Advanced Neointimal Growth is Not Associated With a Low Risk of In-Stent Thrombus Optical Coherence Tomographic Findings After First-Generation Drug-Eluting Stent Implantation

Background: There is a hypothesis that advanced neointimal stent coverage may protect against stent thrombosis. In the present study, differences in neointimal growth and prevalence of in-stent thrombus between paclitaxel- and sirolimus-eluting stent (PES and SES) were evaluated by optical coherence tomography (OCT). Methods and Results: Follow-up angiographic and OCT examinations at approximately 6 months were performed for 40 patients (20 PES, 20 SES). Late loss was measured by quantitative coronary angiography. Neointimal hyperplasia (NIH) thickness on stent struts was measured by cross-sectional OCT images at 1 mm intervals. After measuring the NIH area in each cross-section, NIH volume was calculated as integral of NIH area within the stent. Late loss, NIH thickness, and NIH volume were greater for PES than for SES (0.42 ±0.44 vs 0.13 ±0.12 mm, 118 ±141 vs 31 ±39 μm, 53.2 ±30.5 vs 24.3 ±14.0 mm3; P<0.05, respectively). In-stent thrombus was found more frequently in PES than in SES (50 vs 15%; P=0.02). Conclusions: Although the degree of neointimal growth in PES was generally greater, in-stent thrombus was more common compared with SES. Presence of thrombus in first-generation drug-eluting stents was not related to advanced neointimal growth. (Circ J 2009; 73: 1627-1634)