For Blocked Arteries,
New Device Is a Leap Forward
David Scott Marks, MD
Medical College of Wisconsin Cardiologist;
Director, Cardiac Catheterization Laboratory and Clinical Trials
Named one of the "Best Doctors in America®" 2004 by Best Doctors, Inc.
Last spring, a promising new device hit the medical marketplace. Known variously as the "drug-coated stent" or "drug-eluting stent," it is a major advance in the treatment of arterial blockages. David Marks, MD, tells the story.
Q. What is a drug-coated stent?
A drug-coated stent is a marriage between a stent — which is a stainless steel prosthesis to hold an artery open — and medications to keep scar tissue from forming on that stent.
Q. An interesting history leads up to the drug-coated stent. Can you sketch it for us?
Coronary interventions began with angioplasty in the late 1970s. This is a procedure in which we open arterial blockages using a balloon to dilate the artery rather than using bypass surgery. This was very beneficial in that it was a less traumatic way to provide people relief from their symptoms.
But it was limited in two ways. One was abrupt closure, which means that after we would blow up the artery, the artery would close up and the patient would need to go for emergency surgery. The second was a problem called restenosis or "re-blockage." In almost 40% of the arteries that we fixed, the blockage grew back within nine months — with scar tissue and the artery shrinking rather than with a cholesterol deposit, the original disease. So by traumatizing the blood vessel we created a new problem. Stents are metallic scaffoldings that hold the artery open. They were introduced in the early 80s, and they almost completely did away with the problem of the artery closing up immediately, so emergency bypass surgery after a coronary intervention has become extremely rare. What stents also did was they held the artery open so the artery couldn't shrink, so they reduced the restenosis rate by almost half. The problem was while that's very good, scar tissue formation within the stent was more aggressive.
Now, we have found that if we coat the stent with a medication to inhibit scar tissue formation, we can almost completely abolish restenosis. So it is thought that with drug-eluting stents we're going to be able to move many patients who would otherwise be referred for bypass surgery into the group that can just be treated with angioplasty and a stent. Similarly, for patients currently being treated with medications, we now have a more effective mechanical way to open their arteries.
Q. There was some confusion last summer about the device's safety. What's the latest word?
When a new device is released, it is incumbent on the FDA to inform people of any complications associated with the device. One of those releases included the information that blood clots can form on a stent. This happens rarely, but it happens with bare metal stents and it happens with drug-eluting stents, and we don't see any difference between those two groups. So up until now it has been shown to be a very safe therapy and there have not been significant side effects associated with drug-eluting stents.