Edge restenosis after implantation of high activity 32P radioactive β-emitting stents

Background-A high restenosis rate has been reported at the edges ("edge restenosis") of P-32 radioactive stents with an initial activity level of 3 to 12 mu Ci. This edge effect might be due to balloon injury and to a low dose of radiation at the stent margins. The aim of this study was to evaluate whether the implantation of P-32 radioactive stents with a higher activity level (12 to 21 mu Ci) combined with a nonaggressive stent implantation strategy could solve the problem of edge restenosis. Methods and Results-We compared the results of lesions treated with single radioactive BX stents with an activity of 12 to 21 mu Ci (group 2, n=54 lesions) with the results of lesions treated by single radioactive BX stents with an initial activity level of 3 to 12 mu Ci (group 1, n=42 lesions). There were no procedural events. At the 6-month follow-up, no myocardial infarctions, deaths, or stent thromboses had occurred. Intrastent binary restenosis was 0% in group 1 versus 4% in group 2 (n=2, both at the ostium of the right coronary artery, P=NS). Intrastent neointimal hyperplasia was significantly lower in group 2 than in group 1. The intralesion (intrastent plus peri-stent) restenosis rate was 38% in group 1 versus 30% in group 2 (P=NS), Conclusions-Single P-32 radioactive stents with an initial activity level of 12 to 21 mu Ci reduced intrastent neointimal hyperplasia compared with stents of 3 to 12 mu Ci, but they did not solve the problem of edge restenosis, even if a nonaggressive stent implantation strategy was used.