Reproducibility of neointima quantification with motorized intravascular ultrasound pullback in stented coronary arteries

BACKGROUND: Intravascular ultrasound (IVUS) imaging has shown excellent reproducibility immediately after coronary stent implantation. However, the variability of measurements in lesions late after stent implantation, when neointima formation is present, has not been studied. Neointimal tissue is generally low echogenic and thus difficult to quantify. We therefore sought to analyze the reproducibility of morphometric measurements late after stent implantation. METHODS AND RESULTS: Fifty consecutive patients were investigated 6 months after Palmaz-Schatz stent implantation (motorized catheter pullback 0.5 mm/s). Two experienced investigators independently identified the stent area, lumen area, and neointimal area at different sites within the stent. Planimetric measurements were performed with commercially available software. Correlation coefficient and mean difference for corresponding measurements were calculated for the intraobserver and interobserver comparisons. Variability for the intraobserver and interobserver comparisons was similar. Observer agreement regarding the presence of neointimal hyperplasia was as high as 71% (interobserver comparison 62%). The mean difference for neointima area was 0.06 +/- 1.5 mm(2) (-0.6 +/- 1.5 mm(2)); mean differences for lumen area were 0.02 +/- 0.19 mm(2) (0.03 +/- 0.17 mm(2)) and for stent area 0.01 +/- 0.09 mm(2) (-0.02 +/- 0.12 mm(2)) (values for interobserver comparison are given in parentheses). Correlation between measurements was high for all structures: correlation coefficients were 0.66 (0.69) for neointima, 0.94 (0.95) for lumen, and 0.95 (0. 91) for stent area. CONCLUSIONS: Morphometric measurements of IVUS investigations with motorized IVUS pullback late after stent placement show good reproducibility. Intraobserver variability and interobserver variability are low. Differences for corresponding measurements were more pronounced for neointima area. Motorized catheter pullback guarantees high reliability of IVUS measurements and should be used routinely for clinical IVUS studies.     

Quantitative changes in reference segments during IVUS-guided stent implantation: Impact on the criteria for optimal stent expansion

Intravascular ultrasound is an established method to optimize stent implantation. Stent expansion is estimated from the relation between minimal in-stent cross-sectional area and reference lumen area. We analyzed the periprocedural lumen increment in the reference segments and its impact on intravascular ultrasound (IVUS) criteria for optimized stenting. Seventy-five consecutive patients were studied with a 2.9 Fr, 30-MHz system and motorized pullback (0.5 mm/sec). Lumen area was measured by planimetry; absolute and relative differences in area (Δ area) were calculated. Lumen area increment for reference segments proximal and distal to the stent was 6.4% ± 10.3% and 6.1% ± 10.8%; 49/75 patients fulfilled all IVUS criteria for optimal stent expansion at the final IVUS assessment, and 10/75 patients met all the IVUS criteria in relation to the first measurement of reference lumen area, but not in relation to the final measurement of reference lumen area. During high-pressure dilatation within the stent, reference lumen increment is visible. If reference lumen planimetry is not repeated after additional high-pressure balloon inflation, the final relative stent expansion may be overestimated. Cathet. Cardiovasc. Intervent. 47:434–440, 1999. © 1999 Wiley-Liss, Inc.     

Effect of lumen narrowing within coronary stents on proximal and distal vessel segments following bare metal stent implantation

Adjacent reference vessel response to smaller lumens at stented segments was examined with 3-dimensional intravascular ultrasound analysis. In 128 patients after bare metal stent implantation, minimal lumen area (MLA) within the stent and average lumen area at distal/proximal adjacent reference segments (5 mm) were obtained at baseline and follow-up. In the smaller in-stent MLA group (MLA <3 mm2), lumen area decreased significantly at the distal edge compared with the larger in-stent MLA group (MLA > or =3 mm2), although no significant difference was seen at the proximal edge. In-stent lumen patency may influence vascular responses at adjacent reference segments after bare metal stent implantation.     

Effect of lumen narrowing within sirolimus-eluting stents on proximal and distal vessel segments.

