Abstract 14135: Differential Response of Arterial Healing Following Second- versus First-Generation Drug-Eluting Stents in Humans - A Pathologic Study
Background: Previous pathologic studies in 1st-generation drug-eluting stents (1st-gen DES; sirolimus- [SES] and paclitaxel- [PES]) have demonstrated that delayed arterial healing is accompanied by poor endothelialization as the primary substrate underlying late stent thrombosis (LST). Several clinical studies have reported that 2nd-generation zotarolimus- (ZES) and everolimus-eluting stents (EES) (2nd-gen DES) show a lower incidence of LST than 1st-gen DES. Little is known about the pathologic findings of 2nd-gen DES in human coronary arteries.
Methods: From our stent registry, a total of 114 autopsy cases to include 159 DES lesions (1st-gen=136 [61 SES, 75 PES] and 2nd-gen=23 [6 ZES, 17 EES]) with duration of implant >30 days and ≤2 years were examined. Histomorphometry was performed on 2nd- vs. 1st-gen DES where endothelial strut coverage, fibrin deposition, and inflammatory response were assessed. Coefficient of variation (CV) of neointimal thickness (standard deviation divided by mean neointimal thickness) was calculated as a marker of neointimal uniformity.
Results: Age, sex, risk factors, and duration of implant (1st-gen=211 [91-383] vs. 2nd-gen=180 [99-360] days, p=0.81) were similar between 2 groups. LST was more frequent in 1st-gen than in 2nd-gen DES (25.7% vs. 4.4%, p=0.02). The results of histomorphometry are shown in Table. The percent of uncovered struts was significantly lower in 2nd-gen DES, while mean neointimal thickness did not differ significantly between the groups. CV of neointimal thickness was more prominent in 1st-gen than 2nd-gen DES. Moreover, fibrin deposition was less in 2nd-gen as compared to 1st-gen DES.
Conclusions: ZES and EES show a lower incidence of LST and substantially less uncovered struts with more uniform neointimal coverage with less delayed healing (fibrin deposition) than 1st-gen DES in man; these findings are consistent with greater clinical safety of 2nd-gen DES.
- © 2011 by American Heart Association, Inc.