Late intravascular ultrasound findings of patients treated with brachytherapy for diffuse in-stent restenosis.

This study aimed at evaluating long-term (24-month) effects of beta-irradiation (188Re-MAG3-filled balloon) using intravascular ultrasound (IVUS) in patients with in-stent restenosis (ISR). Long-term effects of beta-irradiation on intimal hyperplasia (IH) within the stented segment and vessel and lumen dimensions of nonstented adjacent segments in patients with ISR have not been sufficiently evaluated. Two-year follow-up IVUS was performed in 30 patients with patent ISR segments at 6-month follow-up angiography. Serial IVUS images were acquired at five equidistant intrastent sites and at three different reference segment sites. IH burden (%) was defined as 100 x (IH/stent area). Mean intrastent IH area and IH burden significantly increased between 6 and 24 months, from 2.1 +/- 1.1 to 2.6 +/- 1.4 mm2 (P < 0.001) and from 26% +/- 10% to 33% +/- 14% (P < 0.001), respectively. There was a significant decrease of mean external elastic membrane (from 10.1 +/- 3.9 to 9.7 +/- 3.9 mm2; P = 0.015) and lumen area (from 5.6 +/- 2.3 to 5.1 +/- 2.3 mm2; P = 0.021) within distal reference segments between 6 and 24 months. Target lesion revascularization (TLR) was performed in six patients (20%) between 6 and 24 months after beta-irradiation therapy. There were no significant differences between TLR and non-TLR groups except for a smaller minimum lumen area at 24 months in the TLR group. Because of a small amount of late loss between 6 and 24 months, most irradiated ISR vessel segments remained stable for up to 2 years. However, quantitative evidence of late catch-up was evident in most patients and was significantly associated with 24-month TLR in some patients.     

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.     

Comparison of intravascular ultrasound and angiographic assessment of coronary reference segment size in patients with type 2 diabetes mellitus

During percutaneous coronary intervention, the reference segment is assessed angiographically. This report described the discrepancy between angiographic and intravascular ultrasound (IVUS) assessment of reference segment size in patients with type 2 diabetes mellitus. Preintervention IVUS was used to study 62 de novo lesions in 41 patients with type 2 diabetes mellitus. The lesion site was the image slice with the smallest lumen cross-sectional area (CSA). The proximal and distal reference segments were the most normal-looking segments within 5 mm proximal and distal to the lesion. Plaque burden was measured as plaque CSA/external elastic membrane (EEM) CSA. Using IVUS, the reference lumen diameter was 2.80 +/- 0.42 mm and the reference EEM diameter was 4.17 +/- 0.56 mm. The angiographic reference diameter was 2.63 +/- 0.36 mm. Mean difference between the IVUS EEM diameter and angiographic reference diameter was 1.56 +/- 0.55 mm. The mean difference between the IVUS reference lumen diameter and angiographic reference lumen diameter was 0.18 +/- 0.44 mm. Plaque burden in the reference segment correlated inversely with the difference between IVUS and quantitative coronary angiographic reference lumen diameter (slope = -0.12, 95% confidence interval -0.17 to -0.07, p <0.001), but it was not related to the absolute angiographic reference lumen diameter. Thus, reference segment diameters in type 2 diabetic patients were larger using IVUS than angiography, especially in the setting of larger plaque burden. In conclusion, these findings combined with inadequate remodeling may explain the angiographic appearance of small arteries in diabetic patients.     

Accuracy of electrocardiographic-gated versus nongated volumetric intravascular ultrasound measurements of coronary arterial narrowing

