Radiation Reduces Artery Reclogging

Zapping arteries with radiation after clearing out blockages dramatically cuts the chances they will clog up again, researchers say. <br><br>Two new studies suggest that the technology can help eliminate

Thursday, January 25th 2001, 12:00 am

By: News On 6

Zapping arteries with radiation after clearing out blockages dramatically cuts the chances they will clog up again, researchers say.

Two new studies suggest that the technology can help eliminate the most discouraging complication of angioplasty â€” the tendency of newly reopened heart arteries to squeeze shut again within a few weeks.

Both technologies involve inserting bits of radioactive material into the arteries, where it is left for a few minutes and then removed. One uses beta radiation, which does not penetrate beyond the patient's body, and the other uses gamma radiation, which requires medical workers to be shielded.

Despite the apparent advantages, experts worry that both approaches could cause cancer decades later. In addition, several patients getting gamma radiation developed dangerous blood clots.

The studies were published in Thursday's New England Journal of Medicine, along with editorials by doctors from the Food and Drug Administration and Jewish General Hospital in Montreal. The editorials urged using the new systems with caution until bigger, longer studies confirm their safety and effectiveness.

Each year, some 750,000 Americans undergo balloon angioplasty to squeeze open clogged arteries. In about 60 percent of cases, doctors also insert a miniature wire coil, called a stent, to try to keep the artery propped open. This cuts the rate of renarrowing â€” what doctors call restenosis â€” from the usual 35 percent to around 25 percent.

When restenosis occurs, chest pain usually returns, and the usual solution is another angioplasty or a bypass operation. Radiation is the latest attempt to avoid this complication.

``It is very exciting news for us,'' said Dr. Rohit Arora, chief of cardiology at the University of Medicine and Dentistry of New Jersey in Newark, who did not participate in the studies.

The study of beta radiation used a system made by Boston Scientific Corp. and was sponsored by the Prevot Foundation and the Swiss National Science Foundation. The gamma radiation study tested a system made by Cordis, a Johnson & Johnson subsidiary, which financed the research.

The study of beta radiation was directed by Dr. Vitali Verin of University Hospital in Geneva and involved 181 patients who were treated after undergoing angioplasty for the first time. Once the blockage was cleared, a radioactive coil was inserted in that part of the artery, then removed after a couple of minutes.

Heart scans six months later found restenosis in 29 percent of patients receiving the lowest radiation dose and in 15 percent of those getting a dose twice as high. Among patients who did not have a stent implanted, just 4 percent at the highest radiation dose suffered restenosis.

The other study used the more common strategy of treating patients who had already undergone a failed angioplasty. After a new angioplasty, doctors inserted a tiny ribbon containing seeds of gamma radiation in 131 patients, removing it after 20 minutes. An additional 121 patients received an identical-looking ribbon but no radiation.

After six months, 28 percent of the patients who got radiation had restenosis, needed a repeat procedure or had died, compared with 44 percent in the comparison group. However, several months after the procedure, 5 percent of the radiation patients developed dangerous blood clots, compared with 1 percent in the comparison group.

Dr. Martin B. Leon of Lenox Hill Hospital in New York, who directed the gamma radiation study, said he has eliminated that problem in more recent patients by limiting use of new stents and keeping patients on anti-clotting medicines for six to 12 months.

The technique means that many patients can be spared bypass surgery or repeated angioplasties, said Leon, who has worked as a consultant for Cordis.

Arora said the beta radiation system is more likely to pan out because it is easier to operate, the radiation is not widely dispersed and, unlike the gamma system, it has been shown to prevent restenosis after a patient's first angioplasty.

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On the Net:

New England Journal of Medicine site: http://www.nejm.com

American Heart Association site on restenosis: http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/sten.html

National Heart, Loan and Blood Institute site on heart disease: http://www.nhlbi.nih.gov/health/public/heart/other/chdfacts.htm