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.     

Comparison of vessel response following sirolimus-eluting stent implantation as assessed by serial 3-D intravascular ultrasound study

Recent sirolimus-eluting stent (SES) studies have suggested higher rates of restenosis in non-left anterior descending (LAD) artery lesions. The aim of this study was to evaluate differential vessel response (LAD versus non-LAD) to SES implantation using serial intravascular ultrasound (IVUS). A total of 94 patients who underwent SES implantation and serial (post-PCI and 8 months) 3-dimensional IVUS were enrolled from our database. Volumetric analysis was performed throughout the stent as well as the adjacent reference segment (up to 5 mm). Volume index (volume/length) was calculated for vessel (VVI), lumen (LVI), and plaque (PVI). Cross-sectional narrowing (CSN) was defined as neointimal area divided by stent area (%). With respect to the in-stent segment, VVI, PVI, and LVI at post-PCI were not significantly different between the LAD (n = 41) and non-LAD (n = 53) lesions. At follow up, however, maximum CSN was significantly greater in the non-LAD lesions (18.3 +/- 15.2% versus 12.2 +/- 10.0%; p = 0.029). At the proximal reference segment, the non-LAD lesions showed a significantly greater LVI decrease than the LAD lesions (p <0.05), primarily due to mild vessel shrinkage observed in the non-LAD lesions. There were no significant differences at the distal reference segment between the LAD and non-LAD lesions. This detailed IVUS analysis suggests that there are minimal differences in the vessel responses following SES implantation. These findings may have potential implications for mechanical and pharmacokinetic properties of next-generation drug-eluting stent technology.     

Evaluation of coronary remodeling after sirolimus-eluting stent implantation by serial three-dimensional intravascular ultrasound

This study evaluates the response of the coronary vessel wall to implantation of the sirolimus-eluting stent (SES), Bx-VELOCITY, by using serial intravascular ultrasound. SESs have a major impact on the inhibition of in-stent neointimal hyperplasia. However, changes in the vessel wall and behind stent struts in animal models and humans have not been evaluated after SES implantation. Thirty-four patients who received a SES (n = 24) or a Bx-VELOCITY bare stent (BS) (n = 10) for single de novo coronary lesions and had serial motorized pullback 3-dimensional intravascular ultrasound were included. Stent, lumen, and vessel volumes were similar in the 2 groups at baseline. At follow-up, significantly larger lumen and lower neointimal hyperplasia volumes (0.7 vs 33 mm(3), p = 0.001) were seen in the SES group compared with the BS group. There was no significant difference between SES and BS in either the vessel volume (+2.4% vs +0.7%, p = NS) or the plaque behind stent volume change (+3.4% vs +2.5%, p = NS) from after the procedure to late follow-up. The stent edges also showed no significant difference between postprocedural and follow-up measurements, either in patients receiving SESs or BSs. No stented or edge segment required redilatation in the SES group, whereas 2 patients underwent repeat percutaneous coronary angioplasty in the BS group. In the SES group, 1 patient (4%) showed late acquired incomplete stent apposition. Thus, the SES is effective in inhibiting neointimal hyperplasia without affecting vessel volume and plaque behind the stent.     

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.     

Recurrence of late-acquired incomplete stent apposition following sirolimus-eluting stent implantation

Stent thrombosis has been recognized as a potentially critical complication in percutaneous coronary intervention. In the bare-metal stent era, stent thrombosis was considered to be an acute or subacute event, occurring within 1 month after stent implantation. Recently, late or very late stent thrombosis after drug-eluting stent implantation has been brought into focus; however, the mechanism underlying this potentially fatal event is largely unknown. We report a case of critical late thrombosis 2 years after sirolimus-eluting stent implantation. Detailed serial intravascular ultrasound analyses revealed that late-acquired incomplete stent apposition, accompanied by extensive positive vascular remodeling, was involved in the pathogenesis of the nearly fatal event described in this case.     

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。     

Distribution pattern of neointimal hyperplasia following sirolimus-eluting stent implantation assessed by 3-dimensional intravascular ultrasound

Sirolimus-eluting stents (SES) have been shown to reduce intimal hyperplasia (IH) within the stent. Although angiographic studies have suggested focal distribution of IH, these data are limited by its spatial resolution and the minimal amount of IH. Therefore, the exact distribution pattern of SES IH remains unclear. Ninety-six SIRIUS trial patients who underwent SES (51) or bare metal stent (45) implantation and three-dimensional IVUS at 8 months follow-up were enrolled. Neointimal area (stent-lumen area) was obtained at every 0.5-mm interval throughout the stented segment. The length of each stent with IVUS-detectable neointima was determined and divided by the stented length in each case to normalize the data. Even with IVUS, IH was detectable in very limited SES stented segments (median 8% of total stented length) compared to the diffuse nature of IH within BMS with only 5 stented lesions having segments free from IH. In 25% (13 of 51) of patients, no IH was detectable within whole SES stented segments. In conclusion, SES has reduced not only the total amount of IH, but also limited the distribution. These data suggest that local conditions (heterogeneity of biological responses of particular plaques, pharmacokinetics, or their combination) may play a role in IH following SES implantation.     

