Drug-Eluting Stent Basics

Sometimes referred to as a “coated” or “medicated” stent, a drug-eluting stent is a regular metal stent that has been coated with a drug that interferes with the restenosis of the artery.  Restenosis is the problem of

in-stent blockage, which can occur in as many as 15 to 30 percent of patients who receive a bare metal stent. The drug imbedded in the stent is slowly released into the lining of the artery, preventing growth of scar tissue around the stent, the primary cause of re-blockage. Restenosis has several causes; it is a very complex process and the solution to its prevention is equally complex. However, so far, the drug-eluting stent has been extremely successful in reducing restenosis. There are three major components to a drug-eluting stent:

• Type of stent that carries the drug coating
• Method by which the drug is delivered (eluted) by the coating to the wall of the artery (polymeric or other)
• The drug itself – how does it act to prevent restenosis?

In addition, there are several decisions made by the interventional cardiologist that result in a successful placement:

• Correct sizing of the stent length to match the length of the blocked area
• Correct sizing of the stent diameter to match the thickness of the healthy part of the artery
• Sufficient deployment of the stent, making sure that the stent, once placed at the optimum site into the blocked artery, is expanded fully to the arterial wall – under-expansion can result in small gaps between the stent and arterial wall which can lead to serious problems such as blood clots, or Sub-Acute Thrombosis (SAT)

Finally, in addition to aspirin, the patient must take an anti-clotting drug for up to six months after the stenting to prevent the blood from reacting to the new device by thickening and clogging up the newly expanded artery. Ideally a smooth, thin layer of cells grows over the stent during this period and the device is incorporated into the artery, reducing the tendency for clotting. In most cases the patient is released within 24 hours. The drug-eluting stent, which was recently approved by the U.S. Food and Drug Administration, represents a turning point in the treatment of coronary artery disease, potentially reducing the need for cardiac bypass surgery or multiple, less-invasive treatments.