ANNOUNCER: When an artery narrows in the heart, one solution to fix the problem is to place a small wire mesh tube called a stent in the artery to support and hold it open. There are two types of stents, a bare metal stent and a drug-eluting stent.
ROBERT S. SCHWARTZ, MD, FACC: Stenting came into common practice in about 1995 or so. It was very commonly used. The first stents were invented only about 1986. Prior to this time, we only opened arteries using balloons, and a major problem was, the artery would often close down, either while the patient was still having the procedure done, or later in the six-month time frame. What the stent has done has solved pretty much both of those problems.
ADOLPH M. HUTTER JR, MD, MACC, FAHA, FESC: A stent is a wire, a type of wire that they actually put into the coronary arteries and balloon up and dilate so they keep the coronary artery open. And there are bare metal stents that just have metal, and then there are drug-eluting stents which have metal and elute a certain drug that keeps the process around the stent from progressing to cause restenosis.
Restenosis is a narrowing up inside that stent, or maybe at the edge of the stent, from the tissue of the coronary artery. And the bare metal stents tend to have a higher restenosis rate than the drug-eluting stents. So the drug in the stent that is eluting helps prevent the restenosis.
ROBERT S. SCHWARTZ, MD, FACC: There's a big difference between bare metal stents and medicated stents. The first stents that we had available to us were bare metal stents, meaning it was nothing but a tube of metal expanded inside your coronary artery on a balloon. A balloon is inflated with liquid, usually water, under high pressure. It opens the stent. The stent is placed in the artery.
While this is better than putting no stent in at all, we soon discovered that if a stent is placed, it in fact increases the likelihood that you'll do well over the next six months to several years. The reason you'll do well is because before this the arteries would close down. Almost half of some arteries would narrow back down due to scar tissue, a process called restenosis.
The advent of the bare metal stent has markedly reduced restenosis from about one in two to about one in three patients. One in three patients is not quite good enough. For this reason, many scientists, engineers and companies have gotten together with many physician researchers and discovered that by putting medicine onto a stent, having the stent actually give medicine to the artery around it after it's been implanted over a long period of time, can really stop in large part the growth of the scar tissue to the point where it becomes a problem
SPENCER B. KING, MD, MACC: The re-narrowing is largely wound healing. It's kind of a scar formulation inside the vessel. You can think of it that way. So if there is this kind of excessive scar formulation that might narrow the artery, the drug-eluting stents can inhibit that.
Now, in some situations, the bare metal stent is perfectly good and as good as the drug-eluting stent, but in other situations, particularly difficult arteries to treat, the drug-eluting stent has offered a big advantage in reducing the chance of re-narrowing.
ROBERT S. SCHWARTZ, MD, FACC: The restenosis rate now with medicated stents is only about one in 10 to maybe even one in 20, depending on how big your artery is and another series of patient factors that are important when the stent is implanted.