Geographical miss and restenosis during catheter-based intracoronary β-radiation for de novo lesions

Objectives: We sought to determine the impact of geographical miss (GM) on restenosis rates after intracoronary β-radiation therapy for de novo lesions. Background: GM is the situation in which injured vessel segments (VSs) are receiving low-dose radiation and is accounted for edge restenosis. Its impact on the overall restenosis rates remains to be determined. Methods: We analyzed 330 patients (356 vessels) treated according to the Beta Radiation in Europe (BRIE) and the Dose Finding study protocols. Using quantitative coronary angiography (QCA), the effective irradiated segment (EIRS), its edges and the total VS were analysed. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis >50% at follow-up. GM was determined by the simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated and surrounded by contrast, at the site of injury, in identical angiographic projections. Results: In 20.5% of the vessels, GM was non-interpretable due to inadequate filming. GM occurred at 30.4% of the interpretable edges and 53% of the interpretable vessels that were analysed. Edge restenosis was significantly increased in the GM compared to non-GM edges (13.16% vs. 4.17%, respectively, P=.001), both in the proximal (P=.03) and the distal (P=.001) edges. GM associated with stent injury significantly increased edge restenosis (P=.006). GM related to balloon injury tended to be associated with increment in edge restenosis (P=.07). The restenosis in the EIRS was similar between vessels with and without GM (17.78% and 14.85%, respectively, P=.6). GM was associated with significant increment in the restenosis at the analyzed VS (31.85% vs. 21.48%, P=.05). Conclusions: GM is strongly associated with edges and restenosis in the analysed VS. GM does not increase restenosis in the EIRS.