Drug eluting coronary stents

• drug-eluting stents (DES) provide all the mechanical properties of the originally developed intracoronary stents, but can inhibit the development of neointimal proliferation
• DES are coated with a plymer within which are mebedded anti-proliferative drugs. These drugs can leach out into the wall of the vessel over the first couple of weeks after treatment and have been shown to have a major effect in lowering the incidence of restenosis. The doses of drugs required to achieve an effect locally have no systemic effects
• DES are recommended in patients with long lesions and those in small vessels (30-40% of all angioplasties) (1)
• unless contraindicated aspirin and clopidogrel are used in all patients and the latter is generally continued for 3-6 months after drug eluting stent implantation

Notes:

• an observational study revealed DES increased risk of late cardiac death or MI more than bare metal stents (2)
  • documented late stent thrombosis and related death/target vessel MI were twice as frequent after DES versus BMS (2.6% vs. 1.3%)
  • the study authors concluded that after the discontinuation of clopidogrel, the benefit of DES in reducing target vessel revascularization were maintained. However this has to be balanced against an increase in late cardiac death or nonfatal MI, possibly related to late stent thrombosis
• a meta-analysis comparing DES versus bare metal stents in coronary heart disease revealed (3)
  • DES for the treatment of coronary artery disease do not reduce total mortality when compared with bare metal stents
  • some evidence suggests that sirolimus- but not paclitaxel-eluting stents may lead to increased non-cardiac mortality
• a further meta-analysis revealed that the significant decrease in angiographic restenosis associated with the use of DES, in comparison with bare metal stents, leads not only to a decreased need for subsequent revascularization procedures but also a decreased incidence of myocardial infarction during the first 12 months after stent implantation (4)

Reference:

1. British Heart Foundation (Factfile 5/2004). Drug Eluting Stents.
2. Pfisterer M et al. Late clinical events after clopidogrel discontinuation may limit the benefit of drug-eluting stents: an observational study of drug-eluting versus bare-metal stents. J Am Coll Cardiol. 2006 Dec 19;48(12):2584-91.
3. Nordmann AJ et al. Mortality in randomized controlled trials comparing drug-eluting vs. bare metal stents in coronary artery disease: a meta-analysis. Eur Heart J. 2006 Dec;27(23):2784-814
4. Moreno R et al. Meta-analysis comparing the effect of drug-eluting versus bare metal stents on risk of acute myocardial infarction during follow-up. Am J Cardiol. 2007 Mar 1;99(5):621-5