Frequency and characteristics of incomplete stent apposition during and after sirolimus-eluting stent implantation

OBJECTIVES: Incomplete stent apposition (ISA) is frequently observed after sirolimus-eluting stent (SES) implantation. This study investigated the incidence, morphological features, and possible mechanisms of this phenomenon. METHODS: Fifty-two lesions in 47 eligible patients were treated with SES and serial intravascular ultrasound (IVUS) assessment at the time of post-intervention and 8-month follow-up. ISA was carefully identified from the IVUS images of these lesions. Specifically, quantitative two dimensional IVUS analysis was performed if the lesions demonstrated ISA, including routine IVUS parameters as well as other measurements related to ISA. RESULTS: Overall, ISA was observed in 13 lesions (25.0%) at follow-up. Persistent ISA (n = 6, 11.5%), defined as ISA consistently observed both at post-intervention and follow-up, and late-acquired ISA (n = 7, 13.5%)were systematically compared. Eighty-three percent of cases of persistent ISA were located around the stent edges, whereas all cases of late-acquired ISA were in the stent body. In the persistent ISA group, no serial changes were observed in the lumen area or external elastic membrane area (EEMA) from post-intervention to follow-up. However, in the late-acquired ISA group, EEMA and lumen area significantly increased from post-intervention to follow-up (EEMA: 13.4 +/- 3.2 vs 17.6 +/- 3.3 mm2, respectively, p < 0.0001 ; lumen area: 6.7 +/- 1.4 vs 9.2 +/- 1.8 mm2, respectively, p = 0.004). No adverse clinical events were observed in either group. CONCLUSIONS: ISA was frequently observed during and after SES implantation in clinical practice. No clinical disadvantages were observed during 16 month clinical follow-up periods. Positive remodeling may potentially cause late-acquired ISA.     

Late incomplete stent apposition after sirolimus-eluting stent implantation: a serial intravascular ultrasound analysis.

OBJECTIVES: We sought to identify the frequency of incomplete stent apposition (ISA) in sirolimus-eluting stents (SES) and clarify its findings and clinical sequelae. BACKGROUND: Late-acquired ISA has been reported in bare-metal stents (BMS) and brachytherapy and recently in drug-eluting stents. However, the characteristics of late ISA in SES have not been clarified. METHODS: From the SIRIUS trial, a randomized, multicenter study comparing SES and BMS, serial qualitative intravascular ultrasound (IVUS; at stent implantation and eight-month follow-up) was available in 141 patients (BMS: n = 61; SES: n = 80). The IVUS images were reviewed for the presence of ISA. RESULTS: Incomplete stent apposition at follow-up was observed in 19 patients (BMS: n = 6 [9.8%]; SES: n = 13 [16.3%]; p = NS). Among these, 12 had ISA after intervention and at follow-up (persistent ISA). Late-acquired ISA was seen in the remaining seven cases, all from the SES group (BMS: n = 0; SES: n = 7 [8.7%]; p < 0.05). In late-acquired ISA, there was an increase in external elastic membrane area (after intervention: 16.2 +/- 2.7 m2; follow-up: 18.9 +/- 3.6 mm2; p < 0.05). The location of stent-vessel wall separation was primarily at the stent edges in persistent ISA cases, whereas late-acquired ISA in SES occurred mostly in the mid portion of the stent. There were no negative clinical events reported for any ISA cases at 12-month clinical follow-up. CONCLUSIONS: Late ISA was observed in 8.7% of patients after SES implantation. There were no negative clinical events associated with this IVUS finding at 12-month clinical follow-up; however, careful long-term follow-up will be necessary.     

Late restenosis following sirolimus-eluting stent implantation

Despite encouraging results from randomized trials, concerns exist about long-term results of sirolimus-eluting stent implantation. We sought to determine whether in-stent restenosis occurring >1 year ("late") after sirolimus-eluting stent implantation is a real clinical entity. We analyzed data on all sirolimus-eluting stents implanted in our institution before March 2003. During the study period 928 lesions in 433 patients were treated. Angiographic follow-up was performed in 306 patients (70.6%) with 679 lesions (73.2%). Angiography after 1 year was performed only in symptomatic patients. We considered restenosis "early" if it occurred during the first year and late if after 1 year. Late restenosis required demonstration of a widely patent stent at 6 to 9 months, with repeat angiography after 1 year demonstrating restenosis. Restenosis occurred in 160 lesions overall (23.5%). Of the 31 (4.6%) that were documented after 1 year, 13 were excluded from analysis due to absence of 6- to 9-month angiography; the remaining 18 (2.6%, 1.7 to 4.2) fulfilled our criteria for late restenosis (median time of documentation 607 days, interquartile range 511 to 923). In conclusion, late restenosis is an infrequent but real entity; its existence implies we should not discount the possibility of restenosis as the cause of symptoms that develop >1 year after sirolimus-eluting stent implantation.     