BACKGROUND: Flow dynamics and shear stress may influence downstream vessel segments. The aim of this study was to investigate the potential impact of lumen narrowing within sirolimus-eluting stents (SES) on vessel response at adjacent reference sites. METHODS AND RESULTS: In 135 patients after SES implantation, minimal lumen area (MLA) within the stent and average lumen area at distal or proximal adjacent reference segments (5 mm) were obtained at baseline and follow up. In the smaller in-stent MLA group (MLA <3 mm(2)), lumen area decreased significantly at the distal reference compared with the larger in-stent MLA group (MLA >or=3 mm(2)), although no significant difference was seen at the proximal reference. CONCLUSION: In-stent lumen patency may influence vascular responses at adjacent reference segments after SES implantation.     

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.     

Intravascular ultrasound parameters associated with stent thrombosis after drug-eluting stent deployment

Drug-eluting stent (DES) thrombosis (ST) can be devastating. The study aim was to evaluate intravascular ultrasound (IVUS) predictors for DES thrombosis by comparing IVUS studies after implantation in 13 patients with 14 DES thrombosis lesions with a group of controls (30 lesions in 27 patients) matched for history of chronic renal failure and type of DES. Five patients (38%) discontinued dual antiplatelet therapy at the time of ST. There were 3 in-stent restenosis lesions (21%) treated using DESs in the ST group compared with 0 in the control group (p <0.05). Compared with the control group, IVUS studies in the ST group showed a smaller minimum stent area (4.6 +/- 1.1 vs 5.6 +/- 1.7 mm(2), p = 0.0489). In the ST group, 11 of 14 stents had a minimum stent area < or =5.0 mm(2) compared with 12 of 30 in the control group (p = 0.0392). Minimum stent area in patients who stopped clopidogrel therapy and developed ST (5.30 +/- 1.15 mm(2)) tended to be larger compared with that in patients who developed ST while using clopidogrel (4.24 +/- 0.96 mm(2), p = 0.091). Within the 5-mm-long proximal and distal reference segments analyzed, the ST group had larger proximal reference maximum plaque burdens and smaller minimum lumen areas, along with a tendency toward similar findings in the distal reference segments. In conclusion, IVUS findings at the time of DES implantation in patients who subsequently developed ST showed a smaller minimum stent area (especially in patients who developed ST while using clopidogrel) and more residual disease at the stent edges.     

Expansion of the Multilink-Tristar stent after direct implantation and predilatation: comparison of clinical,angiography and intravascular ultrasound parameters

Coronary stenting has become the primary therapeutic option for many coronary lesions. As opposed to conventional stenting the advantages of direct stenting are a reduction of procedural time, radiation exposure and costs. However, data about the incidence of in-stent restenosis are so far not available. It was the aim of this prospective study to compare the expansion of the Multilink stent after direct stenting and predilatation by quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS). Between January 2000 and June 2001, 82 patients were assigned to direct stenting (46 lesions) or predilatation (40 lesions) in lesions of coronary arteries > 3 mm. The procedural success rate was 92% in patients undergoing direct stenting. The baseline clinical characteristics were similar in both groups. The comparison of the angiographic data shows that direct stenting was performed in lesions with a lower degree of stenosis (71 +/- 12% vs 79 +/- 11%, p = 0.01) and that significantly shorter stents were used (14.4 +/- 3.0 vs 17.8 +/- 4.1 mm, p = 0.0007). The mean stenosis length was not significantly different in either group (10.5 +/- 3.4 vs 11.7 +/- 4.3 mm, n.s.). The QCA data after stent implantation show no differences of either implantation technique. Stent expansion was assessed by IVUS estimation of the proximal, distal and minimal in stent area. The minimal in-stent area (9.53 +/- 3.23, mm2 vs 8.65 +/- 1.96 mm2, n.s.) and the stent symmetry index (0.88 vs 0.88 n.s.) were not different in either patient group. These results indicate that in this subset of selected coronary lesions > 3 mm, elective stent implantation with and without predilatation effectively can achieve comparable stent expansion as assessed by QCA and IVUS. In comparison to conventional stent implantation stents, which were implanted without predilatation, were significantly shorter to cover the same lesion length.     

Effect of stent oversizing on in-stent stenosis and lumen size in normal porcine veins.

