DALLAS, Nov. 28 – Radiation therapy significantly reduced the re-clogging of blocked leg arteries, researchers report in one of the best-designed studies on the topic to date in today’s Circulation: Journal of the American Heart Association.
In this first double-blind, randomized trial testing radiation therapy to prevent restenosis (the reblockage of an artery), patients who received radiation therapy in addition to angioplasty had a 47 percent lower rate of reblockage six months after treatment than patients who underwent angioplasty alone, reports Erich Minar, M.D., professor in the Department of Angiology at the University of Vienna, General Hospital in Vienna.
Fatty deposits in the arteries leading to the legs and feet increase the risk of blood clots, which can block leg arteries. Treatment is a difficult problem because recurrence rates are high after angioplasty – a procedure in which a balloon-tipped catheter is threaded through the affected artery and inflated to widen the arterial opening.
Radiation is attracting interest for the treatment of blocked arteries because it inhibits overgrowth of smooth muscle cells, which contribute to the blockages.
In the Vienna study, 63 men and 50 women were assigned randomly after successful angioplasty either to receive an application of radiation known as brachytherapy or no further treatment.
In the brachytherapy procedure, a wire with a radioactive tip is threaded to the site, where it remains in place for three to five minutes and delivers a one-time dose of radiation.
This study defined restenosis as a re-narrowing of the artery by more than 50 percent compared with the diameter of normal segments of the afflicted artery.
One year after the treatment, the target arteries remained open in about 64 percent of the patients who received radiation, compared to 35 percent of those who received angioplasty alone. In the brachytherapy group, none of the 15 patients whose condition deteriorated experienced full blockage. In the group receiving angioplasty alone, four of the 29 patients with recurrence experienced complete blockage, or reocclusion.
The patients in the radiation plus angioplasty group reported no difference in quality of life compared to the angioplasty group, says Minar. “However, in the long term there is an advantage for the radiation patients because restenosis, with necessity of further interventions or surgical procedures, is reduced significantly."
The patients felt nothing specifically from the application of radiation and experienced no side effects, Minar says. A few patients experienced minor effects at the incision site that were easily treated, he says.
Despite the significance of the results, Minar and his team consider the restenosis rate in their study “high, because we could not prevent restenosis in about one-third of our patients." Also, he says, even though short-term results are promising, studies are necessary to determine long-term safety and efficacy of brachytherapy plus angioplasty.
The research is lauded in an accompanying editorial in this issue of Circulation.
“This report adds considerably to the growing body of evidence that radiation therapy is an effective anti-restenosis treatment," writes Paul S. Teirstein, M.D., director of interventional cardiology at Scripps Clinic in La Jolla, Calif., in the editorial.
Also, Teirstein writes that while angioplasty has gained wide acceptance as a first-line treatment for other blocked arteries, such as those around the heart, its role with leg vessels “remains poorly defined." In these vessels, “blood flow rates are low, resistance is high and lesions are often very long. These characteristics raise the risk of recurrence to well over 50 percent, and in some reports, over 80 percent."
Many vascular specialists recommend drug treatment and walking programs as therapy, but walking can be difficult because of leg cramping or fatigue during exertion. Thus, other surgical treatments are sometimes recommended as the best option. These, however, have more adverse effects than angioplasty does.
Still, Teirstein notes, the study's influence on treatment of leg artery blockages could be “profound," but he warns that “radiation is not a ‘cure-all,’" and some patients who receive this new therapy with high hopes will be profoundly disappointed.
“Our failures, however, do provide us with the opportunity for improvement," Teirstein writes. In the future, he says, other treatments may improve the efficacy of angioplasty.
Co-authors of the study are Boris Pokrajac, M.D.; Thomas Maca, M.D.; Ramazanali Ahmadi, M.D.; Claudia Fellner, Ph.D.; Martina Mittlböck, Ph.D.; Wolfgang Seitz, M.D.; Roswitha Wolfram, M.D. and Richard Pötter, M.D.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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