Background: Edge restenosis is not an unusual finding after implantation of drug-eluting stents (DES). We hypothesized that mechanical stress imposed on the stent edge would cause vessel wall injury and inflammation, which may consequently lead to edge restenosis.
Methods and results: In total, 1,496 patients were implanted with a sirolimus-eluting stent (SES), paclitaxel-eluting stent (PES) or zotarolimus-eluting stent (ZES) in Seoul National University Hospital between 2007 and 2009. Binary restenosis occurred in 161 lesions in 119 patients. We retrospectively compared the 3 DES with regard to the percentage of edge stent restenosis among all cases of restenosis. We also evaluated the maximal, minimal, and Δ (maximal angle-minimal angle) angles. The percentage of edge restenosis was higher for SES than for ZES (37.5% vs. 16.7%, P=0.017). Maximal angle at the proximal edge was 64.82°±33.46° for 26 stents with proximal edge restenosis compared with 31.84°±31.51° for 89 stents without proximal edge restenosis (P=0.001). The Δ angle was also significantly different between the 2 groups (14.81°±15.98° vs. 7.60°±8.86°, P=0.035). Similar findings were observed for distal edge restenosis. Both the maximal angle (39.09°±21.04° vs. 22.71°±22.83°, P=0.010) and Δ angle (20.23°±15.39° vs. 9.18°±9.66°, P=0.016) at the distal edge were significantly different between the 2 groups.
Conclusions: Physical stress determined by angulation at the stent edge segment and biomechanical properties of the DES can be considered as one of the plausible mechanisms for edge stent restenosis.