Long-term vascular healing in response to sirolimus- and paclitaxel-eluting stents: an optical coherence tomography study

Abstract

Objectives: This study sought to assess stent strut coverage, malapposition, protrusion, and coronary evaginations as markers of healing 5 years after implantation of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES), by optical coherence tomography (OCT).

Background: Early-generation drug-eluting stents have been shown to delay vascular healing.

Methods: A total of 88 event-free patients with 1 randomly selected lesion were suitable for final OCT analysis 5 years after drug-eluting stent implantation. The analytical approach was based on a hierarchical Bayesian random-effects model.

Results: OCT analysis was performed at 5 years in 41 SES lesions with 6,380 struts, and in 47 PES lesions with 6,782 struts. A total of 196 struts were uncovered in SES (1.5%) compared with 185 struts in PES lesions (1.0%, 95% credibility interval [CrI]: 0.5 to 1.6; p = 0.32). Malapposed struts were present in 1.2% of SES compared with 0.7% of PES struts (0.7%, 95% CrI: 0.03 to 1.6; p = 0.23). Protruding struts were more frequent among SES (n = 114; 0.8%) than PES lesions (n = 24; 0.1%, 95% CrI: 0.3 to 1.3; p < 0.01). Coronary evaginations were more common among SES- than PES-treated lesions (17 vs. 7 per 100 cross sections, p = 0.003). During extended clinical follow-up, 2 patients suffered from very late stent thrombosis showing a high degree of malapposition, protrusion, and coronary evaginations at the time of OCT investigation.

Conclusions: Early-generation drug-eluting stents show a similar degree of strut coverage and malapposition at 5 years of follow-up. Despite an overall low degree of uncovered and malapposed struts in event-free patients, some lesions show a clustering of these characteristics, indicating a heterogeneous healing response, which may be the source for very late adverse events.