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Drug-Coated Stent No Riskier Than Bare-Metal Stent, But…

Posted by medconsumers on June 1, 2009

Drug-coated stents, intended to keep coronary arteries from closing up again, have been under suspicion for causing harm to people years after they had an artery-opening procedure. In earlier studies, the powerful drugs used to coat the tiny wire-mesh cylinders known as stents, were linked to a slightly higher rate of death and potentially fatal blood clots. A new study of Swedish people who were implanted with either a bare-metal stent or a drug-coated stent appears to exonerate the latter.

While this is good news for people who already had a drug-coated stent implanted, it should not distract from the fact that too many Americans continue to undergo artery-opening procedures for non-emergency heart conditions that can be just as successfully treated with drugs alone.

The Swedish study was led by Stefan K. James, MD, Uppsala University Hospital, and published last month in The New England Journal of Medicine. It is based on the information reported to a nationwide registry of all people in Sweden implanted with either a bare-metal or drug-coated stent between 2003 and 2006 (nearly 48,000). Registry studies represent real-world care; whereas clinical trials are likely to deliver what is thought of as exceptionally good care, i.e., highly experienced surgeons at academic teaching hospitals operating on patients with the best prognoses.

The Swedish study found that the 1- to 5-year results from the registry patients were the same, regardless of the type of stent implanted. There was only one advantage to the drug-coated stent. The treated artery is less likely to become constricted again (restenosis). This advantage, however, was slim. Dr. James and colleagues described it this way, “The rate of restenosis at one year was low for both types of stents and was 1.5 percentage points lower with drug-coated stents than with the bare-metal stents.”
Dr. James was asked by e-mail who is an appropriate candidate for a stent, given the fact that researchers now know that a constricted artery does not indicate the location of a future heart attack. “You are correct,” he responded. “The use of the drug-coated stent should be reserved for patients at high risk for restenosis, such as diabetics.” Dr. James explained that there is also a role for drug-coated stents for people with long and very narrow constrictions, less than 3mm in diameter, in the coronary arteries.

The Swedish study illustrates the importance of following people for years after a surgical procedure to see how they fare. Earlier research from the Swedish registry, also published in The New England Journal of Medicine, indicated that people implanted with drug-coated stents had a 30% higher mortality rate. This landmark study, published in 2005, alerted doctors for the first time that the drugs used to coat the stents were causing a slightly increased risk of death and potentially fatal blood clots. It generated attention around the world and many cardiovascular surgeons changed their practice accordingly. Now surgeons start their patients on Plavix prior to surgery and continue the drug long after implantation of a drug-coated stent.

Bottom Line: Stents were first introduced to stop the high rate of restenosis that occurred after a coronary artery-opening procedure, also known as angioplasty. When it was discovered that tissue growth around the implanted stent also caused restenosis, the drug-coated stent was introduced. Some stents are coated with paclitaxel, an anti-cancer drug that has anti-inflammatory effects and others with sirolimus, an immunosuppressive drug. When the 2005 Swedish registry study indicated that the drugs used to coat the stent increased the risk of dangerous blood clots, Plavix, was introduced into the mix. Plavix (generic name: clopidogrel), heavily promoted on TV, has its own risks, primarily stomach or intestinal bleeding and ulcers of the stomach or intestines.

For decades, people have been told that large constrictions in the coronary artery signal future heart attacks which must be prevented by an immediate artery-opening procedure called angioplasty. This hypothesis was disproved 3 years ago by two landmark trials.  Many, if not most, of the one million or so Americans who undergo angioplasty each year (with or without stents) can be treated just as successfully with the same multiple-drug regimen advised for just about everyone after angioplasty.

The exception: People in the midst of a heart attack are appropriate candidates for angioplasty. Unfortunately, about one-third of all heart attack patients do not receive artery-opening treatment within the recommended 12 hours after the first symptoms of a heart attack.

More Information About the Two Landmark Trials:
Heart attack patients who did not receive the recommended treatment in time are represented in the federally-funded Occluded Artery Trial (OAT). This trial, published in 2006 in The New England Journal of Medicine, randomly assigned people who were in stable condition 3 to 28 days after a heart attack to have either an artery-opening procedure with stenting plus multiple-drug therapy or multiple-drug therapy alone. After 3 to 5 years, the people given multiple-drug therapy alone did just as well as the people who underwent an artery-opening procedure plus drugs.

The OAT found no benefit to opening a blocked artery after the heart attack patient is stabilized. The procedure “should be reserved only for certain patients such as those who are unstable or continue to have chest pain following a heart attack,” according to an OAT researcher. See 2006 press release.

In 2007, another landmark trial, known as COURAGE [Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation], produced results similar to those of OAT for people with stable heart disease. The people in this trial had angina (average 10 episodes a week) for about two years before they entered the trial; most had hypertension, over one-third had had a heart attack.  In short, they were at very high risk and were highly symptomatic for a long time prior to the start of this trial.  A five-year follow-up showed that those who were randomly assigned to have angioplasty had the same risk of heart attack and death as those who were randomly assigned to multiple drug therapy.

Maryann Napoli, Center for Medical Consumers© June 2009

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