to patients with chronic, stable angina. 

Today, guidelines clearly state that stenting generally should not be used be used as first-line therapy in those with stable angina. Rather, it should be reserved for those whose angina remains uncontrolled on maximal medical therapy, or whose blockages are located in critical areas in which stenting is thought to substantially improve cardiovascular outcomes.