Comparison of the self-expanding Radius stent and the balloon-expandable Multilink stent for elective treatment of coronary stenoses: a serial analysis by intravascular ultrasound.

We compared the outcome of the self-expanding Radius stent and the balloon-expandable Multilink stent serially by angiography and intravascular ultrasound. Successful stent deployment was achieved in 66 lesions of 56 stable angina patients (34 lesions with Radius stents and 32 lesions with Multilink stents). At follow-up, there were no significant differences in minimal lumen diameter or percent diameter stenosis between the groups, nor in restenosis rates, although the Radius stent group rate was slightly lower (23.5% vs. 31.3%). In the Radius stent group, stent cross-sectional area (CSA) increased gradually after implantation until the 6-month follow-up (8.37 +/- 1.83 to 10.16 +/- 2.59 mm(2); n = 15), giving a larger CSA (P = 0.03) than the Multilink stent group, which decreased (9.00 +/- 2.05 to 8.27 +/- 2.15 mm(2); n = 17). The lumen CSA was also slightly larger (6.82 +/- 3.06 vs. 5.84 +/- 1.85 mm(2); P = 0.29) in the Radius stent group. These findings indicated that the Radius stent enlarged progressively after implantation, which might be useful for prevention of restenosis.     

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.     

Polymer-based paclitaxel-eluting stents reduce in-stent neointimal tissue proliferation: a serial volumetric intravascular ultrasound analysis from the TAXUS-IV trial

OBJECTIVES: The aim of this study was to use serial volumetric intravascular ultrasound (IVUS) to evaluate the effects of polymer-based, paclitaxel-eluting stents on in-stent neointima formation and late incomplete stent apposition. BACKGROUND: The TAXUS-IV trial demonstrated that the slow-release, polymer-based, paclitaxel-eluting stent reduces angiographic restenosis and the need for repeat revascularization procedures. Serial IVUS studies reveal details of the pattern of vascular responses provoked by stent implantation that provide insight into device safety and efficacy. METHODS: In the TAXUS-IV trial, patients were randomized to the slow-release, polymer-based, paclitaxel-eluting TAXUS stent or a bare-metal EXPRESS stent (Boston Scientific Corp., Natick, Massachusetts). As part of a formal substudy, complete volumetric IVUS data were available in 170 patients, including 88 TAXUS patients and 82 controls, at implantation and at nine-month follow-up. RESULTS: No baseline differences were present in the clinical characteristics or IVUS parameters between the control and TAXUS groups. At nine-month follow-up, IVUS lumen volumes were larger in the TAXUS group (123 +/- 43 mm(3) vs. 104 +/- 44 mm(3), p = 0.005), due to a reduction in neointimal volume (18 +/- 18 mm(3) vs. 41 +/- 23 mm(3), p < 0.001). Millimeter-by-millimeter analysis within the stent demonstrated uniform suppression of neointimal growth along the entire stent length. Late lumen loss was similar at the proximal edge of the stent between the two groups, and reduced with the TAXUS stent at the distal edge (p = 0.004). Incomplete stent apposition at nine months was observed in only 3.0% of control and 4.0% of TAXUS stents (p = 0.12). CONCLUSIONS: Polymer-based, paclitaxel-eluting TAXUS stents are effective in inhibiting neointimal tissue proliferation, and do not result in late incomplete stent apposition.     

Multiple plaque morphologies in a single coronary artery: insights from volumetric intravascular ultrasound.

Intravascular ultrasound provides detailed information on vessel wall and plaque morphology. This report illustrates the use of three-dimensional volumetric IVUS reconstruction images to characterize different patterns of plaque morphology, including vulnerable and ruptured plaques, within a single coronary artery in a patient with unstable angina.     

