Impact of intravascular ultrasound guidance on directional coronary atherectomy

In contrast to the luminogram of coronary angiography, intravascular ultrasound (IVUS) has proven to accurately assess both coronary lumen and vessel morphology due to its 360 degrees imaging capacity. Directional coronary atherectomy (DCA) improves the coronary lumen by removing plaque mass rather than stretching the vessel and compressing the plaque as with conventional percutaneous transluminal coronary angioplasty. In an attempt to optimize the procedural result of DCA we prospectively investigated the impact of IVUS guidance in a head to head comparison to on-line quantitative coronary angiography (QCA) on the result of DCA. In 16 consecutive patients IVUS demonstrated significant residual plaque mass after DCA irrespective of a satisfactory angiographic result. After a mean of 9 +/- 2 cuts luminal improvement was obtained with an area stenosis by angiography of 39 +/- 17% and by IVUS of 50 +/- 10% (p < 0.05), a diameter stenosis by angiography of 23 +/- 10% and IVUS of 35 +/- 14% (p < 0.05) and finally a minimal lumen diameter (MLD) by angiography of 2.9 +/- 0.5 mm and by IVUS of 2.3 +/- 0.5 mm (p < 0.005). After both on-line QCA and IVUS measurements a second series of 7 +/- 2 cuts were initiated to debulk more atheroma and improve stenosis dimensions. After additional cuts IVUS revealed further luminal improvement with an area stenosis by angiography of 25 +/- 16% and IVUS of 21 +/- 18% (n.s.), a diameter stenosis by angiography of 16 +/- 11% and by IVUS of 13 +/- 19% (n.s.) and finally a MLD by angiography of 3.1 +/- 0.5 mm and by IVUS of 2.8 +/- 0.3 mm (p < 0.05). Intraprocedural use of IVUS is superior to on-line QCA to assess the immediate result of DCA. IVUS-guided DCA results in more effective atheroma debulking than luminographic evaluation. Results of larger follow-up studies are needed to substantiate the intraprocedural advantage of IVUS with DCA.     

Intravascular ultrasound for evaluation of initial vessel patency and early outcome following directional coronary atherectomy

Elastic recoil and thrombus formation may potentially occur following directional coronary atherectomy (DCA) confounding the assessment of late vascular remodeling. Since intravascular ultrasound (IVUS) data on early outcome of DCA is not available, we used IVUS to investigate whether elastic recoil or thrombus formation can affect early (4 hr) outcome. Quantitative coronary angiography (QCA) and IVUS were performed in high-grade coronary lesions in 32 consecutive patients before, immediately after, and 4 hr after DCA. Late clinical follow-up was obtained after a maximum interval of 2 years. Significant acute elastic recoil was observed by both IVUS (19% ± 14%) and QCA (19% ± 12%), but there was no further recoil after 4 hr. DCA reduced plaque area by 51% ± 13%, an effect that was stable after 4 hr, indicating the absence of relevant thrombus formation. Residual area stenosis by IVUS was not related to the occurrence of late clinical events (n = 8). Mechanical recoil or thrombus formation do not hamper initial lumen gain achieved by DCA. Although QCA significantly underestimated residual plaque burden after DCA when compared to IVUS, the degree of residual area stenosis did not identify patients suffering from cardiac events on follow-up.Cathet. Cardiovasc. Intervent. 47:14–22, 1999. © 1999 Wiley-Liss, Inc.     

