Mechanisms of acute lumen gain following cutting balloon angioplasty in calcified and noncalcified lesions: an intravascular ultrasound study.

Several studies have shown that mechanisms for lumen enlargement following conventional balloon angioplasty (BA) consist of plaque reduction and vessel expansion. To assess the mechanisms of lumen enlargement after Cutting Balloon (CB) angioplasty, intravascular ultrasound images were analyzed in 180 lesions (89 CB and 91 BA). External elastic membrane (EEM) cross-sectional area (CSA), lumen CSA, and plaque plus media (P+M) CSA were measured before and after angioplasty. In the CB group, lower balloon pressure was utilized (P < 0.0001). DeltaP+M CSA was significantly larger (P = 0.02) and deltalumen CSA showed a trend toward being larger (P = 0.07) compared to BA group. For noncalcified lesions, CB resulted in a larger deltaP+M CSA (P < 0.05) and a smaller deltaEEM CSA (P = 0.10) than BA. For calcified lesions, deltalumen CSA was significantly larger in the CB group (P < 0.05) without significant differences in deltaEEM CSA and deltaP+M CSA. Dissections complicated with calcified lesions were associated with larger deltalumen CSA for the CB group. In conclusion, for noncalcified lesions, CB achieves similar luminal dimensions with larger plaque reduction and less vessel expansion compared to BA. On the other hand, for calcified lesions, the CB achieves larger lumen gain, especially in lesions with evidence of dissections.     

Intravascular Ultrasound Assessment of the Mechanisms and Predictors of Restenosis Following Coronary Angioplasty

Restenosis occurs after 30% to 50% of transcatheter coronary procedures; its mechanisms remain incompletely understood. Intravascular ultrasound (IVUS) studies were analyzed in 360 nonstented native coronary artery lesions in which follow-up quantitative angiographic and/or IVUS data was available. Pre-intervention, post-intervention, and follow-up, the external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque+media (P+M=EEM D lumen CSA), and cross-sectional narrowing (CSN=P+M/EEM CSA) were calculated. The anatomic slice selected for serial analysis had an axial location within the lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen CSA was due to a decrease in EEM CSA; 27% was due to an increase in P+M CSA. The change in lumen CSA correlated more strongly with the change in EEM CSA than with the change in P+M CSA. The change in EEM CSA was bidirectional; 47 lesions (22%) showed an increase in EEM CSA. Despite a greater increase in P+M CSA, lesions exhibiting an increase in EEM CSA had (1) no change in lumen CSA, (2) decreased restenosis, and (3) a 49% frequency of late lumen gain. The independent clinical, angiographic, and IVUS predictors of angiographic restenosis (3 50% diameter stenosis at follow-up) were the IVUS reference lumen CSA, angiographic pre-intervention diameter stenosis, and post-intervention IVUS CSN. Restenosis appeared to be determined primarily by the direction and magnitude of the change in EEM CSA. An increase in EEM CSA was adaptive while a decrease in EEM CSA contributed to restenosis. The most powerful predictor of restenosis was the IVUS post-procedural CSN. The importance of the post-procedural CSN was related to the change in EEM CSA as a mechanism of restenosis.     

Intravascular Ultrasound Assessment of the Mechanisms and Predictors of Restenosis Following Coronary Angioplasty

Restenosis occurs after 30% to 50% of transcatheter coronary procedures; its mechanisms remain incompletely understood. Intravascular ultrasound (IVUS) studies were analyzed in 360 non-stented native coronary artery lesions in which follow-up quantitative angiographic and/or IVUS data was available. Pre-intervention, post-intervention, and follow-up, the external elastic membrane (EEM) and lumen cross-sectional areas (CSA) were measured; plaque + media (P + M = EEM - lumen CSA), and cross-sectional narrowing (CSN = P + M/EEM CSA) were calculated. The anatomic slice selected for serial analysis had an axial location within the lesion at the smallest follow-up lumen CSA. At follow-up, 73% of the decrease in lumen CSA was due to a decrease in EEM CSA; 27% was due to an increase in P+M CSA. The change in lumen CSA correlated more strongly with the change in EEM CSA than with the change in P + M CSA. The change in EEM CSA was bidirectional; 47 lesions (22%) showed an increase in EEM CSA. Despite a greater increase in P + M CSA, lesions exhibiting an increase in EEM CSA had (1) no change in lumen CSA, (2) decreased restenosis, and (3) a 49% frequency of late lumen gain. The independent clinical, angiographic, and IVUS predictors of angiographic restenosis (3 50% diameter stenosis at follow-up) were the IVUS reference lumen CSA, angiographic pre-intervention diameter stenosis, and post-intervention IVUS CSN. Restenosis appeared to be determined primarily by the direction and magnitude of the change in EEM CSA. An increase in EEM CSA was adaptive while a decrease in EEM CSA contributed to restenosis. The most powerful predictor of restenosis was the IVUS post-procedural CSN. The importance of the post-procedural CSN was related to the change in EEM CSA as a mechanism of restenosis.     