Intravascular ultrasound (IVUS) allows precise measurements of plaque plus media (P+M) volume and neointimal hyperplasia after coronary artery stenting. Conventional IVUS volumetric analysis is performed mostly without electrocardiographically gated acquisition, and the IVUS images are selected at 1-mm intervals, whereas the electrocardiographically gated approach consists of images in end-diastole. The accuracy in the luminal, P+M, and external elastic membrane (EEM) volumes between 2 pullbacks with the electrocardiographically gated and nongated approaches has not previously been compared. In 15 patients, 19 segments were studied with electrocardiographically gated and nongated IVUS systems. Two identical pullbacks were performed with each system using the same IVUS catheter. Volumes of the lumen, EEM, and P+M obtained using the electrocardiographically gated pullback technique did not differ significantly from the corresponding volumes obtained using the nongated pullback technique (lumen: 109.7 +/- 47.7 vs 109.2 +/- 45.0 mm(3), p = NS; EEM: 242.6 +/- 109.2 vs 235.0 +/- 108.1 mm(3), p = NS; P+M: 134.8 +/- 67.7 vs 129.8 +/- 69.1 mm(3), p = NS). No significant differences were seen in changes between 2 electrocardiographically gated and 2 nongated pullbacks (lumen: 0.37 +/- 1.76 vs -0.23 +/- 2.32 mm(3), p = NS; EEM: 0.25 +/- 3.22 vs -0.94 +/- 4.27 mm(3), p = NS; P+M: -0.18 +/- 3.42 vs -0.74 +/- 3.88 mm(3), p = NS). In conclusion, in moderate atherosclerotic or stented coronary arteries, electrocardiographically gated IVUS acquisition is not superior in accuracy to conventional nongated IVUS acquisition.     

Vascular response to sirolimus-eluting stents delivered with a nonaggressive implantation technique: comparison of intravascular ultrasound results from the multicenter, randomized E-SIRIUS, and SIRIUS trials.

BACKGROUND: The effectiveness of SES to reduce the risk of restenosis was initially demonstrated in short lesions using stent implantation with routine pre-dilatation and post-dilatation. This intravascular ultrasound (IVUS) substudy of the E-SIRIUS trial sought to evaluate local arterial responses to sirolimus-eluting stents (SES) delivered with a stent implantation technique allowing direct stenting and only selectively applying high-pressure post-dilatation. METHODS AND RESULTS: IVUS was performed immediately after intervention and at 8-month follow-up in 51 patients randomised to either bare-metal stents (BMS; Bx-Velocitytrade mark; N=20) or SES (Cyphertrade mark N=31). Direct stenting was allowed (24%) and post-dilation was performed only selectively (32%). Lumen dimensions, intimal hyperplasia and vessel remodeling were compared between SES and BMS. Subsequently, results of SES in the E-SIRIUS IVUS substudy (N=31) were compared to those of SES in the IVUS substudy of the SIRIUS trial (N=137). SES in SIRIUS IVUS substudy were delivered with 100% pre-dilatation and 77% post-dilatation. Baseline stent and reference segment measurements were similar between BMS and SES in E-SIRIUS IVUS patients. Using SES there was a 96% reduction in intimal hyperplasia volume within the stented segment (1.8+/-4.9 vs 50.6+/-39.7 mm3, P<0.001) and a significantly larger minimal lumen cross sectional area at 8-month follow-up (4.5+/-1.1 vs 2.3+/-0.9 mm2, P<0.001). No vessel remodeling was observed with the use of SES. The applied stent implantation technique resulted in a minimal stent/reference vessel area ratio of 0.75+/-0.17 in E-SIRIUS SES as compared to 0.84+/-0.23 in SIRIUS SES (P=0.046). Mean intimal hyperplasia cross-sectional area at follow-up was 0.1+/-0.2 mm2 in the SES group of E-SIRIUS and 0.5+/-0.8 mm2 in the SES group of SIRIUS (P=0.003). CONCLUSIONS: An implantation technique of SES which includes direct stenting and minimizes the use of high-pressure post-dilatation results in less optimal stent expansion. However, follow-up results compare very favourable to those of BMS and are characterised by even less intimal hyperplasia than after a more forceful implantation of SES.     

Intravascular ultrasound assessment of remodelling and reference segment plaque burden in type-2 diabetic patients.

