Nov. 15, 1999 (Cleveland) -- Stents, the tiny wire mesh tubes that are threaded into blocked arteries in the heart and then expanded to create a free-flowing passage for blood, have rapidly surpassed balloon angioplasty as the technique of choice to open blocked arteries. Now, however, a small study from Canada suggests that the stents themselves may damage blood vessels.
The researchers compared three different treatments to open blocked arteries in the heart, and stenting was the only one associated with damage to the lining of the vessels. The other two procedures -- balloon angioplasty and directional atherectomy -- were not associated with damaging blood vessels, according to the study, which is published in the Nov. 15 issue of Journal of the American College of Cardiology.
In balloon angioplasty, a tiny deflated balloon is threaded through the heart to the location where a vessel is blocked. The balloon is then inflated, and the inflation forces the vessel open. The third method, directional atherectomy, uses a device with tiny rotating blades. The device is loaded on a catheter and threaded through the blood vessels; when it encounters a blockage the operator activates the blades, which then slice away at the fatty plaque that is blocking the artery.
The researchers tested 12 patients who had received stents, 15 who had balloon angioplasty, and 12 who were treated with directional atherectomy. The team assessed patients more than a year after they had undergone the procedures to open a single vessel. Patients were given a drug, Miochol-E (acetylecholine), that causes damaged vessels to constrict or spasm.
Co-researcher John D. Parker, MD, says that only patients who had undergone stenting responded with significant constriction. "If this is clinically relevant is unclear," he tells WebMD. Parker is an associate professor of medicine at Mount Sinai Hospital at University of Toronto.
In an editorial accompanying the study, Gregory D. Tilton, MD, writes that the group receiving stents had twice as much spasm further down in the blood vessel away from the previous blockage than did the other two groups. Tilton is a clinical instructor at Louisiana State University Health Sciences Center in New Orleans. "Most studies are looking at the effects of stents on the artery at the point the stent is implanted. We have a lot of those studies, but this is a novel study," he tells WebMD.
Although the number of patients in the study was small, Tilton says the fact that so many of the patients receiving stents had the same damage to the blood vessel makes it interesting. "If the stent itself is doing this we need to know if this is real." He says that the presence of a foreign object -- in this case the stent -- may cause the body's immune system to overreact. This reaction, he says, may cause damage to the vessel lining.
If a stent does cause these changes in blood vessels, the next issue is finding out what effect the changes have. "Is it possible that this could lead to angina ... ?" Tilton asks.
Tilton says, however, that there is no need for alarm because with so many stents placed in recent years, enough time has passed that cardiologists would already be talking among themselves about postprocedure problems. He says there has "been no outpouring of concern in the cardiology community about long-term effects."
Parker agrees with Tilton and says that he, too, is unaware of any rising concern among cardiologists.