Inhibition of restenosis with beta-emitting radiotherapy - Report of the Proliferation Reduction with Vascular Energy Trial (PREVENT)

Background-Intracoronary gamma- and beta-radiation have reduced restenosis in animal models. In the clinical setting, the effectiveness of beta-emitte rs has not been studied in a broad spectrum of patients, particularly those receiving stents. Methods and Results-A prospective, randomized, sham-controlled study of int racoronary radiotherapy with the beta-emitting P-32 source wire, using a ce ntering catheter and automated source delivery unit, was conducted. A total of 105 patients with de novo (70%) or restenotic (30%) lesions who were tr eated by stenting (61%) or balloon angioplasty (39%) received 0 (control), 16, 20, or 24 Gy to a depth of 1 mm in the artery wall. Angiography at 6 mo nths showed a target site late loss index of 11+/-36% in radiotherapy patie nts versus 55+/-30% in controls (P<0.0001). A low late loss index was seen in stented and balloon-treated patients and was similar across the 16, 20, and 24 Gy radiotherapy groups. Restenosis (greater than or equal to 50%) ra tes were significantly lower in radiotherapy patients at the target site (8 % versus 39%; P=0.012) and at target site plus adjacent segments (22% versu s 50%; P=0.018). Target lesion revascularization was needed in 5 radiothera py patients (6%) and 6 controls (24%; P<0.05). Stenosis adjacent to the tar get site and late thrombotic events reduced the overall clinical benefit of radiotherapy. Conclusions-beta-radiotherapy with a centered P-32 source is safe and highl y effective in inhibiting restenosis at the target site after stent or ball oon angioplasty. However, minimizing edge narrowing and late thrombotic eve nts must be accomplished to maximize the clinical benefit of this modality.