Optimal duration of antiplatelet therapy in recipients of coronary drug-eluting stents

Four weeks' therapy with clopidogrel, in addition to aspirin (acetylsalicylic acid), is currently standard care after percutaneous coronary intervention (PCI) with stent implantation. The recent availability of drug-eluting stents (DES), which dramatically reduce restenosis at the site of PCI, has again raised the issue of stent thrombosis. In clinical trials, the risk of stent thrombosis appeared unrelated to the presence of the drug eluting from the stent and was documented within the usual range of <= 1% at 9 months after DES implantation. However, these devices feature delayed strut endothelialisation and there are reports describing late DES thrombosis up to 18 months after PCI, in most cases after clopidogrel has been discontinued. Although infrequent after bare-metal stenting (0.4-2.8%), stent thrombosis is a catastrophic event. Before DES availability, adjunctive intravascular brachytherapy significantly reduced in-stent neointimal proliferation, at the price of a higher-than-expected rate of late stent occlusion (6-8%). In such setting, a 12-month aspirin plus clopidogrel regimen showed a beneficial effect on long-term adverse events. An additional consideration is that, among patients undergoing bare-metal stent PCI, combined antithrombotic therapy with aspirin and clopidogrel has been recently associated with favourable effects on cardiovascular outcome beyond stent thrombosis in two large-scale clinical trials. Therefore, we propose that prolonged combination therapy with aspirin and clopidogrel be mandatory up to 1 year after PCI in all patients receiving DES.