Presented by: Alan C. Yeung, M.D.
Li Ka Shing Professor of Medicine; Director, Interventional Cardiology; Chief (Clinical), Division of Cardiovascular Medicine
Stanford University Medical Center
September 8, 2007
Recently, stents have garnered considerable attention as questions of safety and efficacy have been discussed among medical experts as well as in the news. The goal of Dr. Yeung’s lecture was to provide information to those who already have a stent or are faced with a decision about getting a stent. This instructive and topical lecture focused on the safety of drug eluting cardiac stents in comparison to stents without drug coating known simply as bare metal stents. The drug eluting stent (DES), and the bare metal stent (BMS) are small metal mesh implants that are inserted into an artery to help keep it open. The coronary artery, only 3mm in diameter, can become clogged with cholesterol, lipids, calcium build-up, clots, and scar tissue. The stent is inserted as part of angioplasty, a procedure used to reestablish blood flow in a clogged artery. A DES is designed to impede the growth of scar tissue, the body’s injury response to the opening the artery. This proliferation of scar tissue, called restenosis, can grow through the stent, causing re-narrowing of the artery and once again interrupting blood flow, and prompting a repeat procedure.
Randomized, double-blinded trials have shown that the DES does a good job of preventing scar tissue formation and contributes to a decrease in repeat procedures, good news indeed since repeat intervention is not without risk. However, with the use of a DES there is a small risk (.2% or 2:1000 per year) of stent thrombosis where clots are formed, sometimes suddenly, a condition not yet completely understood, with the most likely culprit being the delayed healing. The risk of clot formation has to be weighed against the risk of restenosis, and according to Dr. Yeung the evidence is not so alarming to indicate a DES should not be used. However, the ongoing safety of the stent is very much aligned with the continuation of antiplatelet therapy (usually Plavix), particularly during the first year following implantation of a DES. In fact, there is a 29-30% chance of stent thrombosis if antiplatelet medication is stopped prematurely. Dr. Yeung said that compliance with antiplatelet therapy is exceptionally important even if it means delaying elective procedures (orthopedic, dental, etc.) in order to remain on the antiplatelet therapy.
For More Information:
Dr. Yeung’s Stanford profile
Division of Cardiovascular Medicine