TCT-451 Impact of Stent Recoil and Fracture in RCA Ostium Restenosis Following Stainless Steel or Cobalt Chromium Drug-Eluting Stent Implantation: A Serial Angiographic and IVUS Study

Abstract

Background: PCI procedure of RCA ostium stenosis is still a challenging issue due to high stent restenosis rate, possibly due to mechanical stress. However, mechanisms of restenosis following cobalt-chromium everolimus-eluting stent (EES) or stainless steel biolimus-eluting stent (BES) implantation have not been well clarified. Methods: Sixty-fourRCAostium restenosis cases after 2ndgenerationDES (40EESand 24 BES) were retrospectively analyzed. Serial (post initial stent and follow-up as revascularization) angiographic and IVUS evaluation were performed. In quantitative angiographic analysis (QCA), incidence of stent fracture (defined as complete separation of the stent segments and/or the absence of a stent strut on magnified fluoroscopic image), and partial (only one of the inner or outer struts was separated) and complete (both the inner and outer struts were disconnected) fracture type were evaluated. In IVUS, serial changes ofminimum lumen and stent area (SA), and degree of stent recoil atminimum lumen area, defined as (follow-up SA baseline SA / baseline SA*100), were also measured. Results: Average follow-up phase was 14 10-months. Angiographic and IVUS morphometric parameters were similar in both groups at baseline. Significant lumen narrowingwas observed from baseline to follow-up in both groups (10.2 4.6 to 2.5 2.0, 10.7 5.4 to 2.4 2.3 mm2 in minimum lumen area, EES vs. BES, p<0.01 from baseline to follow-up for all). Stent fracturewasmore frequently observed inBES than EES (85 vs. 8%, p<0.01). In addition, complete fracturewas highly observed inBES (29%) compared to EES (2%, p<0.05). In contrast, significant stent recoil was observed in EES only (11.8 5.7 to 9.0 5.4 mm2, p<0.01 from baseline to follow-up for EES, 11.6 4.8 to 11.3 3.4 mm2, p1⁄4ns for BES, and degree of stent recoil was significantly larger in EES than BES (23.8 vs. 2.6%, p<0.05). Additionally, there was only 1 BES and no EES case that both stent fracture and significant recoil, resulting in stent restenosis, was observed. Conclusions: Stent fracture appears to be the major cause of RCA ostium restenosis after stainless steel BES, whereas stent recoil seem to be associated with restenosis after cobalt-chromium EES.