AIMS: Intravascular ultrasound (IVUS) assesses arterial remodelling by comparing the lesion external elastic membrane (EEM) with the reference segments; however, reference segments are rarely disease-free. The aim was to assess lesion and reference segment remodelling and plaque burden in patients with type-2 diabetes mellitus. METHODS AND RESULTS: We used pre-intervention IVUS to study 62 de novo lesions in 43 patients with type-2 diabetes mellitus. The lesion site was the image slice with the smallest lumen cross-sectional area (CSA). The proximal and distal reference segments were the most normal-looking segments within 5 mm proximal and distal to the lesion. Plaque burden was measured as plaque CSA/EEM CSA. The remodelling index was defined as lesion EEM CSA/mean reference EEM CSA. Reference segment plaque burden measured 0.54 +/- 0.09. The majority of lesions (83.9%) had negative remodelling (lesion EEM < reference). Similarly, the slope of the regression line relating EEM to plaque CSA within the lesion was less than the reference substantiating negative remodelling. The reference segment plaque burden correlated inversely with the difference between IVUS lumen and quantitative coronary angiographic artery size [slope = -0.12 (95% CI -0.17 to -0.07); P < 0.001] in all patients with type-2 diabetes mellitus. CONCLUSION: Lesions in type-2 diabetic patients are different from previous reports in non-diabetics. Lesions in type-2 diabetics are characterized by a large reference segment plaque burden and negative lesion site remodelling. These IVUS findings may explain the angiographic appearance of small arteries in diabetic patients.     

Remodeling index compared to actual vascular remodeling in atherosclerotic left main coronary arteries as assessed with long-term (> or =12 months) serial intravascular ultrasound.

OBJECTIVES: We present the remodeling index (RI) versus serial intravascular ultrasound (IVUS) data. BACKGROUND: The RI, derived by comparing lesion external elastic membrane (EEM) cross-sectional area versus the reference at one time point, is used in various IVUS studies as a substitute of true remodeling (change in EEM over time), assuming that it represents true remodeling. METHODS: We studied 46 non-stenotic left main arteries using serial IVUS (follow-up 18 +/- 8 months). Plaques were divided into subgroups according to the follow-up RI: follow-up RI >1 (n = 27) versus follow-up RI < or =1 (n = 19). RESULTS: Lesions with a follow-up RI >1 had an increase in lumen despite an increase in plaque because of an increase in EEM. Conversely, lesions with a follow-up RI < or =1 had a reduction in lumen as a result of both a plaque increase and EEM decrease. Overall, the follow-up RI correlated directly with changes in lesion site EEM (baseline-to-follow-up). Although there was no correlation between the follow-up RI and changes in reference EEM area, changes in reference EEM area did correlate directly with changes in lesion EEM area. In nearly 90% of lesions with a follow-up RI >1, there was a previously documented increase in EEM area. Using multivariate linear regression analysis, the follow-up RI was dependent on the baseline RI, the increase in lesion EEM area, and the decrease in reference EEM area. The follow-up RI was not dependent on changes in lesion plaque area. CONCLUSIONS: The vast majority of left main lesions with a remodeling index >1 had evidence of a previous increase in lesion-site EEM area.     

Poststenting axial redistribution of atherosclerotic plaque into the reference segments and lumen reduction at the stent edge: a volumetric intravascular ultrasound study

Lumen enlargement during coronary stenting results from vessel expansion and axial redistribution of atheromatous plaque along the stented segment and proximal and distal reference segments. Plaque burden predicts stenosis at the stent edge. The aim of this study was to investigate the fate of shifted plaque with special reference to whether or not plaque shift (PSh) correlates with late lumen reduction. This is a prospective study conducted on 54 consecutive patients who underwent bare metal stenting. In all stent edges (108 edges), PSh volume was measured as postintervention plaque-media volume (PMV) minus preintervention PMV. Changes in lumen volume (DeltaLV), vessel volume (DeltaVV), and PMV (DeltaPMV) were measured by serial intravascular ultrasound (IVUS) examination. After stenting, PSh was detected in 81.5% of proximal edges versus 72.2% of distal edges (P = 0.36). It correlated significantly with DeltaVV (r = 0.34, P = 0.002), and inversely with DeltaLV (r = 0.32, P = 0.003). However, at 6-month follow-up, it did not correlate with DeltaLV (r = -0.03, P = 0.8), DeltaVV (r = 0.1, P = 0.6), or DeltaPMV (r = 0.1, P = 0.4). Furthermore, DeltaLV correlated more strongly with DeltaVV (r = 0.62, P < 0.00001) than with DeltaPMV (r = -0.39, P = 0.001). By multivariate analysis, PSh area was an independent predictor of the postintervention change in lumen area (partial eta squared 0.21, P = 0.01), but not the follow-up change. Two patients (3.7%) developed proximal edge stenosis with no evident PSh after stenting. Thus, axial redistribution of atheromatous plaque into the reference segments was frequently encountered after stenting. Although PSh correlated with the immediate reduction in stent edge lumen volume, it did not correlate with the late lumen reduction.     