Implications of late expansion of self-expanding stents on neointimal response: a serial study with intravascular ultrasound]

INTRODUCTION AND OBJECTIVES: A unique property of self-expanding stents is the continuous force exerted against the vessel wall, which may induce additional arterial damage with implications on restenosis. The main purpose of this study is to evaluate the consequences of late self-expansion of coronary Wallstents. METHODS: Eleven patients with Wallstents implanted in native coronary arteries, in whom baseline, post-stenting, after high pressure balloon inflation and at 6-month follow-up intravascular ultrasound were performed. The stented segments were divided in 2-mm cross-sections, that were analyzed independently and carefully matched at each situation using anatomic landmarks. Multiple regression analysis was performed. RESULTS: Late expansion was present in 93% of the studied sections (mean increase in stent area of 2.0 1.9 mm2) and was clearly related to stent oversizing (r = 0.45; p < 0,0001). Although late expansion was a significant positive predictor of neointimal growth (r = 0.63; p < 0.0001), it showed a negative correlation with late luminal loss (r = 0.33; p < 0.0001). No significant correlation was found between optimization of angiographic results with high pressure inflations and late luminal loss. CONCLUSIONS: Late expansion is a common phenomenon after Wallstent implantation and is mainly determined by stent oversizing. Despite the fact that this phenomenon is associated with greater neointimal proliferation, it seems to have a net beneficial effect on late luminal loss.     

Relation between stent expansion and arterial remodeling: a serial intravascular ultrasound study.

Previous studies suggested that stent area (SA) did not change after the Palmaz-Schatz stent implantation. Whether these findings apply to other types of stent, however, is unknown. This study assessed vascular response to stent implantation using intravascular ultrasound (IVUS) studies. Serial (pre-intervention to follow-up) IVUS imagings were used to study 57 native coronary lesions after the GFX stent or the Multilink stent implantation. The vessel area (VA) at lesion site increased at follow-up (16.92 +/- 3.67 mm(2) after intervention to 18.17 +/- 4.66 mm(2) at follow-up, P < 0.01). The SA also increased from 8.39 +/- 1.90 mm(2) after intervention to 8.80 +/- 2.08 mm(2) at follow-up (P = 0.02). Thirty-two percent of lesions showed late stent expansion. The stent expansion [Delta (after intervention to follow-up) SA] correlated significantly with the VA growth [Delta (after intervention to follow-up) VA] (r = 0.59, P < 0.0001). In conclusion, some lesions reveal late stent expansion after both the GFX stent and the Multilink stent implantation. Adaptive vessel remodeling may be followed by stent expansion.     

Evaluation of four-year coronary artery response after sirolimus-eluting stent implantation using serial quantitative intravascular ultrasound and computer-assisted grayscale value analysis for plaque composition in event-free patients.

OBJECTIVES: This study sought to evaluate the long-term arterial response after sirolimus-eluting stent implantation. BACKGROUND: Sirolimus-eluting stents are effective in inhibiting neointimal hyperplasia without affecting plaque volume behind the stent struts at six months. METHODS: Serial quantitative intravascular ultrasound and computer-assisted grayscale value analysis over four years were performed in 23 event-free patients treated with sirolimus-eluting stents. RESULTS: In the first two years, the mean plaque volume (155.5 +/- 42.8 mm3 post-procedure and 156.8 +/- 57.7 mm3 at two years, p = 0.86) and plaque compositional change expressed as mean percent hypoechogenic tissue of the plaque behind the stent struts (78.9 +/- 8.6% post-procedure and 78.2 +/- 8.9% at two years, p = 0.67) did not significantly change. However, significant plaque shrinking (change in plaque volume = -18.4 mm3, p = 0.02) with an increase in plaque echogenicity (change in percent hypoechogenic tissue = -7.8%, p < 0.0001) was observed between two and four years. The mean neointimal volume increased over four years from 0 to 8.4 +/- 5.8 mm3 (p < 0.0001). However, no further statistically significant change occurred between two and four years (7.0 +/- 6.7 mm3 vs. 8.4 +/- 5.8 mm3, p = 0.25). CONCLUSIONS: Between two and four years after sirolimus-eluting stent implantation, peri-stent tissue shrank with a concomitant increase in echogenicity. These intravascular ultrasound findings suggest that late chronic artery responses may evolve for up to four years after sirolimus-eluting stent implantation. In addition, the fact that the neointima does not significantly change from two to four years may suggest that the biological phenomenon of a delayed healing response has begun to subside.     

Mechanisms and predictors of carotid artery stent restenosis: a serial intravascular ultrasound study.

