Drug-eluting stents to prevent restenosis (DES)
We are evaluating, in clinical research protocols, different methods to stimulate growth of new blood vessels (angiogenesis) or new myocardial cells (stem cell therapy).
Our Center is particularly devoted to the use of advanced techniques to re-open chronically occluded coronary or peripheral arteries.
In the field of interventional cardiology restenosis after stent implantation is a substantial medical problem, occurring in 20-35% of the patients within 6 months from implant. In patients with diabetes, this percentage increases on average to 40%.
In-stent restenosis is the consequence of an excessive scar formation (similar to that occuring on the skin when a cheloid forms). In fact, restenosis occurs when the scar formation, which is the response to the initial vessel wall injury induced by stent implantation, goes beyond the normal vessel wall healing. In detail, this excessive scar formation is due to an increased proliferation of the smooth muscle cells of the vessel wall, which pass through the stent struts, invading the vessel lumen.
Sirolimus, a naturally occurring macrocyclic antibiotic, is a potent immunosuppressive agent inducing late G1 cell cycle arrest (cytostatic agent). The drug, approved in Italy and used clinically for the prevention of rejection after renal transplantation, is incorporated on the stent surface binded to a polimer.
The quantity of Sirolimus delivered in the bloodstream, thus its potential systemic effect after stent implantation, is mimimum (dose 100 times lower) compared with the doses used in the clinical setting, as chronic treatment for the prevention of rejection after renal transplantation. Therefere, there are not the contraindications related to the usage of systemic dosages of the drug.
The Sirolimus-eluting stent accomplishes two tasks:
- Scaffolds the vessel lumen
- Slowly elutes in the 2-3 weeks after implantation the drug which reduces restenosis by its antiproliferative effect
Thanks to this new stent, an increasing number of patients will avoid Coronary Artery Bypass Graft (CABG) surgery, an invasive open-chest surgical intervention performed with cardiac arrest and extracorporeal circulation.
Extraordinary results have been demontrated by recent muticenter double blind randomized trials (RAVEL-SIRIUS-TAXUS-ENDEAVOR-SPIRIT) with two-arm design, which assessed the safety and effectiveness of these Stents.