Late acquired stent malapposition detected by optical coherence tomography examination

Impact of Cigarette Smoking and Smoking Cessation on Stent Changes as Determined by Optical Coherence Tomography After Sirolimus Stent Implantation

There is debate regarding whether smoking results in microstructural changes after stenting. The aim of this study was to evaluate the microstructural changes after stenting in patients with different smoking statuses. We retrospectively identified 220 sirolimus-eluting stents in 179 patients who underwent follow-up optical coherence tomography examination 12 months after sirolimus stenting. Subjects were classified as current smokers (CS, n = 31), smoking cessation ≤1 year (n = 36), smoking cessation >1 year (SC > 1Y, n = 27), and never smokers (NS, n = 85). The neointimal hyperplasia (NIH) area was larger in CS than in NS (1.04 ± 0.72 mm² vs 0.96 ± 0.68 mm²; p = 0.04). The incidence of lipid-laden neointima was lower in SC > 1Y patients (1.6%) than in all other patients (NS: 3.9%, p = 0.002; CS: 3.0%, p = 0.073; SC1Y: 5.0%, p <0.001). Smoking cessation level was negatively correlated with NIH (B = -0.154; 95% confidential interval -0.187, -0.121; p <0.001) and independently associated with the presence of homogeneous neointima (odds ratio: 1.414; 95% confidential interval 1.145, 1.745; p = 0.001). The incidence of malapposed struts was higher in CS than in NS (3.2% vs 1.6%; p = 0.004). However, smoking cessation patients showed a decreased trend in the incidence of malapposed struts (p = 0.0003). In conclusion, continued smoking increases NIH and the incidence of malapposed struts. However, smoking cessation slows down NIH progression and decreases the incidence of malapposed struts. Smoking cessation promotes vascular healing after stenting.

Stent malapposition, as a potential mechanism of very late stent thrombosis after bare-metal stent implantation: a case report

A 90-year-old man was admitted to our hospital with acute ST-segment elevation myocardial infarction. He had a history of post-infarction angina pectoris 79months ago and had a bare-metal stent (BMS) implanted in the proximal left anterior descending artery at our hospital. Emergent coronary angiography demonstrated thrombotic occlusion in the previously stented segment. After catheter thrombectomy, antegrade flow was restored, but 90% stenosis with haziness persisted in the proximal and distal portions of the previously stented segment. Intravascular ultrasound imaging showed interstrut cavities or stent malapposition at the proximal and distal sites of stented segment. In close proximity to the sites, residual thrombi were also observed. Optical coherence tomography (OCT) demonstrated neither lipid-laden neointimal tissue nor rupture but clearly demonstrated residual thrombus adjacent to the malapposed region in addition to the stent malapposition. PCI with balloon was successfully performed and stent apposition was confirmed by OCT. Stent malapposition is an unusual mechanism of very late stent thrombosis after BMS implantation. OCT can clearly reveal the etiology of stent thrombosis.