PURPOSE: To present an in vivo evaluation of the effects of stent oversizing on in-stent stenosis and on actual lumen size in normal veins. METHODS: Twelve self-expanding stents were implanted in the common iliac veins of 6 minipigs, which were divided in 2 groups for follow-up at 1 and 3 months, respectively. Oversizing ranged from 119.5% to 216% of the original vessel diameter. Intravascular ultrasound (IVUS) was used to measure vessel areas at the stent edges and midpoint. In-stent stenosis and decrease in actual lumen size were evaluated with IVUS immediately after implantation and during follow-up. RESULTS: There was a very strong positive linear regression between stent oversizing and in-stent stenosis in the 1-month model (r=0.947, p=0.004), in the 3-month model (r=0.931, p=0.007), and in the sum of these 2 groups (r=0.83, p<0.001). Regarding the change in actual lumen size, we found a strong negative linear regression with stent oversizing in the 1-month (r=-0.754, p=0.083) and the 3-month (r=-0.562, p=0.246) groups, but these did not attain statistical significance. However, a strong correlation between stent oversizing and a decrease in lumen size in all samples proved to be statistically significant (r=0.619, p=0.032). CONCLUSIONS: Stent oversizing was strongly correlated with increased in-stent stenosis and decreased actual lumen size at follow-up in normal non-stenotic porcine veins.     

True 3-dimensional reconstruction of coronary arteries in patients by fusion of angiography and IVUS (ANGUS) and its quantitative validation

BACKGROUND: True 3D reconstruction of coronary arteries in patients based on intravascular ultrasound (IVUS) may be achieved by fusing angiographic and IVUS information (ANGUS). The clinical applicability of ANGUS was tested, and its accuracy was evaluated quantitatively. METHODS AND REUSLTS: In 16 patients who were investigated 6 months after stent implantation, a sheath-based catheter was used to acquire IVUS images during an R-wave-triggered, motorized stepped pullback. First, a single set of end-diastolic biplane angiographic images documented the 3D location of the catheter at the beginning of pullback. From this set, the 3D pullback trajectory was predicted. Second, contours of the lumen or stent obtained from IVUS were fused with the 3D trajectory. Third, the angular rotation of the reconstruction was optimized by quantitative matching of the silhouettes of the 3D reconstruction with the actual biplane images. Reconstructions were obtained in 12 patients. The number of pullback steps, which determines the pullback length, closely agreed with the reconstructed path length (r=0.99). Geometric measurements in silhouette images of the 3D reconstructions showed high correlation (0.84 to 0.97) with corresponding measurements in the actual biplane angiographic images. CONCLUSIONS: With ANGUS, 3D reconstructions of coronary arteries can be successfully and accurately obtained in the majority of patients.     

The effect of paclitaxel-eluting stents on restenosis]

OBJECTIVE: In our study we aimed to investigate the effects of paclitaxel-eluting stent on restenosis. METHODS: Sixteen porcine were randomly assigned to two groups (n=8 per group): control group animals received conventional stent implantation and study group animals -paclitaxel-eluting stent implantation. Both groups were treated with 300 mg acetylsalicylic acid and 75 mg clopidogrel daily. The degree of neointimal proliferation and effect of drug-eluting stent on restenosis were evaluated 6 weeks after by angiography and intravascular ultrasound (IVUS). RESULTS: Angiographic in-stent restenosis was lower in paclitaxel-eluting stent group (12.50 +/- 7.07% versus 41.25 +/- 28.50%, p=0.001). The IVUS data demonstrated that paclitaxel group animals had larger minimal lumen area (8.76 +/- 1.09 mm2 versus 6.23 +/- 3.10 mm2, p=0.028), smaller mean neointimal proliferation area (1.03 +/- 0.75 mm2 versus 3.55 +/- 2.86 mm2, p=0.01) and mean percent stenosis (10.71 +/- 8.10% versus 36.85 +/- 30.93%, p=0.01). CONCLUSION: This study suggests that drug-eluting stents may also have a preventive effect for the in-stent restenosis.     

