Delivering beta radiation following angioplasty may prevent new blockages from forming in the stents placed in heart vessels, according to results of a multi-center study headed by researchers at the University of Maryland Medical Center in Baltimore. Study results were presented at the 42nd annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Boston on October 24.
The study, called the START trial, enrolled 476 patients at 50 medical centers in North America and Europe. It is the first randomized, multi-center, placebo-controlled study to evaluate the safety and effectiveness of beta radiation to prevent the formation of new blockages inside of stents. A stent is a small tube that is inserted into the vessel to help keep it open after angioplasty is performed. The study found that beta radiation, a highly localized form of radiation, reduced the frequency of repeat blockages by as much as 66 percent in the patients receiving therapy.
"This is encouraging news for patients with coronary artery disease who are at risk of repeat blockages within a stent after an angioplasty," says Mohan Suntharalingam, M.D., a radiation oncologist at the University of Maryland Medical Center and vice chairman of the Department of Radiation Oncology at the University of Maryland School of Medicine.
"The treatment, which is called brachytherapy, takes very little time with minimal radiation exposure to healthy tissues in the patient," says Dr. Suntharalingam, who served as the radiation oncology principal investigator and who will present the results. "This technique also exposes the medical team to less radiation."
More than 75 percent of all patients who undergo balloon angioplasty for coronary artery disease about 700,000 people per year in the United States receive stents in an effort to keep the arteries open longer. However, approximately 25 percent of the patients with stents later suffer from "in-stent restenosis," a condition where the stent becomes blocked with new tissue growth. When this happens, cardiologists have to repeat the angioplasty procedure to unclog the stent.
In the study, patients were treated with a three-centimeter long "radiation train" (a series of small pellets that emit radiation) immediately after angioplasty to open their blocked stents. The pellets were delivered through a catheter that was temporarily placed inside the patient's artery and then withdrawn after a few minutes. The patients were randomized to receive either a placebo or active radiation pellets. Patients returned for follow-up examinations eight months after the therapy. Eighty-six percent of patients treated with radiation pellets had no recurrent blockage after eight months, compared to 59 percent in the control group.
The results from this study are very encouraging," says Warren Laskey, M.D., associate director of Cardiology at the University of Maryland Medical Center and professor of medicine at the University of Maryland School of Medicine. "In addition to having a great benefit for our patients, this therapy could potentially save hundreds of thousands of dollars in medical costs each year." Several thousand repeat balloon angioplasties are performed each year, at an average cost of $20,000 per case, according to Dr. Laskey, the cardiology principal investigator of the study.
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