Each year in the United States, about a million people undergo a procedure called angioplasty, in which plaque is cleared from clogged coronary arteries using a balloon-like device. But in one-quarter to one-third of these patients, the arteries again become clogged, requiring additional surgery, often another angioplasty. Results of a new study, however, indicate that if these patients were to spend an extra 30 to 45 minutes on the operating table to receive low-dose radiation therapy, their chances of avoiding a return trip would be improved. The study, which is being presented today at the American Society for Therapeutic Radiology meeting in San Antonio, was carried out on 252 patients at 12 medical facilities across the U.S. Researchers chose to study repeat angioplasty patients because they are at higher risk for a relapse. Results indicated that low-dose radiation treatment can reduce by 41 percent the chances of such patients having to undergo angioplasty for a third time. "To me, spending that extra half-hour to forty-five minutes is worth it," said lead researcher Dr. Prabhakar Tripuraneni, head of radiation oncology at the Scripps Clinic, La Jolla, Calif. After a patient underwent a standard angioplasty, a radiologist--with the aid of a cardiologist--inserted a catheter into the cleared-out artery. Inside the catheter was nylon ribbon with radioactive seeds attached to it. "Because the seeds are attached to a ribbon, they're not floating around in the patient," said Tripuraneni. "We know how many there are, what the distance is between them and the activity of the radiation seeds. So based on that, I can accurately calculate the dose I want to give." The seeds were removed after 20 minutes. The procedure took a total of 30 to 45 additional minutes. In the study, 131 of the patients had the radioactive seeds while the rest had non-radioactive seeds inserted into their cleared arteries. Neither patient nor doctor knew who was getting the active seeds. After nine months, the coronary arteries of only a third of the patients receiving radioactive seeds had re-clogged, while more than half of those receiving the placebo seeds did. Tripuraneni predicted radiation therapy has the potential to reduce the number of angioplasties by 150,000 to 200,000 a year. "The initial results are very encouraging," observed Dr. Robert Schwartz, a consultant for cardiovascular diseases at the Mayo Clinic at Rochester Minnesota. But he cautioned that the issue of adequate control of clotting must be dealt with and that radiation must be proven to be effective in keeping arteries open over the long term. Dr Tripuraneni said he believes that the radiation works because it stops cells that migrate from the outer portion of the artery to the inner portion after angioplasty. This migration forms excess scar tissue, which clogs up the artery. Fortunately, he added, the radiation only affects those scar-producing cells. Clots did appear in about six percent of patients receiving radiation who required a stent to keep the artery open. Such patients, according to Tripuraneni, would require anti-platelet therapy to prevent a clot. No clots formed in patients who did not require a stent.

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