What is a Coated Stent?

In coronary medicine, a drug-coated stent is a device that is inserted into constricted arteries located in and around the heart to prevent blockages. The stent itself props the artery open, while the drug is released into the surrounding tissue to keep smooth muscle cells from growing in the stent and causing an obstruction. Coated stents have been demonstrated to be more effective in the treatment of narrowed arteries than uncoated or bare metal stents.

A stent is relatively simple in form. It consists of a metal frame with a cylindrical lattice mesh, which can expand and flex as needed. When coated, a drug is applied to the stent in one of several layers of chemicals. The other layers are typically designed to help adhere the drug to the stent and govern the length of its release into the body. Depending on the needs of the patient, a coated stent can take anywhere from several weeks to several months to fully release its drug contents.

Though a drug coated stent is an effective way of keeping open a narrowed artery, it is not without risks. The implantation of a coated stent carries the same dangers as any invasive surgery, including infection and bleeding. Unique to stent insertion are specific risks of heart attack and the formation of clots in the stent itself, known as stent thrombosis. To counter the risk of thrombosis, newer coated stent designs feature a coating that is biodegradeable. This is intended to reduce the likelihood of clots occurring as the coating disintegrates, a condition known as late stent thrombosis.

In considering bare metal versus coated stents, debate continues over whether the increased chance of clots inherent in a coated stent is offset by the generally improved effectiveness they offer, along with reduced risk of other problems, such as heart attacks. Most issues that arise with the insertion of a stent relate to the body's automatic response to a foreign object. While stainless steel has traditionally been the material of choice for stents, cobalt and even biodegradable polymer designs are being assessed in an ongoing search for substances that are better tolerated by the body.

Stents are not one-size-fits-all. Both their length and diameter can be customized based on the needs of a particular patient. Stent recipients, in addition to medication they may be prescribed for underlying heart problems, are often advised to take aspirin and other anti-clotting drugs to further minimize the likelihood of complications.