Longitudinal plaque redistribution during stent expansion

The purpose of this study was to clarify the 3-dimensional behavior of plaque during coronary stent expansion. Serial intravascular ultrasound (IVUS) studies, preintervention, and poststenting were evaluated in 32 patients treated with a single-balloon expandable tubular stent. External elastic membrane (EEM), lumen, stent, and plaque + media cross-sectional area were measured at 1-mm intervals through the entire stent as well as proximal and distal reference segments 5 mm from the stent edge. Volumetric calculations were based on Simpson's rule. Overall, the plaque + media volume through the entire lesion did not change during stent expansion (218 +/- 51 vs 217 +/- 47 mm3, p = 0.69). However, EEM and lumen volume increased significantly (EEM volume, 391 +/- 84 vs 448 +/- 87 mm3 [p < 0.0001]; lumen volume, 173 +/- 52 vs 231 +/- 54 mm3 [p < 0.0001]). The change in lumen volume correlated strongly with the change in EEM volume (r = 0.85, p < 0.0001), but poorly with the change in plaque + media volume (r = 0.37, p = 0.03). Plaque + media volume decreased in the midstent zone (59 +/- 14 vs 53 +/- 11 mm3, p = 0.0005), and increased in the distal stent zone (40 +/- 11 vs 44 +/- 9 mm3, p = 0.003), but did not change in either the proximal stent zone or reference segments. The mechanism of stent expansion is a combination of vessel stretch and plaque redistribution, translating disease accumulation from the midstent zone to the distal stent zone.     

Revisiting late loss and neointimal volumetric measurements in a drug-eluting stent trial: analysis from the SPIRIT FIRST trial.

This study was conducted to reevaluate the significance of angiographic late loss and to assess the agreement between new proposed neointimal volumetric measurements derived from quantitative coronary angiography (QCA) and standard intravascular ultrasound (IVUS)-based parameters. Neointimal volumetric measurements may better estimate the magnitude of neointimal growth after stenting than late loss. In 56 in-stent segments (27, everolimus; 29, bare metal) in the SPIRIT FIRST study, we compared QCA measures with the corresponding IVUS parameters. Two IVUS-late loss models were derived from minimal luminal diameter (MLD) using either a circular model or a so-called projected MLD. QCA-neointimal volume was calculated as follows: stent volume (mean area of the stented segment x stent length) at post procedure - lumen volume (mean area of the stented segment x stent length) at follow-up (the stent length either from nominal stent length or the length measured by QCA). Videodensitometric neointimal volume was also evaluated. Each of the three neointimal volume and percentage volume obstruction by QCA showed significant correlation with the corresponding IVUS parameters (r = 0.557-0.594, P < 0.0001), albeit with a broad range of limits of agreement. Late loss and volumetric measurements by QCA had a broader range of standard deviation than those by IVUS. QCA-volumetric measurements successfully confirmed the efficacy of everolimus-eluting stents over bare metal stents (P < 0.05). Our proposed QCA volumetric measurements may be a practical surrogate for IVUS measurements and a discriminant methodological approach for assessment of treatment effects of drug-eluting stents.     

