The SES had incomplete neointimal coverage three to six months after implantation, and this was associated with subclinical thrombus formation.

Background-No-reflow associated with direct angioplasty (PCI) of patients with acute coronary syndromes (ACS) is associated with unfavorable results. Methods and Results-We used a new thrombectomy device to treat 51 lesions in 48 consecutive ACS patients (40 male and 8 female; mean age 63 years) and conducted a microscopic analysis of aspirates and blood samples retrieved from the culprit coronary artery. The first aspirate was collected before PCI and the second was collected separately after percutaneous transluminal coronary angioplasty or stenting, including samples from the no-reflow lumen. Light microscopy showed that the materials obtained from the pre-PCI aspiration consisted of thrombus in 37.5%, thrombus and atheroma in 35.0%, and atheromatous plaque in 27.5%. The materials collected from the post-PCI aspiration were thrombus in 8.3%, thrombus and atheroma in 41.7%, and atheromatous plaque in 50.0%. We then compared the 9 lesions (19.1%) with no-reflow to those without no-reflow. There was no difference in the pre-PCI aspirates. However, after PCI, there was more atheromatous plaque retrieved from patients with no-reflow (PϽ0.001) as well as significantly more platelet and fibrin complex, macrophages, and cholesterol crystals in the blood aspirated from no-reflow cases. Aspiration of these elements improved the no-reflow in 7 of 9 lesions to TIMI-3 flow. Conclusions-No-reflow after angioplasty may be caused by gruel that formed from an atheroma attributable to mechanical plaque disruption during intervention.

Background-The time course of neointimal formation after stent implantation has not been studied extensively by angioscopy in the drug-eluting stent era. Methods and Results-Serial angioscopic findings at first follow-up (3.6Ϯ1.1 months), second follow-up (10.5Ϯ1.6 months), and third follow-up (21.2Ϯ2.2 months) after stent implantation were compared between sirolimus-eluting stents (SES, nϭ17) and bare-metal stents (BMS, nϭ11). Neointimal coverage, thrombus, and presence of yellow plaques underneath the stents were assessed. Neointimal coverage was graded as follows: grade 0, stent struts were fully visible; grade 1, struts bulged into the lumen, although they were covered; grade 2, struts were embedded by the neointima but were seen translucently; or grade 3, struts were fully embedded and invisible. Neointimal coverage was remarkably different between SES and BMS at each follow-up point. Neointimal coverage grade was 1.1Ϯ0.5 in SES versus 2.9Ϯ0.3 in BMS at the first follow-up (PϽ0.0001), 1.1Ϯ0.5 in SES versus 3.0Ϯ0.0 in BMS (PϽ0.0001) at the second follow-up, and 1.3Ϯ0.5 in SES versus 3.0Ϯ0.0 in BMS at the third follow-up (Pϭ0.0009). No significant serial changes in coverage grade were noted in the BMS group, whereas coverage grade slightly but significantly increased at the third follow-up in the SES group (PϽ0.05). Thrombi were detected in 4 SES: a red thrombus was seen from the first to the third follow-up in 2; another was detected only at the third follow-up; and the fourth was seen at the first follow-up but disappeared at the second follow-up, associated with a new white thrombus despite dual antiplatelet therapy. Yellow plaques had disappeared by the time of the second follow-up in BMS. In contrast, yellow plaques were exposed in 71% of SES at the first follow-up and remained exposed until the third follow-up. Neointimal coverage grades correlated with thrombi (Pϭ0.002) and with yellow plaques (PϽ0.0001). Conclusions-Serial angioscopic findings up to 2 years after SES implantation were markedly different from those after BMS. Neointimal coverage was completed by 3 to 6 months in BMS. In contrast, SES demonstrated the presence of thrombi and yellow plaques even as much as 2 years after implantation. (Circulation. 2007;116:910-916.)

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