Very Late Pathological Responses to Cobalt–Chromium Everolimus‐Eluting, Stainless Steel Sirolimus‐Eluting, and Cobalt–Chromium Bare Metal Stents in Humans

Abstract

BackgroundThe “very late” clinical outcomes for durable polymer drug‐eluting stents and bare metal stents (BMSs) have been shown to be dissimilar in clinical studies. Conceptually, the long‐term vascular compatibility of BMSs is still regarded to be superior to drug‐eluting stents; however, no pathologic study to date has specifically addressed this issue. We evaluated the very late (≥1 year) pathologic responses to durable polymer drug‐eluting stents (cobalt–chromium [CoCr] everolimus‐eluting stents [EESs] and stainless steel sirolimus‐eluting stents [SS‐SESs]) versus BMSs (CoCr‐BMSs).Methods and ResultsFrom the CVPath stent registry, we studied a total of 119 lesions (40 CoCr‐EESs, 44 SS‐SESs, 35 CoCr‐BMSs) from 92 autopsy cases with a duration ranging from 1 to 5 years. Sections of stented coronary segments were pathologically analyzed. Inflammation score and the percentage of struts with giant cells were lowest in CoCr‐EESs (median inflammation score: 0.6; median percentage of struts with giant cells: 3.8%) followed by CoCr‐BMSs (median inflammation score: 1.3 [P<0.01]; median percentage of struts with giant cells: 8.9% [P=0.02]) and SS‐SESs (median inflammation score: 1.7 [P<0.01]; median percentage of struts with giant cells: 15.3% [P<0.01]). Polymer delamination was observed exclusively in SS‐SESs and was associated with increased inflammatory and giant cell reactions. The prevalence of neoatherosclerosis with CoCr‐EESs (50%) was significantly less than with SS‐SESs (77%, P=0.02) but significantly greater than with CoCr‐BMSs (20%, P<0.01).ConclusionsCoCr‐EESs, SS‐SESs, and BMSs each demonstrated distinct vascular responses. CoCr‐EESs demonstrated the least inflammation, near‐equivalent healing to BMSs, and lower neointimal formation. These results challenge the belief that BMSs have superior biocompatibility compared with some polymeric coated drug‐eluting stents and may have implications for future stent design.

Favorable early vessel healing after everolimus-eluting stent implantation: 3-, 6-, and 12-month follow-up of optical coherence tomography

“…Although polymer on the first-generation DES and biodegradable polymer of BES could evoke inflammation, high biocompatibility of durable polymer on the EES led to low inflammation at early phase after EES implantation. Mori et al reported that EES demonstrated the least inflammation near-equivalent healing to bare-metal stent and low neointimal formation [24]. Although the drug on the EES is almost released within the first 3 months after implantation, this low inflammation led to a small increase in neointimal thickness from 3 to 12 months, and this neointimal growth did not compromise the lumen area within the stent from our present study.…”

Vascular Responses to First-Generation Sirolimus-Eluting Stents and Bare-Metal Stents Beyond 10 Years

“…In fact, a previous pathological study demonstrated even worse inflammatory responses to cobalt-chromium BMS than to everolimus-eluting stents. 32 If a metal induces atherosclerotic changes after the drug effect has stopped, the amount of metal, represented by size and length of the stent, may have an effect on the development of neoatherosclerosis, as shown in the present study.…”

Five-Year Comparative Efficacy of Everolimus-Eluting vs. Resolute Zotarolimus-Eluting Stents in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

“…One study evaluated very late (1–5 years) pathological response to EES (EES; Abbott Vascular) and BMS (Multilink Vision; Abbott Vascular). A lower inflammatory response of the EES was observed concerning the BMS platform [ 45 ]. The pathology findings translated into better clinical outcomes in the EXAMINATION trial that included 1498 patients with STEMI [ 46 ].…”