急性心肌梗死患者药物支架置入术后支架贴壁不良特征及对预后的影响

目的探讨急性心肌梗死患者置入西罗莫司药物洗脱支架后,支架贴壁不良(ISA)的特征及ISA对临床预后的影响。方法选择197例冠心病(300处病变)患者置入西罗莫司药物洗脱支架。根据临床表现分为急性心肌梗死组(67例,117处病变),不稳定性心绞痛组(73例,99处病变),稳定性心绞痛组(57例,84处病变)。术后1年血管造影时利用血管内超声观察各组患者支架置入处ISA的发生率和特征.根据ISA造声情况又分为贴壁不良患者和非贴壁不良患者.并在复查后1年临床随访主要不良心脏事件(包括靶病变再次血运重建,非致命性心肌梗死,心源性死亡和全因死亡)。结果急性心肌梗死组支架置入后,有17例患者(17处病变.25.4%)在1年随访检查时存在ISA,明显高于不稳定性心绞痛组(7例患者,7处病变,9.6%)和稳定性心绞痛组[(4例患者,4处病变,7.0%),P=0.005]。多因素回归分析显示,病变长度(OR=1.068,P=0.037)、急性心肌梗死(OR=2.399,P=0.031)和非糖尿病(OR=6.472.P=0.013)是晚期ISA的独立危险因素。对ISA患者1年临床随访显示,ISA患者与非ISA患者主要心脏不良事件无统计学差异(7.1% vs 2.4%,P=0.203)。结论急性心肌梗死患者置入西罗莫司药物洗脱支架后ISA的发生率较高。支架置入后晚期ISA与临床事件的关系仍需进一步研究。     

晚期获得性支架贴壁不良研究进展

药物洗脱支架可大大降低支架置入术后再狭窄的发生,因而被誉为介入心脏病学史上"第三个里程碑".但随其广泛使用,相关问题随之浮现.支架贴壁不良[1](stent malapposition,SM)是指在支架置入术后,至少有1处或以上的支架梁与动脉管壁内膜未能完全贴合(非覆盖于边支的支架),而且在支架梁后存在血流.     

Outcome after acute incomplete sirolimus-eluting stent apposition as assessed by serial intravascular ultrasound

We investigated the fate of postprocedural incomplete stent apposition (ISA) after sirolimus-eluting stent (SES) implantation by evaluating long-term intravascular ultrasound findings in 168 consecutive patients (182 de novo lesions). Postprocedural ISA was defined as > or = 1 stent strut that was clearly separated from the vessel wall with evidence of blood speckle behind the strut without overlapping a side branch. After SES implantation, there were 61 ISA sites in 46 stents in 31 patients (23 at the proximal edge, 7 at the distal edge, and 31 within the stent body). There were no clinical, procedural, or intravascular ultrasound measurement differences between patients and lesions with versus without ISA. At follow-up, 15 acute ISA sites (25%) in 11 patients completely resolved and 40 sites (75%) in 20 patients persisted, although 32 of 46 persisting ISA sites (70%) decreased. There was a greater decrease in effective lumen area and a greater increase in peristent plaque area in the complete-resolution group than in the persistent-ISA group. No lesion developed stent thrombosis or in-stent restenosis (angiographic diameter stenosis > 50%). Six acute ISA sites were also associated with new, late acquired ISA, only 1 of which resulted in aneurysm formation. Although most ISAs after SES implantation do not resolve completely, the incidence of restenosis or thrombosis is not affected.     

Impact of asymmetric stent expansion on neointimal hyperplasia following sirolimus-eluting stent implantation

To assess whether asymmetric stent expansion affects suppression of neointimal hyperplasia after sirolimus-eluting stent implantation, 64 patients in the SIRolImUS-coated Bx Velocity stent trial who underwent single 18-mm stent implantation and 3-dimensional intravascular ultrasonography at 8-month follow-up were enrolled. To assess the longitudinal stent asymmetric expansion, 2 cross sections with a maximal/minimal stent area were chosen in each patient. To assess for tomographic stent asymmetric expansion, stent eccentricity was determined by dividing the minimum stent diameter by the maximum stent diameter. At the 2 cross sections with a maximal/minimal stent area, a sirolimus-eluting stent reduced neointimal hyperplasia significantly with no interaction between the treatment and stent areas. A sirolimus-eluting stent also significantly reduced neointimal hyperplasia in the concentric and eccentric stent groups.     

Restenosis and stent fracture following sirolimus-eluting stent (SES) implantation.

