SVG WRIST - SVG WRIST
The goal of SVG WRIST was to determine the efficacy and safety of gamma radiation for the treatment of in-stent restenosis in saphenous vein grafts (SVGs).
Gamma radiation can lower the incidence of in-stent restenosis in SVG lesions.
Patients Enrolled: 120
Mean Follow Up: 12 months
Mean Patient Age: 30-80 years
Mean Ejection Fraction: Mean 48% in the gamma arm and 46% placebo arm.
Age 30-80 years, had a successful percutaneous intervention (defined by residual stenosis <30%) in a vessel with a diameter of 2.5-5.0 mm, with a lesion that was <47 mm long.
Acute or recent MI (within prior 72 hours), left ventricular ejection fraction <20%, angiographic evidence of thrombus, and prior treatment with irradiation of the chest.
Death from cardiac causes, Q wave MI, repeated revascularization of the target vessel, and a composite of these events at 12 months.
Angiographic evidence of restenosis (≥50%) and luminal loss at six months (late loss).
A total of 120 patients with angina and evidence of in-stent restenosis in SVGs were randomized to iridium-192 (n=60) or placebo (n=60), following successful percutaneous transluminal coronary angioplasty (PTCA) with provisional stenting, laser, or atherectomy.
Aspirin (325 mg/day) and either ticlopidine (250 mg twice a day) or clopidogrel (75 mg/day) for one month in the first 85 patients enrolled, and for six months in the remaining 35 patients.
Gamma radiation resulted in a statistically significant reduction in restenosis rates at six months in all segments analyzed when compared with placebo, including in the stented segment (15% vs. 43%, p=0.004) and the analytic segment (21% vs. 44%, p=0.005).
There was no difference between the treatment and placebo arms in 12-month mortality (7% vs. 7%, p=1.0) or Q wave myocardial infarction (MI; 2% vs. 3%, p=1.0). Target vessel revascularization (TVR) was reduced in the gamma arm (28% vs. 62%, p<0.001). Driven largely by TVR, the composite end point at 12 months was reduced in the gamma arm (32% vs. 63%, p<0.001). Late thrombosis rates were similar in the two arms (2% vs. 5%, p=0.62).
Among patients who underwent successful revascularization for in-stent restenosis of SVGs, treatment with gamma radiation brachytherapy was associated with a reduction in TVR, but no difference in mortality or Q wave MI at 12 months. Gamma radiation brachytherapy shows similar benefit in reducing restenosis rates in vein grafts, as previous studies have demonstrated for native coronary arteries.
Use of beta-radiation rather than gamma-radiation may reduce the exposure time from 20-30 minutes to 3-5 minutes, reducing the risk to both the catheterization laboratory staff, as well as the nontarget tissue of the patient. Its use in SVGs has not been well studied, however.
Waksman R, Ajani AE, White RL, et al. Intravascular gamma radiation for in-stent restenosis in saphenous-vein bypass grafts. N Engl J Med 2002;346:1194-9.
Presented at Late-Breaking Trials, ACC 2001.
Keywords: Myocardial Infarction, Atherectomy, Constriction, Pathologic, Angioplasty, Balloon, Coronary, Gamma Rays, Stents, Beta Particles, Thrombosis, Saphenous Vein, Catheterization, Iridium Radioisotopes, Brachytherapy
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