左主干冠状动脉病变的血管内超声研究

目的 血管内超声评价非严蕈钙化性左主干病变的形态特点,探讨开口和非开口部位形成狭窄的不同机制.方法 2004年10月至2007年10月,共入选造影确诊或可疑的狭窄病变并行血管内超声检查的153例(开口47例,非开口106例)非严重钙化性左主干病变,定性和定量分析血管内超声图像;负性重构定义为重构指数＜0.95.结果 左主干参考节段平均管腔直径和血管(外弹力膜)直径为(4.1±0.8)mm和(5.3士0.8)mm.开口病变的纤维性、钙化性和软斑块分别为70.2%、19.2%和8.5%,而非开口病变为35.8%、43.4%和3.8%,两者差异有统计学意义(P=0.01).总体来说,31.1%病例的最小管腔面积＜6 mm2,其中开口组29.5%,非开口组31.9%(P=0.87).最小管腔面积在两组相似,但非开口组的斑块面积[(13.3±5.4)mm2比(10.8±4.5)mm2,P=0.007]和斑块负荷(61.9%±14.5%比54.8%±15.9%,P=0.020)均显著大于开口组,斑块负荷＞50%的比例更高(84.8%比61.3%,P=0.002).开口病变的重构系数显著低于非开口病变(0.9±0.2比1.0.±0.2,P=0.000),而且负性重构更多见(74.5%和34.9%,P=0.000).logistic回归分析发现,病变部位(OR=4.9,P=0.004)、斑块面积(OR=1.2,P=0.01)和斑块负荷(OR=0.003,P=0.000)是左主干发生重构的独立预测因素.结论 负性重构现象在左主干开口病变中更常见,可能是其狭窄形成的机制之一.狭窄程度不确定的冠状动脉左主干病变需要血管内超声精确评价.     

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.     

Do excimer laser angioplasty and rotational atherectomy facilitate balloon angioplasty? Implications for lesion-specific coronary intervention

Objectives. This study sought to determine whether adjunctive balloon angioplasty after rotational atherectomy and excimer laser angioplasty provides better lumen enlargement (“facilitated angioplasty”) than angioplasty alone.Background. Adjunctive angioplasty is often used immediately after atherectomy and laser angioplasty to further enlarge lumen dimensions, but it is not known whether this practice is superior to angioplasty alone.Methods. Balloon angioplasty was performed in 1,266 native coronary lesions alone (n = 541) or after extraction atherectomy (n = 277) rotational atherectomy (Rotablator) (n = 211) or excimer laser angioplasty (n = 237). Quantitative angiographic analysis included final lumen diameter, final diameter stenosis and efficiency of balloon-mediated lumen enlargement.Results. Compared with angioplasty alone (33 ± 12%) [mean ± SD]), final diameter stenosis was higher for adjunctive angioplasty after extraction atherectomy (37 ± 16%, p < 0.001) and excimer laser angioplasty (37 ± 16%, p < 0.001) and lower after rotational atherectomy (27 ± 15%, p < 0.001). However, there was significant undersizing of balloons after all three devices. To correct for differencs in balloon size, the efficiency index (final lumen diameter/balloon diameter ratio) was calculated and was higher for adjunctive angioplasty after the Rotablator (0.78 ± 0.14, p < 0.001) than after angioplasty alone (0.69 ± 0.12). The efficiency indexes suggested facilitated angioplasty after rotational atherectomy for ostial, eccentric, ulcerated and calcified lesions and lesions >20 mm long. Facilitated angioplasty was also observed after extraction atherectomy and excimer laser angioplasty for ostial lesions, but not for any other lesion subsets.Conclusions. Rotational atherectomy, extraction atherectomy and excimer laser angioplasty can facilitate the results of balloon angioplasty. However, the extent of facilitated angioplasty is dependent on the device and baseline lesion morphology, consistent with the need for lesion-specific coronary intervention.     