Comparison of dilatation mechanism and long-term vessel remodeling between directional coronary atherectomy and balloon angioplasty assessed by volumetric intravascular ultrasound

Although acute and late outcomes of coronary interventions have been determined by coronary angiography, this method cannot determine changes in vessel and plaque volume. Volumetric intravascular analysis has the potential to evaluate the morphology and redistribution of plaque after coronary intervention as well as longitudinal vessel remodeling. We used 3-dimensional intravascular ultrasound (3-D IVUS) to delineate the mechanism of coronary dilatation and long-term (> 1 year) remodeling in 25 patients. Ten patients underwent directional coronary atherectomy (DCA), and 15 underwent balloon angioplasty (POBA). No patients exhibited restenosis at 6-month angiographic follow-up. Validated Netra 3-D IVUS was performed pre- and post-intervention, at 6-months and at > 1-year. There were some differences in mechanism of dilatation and time course of change in vessel size between DCA and POBA patients. The principal mechanism was vessel stretching and longitudinal plaque redistribution in the POBA group and plaque debulking in the DCA group. In the POBA group, vessel volume increased just after the procedure; this increase was maintained at 6 months and at > 1-year. However, in the DCA group, vessel volume increased initially 6 months after the procedure. 3-D IVUS revealed a difference in mechanism of dilatation between POBA and DCA; this difference might affect late-term vessel remodeling even in patients without restenosis.     

Relationship between tissue characterization with 40 MHz intravascular ultrasound imaging and 64-slice computed tomography

BackgroundIdentification of coronary plaque composition is important for selecting the treatment strategy, and 64-slice computed tomography (CT) is a noninvasive method of characterizing atherosclerotic plaques. However, the correlation between plaque characteristics detected by CT and intravascular ultrasound (IVUS) is not clear. A 40 MHz IVUS imaging system (iMap-IVUS) has recently been developed to evaluate plaque composition. The aim of this study was to compare iMap-IVUS with 64-slice CT angiography for the characterization of non-calcified coronary plaques.Methods and resultsBoth 64-slice CT angiography and iMap-IVUS were performed in 19 patients (38 plaques). CT values were measured as Hounsfield units (HU) in circular regions of interest (ROI) drawn on the plaques. The iMap-IVUS system analyzed coronary plaques as fibrotic, lipidic, necrotic, or calcified tissue based on the radiofrequency spectrum.A positive correlation was found between CT values and the percentage of fibrotic plaque (r = 0.34, p = 0.036) or calcified plaque (r = 0.40, p = 0.011). Conversely, a negative correlation was found between CT values and the percentage of lipidic plaque (r = ?0.41, p = 0.01), or necrotic plaque (r = ?0.41, p = 0.01).ConclusionsGood correlations were observed between the characteristics of non-calcified plaque determined by iMap-IVUS and the CT values of plaque detected by 64-slice CT scanning.     

Mechanisms of acute gain and late lumen loss after atherectomy in different preintervention arterial remodeling patterns

The main mechanism of restenosis after directional coronary atherectomy (DCA) remains obscure. We investigated mechanisms of restenosis after DCA in different coronary artery remodeling patterns. DCA was performed in 51 de novo lesions. The lesions were evaluated by intravascular ultrasound (IVUS) before, immediately after, and 6 months after the procedure. According to the IVUS findings before DCA, we classified the lesions into the following 3 groups: (1) positive (n = 10), (2) intermediate (n = 25), and (3) negative (n = 16) remodeling. We measured lumen area, vessel area, and plaque area using IVUS before DCA, immediately after DCA, and at follow-up. Lumen area increase after DCA was mainly due to plaque area reduction in the positive and intermediate remodeling groups (90 plus minus 15% and 80 plus minus 25% increase in lumen area, respectively), whereas that in the negative remodeling group was due to both plaque area reduction (57 plus minus 22% increase in lumen area) and vessel area enlargement (43 plus minus 33% increase in lumen area). The plaque area increase correlated strongly with late lumen area loss in the positive and intermediate remodeling groups (r = 0.884, p <0.001; r = 0.626, p <0.001, respectively), but the decrease in vessel area was not correlated with lumen area loss. In contrast, both an increase in plaque area and a decrease in vessel area were correlated with late lumen area loss (r = 0.632, p = 0.009; r = 0.515, p = 0.041) in the negative remodeling group. Coronary artery restenosis after atherectomy was primarily due to an increase in plaque in the positive and/or intermediate remodeling groups. However, in the negative remodeling group, late lumen loss might have been caused by both an increase in plaque and vessel shrinkage.     

