Coronary Angioscopic Evaluation of Drug-Eluting Stents

Toni Rizzo

doi:10.1177/155989771203008

Summary

This article discusses the results of his angioscopic studies of neointimal coverage following drug-eluting stent implantation.

Interventional Techniques & Devices

Masaki Awata, MD, Osaka University Graduate School of Medicine, Osaka, Japan, discussed the results of his angioscopic studies of neointimal coverage (NIC) following drug-eluting stent (DES) implantation. NIC is graded from 0 to 3 as follows: 0=struts exposed similarly to time of implantation; 1=struts covered but not embedded by neointima; 2=struts embedded by neointima but are visible; 3=struts fully covered by neointima. Patients with grade 0/1 coverage have the potential for incomplete re-endothelialization.

Angioscopy of Bare Metal and Drug-Eluting Stents

Angioscopic evaluation at 3 to 6 months after stenting found complete NIC (Grade 2/3) in 2 of 15 patients implanted with the Cypher sirolimus-eluting stent, while all 22 patients with a bare-metal stent (BMS) had complete coverage [Kotani J et al. J Am Coll Cardiol 2006]. In another study [Circulation 2007], Dr. Awata and colleagues used serial angioscopy to evaluate NIC up to 2 years after BMS and DES implantation. He found that patients with the Cypher stent had Grade 1 coverage, 1 to 2 years after implantation; after 4 years, 60% of patients still had grade 1 coverage. Widely exposed struts were reported in 10% of patients 1 year after Cypher implantation. Yellow plaques were detected at 2 years after implantation.

In a study comparing the Cypher versus Taxus paclitaxel-eluting stent, patients with the Taxus stent experienced significantly better NIC at 8 months than those with the Cypher stent (p<0.002) [Awata M et al. JACC Cardiovasc Interv 2009]. A comparison of the Cypher sirolimus-eluting stent and the Endeavor zotarolimus-eluting stent 8 months after implantation demonstrated significantly greater NIC with the Endeavor stent (p=0.0004).

The new Nobori DES is coated abluminally with a biodegradable polymer and Biolimus A9, which is 10-fold more lipophilic than sirolimus. Comparison of heterogeneity of NIC grades at 8 months showed greater homogeneity with the Nobori stent versus the Cypher stent (p=0.045). NIC was not significantly better with the Nobori versus the Cypher at 8 months.

The new Xience V everolimus-eluting stent (0.0032″) is much thinner than the Cypher (0.0055″) and the Nobori (0.0053″) stents. NIC coverage is significantly better with the Xience V versus the Cypher stent at 8 months after implantation (p=0.001; Figure 1) [Awata M et al. J Am Coll Cardiol 2008].

Figure 1.

Comparison of Dominant NIC Grade at 8 Months.

NIC=neointimal coverage; SES=sirolimus-eluting stent; ZES=zotarolimus-eluting stent.Reproduced with permission from the American College of Cardiology. Awata M et al. Angioscopic Comparison of Neointimal Coverage Between Zotarolimus- and Sirolimus-Eluting Stents. J Am Coll Cardiol, August 26, 2008;52:789–790.

Dr. Awata concluded that the new technologies of the Nobori and Xience V stents should be adopted in next generation DES, including the drug and polymer-free luminal surface of the Nobori and the thinner strut of the Xience V.

View Summary