When a stent is implanted the process of pushing back the vessel to open the blockage causes an injury to the vessel wall. In the majority of cases this injury heals with no negative effects. However, in a small percentage of cases (depending on a number of factors such as the length and diameter of the blockage), the healing of the injury may cause excessive scar tissue which re-blocks the vessel. This is called restenosis (re-blockage). Restenosis is not fatal but it may result in you having a repeat procedure within the next year.

Drug-eluting stents were developed to prevent restenosis by delivering a tiny quantity of drug into the surrounding tissue that limits the healing response. These devices have been shown to be very effective in most cases. However the drugs are very powerful and can sometimes prevent any healing for a long period. This places the stent at risk of clotting with blood (like a fresh cut on your skin). In a very small percentage of cases this can lead to a heart attack. To overcome this risk the doctor will get you to take an anti-platelet (blood thinning) drug, normally Plavix together with Aspirin. This drug is normally prescribed for a period of six months to one year, during which time you would be advised not to undergo any form of surgery, as you would need to stop the drug to avoid excessive bleeding.

Research has shown that once you stop the drug there is an increased risk - when compared to a bare metal stent - of a clot forming in the vessel. It is important that you understand the risks and benefits of each of these products and discuss them with your cardiologist before the procedure.