BACKGROUND: Restenosis still occurs, even with the sirolimus-eluting stent (SES), and the precise mechanisms and the impact of stent fracture on restensosis have not yet been elucidated. METHODS AND RESULTS: Intravascular ultrasound (IVUS)-guided SES implantation was performed in 184 lesions in 151 patients with stable and unstable angina. Serial (pre-, post- and follow-up) quantitative coronary angiography analysis was obtained in 169 lesions in 138 patients (angiographic follow-up rate: 91%) and 12-month clinical follow-up was done in all patients. Restenosis occurred in 13 (7.7%) of 169 lesions. Stent fracture occurred in 4 (2.4%) of 169 lesions at follow-up. Of the 13 restenotic lesions, 8 had intimal hyperplasia, 4 had stent fracture, and 1 had late stent thrombosis at 7 months. Although multivariate logistic regression analysis revealed that minimal lumen area (min-LA) post (p=0.027), total stent length (p=0.003) and diabetes (p=0.032) were significant independent predictors of restenosis, univariate analysis showed that stent fracture was more common in the restenosis than in the non-restenosis groups (p=0.001). CONCLUSIONS: Although min-LA post by IVUS, total stent length by QCA and diabetes are independent predictors for angiographic restenosis, stent fracture occurred in 4 lesions (2.4%) and all of them resulted in restenosis (31% of the restenosis). The impact of stent fracture and its potential role in the development of restenosis deserves further study.     

Impact of coronary calcium on outcome following sirolimus-eluting stent implantation

There remain a small but sizable number of patients who develop restenosis after sirolimus-eluting stent (SES) implantation. However, the cause of SES restenosis has not been fully elucidated. The study population consisted of 52 patients with 69 lesions who underwent noninvasive coronary imaging by 64-slice multidetector computed tomography before SES deployment. Agatston calcium scores in target lesions were measured. All patients underwent follow-up coronary angiography at 8 months. Three coronary segments (in stent, proximal edge, and distal edge) were analyzed by quantitative coronary angiography. Agatston calcium score in target lesions averaged 214.7. Late lumen losses in the proximal edge, stent, and distal edge were 0.16 ± 0.45, 0.47 ± 0.58, and 0.07 ± 0.29 mm, respectively. Lesions with restenosis at follow-up showed a trend to produce higher preprocedural calcium scores (629) compared to those without restenosis (153, p = 0.08). There was a significant positive correlation between lesion calcium score and in-stent late lumen loss (r = 0.47, p <0.01). In conclusion, assessment of coronary calcium by multidetector computed tomography might be useful to predict outcomes after SES implantation.     

Late-acquired incomplete stent apposition: morphologic characterization

Incomplete stent apposition (ISA) is a lack of contact between stents and the underlying vessel wall, best described by intravascular ultrasound (IVUS). Late acquired incomplete apposition, defined as complete stent apposition at the time of procedure but ISA at follow-up, is an unusual IVUS finding reported in intracoronary brachytherapy, bare-metal stent (BMS), and drug-eluting stent (DES) implantation. Late-acquired ISA is observed relatively more frequently with DES implantation compared with BMS implantation. Possible mechanisms of this phenomenon include focal/extensive vascular remodeling and dissolution of thrombus. While there are conflicting reports regarding the possible impact of this IVUS finding on clinical outcomes, recent reports of DES have suggested its possible association with late adverse cardiac events including late stent thrombosis. In this paper, we review the incidence, location, underlying pathology, and possible clinical sequelae of late-acquired ISA, primarily focusing on that of DES.     

The incidence and predictors of postprocedural incomplete stent apposition after angiographically successful drug‐eluting stent implantation

Objectives: The aim of this study was to evaluate the incidence and predictors of postprocedural incomplete stent apposition (ISA) after angiographically successful drug‐eluting stent (DES) implantation. Background: The deployed stents are usually evaluated by angiography alone; however, there are possibilities of postprocedural ISA despite the angiographically successful implantation. Methods: A total of 339 lesions in which poststent intravascular ultrasound (IVUS) was performed after successful DES implantation was included. Paclitaxel‐eluting stents were implanted in 237 lesions and sirolimus‐eluting stents (SES) in 102 lesions. Clinical, angiographic and procedural characteristics and IVUS findings for all cases were analyzed. Results: The overall incidence of ISA was 13.9% (47/339). By multivariate analysis, male gender (OR: 2.36, 95% CI: 1.09–5.11), deployment of SES (OR: 2.90, 95% CI: 1.49–5.67), the presence of intracoronary thrombus (OR: 7.47, 95% CI: 1.67–33.47), and non‐ST elevation myocardial infarction (OR: 2.73, 95% CI: 1.09–6.83) were independent predictors for postprocedural ISA after angiographically successful DES implantation. Conclusions: The incidence of postprocedural ISA after angiographically successful implantation of DES was not infrequent. A DES deployment strategy incorporating IVUS guidance might be helpful to reduce the incidence of postprocedural ISA. © 2009 Wiley‐Liss, Inc.