ENDOVASCULAR STENTS - PRELIMINARY CLINICAL-RESULTS AND FUTURE-DEVELOPMENTS

At present, there is an exponential use of new interventional techniques whose proper role and value have not yet been defined. The intracoronary stent is just one example. There is no doubt that stents can be implanted with a high technical success rate associated with highly predictable immediate angiographic results and that they appear to be superior to all other interventional techniques. However the intrinsic thrombogenicity of all devices currently available for clinical use war rants a vigorous anticoagulation, exposing the patient either to the risk of (sub)acute stent thrombosis or to the risk of hemorrhage and vascular complications. It remains to be determined whether stent implantation will reduce the incidence of restenosis and whether this results in an improved long-term event and symptom-free survival. Experimental studies indicate that the thrombogenic nature of stents may be controlled by coating the struts with endothelial cells or polymers. With respect to restenosis, it is evident that as long as mechanical injury is applied to the vessel wall, the vessel wall will respond with neointimal thickening. The intracoronary stent has the potential to control this tissue response by serving as a carrier for local antiproliferative drug delivery or eventually for genetic manipulation. The intensive research which is now going on in combination with experimental animal data, human postmortem pathologic observations, and angiographic studies is yielding clear insights and future directions to address these issues.