Angiographic and intravascular ultrasound predictors of in-stent restenosis

Objectives. This study was performed to determine predictors of in-stent restenosis from a high volume, single-center practice.Background. Intracoronary stents have been shown to reduce the restenosis rate as compared with balloon angioplasty, but in-stent restenosis continues to be an important clinical problem.Methods. Between April 1993 and March 1997, 1,706 patients with 2,343 lesions were treated with a variety of intracoronary stents. The majority of stents were placed with high pressure balloon inflations and intravascular ultrasound (IVUS) guidance. Angiographic follow-up was obtained in 1,173 patients with 1,633 lesions (70%). Clinical, angiographic and IVUS variables were prospectively recorded and analyzed by univariate and multivariate models for the ability to predict the occurrence of in-stent restenosis defined as a diameter stenosis ≥50%.Results. In-stent restenosis was angiographically documented in 282 patients with 409 lesions (25%). The restenosis group had a significantly longer total stent length, smaller reference lumen diameter, smaller final minimal lumen diameter (MLD) by angiography and smaller stent lumen cross-sectional area (CSA) by IVUS. In lesions where IVUS guidance was used, the restenosis rate was 24% as compared with 29% if IVUS was not used (p < 0.05). By multivariate logistic regression analysis, longer total stent length, smaller reference lumen diameter and smaller final MLD were strong predictors of in-stent restenosis. In lesions with IVUS guidance, IVUS stent lumen CSA was a better independent predictor than the angiographic measurements.Conclusions. Achieving an optimal stent lumen CSA by using IVUS guidance during the procedure and minimizing the total stent length may reduce in-stent restenosis.     

Sirolimus-eluting stent in chronic total occlusion: the SICTO study

Coronary stenting can significantly reduce the restenosis and reocclusion rates after successful balloon angioplasty for chronic total occlusions (CTO). Nevertheless, recanalization of CTO remains among the worst predictors for in-stent restenosis and reocclusion. This multicenter, nonrandomized study assessed the safety and effectiveness of the CYPHER sirolimus-eluting stent in reducing angiographic in-stent late loss in totally occluded native coronary arteries. A total of 25 eligible patients were treated with the CYPHER sirolimus-eluting stent. Baseline clinical and angiographic data were collected and 6-month follow-up angiography and intravascular ultrasound (IVUS) were performed. Clinical follow-up was required at 30 days, 6, 12, 18, and 24 months. Study stent implantation was successful in all patients, with a mean stent length of 28.4 +/- 11 mm. Six-month angiographic outcomes showed that mean lumen diameter stenosis did not change (2.22 +/- 0.56 mm postprocedure; 2.26 +/- 0.60 mm at 6 months follow-up; P = NS). Similarly, mean percent diameter stenosis did not change significantly (15.7 +/- 8.6% postprocedure, 19.3 +/- 11% at follow-up; P = NS). The absolute late lumen loss was -0.03 +/- 0.28 mm with a 6-month in-stent restenosis rate of 0%. IVUS follow-up revealed in-stent obstruction volume of only 4.9 +/- 6.8%. Long-term clinical follow-up showed target lesion revascularization at 12 months was only 4%, with target vessel revascularization of only 12%. The CYPHER sirolimus-eluting stent was safe and effective in the treatment of CTO compared to historical data with bare metal stents.     

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.     

Two-year follow-up intravascular ultrasound analysis after bare metal stent implantation in 120 lesions.

The objective of this study was to examine long-term changes after bare metal stent implantation in a relatively large number of patients. There are few reports of intravascular ultrasound (IVUS) studies performed on stented and nonstented (reference) segments beyond 6 months after bare metal stenting. Using IVUS, we evaluated serial changes in stented and reference segments between 6 and 24 months after stent implantation in 110 patients with 120 lesions. Serial IVUS images were acquired at five equidistant intrastent sites and at two different reference segment sites. Measurements were made of the external elastic membrane (EEM), stent, lumen, and intimal hyperplasia (IH = stent - lumen) area. For the whole patient group, between 6 and 24 months, the mean IH area in stented segments decreased from 2.6 +/- 1.0 to 2.3 36+/- 0.9 mm2 (P < 0.001), and the mean lumen area increased from 6.2 +/- 2.0 to 6.5 +/- 1.9 mm2 (P < 0.001). The mean IH area decreased in 91 lesions (76%) and increased in 29 lesions (24%) between 6 and 24 months. There were no significant changes in EEM or lumen area in the reference segments. Late angiographic restenosis (diameter stenosis > or = 50%) occurred in three lesions between 6 and 24 months. A late target lesion revascularization was performed for one lesion. In the period of time between 6 and 24 months after stenting, IH regression occurred in most (76%) stent lesions, resulting in late lumen increase. However, IH progression was observed in 24% of in-stent lesions. No significant changes of EEM or lumen area occurred in the reference segments.     