Comparison of Intravascular Ultrasound and X-ray Computed Tomography of the Thoracic Aorta: Correlation with Ischemic Heart Disease and Risk Factors

To compare plaque and calcification of the thoracic aorta with ischemic heart disease and risk factors, the authors used intravascular ultrasound (IVUS) and X-ray computed tomography (CT). The study included 29 patients (24 males and 5 females, mean age 61 ± 11 years): 21 with ischemic heart disease (IHD) and 8 with valvular disease or dilated cardiomyopathy. A Sonicath Ultra 6 imaging catheter (12.5 MHz, Scimed) was inserted through the femoral artery, and IVUS images were obtained around the descending aorta at the level of the pulmonary artery bifurcation. Percent plaque area (%PA) was calculated as vessel cross sectional area (CSA) surrounded by media minus lumen CSA divided by vessel CSA. The CVIS clear view system (Scimed) was used for image analysis. CT without contrast enhancement was performed from the aortic arch to the diaphragm in horizontal sections of 1 cm. The number of slices showing aortic calcification was determined as the CT calcification score. Coronary angiography (CAG) was also performed in each patient, and the authors analyzed the correlation of these imaging modalities with IHD with multiple risk factors. In the descending aorta the IVUS probe was not eccentric and gave accurate images of plaque. In the ascending aorta or aortic arch, the probe was somewhat eccentric. Plaque was observed to be diffuse without discrete lesions. The %PA was 2.5–28.6 (14.9 ± 5.5) %, and the CT score was 0–25 (8.2 ± 7.9). The %PA and CT score showed a significant correlation with each other (r = 0.57, p <0.05) and with age (r = 0.44 and 0.64, respectively, p <0.05). Neither showed a significant correlation with findings from CAG or risk factors. IVUS accurately detects the presence and extent of plaque in the thoracic aorta. The %PA shows a significant correlation with CT-detected calcification of the aorta. Neither calcification nor plaque is correlated with IHD or risk factors. IVUS-detected plaque and CT-detected calcification are strongly influenced by age.     

Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound

OBJECTIVES: The aim of the present study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) to identify and quantify atherosclerotic coronary lesions in comparison with catheter-based angiography and intravascular ultrasound (IVUS). BACKGROUND: Currently, the ability of multislice CT to quantify the degree of coronary artery stenosis and dimensions of coronary plaques has not been evaluated. METHODS: We included 59 patients scheduled for coronary angiography due to stable angina pectoris. A contrast-enhanced 64-slice CT (Senation 64, Siemens Medical Solutions, Forchheim, Germany) was performed before the invasive angiogram. In a subset of 18 patients, IVUS of 32 vessels was part of the catheterization procedure. RESULTS: In 55 of 59 patients, 64-slice CT enabled the visualization of the entire coronary tree with diagnostic image quality (American Heart Association 15-segment model). The overall correlation between the degree of stenosis detected by quantitative coronary angiography compared with 64-slice CT was r = 0.54. Sensitivity for the detection of stenosis <50%, stenosis >50%, and stenosis >75% was 79%, 73%, and 80%, respectively, and specificity was 97%. In comparison with IVUS, 46 of 55 (84%) lesions were identified correctly. The mean plaque areas and the percentage of vessel obstruction measured by IVUS and 64-slice CT were 8.1 mm2 versus 7.3 mm2 (p < 0.03, r = 0.73) and 50.4% versus 41.1% (p < 0.001, r = 0.61), respectively. CONCLUSIONS: Contrast-enhanced 64-slice CT is a clinically robust modality that allows the identification of proximal coronary lesions with excellent accuracy. Measurements of plaque and lumen areas derived by CT correlated well with IVUS. A major limitation is the insufficient ability of CT to exactly quantify the degree of stenosis.     

