Stenting Techniques and Outcomes Vary

A major study released in the March 2007 New England Journal of Medicine found that using stents (metal-mesh tubes) with heart angioplasty generally provides no more lasting benefit than using drugs alone to keep blood flowing properly and to treat angina or stable coronary artery disease.

The research looked at 2,287 non-emergency heart patients in the US and Canada and was historic in that it called into question the widespread elective use of stents in treating heart conditions. But the conclusions should not be applied to measure the benefit of stenting in other parts of the body, says a Medical College of Wisconsin expert in strokes and new brain stenting procedures.

"When we talk about the brain and the heart, we need to keep in mind that we're talking about two very different organs," said Osama O. (Sam) Zaidat, MD, MSc, Medical College Associate Professor of Neurology and Neurosurgery and Director of the MCW Neuro-Interventional Program. "They respond differently to different approaches and different medications.

"We have to be very careful when drawing any conclusion from the recently published heart study results. This study might only apply to the blocked arteries in the heart and in the same inclusion criteria applied in the study. We need additional future study to confirm these findings. I also would rather see the same results come out from further investigations. Generalizing the results from one study is not the right thing to do and clinical judgment remains the best approach.

"When it comes to brain stents, we need similar studies to show that the newly and specifically-designed cranial Wingspan stent is better than medical therapy, or vice-versa." Dr. Zaidat is a principle investigator in studies to determine the safety and effectiveness of the Wingspan stent designed to help prevent subsequent strokes in ischemic stroke victims.

Heart Stent Findings "Astonishing"
Wide media attention greeted the heart stent study report, and several renowned heart specialists described the findings as "surprising" and even "astonishing." The patients studied were not emergency heart attack patients, but those with chest pain (angina) and coronary artery disease that was considered stable, with at least a 70% blockage of an artery.

Every patient in the study received aggressive treatment through what is known as "optimal medical therapy," which case-by-case may have included one or more of: blood thinners such as aspirin, cholesterol-lowering drugs, drugs such as nitroglycerine to relieve angina, and blood-pressure-lowering drugs.

About half of the heart patients also had stents placed to prop open narrowed arteries. In very general terms, after about five years' worth of follow-up was analyzed, the study revealed that the longer-term risks of heart attack, hospitalization for certain heart problems, stroke and death were not reduced by angioplasty with stenting compared with drug therapy alone.

This study added to the continuing debate over the use of elective angioplasty in general, in which a balloon is inserted and then blown up to widen the artery, not just the fairly recent development of also leaving a permanent stent in place to keep an artery open. In some news reports, Mayo Clinic cardiologist and American Heart Association president Raymond Gibbons went so far as to say that hundreds of thousands of elective angioplasties in the US are not needed.

Other experts called for more considered analysis of when angioplasty or medical therapy, or a combination of the two, is most appropriate. An invasive procedure to treat a narrowed artery is not the only alternative, they said, when drugs can accomplish the same goals. Some also noted that the US health care reimbursement system tends to pay more willingly for surgical procedures than for drug therapy that requires long-term maintenance and monitoring.

Heart and Brain: Different Tissues, Different Responses
While thinning the blood and addressing other heart conditions with drugs may prove equally beneficial and less costly than stenting in the heart, that simply may not be true for stenting to treat circulatory problems in the legs or prevent strokes in the brain, said Dr. Zaidat.

For example, the next phase of research into the new Wingspan brain stent will study longer-term outcomes from brain stenting as compared to using optimal medical therapy alone.

Dr. Zaidat stressed that thinning the blood with aspirin or other drugs to deal with narrowed arteries is not the same thing as using "clot-busters" (thrombolytic drugs) to literally break up acute blockages. However, he said, stenting may prove to be of benefit in the brain for both narrowed arteries and arteries that are acutely blocked by clots.

"Brain stenting with the Wingspan stent is for prevention of subsequent catastrophic stroke," said Dr. Zaidat. "Future studies may show that we can use stents to break up clots instead of trying to take them out. We may learn that stents show promise in treating acute blockage instead of using the thrombolytics. I have in fact treated three patients with this new stent for acute blockage, and they did very well, better than with thrombolytics.

"No matter what the brain stent will be used for, data from heart or leg artery studies cannot be applied to the brain and vice versa, because each tissue has a different response. That's one aspect of the dilemma we faced with brain stenting; we need more study to say whether the brain acts differently or not. And we're using a stent that is different from the heart stent from a safety perspective. The composition of arteries at different organ location (brain, heart, leg, kidney) and the tissue surrounding specific organ arteries are also different and may react differently to placing different types of stents.

"The risk of stroke is different from the risk of heart attack from a blocked artery. The percentage of subsequent stroke when you have a brain artery blocked more than 70% is very high, about 35%. These are totally different creatures. You cannot say, because the stent use in a different body area is shown to be controversial in a single study, that one would recommend that people should be taking aspirin instead of undergoing angioplasty.

"Each specific scenario requires its own study to show whether the stent is better or the pills are better, and nothing supersedes clinical judgment by an experienced cardiologist for the heart and an experienced neurologist for the brain."

Dan Ullrich
HealthLink Contributing Writer

For more information on this topic, see the HealthLink article Brain-Specific Stent Shows Promise in Preventing Strokes.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.