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| |  DG DISPATCH - TCT: Gamma Radiation For In-Stent Restenosis Effective By Andrew Bowser Special to DG News WASHINGTON, D.C. -- September 24, 1999 -- The first randomized, blinded, multi-center trial of gamma radiation to treat in-stent restenosis shows efficacy, but also a trend toward more death and myocardial infarction (MI) versus placebo.
The study, termed Gamma-1, included 252 patients with restenosis lesions less than or equal to 45 mm in length randomized to a placebo control arm or active treatment, followed by eight weeks of ASA and ticlopidine. Compared to placebo, CRT improved follow-up, in-stent, minimal lumen diameters and trended toward improving follow-up, in-lesion, minimum lumen diameters. In addition, CRT improved significantly follow-up, in-stent and in-lesion (percent diameter) stenosis. At nine months, the frequency of in-stent restenosis was reduced by 57 percent in the treated group. Frequency of in-lesion restenosis was reduced by 41 percent compared to placebo with a little more efficacy observed in short lesions (49 percent reduction) and by 52 percent for diabetics in the study. Study results were presented by Dr. Martin B. Leon, of the Washington Hospital Center, at the 11th annual Transcatheter Cardiovascular Therapeutics (TCT), being held this week in Washington, D.C. Total late revascularizaition was clearly reduced by radiation therapy (24.4 percent versus 42.1 percent, p = 0.003). The efficacy findings corroborate two previous single-center trials. One of these was the WRIST (Washington Radiation for In-Stent Restenosis), in which intracoronary gamma radiation reduced the need for target vessel revascularization by 61 percent, reduced the composite of death, MI and target vessel revascularization by 63 percent, and reduced angiographic restenosis by 67 percent. While overall major adverse cardiac event rates at nine months favored radiation therapy (28.2 percent versus 43.8 percent, p = 0.010), there was one death in placebo versus four in active treatment. Additionally, there were eight MIs in the placebo group compared with 16 in the radiation group. Taken together, the difference was not statistically significant but represented a “trend” in favor of placebo. Dr. Leon suggested the difference in mortality and MI might be explained by more late intimal hyperplasia in the irradiated patients (6.1 percent versus 0). "The benefits of late revascularization associated with gamma radiation therapy are partially offset by the higher frequency of late stent closure," Dr. Leon explained. Suboptimal CRT probe placement may have contributed to the problem, he added. Different results may be observed with concomitant treatment. Currently ongoing, for example, is a study to establish the effectiveness of long-term clopidogrel administration to reduce radiation-related late stent closure.
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