Quantitative angiographic comparison of elastic recoil after coronary excimer laser-assisted balloon angioplasty and balloon angioplasty alone

Objectives. Coronary lumen changes during and after excimer laser-assisted balloon angioplasty were measured by quantitative coronary angiography, and the results were compared with the effects of balloon angioplasty alone.Background. Reduction of atherosclerotic tissue mass by laser ablation in the treatment of coronary artery disease may be more effective in enlarging the lumen than balloon angioplasty alone.Methods. A series of 57 consecutive coronary lesions successfully treated by xenon chloride excimer laser-assisted balloon angioplasty were individually matched with 57 coronary artery lesions successfully treated by balloon angioplasty alone. The following variables were measured by quantitative coronary analysis: 1) ablation by laser, 2) stretch by balloon dilation, 3) elastic recoil, and 4) acute gain.Results. Matching by stenosis location, reference diameter and minimal lumen diameter resulted in two comparable groups of 57 lesions with identical baseline stenosis characteristics. Minimal lumen diameter before excimer laser-assisted balloon angioplasty and balloon angioplasty alone were (mean ± SD) 0.73 ± 0.44 and 0.74 ± 0.43 mm, respectively. Laser ablation significantly improved minimal lumen diameter by 0.56 ± 0.44 mm before adjunctive balloon dilation. In both treatment groups, similar-sized balloon catheters (2.59 ± 0.35 and 2.56 ± 0.40 mm, respectively) were used. After laser-assisted balloon angioplasty, elastic recoil was 0.84 ± 0.30 mm (32% of balloon size), which was identical to that after balloon angioplasty alone, namely, 0.82 ± 0.32 mm (32%). Consequently, both interventions resulted in similar acute gains of 1.02 ± 0.52 and 1.00 ± 0.56 mm, respectively. Minimal lumen diameter after intervention was equal in both groups: 1.75 ± 0.35 and 1.75 ± 0.34 mm, respectively. The statistical power of this study in which a 25% difference in elastic recoil (0.2 mm) between groups was considered clinically important was 95%.Conclusions. In matched groups of successfully treated coronary lesions, xenon chloride excimer laser ablation did not reduce immediate elastic recoil after adjunctive balloon dilation or improve the final angiographic outcome compared with balloon angioplasty alone using similar-sized balloon catheters.     

Impact of different definitions on the interpretation of coronary remodeling determined by intravascular ultrasound.

The objective of this study was to compare the categorizations and determinants related to remodeling by the three definitions commonly used. Several morphological and intravascular ultrasound (IVUS) studies have demonstrated the fundamental importance of arterial remodeling in atherosclerosis. However, lack of consensus on how to define remodeling has led to conflicting analyses of factors that influence this process. Analysis of pre-interventional IVUS images of 514 lesions in native coronary arteries was performed. Arterial remodeling was defined as outward by definition 1, when [cross-sectional area (CSA) of the external elastic membrane (EEM) at the lesion site (EEM(lesion))]/[EEM CSA either at the proximal (EEM(prox ref)) or distal (EEM(distal ref)) reference site with the least amount of plaque] was > 1.05, intermediate when this ratio was between 0.95 and 1.05, and inward when < 0.95. Remodeling was defined as outward by definition 2 when EEM(lesion) > both EEM(prox ref) and EEM(distal ref), inward when EEM(lesion) < both EEM(prox ref) and EEM(distal ref), and intermediate when EEM(lesion) was intermediate between EEM(prox ref) and EEM(distal ref). By definition 3, vessel remodeling was defined as outward when EEM(lesion) > (EEM(prox ref) + EEM(distal ref))/2 and intermediate/inward when EEM(lesion) < or = (EEM(prox ref) + EEM(distal ref))/2. The frequency of outward remodeling was significantly higher by definitions 1 and 3 than by definition 2, whereas a higher frequency of inward remodeling was observed in definition 1, resulting in significantly different remodeling distributions between the three definitions (P < 0.0001). By multivariate logistic analysis, the only clinical determinants related to outward remodeling was younger age, and only by definition 3. IVUS determinants varied significantly between the three definitions. The only consistent determinants among the three definitions were smaller lumen CSA at the reference site and larger plaque + media CSA at the lesion site. This study demonstrates the significant impact of different remodeling definitions on the incidence and determinants of remodeling patterns. The marked variability in categorization of remodeling underscores the importance of developing a standard methodology.     