急性冠状动脉综合征患者雷帕霉素洗脱支架晚期贴壁不良及其对临床预后的影响

目的 观察急性冠状动脉综合征(ACS)患者雷帕霉素洗脱支架晚期贴壁不良发生率及其对临床预后的影响.方法 观察2005年2月至2007年3月因ACS(ACS组,54例)和稳定性心绞痛(对照组,83例)行雷帕霉素洗脱支架治疗并于1年后行血管内超声检查患者,检测支架晚期贴壁不良发生率,并观察血管内超声检查后1年内主要不良心血管事件及支架内血栓发生率.结果 所有137例患者219处病变中,16例患者25处病变检测到晚期支架贴壁不良.25处晚期支架贴壁不良中ACS组和对照组分别为20处(22.2%)和5处(3.9%)(P＜0.001).两组患者参照血管外弹力膜面积、参照血管和支架段血管管腔面积和新生内膜面积均相似,但ACS组患者支架段血管外弹力膜面积[(15.34±5.44)mm2比(13.83±4.51)mm2,P=0.026]、支架段血管外弹力膜面积与参照血管外弹力膜面积比值(1.13±0.22比1.02±0.18,P＜0.001)、斑块和中膜面积[(8.43±3.93)mm2比(7.01±2.93)mm2,P:0.002]较对照组明显增大.Logistic多元回归分析显示,ACS(OR=6.477,P＜0.001)和支架长度≥23 mm(OR=3.680,P=0.025)为晚期支架贴壁不良的独立危险因素.血管内超声检查后临床随访1年,两组主要不良心血管事件发生率差异无统计学意义.结论 雷帕霉素洗脱支架置入后,ACS患者较稳定性心绞痛患者更多发生晚期支架贴壁不良,然而随访1年的主要不良心血管事件发生率差异无统计学意义.     

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 moderate lesion calcium on mechanisms of coronary stenting as assessed with three-dimensional intravascular ultrasound in vivo

Axial plaque redistribution is an important mechanism of lumen enlargement after stenting of noncalcified lesions. To assess effects of lesion calcification on mechanisms of coronary stenting, we analyzed 55 lesions with noncircumferential calcification with 3-dimensional intravascular ultrasound (IVUS) (standard qualitative and quantitative analyses) before and after implantation of balloon-expandable stents. Thirty-two plaques (58%) showed arcs of calcium <120 degrees of vessel circumference (group A), whereas 23 lesions (42%) contained arcs of calcium > or =120 degrees of vessel circumference (group B). In the entire cohort of 55 lesions, as well as groups A and B, which were studied separately, both single-slice IVUS analysis (performed at minimum lumen site before intervention) and mean stented segment IVUS analysis showed an increase in lumen and vessel area and a decrease in plaque area (p <0.001). The magnitude of lumen and vessel increase and of plaque decrease was similar in both groups. Group A lesions showed significant plaque extrusion into the distal reference segment that was not observed in group B (increase in plaque area of 1.3 +/- 1.9 vs 0.1 +/- 2.0 mm(2), p <0.04). Stenting did not alter plaque area of the proximal reference segment in either group. In addition, there was an increase in vessel area of the distal reference of both groups, indicating that stent-induced vessel expansion observed within the lesion also affected the distal reference. Thus, longitudinal plaque redistribution and vessel expansion contribute to increased lumen dimensions during stenting of lesions with varying amounts of calcium; however, marked plaque extrusion was found only in lesions with a calcium arc of <120 degrees.     

Peri-stent reference segment plaque burden is associated with disease progression in saphenous vein grafts (a serial intravascular ultrasound assessment)

We are aware of no studies of peri-stent disease progression or luminal compromise in saphenous vein graft (SVG) lesions. We used serial intravascular ultrasound (IVUS) to assess disease progression in peri-stent saphenous vein bypass graft reference segments. We studied 37 peri-stent SVG reference segments in 21 patients; 16 were proximal and 21 were distal to the stent. The same anatomic image slice was analyzed after the intervention and at follow-up; this site was 3.68 +/- 2.22 mm from the stent edge. Graft age was 10.1 +/- 5.4 years, and mean follow-up duration was 13 months (range 3 to 61). Overall, change in SVG area, change in lumen area, and change in plaque burden correlated with postintervention plaque burden (r = 0.448, p = 0.005; r = -0.584, p <0.001; and r = 0.507, p = 0.001, respectively). For the proximal edge, change in lumen area correlated with change in plaque area (r = -0.951, p <0.001), but not with change in SVG area (r = -0.337, p = 0.201). For the distal edge, change in lumen area correlated more strongly with change in plaque area (r = -0.982, p <0.001) than with change in SVG area (r = -0.624, p = 0.003). When peri-stent reference segments were divided into 2 groups according to postintervention plaque burden (>50% [n = 20] vs <50% [n = 17]), there was a greater decrease in lumen area (-1.12 +/- 0.81 vs -0.33 +/- 0.26 mm(2), p <0.001) and greater increases in SVG area (0.26 +/- 0.29 vs 0.09 +/- 0.09 mm(2), p = 0.027), plaque area (1.37 +/- 0.96 vs 0.42 +/- 0.30 mm(2), p <0.001), and plaque burden (8.2 +/- 5.6% vs. 2.8 +/- 1.6%, p <0.001) in segments with a plaque burden >50%. In conclusion, peri-stent reference segment SVG disease progression and lumen loss were more significant in segments with a greater postintervention plaque burden after implantation of a bare metal stent or drug-eluting stent.     

