Two studies, recently published in the New England Journal of Medicine, have suggested a role for radiation therapy in the treatment of restenosis. Every year, thousands of patients undergo balloon angioplasty to open clogged arteries. In 60% of these cases, physicians also insert a stent to keep the artery propped open. Unfortunately, in 35% of cases, restenosis occurs and the patient has to undergo another angioplasty or a bypass operation. Both studies investigated the use of placing radioactive materials into the arteries for a short period of time, and then removing them. Where the studies differ is in the type of radiation that is used. In the first study, the researchers used beta radiation, considered safer because it does not penetrate past the body of the patient. In the second study, gamma radiation was used, and health-care workers had to be shielded.
In the study of beta radiation, 181 patients were treated who had undergone angioplasty for the first time. Once the blockage had been cleared, a radioactive coil was inserted into the artery and was subsequently removed, after a few minutes. Patients were given heart scans six months later and it was found that restenosis had occurred in only 29% of patients who had received the lowest dose of radiation, and in 15% of those who had received a dose that was two times as high.
In the second study, patients had already undergone a previous angioplasty procedure. In 131 patients, after undergoing a new angioplasty, a tiny ribbon containing gamma radiation was inserted and was removed after 20 minutes. In another 121 patients, the procedure was replicated with an identical looking ribbon that contained no radiation. At 6 months post-procedure, 28% of the patients in the radiation treatment group had restenosis, as compared to 44% in the comparison group. Unfortunately, several months after the procedure, 5% of radiation patients developed dangerous blood clots, as compared to only 1% in the control group.
The technique would mean that many patients could be spared bypass surgery or repeated angioplasties, but is obviously associated with several caveats. Further studies with larger numbers of patients are required before any definitive conclusions can be made regarding the effectiveness of the technique. In addition, the possible development of cancers, as a side effect of the radiation treatment in these patients, is of major concern.
Sources
- Verin, V et al. Endoluminal Beta-Radiation Therapy for the Prevention of Coronary Restenosis after Balloon Angioplasty. NEJM 2001;344:243.
- Leon, MB et al. Localized Intracoronary Gamma-Radiation Therapy to Inhibit the Recurrence of Restenosis after Stenting. NEJM 2001;344:250.