Intravascular ultrasound imaging after excimer laser angioplasty

To help elucidate the mechanism of excimer laser coronary angioplasty (ELCA), intra-vascular ultrasound (IVUS) imaging was performed in 19 of 29 patients who were treated with ELCA. The results were compared with a non-randomized control group of 18 patients who had IVUS studies both before and after PTCA alone. After ELCA alone, lumen diameter (1.9 × 1.7 mm) and lumen cross-sectional area (CSA) (2.9 mm²) by IVUS were not significantly different from baseline values in the patients before PTCA alone (2.1 × 1.8 mm, 3.2 mm²). After balloon dilatation in the laser treated group, lumen diameter (2.5 × 2.1 mm) and lumen CSA (4.9 mm²) were significantly greater than those post ELCA alone. However, there was no difference in lumen CSA or atheroma CSA in the group treated with excimer laser plus balloon dilatation vs. these measurements in the group treated with PTCA alone. ELCA does not ablate a large amount of atheroma (9% reduction) but creates a pathway to permit easier passage of a PTCA balloon. These quantitative and morphologic results may help explain why the restenosis rate with ELCA is similar to PTCA alone. © 1994 Wiley-Liss,Inc..     

Comparison of Men Versus Women in Cross-Sectional Area Luminal Narrowing, Quantity of Plaque, Presence of Calcium in Plaque, and Lumen Location in Coronary Arteries by Intravascular Ultrasound in Patients with Stable Angina Pectoris

Women have an increased mortality after coronary interventions compared with men, which may be partly explained by differences in comorbid clinical conditions. However, whether women also have quantitative differences in coronary atherosclerosis is not known. Preinterventional intravascular ultrasound (IVUS) was used to study de novo, nonostial native coronary lesions in 169 women and 549 men with chronic angina. The external elastic membrane (EEM), lumen, and plaque + media (P + M) areas, plaque burden, plaque eccentricity, and calcium were measured at the target lesion and at a proximal reference site. All cross-sectional IVUS measures were also corrected for body surface area. Results are reported as mean ± 1 SD. Women had significantly smaller reference site EEM (16.5 ± 5.3 vs 19.4 ± 6.3 mm², p <0.0001), lumen (8.7 ± 3.0 vs 9.9 ± 4.0 mm², p = 0.0020), and P + M areas (7.8 ± 3.7 vs 9.5 ± 4.2 mm², p = 0.0001). Women also had significantly smaller lesion site EEM (16.2 ± 5.9 vs 18.3 ± 6.7 mm², p = 0.0028), lumen (2.4 ± 1.7 vs 2.9 ± 2.6 mm², p = 0.0273), and P + M areas (13.6 ± 5.7 vs 15.3 ± 6.4 mm², p = 0.0112). However, when corrected for BSA, these differences were no longer significant. Women and men also had similar reference and lesion plaque burden, eccentricity, and calcium. Preinterventional IVUS analysis failed to detect any quantitative or qualitative differences in coronary atherosclerosis in men compared with women.

To determine whether there are quantitative differences in coronary atherosclerosis in men compared with women, preinterventional intravascular ultrasound (IVUS) was used to study de novo, nonostial native vessel lesions in 169 women and 549 men with chronic angina. Women had significantly smaller reference segment and target lesion external elastic membrane, lumen, and plaque cross-sectional areas; however, when corrected for body surface area, these differences were no longer significant. Women and men also had similar reference segment and target lesion plaque burden, eccentricity, and calcification. Preinterventional IVUS analysis failed to detect any quantitative differences in coronary atherosclerosis in men compared with women.     

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.     