Intravascular ultrasound assessed incomplete stent apposition and stent fracture in stent thrombosis after bare metal versus drug-eluting stent treatment the Nordic Intravascular Ultrasound Study (NIVUS)

Background

This prospective multicenter registry used intravascular ultrasound (IVUS) in patients with definite stent thrombosis (ST) to compare rates of incomplete stent apposition (ISA), stent fracture and stent expansion in patients treated with drug-eluting (DES) versus bare metal (BMS) stents. ST is a rare, but potential life threatening event after coronary stent implantation. The etiology seems to be multifactorial.

Methods

124 patients with definite ST were assessed by IVUS during the acute ST event. The study was conducted in 15 high-volume percutaneous coronary intervention -centers in the Nordic–Baltic countries.

Results

In early or late ST there were no differences in ISA between DES and BMS. In very late ST, ISA was a more frequent finding in DES than in BMS (52% vs.16%; p = 0.005) and the maximum ISA area was larger in DES compared to BMS (1.1 ± 2.3 mm² vs. 0.1 ± 0.5 mm²; p = 0.004). Further, ISA was more prevalent in sirolimus-eluting than in paclitaxel-eluting stents (58% vs. 37%; p = 0.02). Stent fractures were found both in DES (16%) and BMS (24%); p = 0.28, and not related to time of stent thrombosis occurrence. For stents with nominal diameters ≥ 2.75 mm, 38% of the DES and 22% of the BMS had a minimum stent area of less than 5 mm²; p = 0.14.

Conclusions

Very late stent thrombosis was more prevalent and associated with more extensive ISA in DES than in BMS treated patients. Stent fracture was a common finding in ST after DES and BMS implantation.     

Impact of final stent dimensions on long-term results following sirolimus-eluting stent implantation: serial intravascular ultrasound analysis from the sirius trial

OBJECTIVES: We assessed the predictive value of minimum stent area (MSA) for long-term patency of sirolimus-eluting stents (SES) implantation compared to bare metal stents (BMS). BACKGROUND: Although MSA is a consistent predictor of in-stent restenosis, its predictive value in BMS is still limited because of biologic variability in the restenosis process. METHODS: From the SIRolImUS (SIRIUS) trial, 122 cases (SES: 72; BMS: 50) with complete serial intravascular ultrasound (IVUS) (baseline and 8-month follow-up) were analyzed. Postprocedure MSA and follow-up minimum lumen area (MLA) were obtained. Based on previous physiologic studies, adequate stent patency at follow-up was defined as MLA >4 mm(2). RESULTS: In both groups, a significant positive correlation was observed between baseline MSA and follow-up MLA (SES: p < 0.0001, BMS: p < 0.0001). However, SES showed higher correlation than BMS (0.8 vs. 0.65) with a higher regression coefficient (0.92 vs. 0.59). The sensitivity and specificity curves identified different optimal thresholds of MSA to predict adequate follow-up MLA: 5 mm(2) for SES and 6.5 mm(2) for BMS. The positive predictive values with these cutoff points were 90% and 56%, respectively. CONCLUSIONS: In this SIRIUS IVUS substudy, SES reduced both biologic variability and restenosis, resulting in increased predictability of long-term stent patency with postprocedure MSA. In addition, SES had a considerably lower optimal MSA threshold compared to BMS.     

Simultaneous two-vessel very late stent thrombosis and coronary aneurysm formation after sirolimus-eluting stent implantation: an intravascular ultrasound evaluation

Very late stent thrombosis is a rare but devastating complication. Several factors are known to contribute to its occurrence, and are related to the patient, procedure, lesion and premature discontinuation of antiplatelet therapy. This report describes the case of a 49-year-old patient with simultaneous two-vessel stent thrombosis (left anterior descending and circumflex arteries) 24 months after sirolimus-eluting stent implantation. The importance of intravascular ultrasound is enhanced. The potential contributing factors to the stent thrombosis are analyzed.     

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.