DALLAS, Feb. 1 -- Radiation has long been used as a method for killing cancer cells. Now researchers say radiation looks promising as a way to kill the overgrowth of tissue cells that can lead to a reblockage of a heart artery, according to a report in today's issue of Circulation: Journal of the American Heart Association.
"Radiation may one day offer a solution to a long-standing problem – reblockage of a heart artery following angioplasty, particularly in patients who receive stents," says lead author Paul S. Teirstein, M.D., director of interventional cardiology at Scripps Clinic in La Jolla, Calif. In angioplasty, a balloon-tipped catheter is threaded into the blocked artery and the balloon is then inflated to widen the narrowed vessel. Sometimes a stent -- a metal coil -- is implanted as well to hold the walls of the vessel open. However, doctors have found that a build-up of scar tissue resulting in a reblockage of the artery is a common complication after a stent is put in.
In this study, a ribbon containing sealed radioactive pellets -- a technique called brachytherapy -- was threaded into the affected artery. The ribbon was left in place for 20 to 45 minutes to administer the prescribed dose of radiation to the artery, and then removed. Researchers report that after three years the patients who received the radiation had less than half the rate of reblockage as patients who did not undergo the radiation treatment.
"Brachytherapy is of particular value to patients with in-stent reblockage for whom there is no effective alternative because their coronary artery disease is so severe," say the authors of an accompanying editorial, David O. Williams, M.D., and Barry L. Sharaf, M.D., division of cardiology at Brown University. Sharaf, an associate professor of medicine at Brown University says the "study alleviates some of the unknowns" about the long-term effectiveness of the radiation treatment. "This is now the largest study with long-term follow-up of this treatment," he says. Although previous studies had found intracoronary radiation to be safe and effective, the scientists involved in this latest study wanted to find out if the procedure was successful over the long-term, and also to make sure there were no long-term adverse health effects associated with it.
"We were concerned that there might be adverse effects that would outweigh the benefits, and that we would be merely delaying the reblockage of these arteries," Teirstein says. "However, this study tells us that after three years, intracoronary radiation continues to be a safe way to treat reblockages of heart arteries."
All the patients in the study had stents, and some had in-stent reblockages. Twenty-six patients received the radiation treatment and 29 did not. Three years later, only 15.4 percent of the patients in the radiation-treated group had reblockages of the affected heart artery, compared to 48.3 percent of the untreated group.
Additionally, researchers found that the rate of deaths, heart attacks and reblockages was much lower in the radiation-treated patients compared to the untreated group (23.1 percent vs. 55.2 percent).
Teirstein says that although the study results are promising, it does not mean that 10 to 20 years out the procedure will show the same effectiveness. "It would be premature to recommend radiation therapy as the first line of treatment for patients with clogged heart arteries," he says, and adds that additional scientific study is needed.
The editorial writers add that further study should be done of specific patient subgroups, including those who receive the radiation implants both with or without stents, and that these patients need to be observed for a longer time period, such as five to 15 years following the procedure.
Co-authors include Vincent Massullo, M.D.; Shirish Jani, Ph.D.; Jeffrey J. Popma, M.D.; Robert J. Russo, M.D., Ph.D.; Richard A. Schatz, M.D.; Erminia M. Guarneri, M.D.; Stephen Steuterman, M.S.; Kathleen Sirkin, R.C.V.T.; David A. Cloutier, B.S.; Martin B. Leon, M.D. and Prabhakar Tripuraneni, M.D.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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