The impact of coronary artery disease risk factors on intravascular ultrasound-derived morphologic indices of human coronaries

OBJECTIVE: The relationship of intravascular ultrasound (IVUS)-derived measurements of atherosclerotic plaque to various coronary artery disease (CAD) risk factors is not well known. The purpose of this study was to examine the relationship of percent coronary luminal stenosis by IVUS to other IVUS measures of CAD, as well as the relationship of common IVUS measures of CAD to traditional CAD risk factors. We hypothesized that one or more IVUS measures of CAD might relate more strongly to CAD risk factors than does percent luminal coronary stenosis. METHODS: The records of 897 consecutive patients (57% men, mean age 62 years) who underwent IVUS investigation of their coronary arteries from 1996 through 2001 were retrospectively reviewed. IVUS was performed using a 20-MHz probe (Jomed, Rancho Cordoba, CA) and a manual pull-back technique to image the coronary arteries. Coronary artery remodeling ratio-i.e., the ratio of coronary lesion external elastic membrane cross-sectional area (EEM CSA) to proximal reference artery EEM CSA; plaque burden-i.e., plaque plus media CSA divided by EEM CSA; calcium arc; and percent stenosis of luminal cross-sectional area were measured by a single reader. RESULTS: Percent area stenosis, the most commonly used IVUS parameter, did not correlate with the other three IVUS-derived parameters, nor was it related to any of the CAD risk factors considered. In contrast, remodeling ratio was directly correlated with plaque burden (r=0.22, P<0.001), but inversely related to calcium arc (r=-0.13, P=0.01). IVUS plaque burden was significantly correlated with male gender (P<0.0001) and diabetes mellitus (DM) (P=0.003). In multivariate analyses including age, gender, and CAD risk factors, plaque burden was significantly associated with age, male gender, and DM, but not with chronic renal failure, hypertension, or hypercholesterolemia. The multivariate model also revealed that the calcium arc was significantly associated with male gender and age. These IVUS findings provide anatomic documentation that the traditional CAD risk factors relate more strongly to plaque burden than to percent coronary arterial luminal narrowing.     

Correlation of coronary arterial remodeling determined by intravascular ultrasound with angiographic diameter reduction of 20% to 60%

Negative remodeling is commonly observed in stenotic coronary lesions. It is unknown whether negative remodeling is an early or late event. This study was designed to elucidate when negative remodeling occurs in the development of coronary stenosis. Remodeling was assessed by preintervention intravascular ultrasound in 104 native coronary lesions with intermediate stenosis (20% to 60% of diameter stenosis measured by quantitative coronary angiography). Positive remodeling was defined as lesion external elastic membrane (EEM) cross-sectional area (CSA) greater than the proximal reference, intermediate remodeling as lesion EEM CSA between those of the proximal and distal references, and negative remodeling as lesion EEM CSA less than the distal reference. Positive, intermediate, and negative remodeling were observed in 18%, 32%, and 50%, respectively, of lesions with intermediate stenosis. Lesions with negative and intermediate remodeling had more hard plaque compared with those with positive remodeling (79% vs 70% vs 42%, p = 0.02). Calcium was more frequent in lesions with negative and intermediate remodeling than in those with positive remodeling (52% vs 55% vs 16%, p = 0.01). Lesions with negative remodeling had smaller EEM CSA (11.5 +/- 5.2 vs. 13.7 +/- 3.4 vs 14.5 +/- 5.6 mm(2), p = 0.03) and less plaque (7.9 +/- 4.6 vs 10.8 +/- 3.4 vs 10.8 +/- 4.9 mm(2), p = 0.004) compared with positive and intermediate remodeling lesions, although lumen CSA (3.7 +/- 1.7 vs 2.8 +/- 0.8 vs 3.6 +/- 1.3 mm(2), p = 0.1) and area stenosis (57 +/- 15% vs 59 +/- 14% vs 56 +/- 10%, p = 0.7) were similar. Negative remodeling is frequently observed in lesions with intermediate stenosis. This suggests that negative remodeling occurs early in lesion formation.     

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.     

Eccentric atherosclerotic plaques with positive remodelling have a pericardial distribution: a permissive role of epicardial fat? A three-dimensional intravascular ultrasound study of left anterior descending artery lesions.

AIMS: The transversal distribution of coronary atherosclerotic plaques (AP) (myocardial vs pericardial) affects vessel remodelling. The aim of this study was to define the impact of transversal lesion distribution on vessel remodelling in proximal and distal coronary segments using a 3D intravascular ultrasound (IVUS) reconstruction. METHODS: The study group included 70 lesions located in the left anterior descending artery within 5mm of the septal take-off, and imaged using 3D-IVUS. The take-off of the septal branch was used to divide the plaque into a myocardial and pericardial surface. The IVUS index of vessel remodelling was calculated as: [narrowest external elastic membrane (EEM) site cross-sectional area (CSA)-reference EEM CSA)/reference EEM CSAx100]. The lesions with an intermediate vessel remodelling index (between -25% and +15%) were excluded from analysis. RESULTS: Of the 38 APs with a pericardial distribution, 34 (89%) showed positive remodelling (P<0.001). The distal lesions had a positive vessel remodelling index regardless of transversal plaque distribution. At multivariate analysis, pericardial distribution and the distal location of AP were the only independent variables predictive of positive remodelling. CONCLUSIONS: The transversal distribution of atherosclerotic plaque affects vessel remodelling in left anterior descending coronary lesions, probably because of an extravascular splinting effect. Distal lesions usually show positive remodelling regardless of transversal plaque distribution.     

