[Drug-eluting stents do they make the difference? ].
The main limitation to further expansion of PTCI (percutaneous transluminal coronary intervention) is restenosis that occurs in 30% of the patients within 6-months after the procedure. Coronary stenting decreases the percent of restenosis due to arterial remodeling after PTCI but proliferation of smooth muscle cells due to vascular injury still remains. A mechanical approach the only treatment up to now (further balloon expansion, plaque removal with rotablator or directional atherectomy) failed. Because the restenotic process is due to a complex series of biological events which start with platelet aggregation, grow-factors and cytochine release, the use of antiflammatory, antithrombotic and antiproliferative drugs were attempted. Cortisone and heparin showed low benefits in clinical trial. New drugs (rapamycin, taxol, actinomycin D, tacrolimus, estradiol, dexamethazone) with antiproliferative and antiflammatory activities are under evaluation. They act as inhibitors of the cell migration and of the cell cicle progression with different specific molecular mechanisms. The first pilot study performed in 45 patients with sirolimus-eluting stents has shown a sustained suppression (25% in the fast release group and 23% in the slow release group) of neointimal formation at 12 months after procedure with absence of restenosis. The Ravel study, a randomized trial, has enrolled 238 patients treated with sirolimus coated stent vs a control group: the results confirm the previous data with a complete suppression of intimal hyperproliferation and restenosis at six months follow-up. The first 400 patients treated in the Sirius trial a similar study which will randomize 1100 pts show a low, but not a complete inhibition of the restenotic process probably due to a more complexity of the lesions treated in comparison to Ravel trial (9.2% of restenosis). Another very promising drug is taxol (paclitaxel). It is an antiproliferative and antinflammatory molecule tested in a series of clinical trials called Taxus. The still unpublished data of TAXUS I and TAXUS II randomized trial show extremely low restenosis rate. Other drugs (actinomycin D, estradiol, tacrolimus, dexamethazone) show to have a potential effect on restenosis and neointimal proliferation and are under investigation. Is very important to maintain lessons learned from the past. The design, the type, the smooth surface of the stent still remains very important as it is a good expansion and a full coverage of the lesions with a "good stent" in the attempt to reduce restenosis. Drug-eluting stents will add further improvement.
Presbitero
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Laboratorio di Emodinamica e Cardiologia Interventistica, Istituto di Clinica Humanitas, Rozzano, Milan, Italy.
Asioli
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D020533:Angiogenesis Inhibitors; D015906:Angioplasty, Balloon, Coronary; D002986:Clinical Trials as Topic; D020099:Coated Materials, Biocompatible; D023903:Coronary Restenosis / Q000517:prevention & control*; D004958:Estradiol; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D007166:Immunosuppressive Agents; D015337:Multicenter Studies as Topic; D017239:Paclitaxel; D004364:Pharmaceutical Preparations; D010865:Pilot Projects; D016032:Randomized Controlled Trials as Topic; D015607:Stents; D016559:Tacrolimus; D013997:Time Factors
D020533:Angiogenesis Inhibitors; D020099:Coated Materials, Biocompatible; D007166:Immunosuppressive Agents; D004364:Pharmaceutical Preparations; D004958:Estradiol; D017239:Paclitaxel; D016559:Tacrolimus