Does a coronary stent make sense for stable angina?

The chest discomfort known as angina (which comes from the Latin word angere, meaning to choke or strangle) occurs in many people with coronary artery disease. Fatty plaque narrows the heart's arteries, slowing blood flow to the heart. During exercise or periods of emotional stress, the increased demand for blood may outpace the heart's supply. The resulting drop in oxygen delivery to the heart muscle triggers angina.

Severe, unrelenting angina is a medical emergency (see "What is acute coronary syndrome?"). But angina that subsides within a few minutes with rest is known as stable angina. Treating this common problem has long been a matter of debate.

Since the late 1970s, cardiologists have known that inserting a tiny mesh tube called a stent to open a narrowed heart artery can relieve stable angina and may help people exercise more easily. "This led to a widespread assumption of cause and effect: that blockages caused symptoms, and stents relieved them," says cardiologist Dr. William Boden, scientific director of the Clinical Trials Network of the VA New England Healthcare System and lecturer in medicine at Harvard Medical School. However, that belief ignores the well-known placebo effect, which can influence many treatments and conditions, he adds.

Stents on trial

In 2017, the ORBITA study compared angioplasty and stenting with a placebo (a sham procedure) in 200 people with stable angina. Neither the patients nor the staff knew who received which treatment. What happened? "There was no difference in angina relief or exercise performance between the two groups, which shows the potentially powerful placebo effect associated with receiving a stent," says Dr. Boden. Of note: all the study participants were taking two to three medications to help reduce their angina symptoms. Critics contended that this treatment — which is routinely recommended for angina — minimized the possible differences between the two groups.

The response to that criticism was ORBITA-2: a larger, longer study that required participants to stop taking anti-anginal drugs two weeks before the procedure. Compared with people who got the sham treatment, those who received stents had lower scores on an angina symptom scale (that is, they had fewer symptoms) and were able to exercise about a minute longer — benefits that lasted at least 12 weeks.

What should people take away from this new finding? Medications contribute to angina relief above and beyond getting a stent or having a sham procedure, says Dr. Boden. "Both stents and medications are effective. But stents have far more downsides," he says.

Complications and cost

Doctors can sometimes overlook the risks of the procedure. Complication rates are very low, but they're not zero, says Dr. Boden. They include bleeding at the leg or wrist insertion site and about a 1% risk of having a heart attack or stroke during or soon after the procedure. People must also take drugs for at least six months to prevent clots from forming inside the stent, and those drugs carry a risk for bleeding.

In addition, the price of these procedures ranges from $20,000 to more than $80,000, which means that the out-of-pocket costs even for patients with insurance can be substantial.

But despite that high cost, there is no evidence that a stent will prevent a future heart attack or increase survival compared with drug therapy, Dr. Boden says. That's because most heart attacks occur in arteries that are narrowed by only about 40% or less but harbor what's called vulnerable plaque, which can rupture without warning. The resulting blood clot blocks blood flow, triggering a heart attack.

What's more, those partly blocked arteries do not cause angina, which usually occur only in arteries that are more than 70% blocked. In fact, most angina may occurs when the heart's tiniest arteries (called microvessels) are impaired — a problem that cannot be treated with stents, says Dr. Boden.

The bottom line

"The ORBITA-2 trial reinforces current guidelines, which recommend medications as the first and preferred treatment for stable angina. People should get a stent only when medications don't relieve their symptoms," says Dr. Boden.

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