Dec. 13, 2002
Last reviewed by Faculty of Harvard Medical School on Decenber 1, 2008
By Thomas H. Lee, M.D.
Brigham and Women's Hospital
Innovations that are supposed to revolutionize the care of various diseases are rumored and written about all the time, but very few of them actually pan out. In the last few years, however, a technology has reached the U.S. marketplace that is the real deal. The main unanswered question is whether these devices are going to influence the care of people who do not even think of themselves as having heart disease right now.
The innovation is drug-coated stents for coronary angioplasty. For a decade now, cardiologists have been increasingly using wire-mesh stents to hold open coronary arteries after dilating narrowings with balloon-tipped catheters. The problem that plagues about one-third of patients who receive angioplasty with or without stents is “restenosis” – the recurrence of the narrowing of the blood vessel.
The cause of this re-narrowing is not new formation of atherosclerotic plaque. Instead, the problem is that the body is a bit overzealous in its efforts to repair damage to the blood vessel caused by the angioplasty. The scar that results can bulge into the blood vessel, reducing the amount of blood flow within it. Several treatment strategies, including the use of statins, antioxidant vitamins, and radiation, have been tried. Some have helped to reduce the chances of restenosis modestly, but not enough.
The new drug-coated stents release a medication that blocks that scarring process. In published research studies, the rate of recurrence of narrowings has been much lower than with regular "bare metal" stents — under 10 percent. This means that the vast majority of patients who undergo angioplasty with drug eluting stents do not come back for a second procedure.
These stents have been in wide use in Europe, South America and the rest of the world for years, and now there are two types of stents available in the United States. There have been some problems with these new devices during their placement in the patient, but if the procedure goes well, patients have generally done well, too.
While the bugs get worked out of these new drug-coated stents, the question that experts are asking is what will be their impact on all patients with heart disease, including those who might not be candidates for angioplasty today. Here's a list of possibilities.
- Fewer patients will need repeat cardiac catheterizations and angioplasty due to restenosis. This is the easiest change to predict. Right now, about one-fourth of angioplasty procedures are on patients who have had restenosis. These procedures presumably will become much less common.
- Fewer patients need coronary artery bypass graft (CABG) surgery. Many patients who have repeated restenosis currently go on to bypass surgery; those patients will likely do just fine with their stents. In addition, physicians are more likely to advise patients to get rid of angina pain by using stents instead of bypass, since the "downside" of stents will be so much lower. For both reasons, many hospitals have already seen a 15-percent decrease — or more — in the number of coronary artery bypass graft operations that they are performing each year.
- More patients are likely to undergo coronary angiography and angioplasty with stent placement. Because stents no longer will carry much risk of restenosis, physicians are becoming more willing to recommend catheterization so they can see if patients have a narrowing that is "stent-able." For example, a patient who gets occasional angina while playing tennis might be treated with medications alone right now, particularly if the pain always goes away with one or two nitroglycerin tablets. I would not have recommended a stent for such a patient just a couple of years ago due to the risk of restenosis. Now I am more inclined to say to that patient, "Let's see if there is something we can fix permanently."
- The most uncertain possibility is the potential use of stents in many people who have no symptoms of heart disease at all. New testing technologies are developing to screen people who have no angina at all. Since putting in one of the new coronary stents provides protection without risk of restenosis, many cardiologists believe that we should begin looking for patients with atherosclerosis but who do not have symptoms of angina. Atherosclerotic plaques that are too small to disrupt blood flow but are full of gooey lipids can break open and cause a heart attack — the major reason heart attacks occur to some people who have had no warning of heart disease at all. In the future, we may be able to use a variety of new testing technologies to look for "unstable plaques" among people without symptoms. And when they are found, these patients might benefit from coronary angiography and one of the new stents. This approach is far from proven, but many researchers believe it may one day come to pass. On the other hand, other experts think that atherosclerosis is so diffusely spread out when it occurs that stents should mainly be seen as a way of relieving symptoms from tight narrowings — not as a tool for trying to make people who do not have symptoms live longer.
So, the impact of stents is going to go well beyond people who are in the hospital now, and may extend beyond those living with angina. Stents may influence the way physicians evaluate people who feel perfectly healthy. These stents are quite expensive and will make a dramatic contribution to rising health-care costs. It will take a few years before we know for sure how and when they should be used.
Thomas H. Lee, M.D., is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.
