Clinical Characteristics of In-stent Neoatherosclerosis Causing Late Stent Failure

Background: In-stent neoatherosclerosis (NA) is a cause of late stent failure. Late stent failure remains a challenging issue after stenting, and its causal mechanism has not been elucidated. Objectives: The aim of this study was to investigate the clinical characteristics of late stent failure with or without NA by optical coherence tomography (OCT). Methods and results: Among 179 patients who had undergone coronary stent implantation (bare metal stent and drug-eluting stent), 22 patients experienced late stent failure with and without NA identified by OCT. The presence of lipid-laden plaque or calcification inside the stent was defined as NA. The 22 patients were divided into two groups according to OCT images: 13 patients with NA (NA group) and 9 patients without NA (non-NA group). OCT analysis also showed that thrombus was more frequently observed and maximum intimal thickness was significantly larger in the NA than in the non-NA group (35.7 % vs 0.0 % and 1.26 mm vs 0.98 mm, p<0.05, respectively). In terms of characteristics, in-stent restenosis lesions and use of oral anticoagulants occurred at a lower frequency, and the minimal lumen diameter was significantly smaller in the NA group than in the non-NA group (7.7 % vs 44.4 %, 0.0 % vs 66.7 %, and 0.33 mm vs 0.83 mm, p<0.05, respectively). Conclusion: In-stent restenosis and use of anticoagulants may be associated with the mechanism of in-stent neoatherosclerosis.