SVG WRIST - SVG WRIST

Description:

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).

Hypothesis:

Gamma radiation can lower the incidence of in-stent restenosis in SVG lesions.

Study Design

Study Design:

Patients Enrolled: 120
Mean Follow Up: 12 months
Mean Patient Age: 30-80 years
Female: 20%
Mean Ejection Fraction: Mean 48% in the gamma arm and 46% placebo arm.

Patient Populations:

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.

Exclusions:

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.

Primary Endpoints:

Death from cardiac causes, Q wave MI, repeated revascularization of the target vessel, and a composite of these events at 12 months.

Secondary Endpoints:

Angiographic evidence of restenosis (≥50%) and luminal loss at six months (late loss).

Drug/Procedures Used:

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.

Concomitant Medications:

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.

Principal Findings:

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).

Interpretation:

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.

References:

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.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Aortic Surgery

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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