Heterogeneity of neointimal distribution of in-stent restenosis in patients with diabetes mellitus

Diabetes mellitus is an independent predictor of restenosis after percutaneous coronary intervention. The pattern of restenosis after bare metal stent implantation in diabetic patients was examined with 3-dimensional intravascular ultrasound analysis. Lumen and stent were manually traced at every 0.5-mm interval in stented segments. Using Simpson's method, stent, luminal, and neointimal (stent minus lumen) volumes were calculated and average area was calculated as volume data divided by length. To measure the cross-sectional and longitudinal severities of luminal encroachment by the neointima, percent neointimal area (neointimal area divided by stent area) and neointimal hyperplasia 50 (IH50) (defined as percent stent length with percent neointimal area >50%) were calculated. In 278 patients (68 with diabetes and 210 without diabetes), there was a significantly higher percentage of maximal percent neointimal area with significantly longer percent stent length that was severely encroached by the neointima in diabetic patients. Diabetic patients showed a more heterogenous pattern of the neointima after bare metal stenting, resulting in longer high-grade obstruction segments. This may have important implications for stent design and pharmacokinetic properties of next-generation drug-eluting technology for this complex patient subset.     

Effects of stent length and lesion length on coronary restenosis

The choice of drug-eluting versus bare metal stents is based on costs and expectations of restenosis and thrombosis risk. Approaches to stent placement vary from covering just the zone of maximal obstruction to stenting well beyond the lesion boundaries (normal-to-normal vessel). The independent effects of stented lesion length, nonstented lesion length, and excess stent length, on coronary restenosis have not been evaluated for bare metal or drug-eluting stents. We analyzed the angiographic follow-up cohort (1,181 patients) from 6 recent bare metal stent trials of de novo lesions in native coronary arteries. Stent length exceeded lesion length in 87% of lesions (mean lesion length 12.4 +/- 6.3 mm, mean stent length 20.0 +/- 7.9 mm, mean difference 7.6 +/- 7.9 mm). At 6- to 9-month follow-up, the mean percent diameter stenosis was 39.1 +/- 20.1%. In an adjusted multivariable model of percent diameter stenosis, each 10 mm of stented lesion length was associated with an absolute increase in percent diameter stenosis of 7.7% (p <0.0001), whereas each 10 mm of excess stent length independently increased percent diameter stenosis by 4.0% (p <0.0001) and increased target lesion revascularization at 9 months (odds ratio 1.12, 95% confidence interval 1.02 to 1.24). Significant nonstented lesion length was uncommon (12.5% of cases). In summary, stent length exceeded lesion length in most stented lesions, and the amount of excess stent length increased the risk of restenosis independent of the stented lesion length. This analysis supports a conservative approach of matching stent length to lesion length to reduce the risk of restenosis with bare metal stents.     

IVUS analysis of the acute and long-term stent result using motorized pullback: intraobserver and interobserver variability.

Intravascular ultrasound imaging has become an established method for analysis of intra-coronary stents. We analyzed the reproducibility of morphometric measurements immediately and late after stent implantation and the variability in the selection of predefined sites during motorized catheter pullback. Fifty consecutive patients were investigated immediately and 6 months after Palmaz-Schatz stent implantation (motorized catheter pullback 0.5 mm/sec; 2.9 Fr; 30-MHz transducer). Two experienced investigators independently identified the proximal and distal reference, stent inlet, stent outlet, and the minimal in-stent area in each imaging run. The longitudinal distance between corresponding measurement sites was calculated. Lumen, stent, and vessel area were assessed by planimetry, mean difference was calculated. Long-term reproducibility was analyzed by comparison of measurements made at predefined sites within the stent, immediately and late after implantation. Observer agreement in identification of predefined measurement sites was high. Longitudinal distance between corresponding measurement sites was low and pronounced for the minimal in-stent lumen area. Variabilities for the intra- and interobserver comparison were similar. Values for interobserver comparison were given in brackets. Acute after stent implantation, the variability for the reference proximal was 4.9% (0.4%), distal -1.0% (-4.2%), minimal in-stent lumen -0.5% (1.3%). At follow-up, variability for the reference proximal was -11.0% (-2.2%), distal -1.0% (-2.3%), minimal in-stent lumen 1.9% (6.1%). Long-term reproducibility for the proximal stent inlet was 2.7% (observer 1) and -0.4% (observer 2), for the distal stent outlet 1.3% (observer 1), -3.0% (observer 2), respectively. IVUS investigations with motorized IVUS pullback in stented coronary segments show a low intra- and interobserver variability, both immediately and late after stent implantation. Absolute and relative area differences are low. Long-term reproducibility of measurements within predefined stent sites was high. Motorized catheter pullback guarantees high reliability of IVUS measurements and should be routinely used 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.     

