Prevention of vascular restenosis with radiation

Recently, ionizing radiation has been shown to decrease the proliferative response to injury in animal models of restenosis. The Scripps Coronary Radiation to Inhibit Proliferation Post-Stenting (SCRIPPS) trial was a double-blind, placebo-controlled, randomized trial to test this new treatment modality in restenotic stented human coronary arteries. Patients with previous restenosis and stent implantation were randomized to receive catheter-based radiation with Iridium-192 or a placebo using a catheter-based delivery system. Fifty-five patients were enrolled; 26 were assigned to Iridium-192 and 29 to the placebo. Follow-up angiography was obtained in 96% of patients. Restenosis was observed in 53.6% of placebo patients compared with only 16.7% of treated patients (P = 0.025). Late luminal loss was also significantly lower in the Iridium-192 group (0.38 +/- 1.06 mm vs 1.03 +/- 0.97 mm, P = 0.009). Clinical outcome also revealed a significant reduction in the need for target lesion revascularization in the Iridium-192 group (44.8% vs 11.5%, P = 0.008). In this preliminary study, catheter-based intracoronary radiotherapy substantially reduced the rate of subsequent restenosis. Clinical trials using gamma emitters, beta emitters, and beta-emitting radioactive stents are ongoing.