Question: When do cardiologists use drug-coated stents and when do they use regular stents?
Answer: There are two types of stents. As a general classification the cardiologists choose from: bare metal stents and special, coated stents, which we call drug-eluting stents. The stents are the same as far as their metallic backbone.
They hold open the blockage. If there's any tears in the artery, they seal and fix the tears, and you get a beautiful, wide-open blood vessel when you're done.
However, with a bare-metal stent, in approximately 30 percent of patients -- not quite one in three -- within the first six months or one year, the blockage will re-narrow.
And I make the analogy, this is like when you injure yourself. If you cut your hand, you get a scab that forms, a little bit of scar tissue -- that's the normal body's way of healing any sort of injury.
Now most people, approximately two thirds, will get a thin little scar or scab inside the artery, and that heals the artery very nicely.
But approximately a third of patients will have an excessive amount of scar or scab form, given the size of the artery, because these arteries are actually quite small, and that will gradually re-narrow the artery within the first six or twelve months, and that's what we call re-stenosis.
And when that happens, a patient who was initially feeling very well will suddenly get his discomfort back, his angina, or get short of breath again, or have other limitations that requires another visit, and usually either another angioplasty or, in some cases, bypass surgery.
Now, a drug-eluting stent is meant to try to prevent the scar tissue from coming back, and there are several different types now -- two that are approved in the United States and more that will be coming -- that basically have a special drug that delivers the agent right at the site of the injury to the artery and prevents much of the scar tissue from recurring.
And we know that the likelihood of the arteries re-narrowing after drug-eluting stents are much less than after bare metal stents, but these are very potent compounds, and sometimes they cause the artery to heal to a minimal degree. And, as a result, occasionally blood clots can form on drug-coated stents.
To prevent this, patients have to take two different anti-platelet agents. So, aspirin inhibits platelets, it's a fairly mild drug, and there's another drug we use routinely called clopidogrel. With bare metal stents you take both for 30 days; with drug-eluting stents, you take both for one year and sometimes longer.
And for the most part, this means that the likelihood of getting a blood clot is very, very small, and patients benefit from having long-term survival free from recurrent symptoms, repeat hospitalizations, and need for second angioplasty procedures or surgery.