Localized Hypersensitivity and Late Coronary Thrombosis Secondary to a Sirolimus-Eluting Stent

TLDR

The FDA warned of subacute thrombosis and hypersensitivity reactions to sirolimus‑eluting Cypher stents, but the causes and incidence remain unclear. The authors recommend careful long‑term follow‑up of patients who develop vessel enlargement after Cypher stent implantation. In a 58‑year‑old man who died of late stent thrombosis 18 months after Cypher stent placement, angiography and IVUS at 8 months showed vessel enlargement without neointimal growth, and autopsy revealed aneurysmal dilation with a severe localized hypersensitivity reaction dominated by T lymphocytes and eosinophils, indicating a polymer‑induced reaction may have caused the thrombosis.

Abstract

Background— The US Food and Drug Administration recently issued a warning of subacute thrombosis and hypersensitivity reactions to sirolimus-eluting stents (Cypher). The cause and incidence of these events have not been determined. Methods and Results— We present findings of a 58-year-old man who died of late stent thrombosis 18 months after receiving 2 Cypher stents for unstable angina. Although angiographic and intravascular ultrasound results at 8 months demonstrated the absence of neointimal formation, vessel enlargement was present. An autopsy showed aneurysmal dilation of the stented arterial segments with a severe localized hypersensitivity reaction consisting predominantly of T lymphocytes and eosinophils. Conclusions— The known pharmacokinetic elution profile of Cypher stents and the presence of polymer fragments surrounded by giant cells and eosinophils suggest that a reaction to the polymer may have caused late stent thrombosis. Careful long-term follow-up of patients with vessel enlargement after Cypher stent placement is recommended.