64层双源螺旋CT与血管内超声对冠状动脉粥样硬化斑块性质的对比研究

目的对比冠状动脉血管内超声(IVUS)与64层双源螺旋CT(64-sCT)检查对冠状动脉粥样硬化斑块特征判定的准确性。方法选择35例不稳定性心绞痛患者行64-sCT与IVUS检查,分别测定同一病变同一位置的血管横截面积、管腔横截面积、斑块负荷;采用IVUS判定斑块性质,64-sCT测定其CT值。结果 45支血管(左前降支23支;左回旋支15支;右冠状动脉7支)的72个不同截面行IVUS与64-sCT检查,在可用于评估的68个截面中,64-sCT对51个存在斑块的截面,正确显示49个存在斑块(敏感性96%),对提示17个无斑块的截面,正确显示16个无斑块存在(特异性94%)。脂质斑块(25±14)HU、纤维斑块(90±20)HU、钙化斑块(530±185)HU;混合斑块中,钙化-脂质斑块(540±175)HU、钙化-纤维斑块(540±195)HU、纤维-脂质斑块(91±22)HU。纤维-脂质斑块与纤维斑块差异无统计学意义;钙化-脂质斑块、钙化-纤维斑块与钙化斑块差异无统计学意义。靶血管外弹力膜截面积、管腔截面积、斑块负荷、狭窄程度之间差异无统计学意义。结论对比IVUS与64-sCT检查能够定性及定量分析冠状动脉粥样硬化斑块,但其精确度仍有一定的限制。     

Accuracy of nonstenotic coronary atherosclerosis assessment by multi-detector computed tomography.

BACKGROUND: The ability to evaluate coronary stenosis using multi-detector computed tomography (MDCT) has been well discussed. In contrast, several studies demonstrated that the plaque burden measured by intravascular ultrasound (IVUS) has a relationship to the risk of cardiovascular events. the accuracy of MDCT was studied to determine plaque and vessel size compared with IVUS. METHODS AND RESULTS: Fifty-six proximal lesions (American College of Cardiology/American Heart Association classification: segment 1, 5, 6) from 33 patients were assessed using MDCT and IVUS. The plaque and vessel area were measured from the cross-sectional image using both MDCT and IVUS. Eight coronary artery lesions with motion artifacts and heavily calcified plaques were excluded from the analysis. The vessel and lumen size evaluated using MDCT were closely correlated with those evaluated by IVUS (R(2)=0.614, 0.750 respectively). Furthermore, there was a strong correlation between percentage plaque area assessed by MDCT and IVUS (R(2)=0.824). CONCLUSION: MDCT can noninvasively quantify coronary atherosclerotic plaque with good correlation compared with IVUS in patients with atherosclerosis.     

Coronary artery restenosis after atherectomy is primarily due to negative remodeling.

The primary cause of restenosis following directional coronary atherectomy (DCA) remains obscure. "Negative remodeling," a decrease in vessel area, is believed to be more causative than is increase in plaque area. The DCA technique used in these patients, designed to facilitate the removal of plaque, should allow a more precise evaluation of the relative roles of these two mechanisms. Twenty-five patients underwent DCA. In 17, complete angiographic and intravascular ultrasound (IVUS) images were obtained before and after DCA and at follow-up (6 to 9 months). Internal elastic lamina (IEL), lumen, and plaque areas were calculated at preatherectomy, postatherectomy, and follow-up. Postatherectomy, the mean IEL area increased by 32% and the mean plaque area decreased by 51%, resulting in a significant mean increase in lumen area, 500%. At follow-up when compared to postatherectomy, the change in IEL area was variable; however, the mean did not change significantly (p = 0.58). Plaque area change, when standardized for initial vessel size, was small (mean increase 2.8 +/- 3.5%). The mean lumen area did not decrease significantly at follow-up (p = 0.43). A highly significant correlation (r = 0.96) was noted between IEL area change and lumen area at follow-up. In contrast, the correlation between plaque area change and lumen area change over the same period was much less significant (r = 0.64). These data indicate that decrease in IEL area primarily is responsible for restenosis.     

