"The important thing we learned from the five-year follow-up of our patients is that radiation therapy is a durable treatment for restenosis," says Paul S. Teirstein, M.D., the study's senior author.

Equally as important, he and his colleagues found no evidence of serious adverse effects caused by the brachytherapy, which used tiny beads of radioactive iridium.

"We didn't see any unwanted swelling of the arteries, any holes in the arteries, or any other unwanted effects of the radiation therapy," says Teirstein.

The study involved 55 patients, 26 of whom received radiation treatment during angioplasty and 29 of whom received a placebo treatment. Five years later, the researchers found a significant difference between the two groups in a combination of three outcomes--death from any cause, a nonfatal myocardial infarction, or additional reperfusion procedure.

In the placebo group, 86.2 percent had a bypass during the follow-up period or experienced at least one of the three adverse events, compared with 57.7 percent of patients in the radiation group.

"At the beginning of the study, radiation appeared to be a likely candidate to prevent restenosis and beat this cycle of repeat procedures because it had been used in noncoronary cell-proliferation disorders," Teirstein says.

During the active brachytherapy procedures, researchers placed a 0.03-inch (0.076-cm) ribbon containing sealed beads of radioactive iridium in the arteries of one group of patients after their arteries were reopened. The placebo group received similar ribbons but without the iridium. Each ribbon was left in the artery for 20 to 45 minutes and then removed.

"This procedure is designed to reduce the need for repeat procedures," Teirstein says. "Over the five years, fewer of the radiation patients came back with restenosis compared to the placebo group."

Patients were examined at six months, three years, and five years.

After six months, the radiation group had a statistically significant reduction of 74 percent in restenosis at the site of previous narrowing compared with the restenosis rate in the placebo patients. At three years, the reduction was 68 percent; and at five years, it was 48 percent, both also statistically significant.

The number of patients in the study was small, a fact noted by cardiologist David O. Williams, M.D., in an editorial that accompanies Teirstein's study.

"The very small sample size of this trial limits our ability to be conclusive when interpreting its results," writes Williams. "Nonetheless, it appears that efficacy of brachytherapy was sustained over the period of five years."

"This was a pilot study designed to inspire larger studies, which it did," says Teirstein. "These larger studies have shown significant short-term reductions in restenosis, but not all of them have shown benefit in death and nonfatal heart attacks. Given that we have no other long-term data on this type brachytherapy, which is now used in probably 100,000 patients a year, it is nice to have some information over five years."