Pathology of Second-Generation Everolimus-Eluting Stents versus First-Generation Sirolimus- and Paclitaxel-Eluting Stents in Humans
Background—Clinical trials have demonstrated that second-generation cobalt-chromium everolimus-eluting stent (CoCr-EES) is superior to first-generation paclitaxel-eluting stent (PES) and is non-inferior or superior to sirolimus-eluting stent (SES) in terms of safety and efficacy. It remains unclear whether vascular responses to CoCr-EES are different from SES and PES, since the pathology of CoCr-EES has not been described in humans.
Methods and Results—A total of 204 lesions (SES=73, PES=85, CoCr-EES=46) from 149 autopsy cases with duration of implant >30 days and ≤3 years were pathologically analyzed, where comparison of vascular responses was corrected for duration of implant. The observed frequency of late and very late stent thrombosis (LST/VLST) was less in CoCr-EES (4%) versus SES (21%, p=0.029) and PES (26%, p=0.008). Neointimal thickness was comparable among the groups, while the percent uncovered struts was strikingly lower in CoCr-EES (median=2.6%) versus SES (18.0%, p<0.0005) and PES (18.7%, p<0.0005). CoCr-EES showed less inflammation score (with no hypersensitivity) and less fibrin deposition versus SES and PES. The observed frequency of neoatherosclerosis, however, did not differ significantly among the groups (CoCr-EES=29%, SES=35%, PES=19%). CoCr-EES had the least frequency of stent fracture (CoCr-EES=13%, SES=40%, PES=19%; p=0.007 for CoCr-EES versus SES), whereas fracture-related restenosis or thrombosis was comparable among the groups (CoCr-EES=6.5%, SES=5.5%, PES=1.2%).
Conclusions—CoCr-EES demonstrated greater strut coverage with less inflammation, less fibrin deposition, and less LST/VLST as compared to SES and PES in human autopsy analysis. Nevertheless, the observed frequencies of neoatherosclerosis and fracture-related adverse pathologic events were comparable in these devices, indicating that careful long-term follow-up remains important even after CoCr-EES placement.
- Received February 2, 2013.
- Revision received September 30, 2013.
- Accepted October 15, 2013.