Each year, an estimated 300,000 Americans with angina have stents implanted to ease chest pain or discomfort caused by the reduced flow of oxygen-rich blood to the heart. The stenting procedure, called percutaneous coronary intervention (PCI), has been widely performed for almost four decades. Now, surprising new findings, published in The Lancet last November, cast doubts on the benefits of stents for many of those patients.
The unexpected results, from the ORBITA (Objective Randomised Blinded Investigation with Optimal Medical Therapy of Angioplasty in Stable Angina) trial, have sparked a furor among cardiologists. Some heart specialists have halted planned PCI procedures because of the new results. Others insist that the results from a single trial are no reason to stop using stents. For millions of Americans diagnosed with heart disease, the controversy raises troubling concerns and many questions. Here’s what you need to know.
Stable vs. unstable heart disease
Stable ischemic heart disease develops gradually as cholesterol-laden plaque builds up in the coronary arteries, partially obstructing blood flow to the heart. Stable angina can occur when an artery is blocked by about 70 percent. Physical exertion, such as walking, climbing stairs, sweeping, or similar activities, and emotional stress can trigger chest pain or discomfort, which typically lasts less than five minutes.
Unstable ischemic heart disease, in contrast, occurs suddenly, often with severe angina, even during rest. Rest or a medication like nitroglycerin doesn’t relieve unstable angina. Its distinction from stable angina is critical. Unstable angina is a medical emergency and could be a sign that a heart attack may occur in the next few hours. Here, stents can be lifesaving.
Stenting involves inserting a narrow catheter into a blood vessel in the wrist or groin area and threading it toward the heart. Cardiologists then insert wire mesh stents to widen obstructed arteries and restore blood flow.
The big question-and one that’s been debated for more than a decade-is whether stents benefit patients with stable angina. Particularly, do they offer any additional benefit beyond the well known benefits of cardiovascular drugs such as blood thinners, statins, blood pressure medications, and aspirin?
High hopes knocked down
In the 1980s, many cardiologists became convinced that stents would prevent heart attacks and save lives. Those hopes were toppled in 2007, when results from the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial were published in The New England Journal of Medicine. In this carefully designed study of 2,287 volunteers, adding stenting to drug therapy didn’t reduce the rate of heart attacks or death compared with using drugs alone.
Many cardiologists continued to use the devices. The reason: Even though stents didn’t save lives, the cardiologists remained convinced that they would ease angina and improve patients’ quality of life.
Now, even that’s in doubt. In ORBITA, British researchers recruited 200 patients with angina, mostly in their 60s, who had a severe obstruction in a single blood vessel supplying the heart. The volunteers were prescribed intensive, six-week drug therapy to reduce angina symptoms. After that time, a random group of 105 patients underwent PCI with drug-eluting stents.
A second group of 95 patients were sedated and had catheters inserted, but no stents were deployed-this sham (fake) stent procedure served as a placebo control. The trial was double-blinded so that neither patients nor researchers knew who was given a stent and who had sham treatment.
Six weeks after the procedures, researchers tested how long patients could exercise on a treadmill before experiencing chest pain, a standard exercise-tolerance test for angina. The results showed no statistical difference between the stent and placebo groups. On almost every measure, patients who received stents were no better off than those who didn’t.
The power of the placebo
ORBITA carries special weight because it’s the first time researchers tested stents against a placebo in a double-blinded, randomized study-considered the gold standard of trial types. Researchers have long known that the placebo effect can be extremely powerful. Patients given a sugar pill and told it will make them better often do feel better. Previous research shows that medical procedures are likely to have an even stronger placebo effect than drugs.
Based on ORBITA’s results, many experts say cardiologists should stop routinely using stents to treat stable angina. In an editorial that accompanied the study, heart disease experts didn’t mince words. “First and foremost, the results of ORBITA show unequivocally that there are not benefits for PCI compared with medical therapy for stable angina,” they wrote. “Based on these data, all cardiology guidelines should be revised.”
Without a doubt, updating guidelines based on one study is premature. Still, many experts acknowledge that a placebo study like this one represents substantial evidence. Whatever its limitations, it calls into serious question the widespread use of stents to ease stable angina and emphasizes the need for additional robust research.
The burden of proof
Critics of the study argue that:
- Because the trial included only 200 people, it doesn’t have enough statistical power to make sweeping conclusions.
- Small differences in baseline characteristics between the treatment and placebo groups might have affected outcomes.
- The study’s conclusions are based on tests given six weeks after treatment-perhaps too soon to detect potential benefits and for any placebo effect to wane.
- The patients were given a strict drug regimen to follow at the start of the trial, and many had low levels of angina by the time of the procedure. It’s questionable whether a stent could add any benefit to such patients, who normally wouldn’t be ideal candidates for PCI.
- Patients had an obstruction in only a single blood vessel. Patients with multiple obstructed blood vessels may still benefit from stents.
One thing is clear: It can’t be overstated that ORBITA’s results apply to a certain study population with one blocked vessel and not to people with multiple blocked arteries or unstable angina, for which stenting is a lifesaving procedure.
The bottom line
For now, if you have a stent for stable angina, you shouldn’t worry. True, ORBITA’s results suggest stents may not offer as much benefit as once thought. But the trial did not conclude that intensive drug therapy was more effective than stents-only that both have the same effect.
According to guidelines, drugs are the first-line treatment for stable ischemic heart disease. ORBITA underscores how effective proper drug therapy is in improving angina. Stents should be considered when drugs don’t work adequately. In practice, the intensive drug regimen employed in ORBITA-and frequent physician oversight of patients-isn’t always standard therapy. In fact, fewer than half of patients undergoing PCI were taking the ideal drug regimen to improve blood flow prior to stenting, according to the U.S. National Cardiovascular Data Registry.
If you have been diagnosed with heart disease and are a candidate for PCI, ask your doctor whether stents would offer any benefit beyond that already provided by medication. Factor into the decision your willingness to comply with a long-term regimen of taking two to four drugs, one or more times a day, to relieve angina. Some people might opt for stenting to control symptoms because it could potentially reduce the need for intensive drug therapy and its side effects. But people who undergo PCI must take two anticlotting drugs-aspirin indefinitely and clopidogrel for one year or more.
You should also carefully consider the procedure’s risks. Fortunately, the overall risk of complications from stents is low-only about 1 to 2 percent. And most complications can be managed effectively. Risks include bleeding during or after the procedure, hematoma (blood seeping out of a vessel into surrounding tissue), allergic reactions to the contrast agent used during the procedure, renarrowing of the treated artery (called restenosis), blood clots, and stroke. And be sure to weigh the costs of PCI versus ongoing drug therapy.
Given the new findings, many cardiologists are reappraising their usual advice. Whatever you and your cardiologist decide, make sure you continue to take your heart medications as directed.