Ask The Doctors: July 2015
When I got a stent I was told the artery might close up again one day. I’d like to know a few things: How quickly does that usually happen? How will I know if it’s starting to happen? If the artery closes, will a new stent be put in and the old one removed? Are there any prevention tips?
Most people know that a coronary artery stent is a metallic tube which, when deployed in a narrowed section of a blood vessel, helps open it up so blood can flow freely again. But a stent is not always a permanent fix. Stents are implanted during one of two major situations. The first is during an acute coronary syndrome (ACS), such as a myocardial infarction (MI) or unstable angina. The second is when individuals experience stable symptoms of chest discomfort which worsen their quality of life. In either case, the goal is to restore adequate blood flow to oxygen-starved heart muscle tissue, and stents accomplish this extremely well. It is very rare for blood clots to form inside of stents, as long as patients reliably take the combination of medications prescribed to them after stent placement, such as clopidogrel and aspirin. One downside of a stent is that it is a foreign object placed inside of a living blood vessel. Our bodies sometimes react to the stent in ways which are unhelpful. For example, scar tissue may form inside the stent and impair circulation. This is called “in-stent restenosis.”
The first stents ever made were constructed of plain metal, hence the term “bare metal stents.” The rate of restenosis was too high in these devices, so stents were developed which would slowly release drugs to inhibit restenosis. We have moved through several generations of these “drug-eluting stents,” or DES. Under the best conditions, less than five percent of DES require re-intervention at one year, while about 10 percent will need another procedure within five years. The more complex the coronary lesion, the higher the chance that another intervention will be required. Your question of whether or not stents are removed is a good one, which is frequently asked. The answer is that stent placement is permanent. They are incorporated into blood vessel walls. Symptoms from restenosis such as chest discomfort usually develop gradually, giving time for patients and their doctors to investigate. Also, there are multiple options to treat re-narrowed stents, including balloon angioplasty (which can cut out scar tissue) and the placement of a stent inside the previous stent. In centers such as Cleveland Clinic, intravascular ultrasound (IVUS) is often used to ensure that the new stent is well-positioned up against the old one. As for what you can do, following a heart-healthy diet, taking medications as prescribed, not smoking, and keeping in close contact with your cardiologist are the best ways to reduce the likelihood of in-stent restenosis.
I’ve read a lot about studies of new heart medications, but have always wondered who the people are in these clinical trials. How does one get involved in a study of an experimental drug or procedure?
There is a long road between being interested in a clinical trial and actually becoming a study subject. Not only are these studies multi-million-dollar projects involving thousands of workers and patients, they also bear a weighty responsibility: to determine if a new drug or device can safely and reliably improve people’s health. Before the first patient is ever enrolled in a trial, years have been spent determining the ideal population to test the treatment, and how to increase the likelihood of obtaining a useful conclusion. A lengthy list of inclusion and exclusion criteria must be applied to each and every potential subject. Because of these stringent requirements, a large number of possible subjects never end up in the trial itself. However, don’t give up hope because of the odds! Ask your doctor if you might be a candidate for a clinical trial, and he or she can put you in touch with the team of individuals tasked with recruitment.