| Objective: Previous study indicates that the durable presence of polymer coating on drug eluting-stent (DES) surface may be one of the principal reasons for localized arterial wall in?ammation, hypersensitivity reactions, delayed or incomplete neointimal healing, and induction of stent thrombosis. The biodegradable polymer coating on biodegradable polymer-coated sirolimus-eluting stent (BSES), which is gradually biodegraded as time went by, would have theoretic advantages of producing less toxicity to the arterial wall and facilitating neointimal healing. This can avoid the above adverse effects possibly caused by persistent residue of drug-carrier coating. However, the long-term coronary arterial response to the BSES in vivo remained unclear. The purpose of this study was to assess long-term native artery vascular responses after implantation of BSES compared with durable polymer-coated SES(DSES) using VH-IVUS analysis.Methods: Between May and November 2010, we identified a total of 41 patients only implanted in de novo coronary lesions with BSESs (EXCELTM , JWMS) or/ and DSESs (Cypher-SelectTM, Cordis, USA) in the percutaneous coronary intervention (PCI) database of our catheter center. Then, angiography and VH-IVUS were performed at follow-up. According to the different type of DES that had been implanted in prior intervention, they were divided into two groups: EXCEL group and CYPHER group. Exclusion criteria: age <18 years or >80 years; follow-up period <6 months or >24 months; chronic total occlusions; bifurcation lesions needing kissing balloon or with a diameter >2.5 mm side branch; left main lesions; coronary artery bypass graft history; target vessel treated with two types DES; previous PCI complication (presence of no-reflow or slow-reflow or dissection in procedure); unsuitable for VH-IVUS interrogation (presence of extensive angiographic calcification and/or severe vessel tortuosity).VH-IVUS examination and follow-up coronary angiography were performed for all enrolled patients. Subsequently, Quantitative coronary angiography (QCA) and VH-IVUS analysis were carried out to assess the native artery vascular responses to BSES compared with DSES during long-term follow-up (median: 8 months). The incidence of necrotic core abutting to the lumen was evaluated at follow-up.Follow-up coronary angiography was performed using Allura Xper FD10 or FD20(Philips Healthcare, Best, The Netherlands)and data were digitally recorded. Prior angiographic data were retrieved from PCI database of our catheter center. QCA analysis was performed for pre-, post-procedure and follow-up coronary angiography data using automated edge-detection software (QAngio XA version 7.2, Medis Medical Imaging System, Netherlands) at a single projection showing the most severe stenosis. The same projection was used at follow-up. The proximal and distal edges were evaluated up to 5 mm from the stent. The results of QCA analysis were reported as late luminal loss, which was defined as the difference between the minimum lumen diameter immediately after stenting and during follow-up.VH-IVUS examination system consists of intravascular ultrasound catheter, pullback device and VH-IVUS console. A 20 MHz, 2.9 Fr intravascular ultrasound catheter (Eagle Eye, Volcano Corp., USA) and R-100 mechanical pullback device (Volcano Corp.) were used. VH-IVUS examination was performed using standard PCI technique. Volumetric data were generated by software using the Simpson's method with a dedicated VH-IVUS console (IVG3, Volcano Corp.). Data were stored digitally on DVD for offline analysis. The region of interest (ROI) defined as the stented segment and the stent edge (5 mm length adjacent to each stent edge) was assessed every 1 mm. VH-IVUS analysis results were reported as absolute and relative volume. All volumes calculated using Simpson's rule were normalized for analysis length (normalized volume).Statistical analysis: SPSS 13.0 (SPSS Inc., USA) for windows was used for all analysis. Categorical variables were presented as numbers or percentages and compared using Chi-square statistics or Fisher's exact test as appropriate. Continuous variables were presented as medians and interquartile ranges and compared using Student's t test. Moreover, if normality assumption was violated, Mann-Whitney U test or Wilcoxon signed ranks test would be used. For all comparisons, a P value of <0.05 (2-sided) was considered statistically significant.Results: With similar in-stent late luminal loss (0.15 mm (0.06–0.30 mm) vs. 0.19 mm (0.03–0.30 mm), P=0.772), the overall incidence of necrotic core abutting to the lumen was significantly less in BSES group than in DSES group (44% vs. 63%, P <0.05) ( proximal 18%, stented site 14% and distal 12% in BSES group, proximal 19%, stented site 28% and distal 16% in DSES group). The DSES-treated segments had a significant higher incidence of necrotic core abutting to the lumen through the stent struts (73% vs. 36%, P <0.01). In addition, more multiple necrotic core abutting to the lumen was observed in DSES group (overall: 63% vs. 36%, P <0.05). Furthermore, when the stented segments with necrotic core abutting to the lumen had been taken into account only, DSES-treated lesions tented to contain more multiple necrotic core abutting to the lumen through the stent struts than BSES-treated lesions (74% vs. 33%), although there was no statistically significant difference between them (P=0.06).Conclusions: By VH-IVUS analysis at follow-up, a lower incidence of necrotic core abutting to the lumen was shown in lesions treated with BSESs compared with lesions treated with DSESs, and more single necrotic core abutting to the lumen was observed. It suggested that the lesion morphometry at the site of BSES treating was more stable than at the site of DSES treating. The major reason was BSES produced less toxicity to the arterial wall and facilitated neointimal healing as a result of polymer coating on DES surface biodegraded as time went by. |
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