OBJECTIVES: The aim of this study was to determine the mechanisms and predictors of carotid artery restenosis after carotid artery stenting (CAS) using serial intravascular ultrasound (IVUS) imaging. BACKGROUND: Carotid artery stenting is increasingly used to treat high-grade obstructive carotid disease, but our knowledge of carotid in-stent restenosis and remodeling remains limited. METHODS: Post-procedural and 6-month (median 6 months) follow-up quantitative carotid angiography and IVUS were performed after self-expanding stent deployment in 50 internal carotid arteries (ICA). The IVUS measurements at multiple designated sites included minimal luminal diameter, lumen area, stent area (SA), and neointimal hyperplasia area (NIH). RESULTS: Late stent enlargement at follow-up was found at all segments, and the percentage increase was greatest at the ICA lesion site (mean +/- SD, 48.9 +/- 35.3%). The NIH, expressed as a percentage of SA, was seen within all segments of the stent and was greatest at the ICA lesion site (37.3 +/- 23.3%). There was a strong positive correlation between the amount of NIH and late stent enlargement (r = 0.64; p < 0.001). Immediate post-procedural minimum ICA SA (r = -0.37; p < 0.01) and stent expansion (r = -0.44; p = 0.001) correlated negatively with the percentage restenotic area at follow-up. CONCLUSIONS: Although self-expanding carotid stents generate considerable neointimal hyperplasia, the process is balanced by marked late stent enlargement. Small stent dimensions immediately post-procedure were associated with a higher risk of restenosis.     

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.     

Neointima in coronary stent does not increase during over 1-year in non-restenosed lesion at 6 months follow-up: serial volumetric intravascular ultrasound study

The long-term outcomes of coronary artery stenting have been determined by coronary angiography only with has the limitation of determining stent expansion and neointimal proliferation at long-term follow-up. Volumetric intravascular analysis has the potential to evaluate the morphology and distribution of neointima longitudinally after coronary artery stenting. We used three-dimensional intravascular ultrasound (3-D IVUS) to evaluate serial changes in stent and neointimal volumes for over 1-year in 9 patients who did not exhibit angiographic restenosis at 6-month follow-up. Volumetric analysis by a validated Netra 3-D IVUS system was performed pre- and post-intervention, at 6-month follow-up (FU1), and at over one-year follow-up (FU2). Lumen volume in the stented lesions increased significantly after intervention, and the increase persisted until FU2. There were no significant changes in stent volume between just after stent implantation and at FU2. Neointimal volume within the stents did not change from FUI to FU2 (FU1; 38.4 +/- 9.0 mm3 vs FU2; 33.8 +/- 10.3 mm3). In 33% (3/9) of all lesions, neointimal volume increased between from 6-months to over 1-year after stent implantation. Neointimal distribution after stenting seemed to be almost equal and unrelated to the plaque burden at pre-intervention. Neointimal volume within the stents did not increase and stent volume did not change over the 1st-year in patients who did not exhibit angiographic restenosis at 6-months.     

Stent boost enhancement compared to intravascular ultrasound in the evaluation of stent expansion in elective percutaneous coronary interventions

Background

Stent underexpansion is a major risk factor for in-stent restenosis and acute in-stent thrombosis¹Intravascular ultrasound (IVUS) is one of the standards for detection of stent underexpansion (de Feyter et al. 1999; Mintz et al., 2001). StentBoost (SB) enhancement allows an improved angiographic visualization of the stent (Koolen et al., 2005).

Extramural vessel wall hematoma causing a reduced vessel diameter after coronary stenting: Diagnosis by intravascular ultrasound and treatment by stent implantation

An extramural vessel wall hematoma occured immediately after implanting a coronary stent in an in-stent-restenosis of the intermedius branch. Angiography showed a significant luminal reduction distal to the intervention site. Intravascular ultrasound revealed an extramural echolucent zone compressing the vessel lumen. Stent implantation compressed the hematoma and allowed adequate myocardial perfusion. This demonstrates the value of intravascular ultrasound (IVUS) in cases of unusual angiographic results which can help to manage complications after coronary intervention. Cathet. Cardiovasc. Diagn. 43:438–443, 1998. © 1998 Wiley-Liss, Inc.