Polymer For drug distribution and safety one needs to consider the relationship between the stent design and the drug tissue con- centration. Currently used polymers for stent coatings have been proven safe. They release drugs at predictable rates and it is interesting to observe that fast and slow release polymers lead to similar tissue concentrations. The tissue penetration depends more on the hydrophobic or hydrophilic properties of the drug. A hydrophobic or lipophilic drug will easily penetrate and be found in high concentrations regardless of slow or fast release. The difference between slow and fast release may lie in the tissue toxicity; a high tissue level, built up quickly, may have toxic necrotic effects, as seen with paclitaxel. This can lead to thrombus formation; the stent may no longer be adherent to the necrotic wall. Overall, clinical and histological toxicity is a concern. Controlled release is crucial to the efﬁcacy of DES. The CYPHER stent has a unique polymer coating, which allows for localized delivery of sirolimus precisely to the site of the lesion. It contains a speciﬁc concentration of sirolimus and the polymer ensures that the drug does not wash off dur- ing the most time-intensive procedures. The polymer also ensures that there is no rapid “dumping” of the drug, but rather tightly regulated drug release over a deﬁned period of time. Essentially all the drug is delivered in the ﬁrst 3 months after implantation. Impact on patients Over the past 25 years coronary angioplasty has developed into a highly sophisticated series of techniques that has the potential to match surgery, and in many cases surpass it. Implantation of SES has revolutionized the ﬁeld of percu- taneous coronary angioplasty with an impressive reduction of in-stent restenosis compared with bare metal stents. This advantage translates into fewer repeat treatments for the patient, a reduction in the need for surgical interven- tion, and the ability to treat more patients. Thankfully, the incidence of stent thrombosis appears to be in line with that of bare metal stents. That being said, the ability to identify the patient who is at risk of stent thrombosis is a major and urgent challenge. Conclusions and place in therapy The introduction of SES was a major breakthrough for interventional cardiology. Many large, randomized, clini- cal trials using SES have shown a remarkable reduction in angiographic restenosis and target vessel revascularization Sirolimus-eluting coronary stents compared with bare metal stents. The results of these trials also appear to be supported by evidence from everyday prac- tice and non-controlled clinical trials. 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