This study will use OCT to examine how two different types of commonly used drug-eluting stents relate to the artery wall. The Xience V (Abbott Vascular, USA) stent has thinner struts and a more open frame than the Cypher (Cordis, USA) stent. We hypothesise therefore that the potentially more pliable structure of the Xience V stent will be associated with greater contact with the vessel wall. This may have a bearing on the relative rate of SSM, although large studies have shown the rate to be low in both the Cypher and the Xience V stent. We believe that OCT imaging of SSM and symmetry of the stent immediately after angioplasty will compliment conventional visual assessment and may identify those patients in whom further improvement of stent with a balloon is necessary.