Radiation Rids Arteries Of Re-Narrowing For Up To Five Years

The radiation was given inside the artery to prevent restenosis, a potentially fatal renarrowing of the vessel. Restenosis occurs in about 20 percent of heart patients undergoing procedures such as angioplasty or stenting. Such patients require another procedure or bypass surgery. Stents are metal mesh tubes placed in a blood vessel to prop it open where there is a blockage.

“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 treatment, 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, who is director of interventional cardiology at the Scripps Clinic in La Jolla, Calif.

The study involved 55 patients, 26 of whom received radiation and 29 who took a placebo treatment.

Five years later, the researchers found a significant difference between the two groups when they looked at a combination of three outcomes—death from any cause, a nonfatal heart attack, or any procedure to restore the heart’s blood flow.

In the placebo group, 86.2 percent had bypass or suffered at least one of the three adverse events compared to 57.7 percent 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 procedures, researchers placed a 0.03-inch ribbon containing sealed beads of radioactive iridium in the arteries of one group of patients after their arteries were reopened. This form of radiation treatment is called brachytherapy.

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 5 years, fewer of the radiation patients came back with restenosis compared to the placebo group.”

Patients were examined at 6 months, 3 years, and 5 years.

After 6 months, the radiation group had a statistically significant reduction of 74 percent restenosis at the site of their previous narrowing compared to the placebo patients. At 3 years, the reduction was 68 percent and at 5 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. Williams is professor of medicine at Brown University School of Medicine in Providence, R.I.

“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.”

Co-authors include Mark A. Grise, M.D.; Vincent Massullo, M.D.; Shirish Jani, Ph.D.; Jeffrey J. Popma, M.D.; Robert J. Russo, M.D., Ph.D.; Richard Schatz, M. D.; Erminia M. Guarneri, M.D.; Stephen Steuterman, M.S.; David A. Cloutier, B. S.; Martin B. Leon, M.D.; and Prabhakar Tripuraneni, M.D.