Abstract 3440: Hydroxy apatite coating eluting low dose sirolimus shows less delayed healing but equal efficacy to Cypher In Porcine Coronary Arteries
Polymer based sirolimus (S) eluting stents such as Cypher interfere with vascular healing, probably due to the permanent polymer presence and high drug dose. The use of inert non-polymeric but biodegradable coatings such as hydroxy-apatite (H) may be more appropriate. We compared efficacy of low and high dose drug release (25, 40 or 100 μg S) from H to Cypher (Cordis, 100 μg S) in porcine coronary arteries.
Methods. Stents were implanted using QCA. All swine received clopidogrel and ASA during 28 days follow-up. Safety (no drug, study I, n=6/stent) was studied comparing H to Bare metal stents (B). Efficacy (with drug release, study II, n=13/stent) compared H-25, H-40 and H-100 to Cypher.
Results. All stents remained patent. Morphometry of study I showed no differences in neointimal thickening (N) and complete healing in all groups. In study II (Table⇓), N was similar in all groups regardless of dose and with a normal appearance of the endothelium. There was, however, a dose dependent increase in fibrinoid (F, p=0.004), considered to be a marker of delayed healing. In addition, Cypher induced more inflammation than the other groups.
Conclusion. Hydroxy-apatite is a safe coating and effectively releases Sirolimus. All dosages were equivalent to Cypher at 28 days even at a 4-fold lower dose and shows significantly less fibrinoid.