Test of Long-Term Safety and Efficacy of Sirolimus-Permanent-Polymer Eluting Stent (Cypher)- and Sirolimus-Polymer-free Eluting Stents (PPS/PFS) Assessed by Optical Coherence Tomography

The mid-term efficacy of drug-eluting stents has been well-established, but there is an ongoing debate on the potential of an increased incidence of late stent thrombosis, particularly after discontinuation of thienopyridine therapy, as well as of delayed onset of restenosis or catch-up phenomenon with permanent polymer-based DES. The extent of strut coverage with reduction of exposed thrombogenic material has been shown to be associated with the inflammatory reaction grade and with the incidence of stent thrombosis. The optical coherence tomography (OCT) is an intravascular imaging modality based on light. The principle is similar to intravascular ultrasound, but due to the much shorter wave length of light, it offers a much better resolution up to 10µm, enabling the exact determination of strut coverage, neointimal thickness, vessel size, presence of dissections, and even the presence of inflammation. Patients who received a polymer-free or a permanent-polymer sirolimus-eluting stent about 5 years ago without in-segment intervention since, will be evaluated by OCT regarding the healing pattern and the late lumen loss of the stent.