If your coronary arteries become significantly blocked by plaque buildup, your doctor may recommend angioplasty to improve blood flow to your heart. Approximately 1.3 million angioplasties are performed annually—to reduce symptoms of angina (chest pain) and to treat heart attacks.
Also called percutaneous coronary intervention (PCI), angioplasty is a minimally invasive surgical procedure in which a thin, flexible catheter is inserted in an artery in the leg or arm and guided to the obstructed coronary artery. A tiny balloon placed at the end of the catheter is then inflated at the site of the plaque buildup, which flattens the plaque against the artery walls and improves blood flow to the heart.
The majority of angioplasties involve the placement of a stent, a metal mesh tube that remains permanently in the artery . Stents are used to minimize the occurrence of a common angioplasty complication known as restenosis, a renarrowing of the artery. Without the use of a stent, up to 40 percent of arteries become blocked again, often requiring a repeat angioplasty or bypass surgery.
Types of Stents
There are two kinds of stents: bare-metal stents and drug-eluting stents.
Bare-metal stents act as simple scaffolding to help keep blood vessels open after they're widened by angioplasty. As the artery heals, scar tissue grows over the stent, holding it in place. However, overgrowth of this scar tissue, which occurs in about 20% of people who receive a bare-metal stent, can also reblock the artery.
Drug-eluting stents were developed to prevent this form of restenosis. The stents are coated with medication that is slowly released (eluted) to help prevent the growth of scar tissue in the artery lining. The use of a drugeluting stent reduces the rate of restenosis to less than 10 percent.
Four types of drug-eluting stents are approved by the U.S. Food and Drug Administration (FDA), each containing a different medication to halt new tissue growth. About three quarters of people who receive a stent get a drug-eluting one.
FDA-Approved Drug-Eluting Stents
The FDA has approved several types of drug-eluting stents. Researchers are also developing other stent types that will hopefully lead to fewer cases of stent thrombosis. These include biodegradable stents that dissolve over time and stents with novel coatings.
Stent name (eluting drug)
- Cypher (sirolimus)
- Taxus Express (paclitaxel)
- Taxus Liberté (paclitaxel)
- Endeavor (zotarolimus)
- Xience V (everolimus)
Questions About Stent Safety
Back in 2006, the safety of drug-eluting stents was called into question when researchers reported a small increased risk of blood clots at the stent site, particularly in people with more severe coronary heart disease and in those who didn't take antiplatelet medications. This phenomenon, known as stent thrombosis, can occur more than a year after stent implantation and can lead to a heart attack or death.
Experts are not exactly sure why stent thrombosis occurs, but one possibility has to do with the slowed tissue growth around the stent. Without that barrier of tissue, the rough surfaces of the stent attract blood platelets that can accumulate to form a clot.
In response to the reports of stent thrombosis, the American Heart Association and several other medical societies issued an advisory in 2007, stating that people who receive drug-eluting stents should take aspirin indefinitely and the antiplatelet medication clopidogrel (Plavix) for at least one year after stent implantation to reduce the risk of blood clots at the stent site. These organizations alsorecommended that drug-eluting stents be used only in individuals with less severe disease —that is, those not having a heart attack, multiple blockages, or other chronic conditions like diabetes.
Newer Research Allays Stent Safety Concerns
Research on the safety of drug-eluting stents has continued since 2006, and recent analyses show that concerns about stent thrombosis have not translated to a higher risk of heart attack or death —either in the long term or in people with more severe disease.
In one of these analyses, researchers looked at data from 56 studies—22 randomized, controlled trials and 34 reviews of patient registries. Pooled data from the randomized, controlled trials showed that people who received a drug-eluting stent (either a Cypher or a Taxus stent, see the chart above, right) did not have a higher risk of heart attack or death over a three-year period than those who received bare-metal stents.
The patient registries, which more closely reflect "real world" use of stents (that is, patients with less stable coronary heart disease, more complex blockages, and other chronic conditions), showed even better results over this time period. Specifically, drug-eluting stents were associated with a 13% reduced risk of heart attack and a 22% reduced risk of death, compared with bare-metal stents.
Another registry study followed 48,000 people who underwent angioplasty with stenting in Sweden from 2003 to 2006. Most participants received a Cypher or Taxus stent. The results revealed that over a three-year period, those treated with drug-eluting stents had the same risk of a heart attack or death as those who had bare-metal stents implanted.
Which Stent's for You?
Though some studies report that drug-eluting stents are about 50 percent better than bare-metal stents at preventing restenosis, they are not right for everyone. You may be a candidate for a bare-metal stent instead of a drug-eluting one if:
- You can't reliably take dual antiplatelet therapy (aspirin and Plavix) every day for 12 months. With a bare-metal stent, only a one-month course of dual antiplatelet therapy is required.
- You are likely to need noncardiac surgery (such as a joint replacement) in the next year. To reduce the risk of bleeding during surgery, you will need to temporarily stop taking Plavix. But doing so could increase your risk of stent thrombosis if you have a drug-eluting stent. Talk to your cardiologist, who can weigh the risk of bleeding during the surgical procedure against the risk of blood clots forming if you forgo anticlotting therapy.
- You have a high risk of bleeding, for example, because you are already taking another anticlotting medication, such as warfarin (Coumadin, Jantoven) to manage atrial fibrillation or have had a hemorrhagic (bleeding) stroke or gastrointestinal bleeding.
Also, angioplasty is not the only option for coronary heart disease. Medication and bypass surgery are options as well, depending on the location, type, number, and severity of the blockages in the coronary arteries.