Radioactive stents delay but do not prevent in-stent neointimal hyperplasia

Background-Restenosis after conventional stenting is almost exclusively cau sed by neointimal hyperplasia. beta -Particle-emitting radioactive stents d ecrease in-stent neointimal hyperplasia at 6-month follow-up. The purpose o f this study was to evaluate the I-year outcome of P-32 radioactive stents with an initial activity of 6 to 12 mu Ci using serial quantitative coronar y angiography and volumetric EGG-gated 3D intravascular ultrasound (NUS). Methods and Results-Of 40 patients undergoing initial stent implantation, 2 6 were event-free after the 6-month follow-up period and 22 underwent repea t catheterization and IVUS at 1 year; they comprised half of the study popu lation. Significant luminal deterioration was observed within the stents be tween 6 months and 1 year, as evidenced by a decrease in the angiographic m inimum lumen diameter (-0.43 +/- 0.56 mm; P = 0.028) and in the mean lumen diameter in the stent (-0.55 +/- 0.63 mm; P = 0.001); a significant increas e in in-stent neointimal hyperplasia by IVUS (18.16 +/- 12.59 mm(3) at 6 mo nths to 27.75 +/- 11.99 mm(3) at 1 year; P = 0.001) was also observed. Targ et vessel revascularization was performed in 5 patients (23%). No patient e xperienced late occlusion, myocardial infarction, or death. By 1 year, 21 o f the initial 40 patients (65%) remained event-free. Conclusions-Neointimal proliferation is delayed rather than prevented by ra dioactive stent implantation. Clinical outcome 1 year after the implantatio n of stents with an initial activity of 6 to 12 mu Ci is not favorable when compared with conventional stenting.