DOCTOR'S VIEW ARCHIVE
The New "Coated" Stents - What's The Story?
Much has been written and spoken in the media recently about the new "coated" intracoronary stents, and how they are a major advance in the management of coronary artery disease. I would like to present the background on this and discuss the impact and future of these stents.
The nonsurgical treatment of coronary artery disease began with the introduction of balloon angioplasty (PTCA) in the late 1970's. The major drawback of PTCA was recurrence in the first 6-12 months following the procedure, called restenosis (recurrent narrowing), with reported "failure" rates of 30-60%. Many trials were conducted over the next 15 or so years with a multitude of drugs and atherectomy ("roto-rooter") devices, with no appreciable impact on the rate of restenosis. About ten years ago, intracoronary stents became widely available, and reduced the restenosis rate to about 15-30%. The stent is a thin slotted metal tube which is implanted in the coronary artery using a small balloon, in a procedure very similar to standard PTCA. Restenosis after stent implantation occurs because of the formation of soft scar tissue in the center of the stent, which blocks coronary blood flow in a fashion similar to the original blockage that was present before the stent was implanted; the process of restenosis is likely caused by trauma to the inner lining of the wall of the coronary artery when the stent is implanted. Restenosis inside a stent almost invariably occurs in the first 3-12 months after the stent is implanted, and is decidedly unusual after that time period.