# Histopathological findings of biodegradable polymer sirolimus eluting stent 7 years after stent implantation

## TL;DR

A biodegradable polymer drug-eluting stent showed favorable long-term healing and low risk of complications seven years after implantation.

## Contribution

This case provides the first long-term histopathological evidence of biodegradable polymer stent performance in humans.

## Key findings

- No in-stent thrombosis or restenosis was observed seven years post-implantation.
- Minimal neoatherosclerosis and favorable vessel healing were noted with near-complete endothelialization.
- Stent struts were embedded in the neointima with no significant inflammation or late thrombosis.

## Abstract

This report analyzes a biodegradable polymer coated drug-eluting stent (DES), Ultimaster (Terumo, Tokyo, Japan), seven years after implantation in a 73-year-old man who died from acute myocardial infarction after discontinuing his medications. Autopsy revealed no in-stent thrombosis or restenosis. Two stents exhibited neoatherosclerosis with calcifying necrotic core and foamy macrophages, indicating a lesser risk of very late stent thrombosis. The findings support the notion that third-generation DES might result in healthier long-term vessel healing and reduced neoatherosclerosis compared to earlier generations, consistent with prior animal studies. This suggests a sustained benefit and safety of the biodegradable polymer coated DES over an extended period.

A 65-year-old male received three 3rd generation biodegradable polymer coated drug-eluting stents (BP-DES), Ultimaster (Terumo, Tokyo, Japan), during percutaneous coronary intervention. Seven years post-implantation, post-mortem histopathological analysis revealed well-healed arterial tissue with near-complete endothelialization and minimal neoatherosclerosis. No significant inflammation or late stent thrombosis was observed, with stent struts embedded in the neointima, indicating favorable long-term vessel healing. This case underscores the long-term biocompatibility of BP-DES, highlighting reduced risks of late stent thrombosis and neointimal hyperplasia over extended follow-up periods.