Pathology of drug-eluting stents: implications for coronary intervention

Polymer-based sirolimus (Cypher) and paclitaxel (Taxus) drug-eluting stents (DES) have become the treatment of choice for patients with symptomatic coronary artery disease. While these stents have reduced rates of restenosis and target lesion revascularization compared with bare metal stents (BMS), late thrombosis [i.e. stent thrombosis occurring > 30 days after percutaneous coronary intervention (PCI)], an often life-threatening complication, has emerged as a major safety concern.

Using human pathological data, we have demonstrated that the current generation US Food and Drug Administration (FDA) Cypher and Taxus DES cause substantial impairment of arterial healing, defined as impaired re-endothelialization, persistent fibrin deposition, and absence or focal presence of smooth muscle cells covering the stent struts compared with BMS. This delay in healing constitutes the most important pathological substrate underlying cases of late DES thrombosis.

This review will focus on the effects of these vascular implants in both animals and humans, especially as they relate to the process of late-stent thrombosis. We will use these data to make practical recommendations regarding anatomic and lesion considerations that may help the interventionalist to minimize the late thrombotic risk of these devices.