[When are drug-eluting stents effective? A critical analysis of the presently available data]

The use of drugeluting stents (DES) has tackled the "Achilles' heel" of percutaneous coronary interventions (PCI) like no innovation before: the restenosis following initially successful PCI of de novo stenoses. Today, with DES, the pivotal clinical parameter TVF (target vessel failure) is in the upper single- digit range for "standard" lesions and 16% for long lesions. Numerous studies have assessed the effects of various antiproliferative and antiinflammatory substances, like Sirolimus, Tacrolimus, Everolimus, ABT-578, Biolimus, Paclitaxel, QP2 as well as of other drugs, like Dexamethasone, 17-beta-Estradiol, Batimastat, Actinomycin-D, Methotrexat, Angiopeptin, Tyrosinkinase inhibitors, Vincristin, Mitomycin, Cyclosporin, and also the C-myc antisense technology (Resten-NG, AVI-4126). At the time of this analysis, four DES are CE-certified and commercially available in Europe: The Cypher stent, releasing Sirolimus from a polymer (Cordis, J&J), the Taxus stent, releasing Paclitaxel from a polymer (Boston-Scientific), the V-Flex stent, releasing Paclitaxel without a polymer (Cook) and the Dexamet stent, releasing Dexamethasone from a PC coating (Abbott). Since more DES will be CE-certified soon, an increasing challenge vexes interventional cardiologists and health care providers: Which DES should be chosen for routine patient care?A prerequisite for assessing the efficacy of DES are randomized, controlled trials. Registries, even with strong monitoring, are limited by the known restrictions, comparing data to historical controls. At the time of this analysis, only three drugs had proven their efficacy in 13 randomized studies in 5669 patients: Paclitaxel, Sirolimus and Everolimus, with 3815 patients in Paclitaxel studies, 1748 patients in Sirolimus studies and 106 patients in Everolimus studies. For further analysis, it makes sense to divide the primary endpoints into non-clinical and clinical endpoints. Non-clinical primary endpoints are usually angiographic parameters, like the percentage of DS (diameter stenosis, ASPECT, ELUTES), the instent LLL (late lumen loss, RAVEL, FUTURE-II), the in-stent MLD (minimal lumen diameter, E-SIRIUS, C-SIRIUS) or, like in TAXUS-II, the IVUS-determined percentage of volume obstruction. Clinical primary endpoints were either MACE (major adverse cardiac events, TAXUS-I, FUTUREI), TVF (target vessel failure, DELIVER-I, SIRIUS) or TVR (target vessel revascularization, TAXUS-IV und TAXUS-VI). As ASPECT, ELUTES and DELIVER-I have shown, even a statistically significant effect on an angiographic primary endpoint does not necessarily translate into a significant clinical effect, which is completely absent in some such cases. Since it is not the goal of PCI to improve angiographic parameters but rather to improve patients' outcome, the choice of DES for routine treatment should be based on the results of randomized controlled studies with a clinical primary endpoint at an appropriate time interval. At the present time, these criteria have been met by only the Cypher and the Taxus stents.