Implants and contact allergy: are sensitizing metals released as haptens from coronary stents?

The possible impact of metal release from coronary artery stents has, with their increased use, become a concern.

To study in vitro metal release in biologically relevant milieu from coronary stents made of different alloys.

Coronary stents in common use in a department of cardiology at the time of the study were tested. A previously described in vitro technique was used, whereby the stents were kept in the extraction media for a week. Two different extraction media were used to show the necessity of studying the actual biological surrounding of the implant when metal release is investigated. Metal release was determined with atomic absorption spectrometry.

In this study, we show metal release from stents after immersion in extraction media of artificial sweat and cysteine solution, as illustrative media.

Metal release from coronary stents is shown. The magnitude of release is influenced by several factors. The extent to which metal release in vitro has potential biological effects, in terms of elicitation of an allergic reaction or induction of sensitization, in vivo needs to be explored. However, as metal release from an implant in a biologically appropriate medium has been established, better risk assessments in relation to delayed hypersensitivity may be undertaken.