Failure of angiography to accurately depict the extent of coronary artery narrowing in three fatal cases of percutaneous transluminal coronary angioplasty.

The angiographic and pathologic findings are described in three patients who died less than 24 h after failed percutaneous transluminal coronary angioplasty. In two of the three patients, coronary angiography performed before angioplasty disclosed apparently focal lesions in the left anterior descending and right coronary arteries. In these two patients quantitative angiographic analysis disclosed a minimal lumen cross-sectional area of 1.82 and 0.47 mm2, respectively, at the sites of apparently focal stenoses before angioplasty; corresponding percent lumen area narrowing measured 84% and 91%, respectively, by quantitative angiography at these two sites. In the third patient, coronary angioplasty was undertaken when the patient developed spontaneous occlusion of the right coronary artery several hours after diagnostic angiography. Retrospective quantitative angiographic analysis of the right coronary artery revealed a minimal lumen cross-sectional area of 1.14 mm2, with 85% lumen area narrowing at the site of subsequent total occlusion and angioplasty. In each of these three patients, necropsy examination disclosed that the distribution of coronary narrowing in the artery treated by angioplasty was in fact not focal; rather, in each of these three patients, the artery treated by angioplasty, as well as the extramural coronary arteries not treated by angioplasty, were severely narrowed by diffusely distributed atherosclerotic plaque. The angiographic and necropsy findings in these three patients document that coronary narrowing that remains occult by virtue of diffuse distribution may complicate evaluation of patients being considered for coronary angioplasty.     

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.     

Characteristics of atherosclerotic plaque distribution in coronary artery bifurcations: an intravascular ultrasound analysis

OBJECTIVE: Vessel bifurcations are prone to atherosclerotic plaque accumulation. Using volumetric intravascular ultrasound analysis, we investigated atheroma distribution at human coronary bifurcations in vivo. METHODS: We analyzed plaque distribution in 49 left anterior descending coronary artery-diagonal and 20 left circumflex coronary artery-obtuse marginal bifurcations with <50% angiographic stenosis. Cross-sections were analyzed at 1 mm intervals in segments 5 mm proximal and distal from the bifurcation. Planimetry of the lumen and external elastic membrane (EEM) was performed and plaque thickness measured at four different points relative to the branch: 0 degrees, 90 degrees, 180 degrees and 270 degrees. EEM, lumen and plaque volume and percentage plaque burden (plaque volume/EEM volume) were calculated in the proximal and distal segments. The side-branch take-off angle was analyzed in the cross-sectional images. RESULTS: Volumetric analysis showed that EEM, lumen and plaque were larger (P<0.001) in proximal segments than distal segments, whereas percent plaque burden was similar in these segments. Plaque accumulated on the opposite wall to the flow divider. Plaque distribution tended to be more eccentric in distal segments (P=0.05) compared to proximal segments. In 26 of 69 lesions, an asymmetric side-branch take-off was found and was associated with asymmetric plaque distribution compared to those lesions that had a symmetric side-branch take-off (P<0.01). CONCLUSION: We found characteristic patterns of plaque distribution at coronary bifurcations. Proximal segments demonstrated larger plaque volume than distal segments, despite similar percentages of plaque burden. Plaque volume accumulated opposite to the flow divider, especially in distal segments. The side-branch take-off angle in the cross-sectional plane influenced the plaque distribution in bifurcation lesions.     