Angiography-guided routine coronary stent implantation results in suboptimal dilatation

The resistance of the atherosclerotic lesion counteracts the expansion of the stent, resulting in suboptimal stent expansion. Intravascular ultrasound provides more precise information on stent expansion than coronary angiography but adds cost and time to the percutaneous transluminal coronary angiography procedure. The aim of this study was to evaluate the need for intravascular ultrasound at routine angiography-guided high pressure stent implantation by comparing stent expansion with predefined intracoronary ultrasound criteria for optimal stent implantation. In 32 patients, 48 stents (35 NIR, 12 AVE, and 1 Cordis) were implanted in A, B, and C stenoses using a high-pressure inflation technique until an optimal result was achieved according to angiography. Stent expansion was then evaluated by intravascular ultrasound as minimal lumen diameter, minimal lumen area, proximal and distal stent area, and a minimal lumen area symmetry index. These variables were then compared with the nominal stent size in vitro. Finally the stents were also evaluated with respect to the MUSIC criteria, ie, strict criteria regarding symmetry, apposition, and vessel geometry according to intravascular ultrasound after stent expansion. Forty-five stents could be completely analyzed. The mean balloon inflation pressure was 12.8 (range, 10-17) atm. The nominal stent size was not achieved in any patient. Minimal lumen diameter attained 77% and minimal lumen area 78% of expected nominal values (p<0.0001), distal stent area 88% (p < 0.001), and proximal stent area 92% (ns). Application of the MUSIC criteria showed that almost all stents (96%) had good stent apposition and symmetry index. Optimal proximal stent entrance was found in 70%. Optimal minimal lumen area in comparison to the reference areas was present in 41%. This lead to fulfilling of all MUSIC criteria in 47% of the stents. If nominal stent size had been achieved, symmetry index and apposition would have been fulfilled in all cases and optimal minimal lumen area increased to 75%. Acceptable proximal entrance however would have decreased to 55% and the fulfillment of all MUSIC criteria would increase only to 52%. In routine angiography-guided stent implantation in stenoses with a wide range of severities using modern stents and high pressure inflation technique to reach a visually optimal result, the nominal stent size was never achieved mainly due to residual intrastent stenosis. If nominal stent size had been achieved, the results would have improved only marginally and would still be suboptimal in almost half of the stents. These results highlight the shortcoming of angiography and the need for intravascular ultrasound in choosing correct stent size.     

Results of the Jostent coronary stent graft implantation in various clinical settings: procedural and follow-up results.

