Comparison of Rates of Strut Malapposition Between Everolimus and Sirolimus Eluting Stents - A Randomised Optical Coherence Tomography Study

Despite recent advances in stent technology and clot reducing drug therapy, acute stent occlusion or thrombosis (ST), still occurs and can be life threatening. It has been shown that certain features of how the stent relates to the artery wall may predict ST. One such feature, so-called stent strut malapposition (SSM), can be assessed after implantation but current imaging techniques are relatively unreliable. Optical Coherence Tomography (OCT) is a newer technology that can be performed safely and easily after angioplasty and may allow the stent struts to be assessed more accurately and reliably.

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.

This study will involve the random allocation of forty patients requiring coronary angioplasty to one of the Cypher or Xience V stent. The procedure will be performed in the usual manner as indicated clinically and will include imaging of the stented artery segment with OCT once the operator is satisfied with the visual result by angiography.