 Stenosis of the coronary arteries may be treated by balloon dilatation followed by the implantation of a metal stent. However, restenosis occurs in 10-20 of patients treated with bare metal stents BMS. Restenosis and treatment of restenosis is associated with risk of myocardial infarction MI and death. Drug eluting stents DESrelease drugs to the vessel wall that delay or inhibit the process of restenosis. Some reports have found that DES are associated with risk of acute stent thrombosis, MI and death. The precise magnitude of this risk is not known. Current evidence is therefore insufficient to balance the long-term risk and benefit of BMS vs DES. 