Mechanisms and immediate and long-term results of adjunct directional coronary atherectomy after rotational atherectomy

Objectives.The purpose of this study was to confirm the mechanisms and the immediate and long-term results of rotational atherectomy and adjunct directional coronaryatherectomy.Background.Rotational atherectomy is best suited for treating calcific stenoses, but the ability of rotational atherectomy alone to optimize lumen dimensions in large vessels is limited; this is only partly improved by adjunct balloon angioplasty.Methods.We treated 165 lesions in 163 patients by use of rotational atherectomy and adjunct directional coronary atherectomy. Quantitative angiography and intravascular ultrasond were used for lesion analysis. A matched comparison with 208 lesions treated with rotational atherectomy and adjunct coronary angioplasty was performed. Patients were then followed up for at least 9 months, and target-lesion revascularization was assessed.Results.In the 61 lesions imaged sequentially, lumen area increased from 1.7 ± 0.8 (mean ± 1 SD) to 3.9 ± 1.1 mm²after rotational atherectomy, owing to a decrease in plaque plus media area from 16.8 ± 5.0 to 15.2 ± 5.2 mm²(both p < 0.0001). After adjunct directional coronary atherectomy, lumen area increased even more to 6.7 ± 2.0 mm²(vs. 5.1 ± 1.4 mm²after adjunct coronary angioplasty, p < 0.0001) as a result of both vessel expansion (18.8 ± 5.3 to 20.8 ± 5.7 mm²) and additional plaque removal (to 14.1 ± 5.0 mm², all p < 0.0001). The total arcs of calcium decreased from 207 ± 107° to 166 ± 93° after rotational atherectomy and to 145 ± 87° after directional coronary atherectomy.Overall, procedural success was 96%, and final diameter stenosis was 15 ± 17%. Target-lesion revascularization was 23%. The only independent predictor of target-lesion revascularization was a larger overall atherectomy index (84% vs. 59%, p = 0.048).Conclusions.There is a synergistic relationship between rotational atherectomy and directional coronary atherectomy in the treatment of calcific lesions. The immediate results show a high procedural success—lumen dimensions were larger and late target-lesion revascularization was lower in lesions treated with rotational atherectomy and directional coronary atherectomy than in those treated with rotational atherectomy and adjunct balloon angioplasty.     

Cutting-balloon angioplasty before drug-eluting stent implantation for the treatment of severely calcified coronary lesions

Background Severely calcified coronary lesions respond poorly to balloon angioplasty, resulting in incomplete and asymmetrical stent expansion. Therefore, adequate plaque modification prior to drug-eluting stent （DES） implantation is the key for calcified lesion treat- ment. This study was to evaluate the safety and efficacy of cutting balloon angioplasty for severely calcified coronary lesions. Methods Ninety-two consecutive patients with severely calcified lesions （defined as calcium arc 〉 180% calcium length ratio 〉 0.5） treated with bal- loon dilatation before DES implantation were randomly divided into two groups based on the balloon type： 45 patients in the conventional balloon angioplasty （BA） group and 47 patients in the cutting balloon angioplasty （CB） group. Seven cases in BA group did not satisfactorily achieve dilatation and were transferred into the CB group. Intravascular ultrasound （IVUS） was performed before balloon dilatation and after stent implantation to obtain qualitative and quantitative lesion characteristics and evaluate the stent, including minimum lumen cross-sectional area （CSA）, calcified arc and length, minimum stent CSA, stent apposition, stent symmetry, stent expansion, vessel dissection, and branch vessel jail. In-hospital, 1-month, and 6-month major adverse cardiac events （MACE） were reported. Results There were no statistical differences in clinical characteristics between the two groups, including calcium arc （222.2° ± 22.2° vs. 235.0° ± 22.1 °, p=0.570）, calcium length ratio （0.67 ± 0.06 vs. 0.77± 0.05, P = 0.130）, and minimum lumen CSA before PCI （2.59 ±0.08 mm2 vs. 2.52 ± 0.08 mm2, P = 0.550）. After stent implantation, the final minimum stent CSA （6.26 ± 0.40 mm2 vs. 5.03 ± 0.33 mm2; P = 0.031） and acute lumen gain （3.74 ±0.38 mm2 w. 2.44 ± 0.29 mm2, P = 0.015） were significantly larger ila the CB group than that of the BA group. There were not statis tically differences in stent expansion, stent symmetry, incomplete stent apposition, vessel dissection and branch vessel jail between two groups. The 30-day and 6-month MACE rates were also not different. Conclusions Cutting balloon angioplasty before DES implantation in severely calcified lesions appears to be more efficacies including significantly larger final stent CSA and larger acute lumen gain, without increasing complications during operations and the MACE rate in 6-month.