The Jostent coronary stent graft (CSG) is composed of a PTFE layer sandwiched between two stainless steel stents, initially introduced for the treatment of coronary perforations and aneurysms with excellent results. By providing a mechanical barrier, this stent design also may be beneficial in the treatment of complex ulcerated lesions and in-stent restenosis by preventing debris protrusion and neointimal proliferation through the stent struts. To evaluate the safety and efficacy of this stent graft, we implanted 78 CSGs in 70 patients for a broad range of indications, including coronary perforations, aneurysms, degenerated saphenous vein grafts, complex lesions, and in-stent restenosis. The primary angiographic success rate (95.9%) was high, and using intravascular ultrasound (IVUS) guidance during stent implantation and high inflation pressures (19.3 +/- 3.2 atm), stent expansion with optimal symmetry was achieved in 94.7%. One limitation of the Jostent CSG was the side-branch occlusion rate (18.6%) and the resulting non-Q-wave infarction rate in seven cases (mean CK elevation, 238 U/l), acute Q-wave MI in two cases, and transient ventricular fibrillation in one patient after occlusion of the proximal RCA side branch without further complications. Subacute stent thrombosis occurred in four cases (5.7%) 7 to 70 days after stent implantation, despite using combined antiplatelet therapy with aspirin (ASA), ticlopidine, and/or clopidogrel for 30 days. Angiographic follow-up was available in 56 patients (80.0%) after a mean of 159 +/- 49 days, and follow-up IVUS was available in 38 cases. The overall restenosis rate (> 50% diameter stenosis) was 31.6% manifest primarily as edge restenosis (29.8% stent edge vs. 8.8% stent center; P < 0.001). IVUS examinations showed a minimal late lumen loss of 0.4 +/- 2.2 mm(2) within the center of the stent graft vs. 3.2 +/- 2.3 mm(2) at the stent edges (P < 0.001). The restenosis rate in the prespecified subgroups was 33.3% for saphenous vein grafts (2/6 lesions), 30.0% in complex lesions (6/20 lesions), and 38.5% (10/26 lesions) for the treatment of in-stent restenosis. Implantation of the Jostent CSG is feasible and safe, even in complex lesion subsets, and is associated with high primary success rates provided major side branches are avoided. The use of this stent may require an extended time course of antiplatelet therapy. Frequent focal stent edge renarrowing influences the overall restenosis rate. However, in treatment of complex in-stent restenosis and vein graft lesions, stent grafts may offer benefit over conventional therapies. Covered stents such as the JoMed coronary stent graft may become essential for bailout treatment of coronary perforations.     

Mechanism of cutting balloon angioplasty for in-stent restenosis: an intravascular ultrasound study.

We investigated by intravascular ultrasound (IVUS) the mechanism of action of cutting balloon (CB) angioplasty in patients with in-stent restenosis. Seventy-one consecutive restenotic lesions of 66 patients were studied by quantitative coronary angiography (QCA) and IVUS before, immediately after, and, in 20 cases, at 24-hr time interval after CB. CB was selected according to 1:1 CB-to-stent ratio and inflated at 8 atm for 60-90 sec. Both IVUS planar and volumetric (Simpson's rule, 25 patients) analysis were carried out. IVUS measurements included external elastic membrane area (EEMA), stent area (SA), minimal lumen area (MLA), and restenosis area (RA). Following CB, QCA analysis showed increase of minimal lumen diameter (1.17 +/- 0.46 vs. 2.45 +/- 0.51 mm; P < 0.0001) and decrease of diameter stenosis (64% +/- 13% vs. 21% +/- 9%; P < 0.0001). IVUS measurements showed a significant increase of MLA (2.18 +/- 0.80 vs. 7.31 +/- 1.8 mm(2); P < 0.0001), SA (9.62 +/- 2.6 vs. 10.7 +/- 2.75 mm(2); P < 0.0001), and EEMA (17.27 +/- 5 vs. 18.1 +/- 5 mm(2); P < 0.0001) and a decrease of RA (7.43 +/- 2.63 vs. 3.45 +/- 1.39 mm(2); P < 0.0001). No significant change was observed in the original plaque + media area (7.65 +/- 3 vs. 7.38 +/- 2.9 mm(2); P = NS). Thus, of the total lumen enlargement (5.13 +/- 1.85 mm(2)), 23% was the result of increase in mean SA, whereas 77% was the result of a decrease in mean RA. These changes were associated with a 5% increase in EEMA. IVUS volumetric changes paralleled planar variations. Angiographic and IVUS changes were well maintained at 24 hr. CB enlarges coronary lumen mainly by in-stent tissue reduction associated with a moderate degree of additional stent expansion. Favorable QCA and IVUS acute results are maintained at 24 hr.     

Impact of the acute results on the long-term outcome after the treatment of in-stent restenosis: a serial intravascular ultrasound study.

