Short-term success in reopening stenotic vessels is high, but recurrent stenosis affects a substantial number of patients. Stenting after angioplasty has improved the restenosis rate, but even stented lesions can become clogged over time. Saphenous vein coronary bypass grafts have high rates of stenosis, and angio-plasty of these grafts is often challenging, so any method to prevent blockages in these vessels would be welcome. Waksman and colleagues examined the effects of intravascular radiation therapy on the prevention of restenosis of blocked bypass grafts that had been successfully revascularized.
The investigators enrolled 120 patients who had just undergone revascularization of a blocked graft via angioplasty, laser ablation, or atherectomy drill, followed by stenting. Patients were randomized to brief placement of a thin intravascular ribbon at the stent site with iridium-impregnated or nonradioactive seeds. Patients were eligible only if they had vessel stenoses of certain dimensions that were amenable to stenting.
Inaccurate placement of the ribbon beyond the stent site occurred in 8 percent of patients. There were no differences in postprocedure complications between the radiation and placebo groups. Follow-up angiography was done six months after treatment, and the evaluators were blinded to the treatment group. Restenosis was defined as at least 50 percent narrowing of the graft vessel lumen.
Twice as many placebo-treated patients had restenosis at six months (44 percent versus 21 percent of radiotherapy patients). At 12 months after the procedure, there were no significant differences in the rates of death or myocardial infarction, but the need for repeat revascularization of the treated graft vessel was significantly lower in the radiotherapy group (28 percent versus 62 percent of placebo-treated patients). No perforations or aneurysms occurred in any radiation-treated bypass graft.
The authors conclude that intravascular radiotherapy following reopening of blocked coronary bypass grafts significantly reduces the need for repeat revascularization at 12 months, but it does not change rates of myocardial infarction or survival.