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New Heart Attack Treatment Vacuums Blood Clots From Blocked Arteries
Daniel J. DeNoon
WebMD Health News
Reviewed By Louise Chang, MD
Feb. 6, 2008 -- A tiny vacuum threaded through an artery sucks blood clots away from the heart, improving outcomes for heart attack patients.
Blood clots in the heart arteries cause heart attacks, angina, and other problems. The current treatment -- balloon angioplasty with wire-mesh stents to prop open the artery -- has enormously increased the chances of surviving a heart attack.
Now, the odds of surviving a heart attack may be even better. Instead of using a balloon to squash the clot against the sides of the artery, a new technique allows doctors to vacuum away the clot.
A clinical trial compared the technique -- using the commercially available 6-French Export Aspiration Catheter from Medtronic -- to balloon angioplasty. Felix Zijlstra, MD, PhD, director of the thorax center at the University of Groningen, Netherlands, and colleagues randomly assigned 1,071 heart attack patients to one treatment or the other.
"We are on the brink of a new development," Zijlstra tells WebMD. "Instead of fragmenting clot material with a balloon -- and potentially [sending it downstream to damage the heart], it makes sense to get rid of the debris to start with."
As in balloon angioplasty, the new technique calls for doctors to run a guide wire into the artery and through the middle of the blood clot. But instead of running a balloon catheter along the guide wire, doctors use an "aspiration catheter" -- a thin vacuum -- to suck away the clot. A balloon is then used to push open the artery, and a stent is placed to support the opened artery.
The idea is to keep pieces of the clot -- embolisms -- from breaking loose and blocking smaller arteries, which can kill the sections of the heart fed by these arteries.
In the Zijlstra study, such blockages were seen in 17% of the patients treated with the new technique and in 26% of those treated with traditional balloon angioplasty. The less downstream blockage patients had, the better their outcomes.
Thrombus Aspiration: Treatment Wave of the Future
The technique isn't perfect. Even the highly experienced study researchers failed to remove the clot in 27% of cases. Still, electrocardiogram results returned to near-normal for 56.6% of patients treated with the technique, compared with 44.2% of patients treated with balloon angioplasty.
This isn't a giant breakthrough, but it could represent a significant improvement in the treatment of heart attack, says George W. Vetrovec MD, chairman of the division of cardiology and director of the adult cardiac catheterization laboratory at Virginia Commonwealth University, Richmond. Vetrovec's editorial accompanies the Zijlstra team's report in the Feb. 7 issue of The New England Journal of Medicine.
"What you are really trying to do here is to limit damage to the heart muscle by preventing clots from blocking the small vessels beyond the major obstruction," Vetrovec tells WebMD. "Every bit of heart muscle you save will help -- and in the heart attack setting, that is very important. You just reduce the amount of debris going downstream and therefore have better outcomes."
Zijlstra says that the technique is not hard for doctors to learn. He expects it to become a routine part of medical practice -- although Vetrovec says it remains to be seen whether doctors will be able to perform the procedure on a routine basis. It appears to be cost effective. And one-year follow-up data on the patients in the study suggest a promising trend toward better outcomes.
"Thrombus aspiration will be here to stay," Zijlstra says. "It will be very important for all patients with acute heart attacks. We are now trying to see if other categories of patients will benefit, such as those with unstable angina and other forms of coronary artery disease in which we know blood clots play a role."
SOURCES: Svilaas, T. The New England Journal of Medicine, Feb. 7, 2008; vol 358: pp 557-567. Vetrovec, G.W. The New England Journal of Medicine, Feb. 7, 2008; vol 358: pp 634-637. Felix Zijlstra, MD, PhD, director, thorax center, University Medical Center, University of Groningen, Netherlands. George W. Vetrovec, MD, chairman, division of cardiology, and director, of adult cardiac catheterization laboratory, Virginia Commonwealth University, Richmond.
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