The current study used serial (postintervention and follow-up) intravascular ultrasound (IVUS) to assess the impact of acute results on long-term follow-up of patients with in-stent restenosis (ISR). All patients (n = 180) with serial IVUS studies of ISR lesions from the following gamma-irradiation brachytherapy trials were included: Washington Radiation for In-Stent Restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent Restenosis Trial in Native Coronaries (ARTISTIC). There were 106 irradiated and 74 placebo patients. Quantitative analysis was performed according to the American College of Cardiology Clinical Expert Consensus Document on Standards for Acquisition, Measurement and Reporting of IVUS. Images were acquired using motorized transducer pullback, cross-sectional analysis was performed every 1 mm, and volumetric and mean planar dimensions were calculated. The independent predictors for the absolute follow-up minimum lumen area (MLA) were the postintervention MLA, the postintervention minimum stent area, and the use of brachytherapy. Placebo patients lost 45% of the postintervention MLA while irradiated patients lost only 17% of the MLA. The independent predictors of the follow-up percent intimal hyperplasia (intimal hyperplasia volume divided by stent volume) and the independent predictors of the absolute increase in intimal hyperplasia were the postintervention percent intimal hyperplasia and the use of brachytherapy. Serial IVUS analysis shows that the follow-up MLA and percent intimal hyperplasia are dependent on the results obtained during the treatment of ISR lesions.     

Treatment of in-stent restenosis with high speed rotational atherectomy and IVUS guidance in small <3.0 mm vessels

The management of in-stent restenosis remains a subject for debate because no one revascularization option is considered the most appropriate. Since a high restenosis rate still occurs after repeat balloon angioplasty, new techniques are attempted in order to reduce this rate. A combination of high speed rotational atherectomy (HSRA) and adjunctive balloon angioplasty is likely to achieve good results. In small (<3.0 mm diameter) vessels, the risk of interaction between the burr and the stent increases. We thus used intravascular ultrasound (IVUS) guidance in the treatment of in-stent restenosis with HSRA in small <3.0 mm small diameter vessels. Nine patients with in-stent restenosis in small vessels were referred for repeat angioplasty. Initial IVUS examination was used to assess the minimal stent struts diameter and to guide the burr size selection. A combination of HSRA and additional balloon angioplasty was performed under IVUS and angiographic guidance. Mean angiographic reference diameter was 2.25 ± 0.35 mm and mean stent struts diameter was 2.38 ± 0.20 mm. Burr size was selected ∼0.5 mm smaller than stent struts diameter and ranged from 1.75 to 2.5 mm, with a 0.88 ± 0.12 mean burr/artery ratio (range 0.71, 1.08). In two patients, a second larger burr was used. In 4/9 patients, the burr size chosen under IVUS guidance was close to angiographic MLD at stent implantation and thus larger than what would be used without IVUS guidance. Additional balloon angioplasty was decided in all cases, using a 1.1 ± 0.15 balloon/artery ratio. No complication occurred. Mean relative gain in minimal lumen diameter (MLD) was 94 ± 90% after HSRA and 54 ± 34% after balloon angioplasty (total relative gain 180 ± 100%). IVUS guidance allowed safe management of in-stent restenosis in small vessels using combination of HSRA and balloon angioplasty. Long-term follow-up and comparison with other techniques are necessary to assess whether this technique should be used routinely. Cathet. Cardiovasc. Diagn. 44:77–82, 1998. © 1998 Wiley-Liss, Inc.     

Analysis of reproducibility of reference lumen quantitation with intravascular ultrasound in stented coronary arteries

Intravascular ultrasound is widely used to guide coronary stent implantation. The key quantitative criterion for successful implantation is the demonstration of adequate expansion of the stented lumen relative to that of the adjacent reference vessel segments. In this study we aimed to establish the reproducibility of intravascular ultrasound measurements of the reference segments in lesions undergoing coronary stenting. Measurements of the reference segment lumen dimensions were made in a blinded fashion by two experienced observers, and reproducibility was assessed by calculating the mean difference and standard deviation of the paired measurements. The unselected intraobserver random variability of the mean reference lumen area measured 0.8 mm². The interobserver random variability was 0.94 mm². The intraobserver and interobserver variability of minimum lumen area within the stent was smaller, measuring 0.30 mm² and 0.52 mm², respectively. There was 91% intraobserver agreement, and 75% interobserver agreement, in identifying adequate stent expansion as defined by a stent-to-mean reference lumen area ratio of >0.8. The potentially significant level of variability inherent in selecting and measuring the reference segments, and its impact on clinical decision-making, should be remembered when this method of assessing the acute quantitative outcome of stent implantation is applied. Cathet Cardiovasc Diagn 40:1–7, 1997. © 1997 Wiley-Liss, Inc.