Specialties: Stenting, therapeutic angiogenesis and novel forms of coronary revascularization, genetic abnormalities predisposing to coronary atherosclerosis, percutaneous valve repair.
Hello. I’m Dr. Stephen Ellis, an interventional cardiologist in the Miller Family Heart & Vascular Institute. I specialize in the nonsurgical treatment of patients with coronary artery disease. Today, I would like to talk about stents, which are one of the most common types of interventions we use.
Stents are a nonsurgical way of holding a narrowed or blocked artery open to increase blood flow to the heart in people with coronary artery disease. This technology was first approved by the first approved by the U.S. Food and Drug Administration in 1994.
Stents are tiny metal mesh tubes that are placed in the artery using a balloon angioplasty to open up a clogged artery. The stent acts as a scaffold to provide support inside the coronary artery. This is necessary because about 30 percent of patient of patients who undergo angioplasty experience restenosis – or a closing up again of the artery.
The advent of stents has helped. But in-stent restenosis still occurs in approximately 15 to 20 percent of patients within six to nine months. We have learned that restenosis is a very complex process.
Here’s what happens: After the placement of a stent, the body begins healing – a process that takes about six months to complete. This is somewhat different than the process that occurred when the original blockage took place. That process is largely related to cholesterol and inflammation. Healing around the stent involves the production of scar tissue to certain degree. Therefore, restenosis has to do with the growth of smooth muscle cells, not the recurrence of coronary artery disease.
To improve restenosis rates further, a new approach – pharmacologic not just mechanical – was taken. A generation of stents was created using a drug-coating to interrupt the restenosis process. Two drug-eluted stents were approved by the FDA in 2003 and 2004.
Cardiologists determine which type and size of stent is best by using angiogram or intravascular ultrasound just before placement. The stent must be the correct length and size to match the blocked area in the artery. It also must be placed precisely and expanded so that it sits tightly against the artery wall, with no gaps.
After the stent is placed, patients need to take low-dose aspirin daily for life, and another antiplatelet drug, called clopidogrel, for at least one month after bare metal stenting or 12 months after drug-eluted stenting.
While drug-eluting stents do a great job of preventing restenosis, there have been some recent studies questioning the safety of these stents. A U.S. Food and Drug Administration panel addressing this issue made several recommendations in December 2006.
The panel found that while it is important to note that drug-eluting stents are associated with a higher rate of thrombosis – or blood clots forming in the stent – a year after they were implanted, data also shows that drug-eluting stents are not associated with higher death rates in most patients. Patients with more complex disease do have a higher risk of heart attack and death with drug-eluting stents due to late thrombosis than patients with less complex disease. That said, the FDA concluded, these safety concerns do not outweigh the benefits of drug-eluting stents when they are used in patients that meet very strict criteria for severity of disease and size of their blood vessels. After stent placement, these patients also must follow their doctor’s orders regarding taking aspirin and a blood thinner.
At the Miller Family Heart & Vascular Institute, our interventional cardiologists agree with the FDA that careful patient selection is the key to safe use of stents. Stents are simply one valuable tool in the management of coronary artery disease. There are risks involved. They are not a panacea.
We continue to be at the forefront of research of the long-term effects of current treatments, including stents, are actively searching for ways to improve outcomes for our patients. Until further data is available, you should always discuss your options with your doctor to make sure that you are confident in the treatment being recommended.
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