Abstract 3424: Incidence, Magnitude and Predictor of Thrombus Following Stent Implantation. An Angioscopic Assessment of 159 Stents
Background: The mechanisms of thrombus formation following stent implantation are not well known. Coronary angioscopy is a robust tool for investigating thrombus in living human.
Method and Results: The aim of this study was to investigate the incidence, magnitude and predictor of thrombus following stent implantation using angioscopy. We reviewed consecutive angioscopic images recorded for 159 stents at follow-up evaluation (231±105days). Angio-scopic evidence of thrombus was defined according to the European working group on coronary angioscopy. Neointimal proliferation was classified into 4 grades: grade 0=struts were exposed, and grade 3=struts were fully embedded and invisible; transparent neointima were divided into grade 1 and 2 according to the degree of translucency to the struts. Thrombi were detected in 30 stented segments (18.9%). Twenty-five were red and 5 were white, all were mural and adhesive. No occlusive thrombi were noted. Procedural strategy did not affect the frequency of thrombus: 14.9% of bare-metal stent, 21.3% of drug-eluting stent, 17.6% of balloon for in-stent restenosis and 28.6% of radiation (P=0.6). Thrombi tended to be more common in the right coronary artery (60%, P=0.01), in cases of inadequate neointimal coverage (83.3%, P<0.01), late loss (0.6±1.5 versus 0.3±0.6mm, P=0.1) and large vessel (3.1±0.7 versus 2.8±0.4mm, P=0.01). There were no correlations with risk factors or lesion subsets. Duration of dual-antiplatelet therapy (209±110 versus 174±98 days, P=0.4), follow-up term (232±103 versus 231±116 days, P=1.0) and stenting for ACS lesions (7.8 versus 6.7%, P=0.2) were not associated with the presence of thrombus. Multivariate analysis (P<0.2 was entered into the model) showed that neointimal grade (coef.= −0.13) and lumen late loss (coef.= 0.10) correlated with the presence of thrombus (P=0.003).
Conclusion: Subclinical thrombus existed in approximately 20% of stented segments. Treatment strategy did not affect thrombus formation directly, but the subsequent healing process may have been associated with thrombus formation.