Serial Intravascular Ultrasound Analysis of the Impact of Myocardial Bridge on Neointimal Proliferation After Coronary Stenting in Patients with Acute Myocardial Infarction

Background: Mechanisms underlying the association between myocardial bridge (MB)‐stenting and in‐stent restenosis (ISR) are still unclear. Objective: To assess the impact of MB on ISR using intravascular ultrasound (IVUS). Methods: In the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS‐AMI) trial, 100 left anterior descending artery (LAD) culprit lesions (79 treated with paclitaxel‐eluting stents [PES] and 21 treated with bare metal stents) were imaged with serial IVUS immediately postprocedure and at 13 months. Results: At baseline the LAD stent extended into the MB segment beyond the culprit lesion in seven patients (MB‐stent group). In the remaining 93 patients the LAD stent was implanted only in the culprit lesion without extending into the MB segment (non‐MB‐stent group). In PES‐treated lesions intimal hyperplasia (IH) was greater in MB‐stent group than in non‐MB‐stent group (1.0 [0.9, 1.3] mm² vs. 0.4 [0.2, 0.7] mm², P = 0.007). When comparing the MB‐stent segment with the non‐MB‐stent segment in the MB‐stent group treated with PES, a significant reduction in lumen area was observed in only the MB‐stent segment, owing to an augmented IH within the MB‐stent segment (1.56 [1.40, 1.91] mm² vs. 0.77 [0.55, 1.23] mm² for non‐MB‐stent segment, P = 0.08), not significant stent recoil (Δstent area). At follow‐up, the minimum lumen area was smaller in the MB‐stent group than in the non‐MB‐stent group (2.9 [2.5, 4.2] mm² vs. 5.2 [4.1, 6.7] mm², P = 0.02). Conclusions: Increased incidence of ISR associated with MB‐stenting may be attributable to enhanced IH, specific to stented MB segment, not to chronic stent recoil. (J Interven Cardiol 2010;23:114‐122)     

Effect of amlodipine on vascular responses after coronary stenting compared with an angiotensin-converting enzyme inhibitor.

BACKGROUND: Prevention of restenosis after coronary stenting is clinically important. We compared amlodipine and quinapril to determine which is more effective in preventing restenosis after stenting. METHODS AND RESULTS: Immediately after successful coronary stenting of 101 lesions in 63 consecutive patients, the patients were randomly divided into 2 groups: 32 patients with 48 lesions were administered amlodipine 5 mg/day (group A), and 31 patients with 53 lesions were administered quinapril 10 mg/day (group Q). Lesions were assessed by quantitative coronary angiography (QCA) before and immediately after stenting and in the follow-up phase. Intravascular ultrasound (IVUS) could only be performed on 20 lesions in group A and 16 lesions in group Q throughout the follow-up period. We analyzed each lesion at 5 sites. In the follow-up phase, the minimal lumen diameter in group A was significantly larger than that in group Q (1.88 +/- 0.64 mm vs 1.52 +/- 0.53 mm, p<0.01). In the follow-up phase, the neointimal area (stent area-lumen area) in group A was significantly smaller than that in group Q (1.9 +/- 0.5 mm2 vs 2.7 +/- 0.8 mm2 at the middle portion of stent, p<0.01). CONCLUSION: These QCA and IVUS findings suggest that amlodipine has beneficial effects in inhibiting neointimal hyperplasia in stented lesions compared with quinapril.