Comparing Bare Metal Stents and Drug Eluting Stents
Drug eluting stents and bare metal stents are in the news these days, especially on the business pages as companies try to prove that "mine is better". I am asked on numerous occasions by patients what they should do if they have one or the other type of stent put in. The answer to this one is quite easy. Just follow the advice of your doctor about control of your medicines, nutrition and exercise, and don't spend any time at all worrying about which one of these stents is better. Let me explain.
When a tight spot (blockage or stenosis) is found in a coronary artery it is similar to when a pipe is blocked in your house, flow does not go through adequately. We try to unblock the flow of blood in the coronary artery. There are several ways to do this that involve different instruments. In the early days of intervention on coronary arteries, we used balloons to open the vessel and they worked pretty well. When they worked (80% of the time) the artery often started to close again within a month, so that we had to go back and redo the same procedure. This occurred about 30% of the time. As you might expect, hospitals, doctors and patients were not especially thrilled that out of every 100 patients, 80 would benefit and 24 of those would still have to be done again within 30 days. To solve this problem, little devices called stents that act as scaffolds to hold the vessel open were developed. These devices look a bit like the spring in a ballpoint pen but are more complex. These tiny metal devices are terribly expensive, but they're helpful because they increased our success rate and decreased the number of patients returning within one month by more than half (perhaps a 90% success rate, and 10% readmission rate).
Although this was much better, we felt that there was still improvement to be made and several solutions were considered. One solution was to change the way the scaffolding was built (and there are now many different designs, each of which claims to be "improved" over the last). Another solution was to use radiation inside the vessel to keep cells from growing inside the stent (this is called brachytherapy). Yet another thought was to place a medicine inside the metal stent that would keep cells from growing there and causing a blockage. In order to do this, a process was put in place that would design a stent that would slowly release (elute) different types of medications into the blood vessel wall. This technique is called a drug eluting stent and the drugs most often used are rapamycin and paclitaxil. There is a great deal of money to be made by "having the best stent". Some recent studies however have looked at things two years down the road, and found out that although early stent problems may occur with bare metal stents, the problem still occurs, albeit a bit later with the drug eluting stents. One recent study demonstrates that results of all stents at 5 years is still quite good.
So what have we learned? That is easy. The interventional cardiologist now has a greater choice of instruments to treat you with. The results are far more successful than they used to be. It is not surprising that in some smaller vessels one type of stent may be better than another. Likewise, it is not surprising that a certain type of stent may be better for a longer blockage or around a different curve. These are issues that may make an interventional cardiologist choose one or another of these small instruments. Therefore, I would not be concerned that the more expensive drug eluting stents do not appear in the long run to be any better than brachytherapy or bare metal stents. Each may have its place.
All patients who receive any kind of stent do need to be aware of the need to continue on aspirin and clopidogrel (Plavix), the latter for at least 12 months. Patients who receive stents must aim to get their diabetes under control (if they have this diagnosis), to lower the LDL cholesterol to 70, to refrain from smoking, and to maintain their weight close to ideal body weight (the National Institute for Health, National Heart Lung and Blood Institute publishes a good guideline for weight and BMI or body mass index that is used by most cardiologists).