Plaque Characterization with Computed Tomography Angiography Based on a Diluted-contrast Injection Protocol

Objective Coronary plaques with low attenuation on computed tomography (CT) angiography may indicate vulnerable plaques. However, plaque CT attenuation is reported to be significantly affected by intracoronary attenuation. Recently, the diluted-contrast injection protocol was established to facilitate more uniform intracoronary attenuation than can be achieved with the generally used body-weight-adjusted protocol. We validated the relationship between low-attenuation plaque on CT and lipid-rich plaque using integrated backscatter-intravascular ultrasound (IB-IVUS) as the standard reference. Methods Plaques were divided into tertiles (T1, T2, and T3) according to the plaque CT attenuation, calculated as the average of five intra-plaque regions of interest, and compared with the plaque characteristics noted on IB-IVUS. Patients Patients who underwent both CT angiography using a diluted-contrast injection protocol and IB-IVUS were retrospectively analyzed. Results Thirty-nine plaques in 32 patients were analyzed by CT angiography and IB-IVUS. The median plaque CT attenuation (Hounsfield units) of each tertile was 30 (T1), 48 (T2), and 68 (T3). Although no significant difference was noted in conventional quantitative IVUS parameters (e.g. plaque burden), the T1 with lowest plaque CT attenuation had the highest percentage lipid area by IB-IVUS [75.1% (T1), 57.8% (T2), and 50.8% (T3), respectively, p<0.01]. Furthermore, the plaque CT attenuation had a significant negative correlation with the percentage lipid area (r=-0.59, p<0.01). Conclusion CT angiography-based plaque characterization using a diluted-contrast injection protocol may aid in the quantitative detection of lipid-rich plaque.     

Association between increased epicardial adipose tissue volume and coronary plaque composition

To assess the relationship between epicardial adipose tissue volume (EATV) and plaque vulnerability in significant coronary stenosis using a 40-MHz intravascular ultrasound (IVUS) imaging system (iMap-IVUS), we analyzed 130 consecutive patients with coronary stenosis who underwent dual-source computed tomography (CT) and cardiac catheterization. Culprit lesions were imaged by iMap-IVUS before stenting. The iMAP-IVUS system classified coronary plaque components as fibrous, lipid, necrotic, or calcified tissue, based on the radiofrequency spectrum. Epicardial adipose tissue was measured as the tissue ranging from ?190 to ?30 Hounsfield units. EATV, calculated as the sum of the fat areas on short-axis images, was 85.0 ± 34.0 cm³. There was a positive correlation between EATV and the percentage of necrotic plaque tissue (R ² = 0.34, P < 0.01), while there was a negative correlation between EATV and the percentage of fibrous tissue (R ² = 0.24, P < 0.01). Multivariate analysis revealed that an increased low-density lipoprotein cholesterol level (β = 0.15, P = 0.03) and EATV (β = 0.14, P = 0.02) were independently associated with the percentage of necrotic plaque tissue. An increase in EATV was associated with the development of coronary atherosclerosis and, potentially, with the most dangerous type of plaque.     

Stenting after directional coronary atherectomy compared with directional coronary atherectomy alone and stenting alone: a serial intravascular ultrasound study.

BACKGROUND: Directional coronary atherectomy prior to stent implantation (DCA-stent) is expected to be an effective approach to reduce restenosis. The purpose of this study was to determine whether DCA-stent has advantages over DCA alone or stenting alone using serial intravascular ultrasound (IVUS). METHODS AND RESULTS: Serial (pre-, post- and follow-up) IVUS was performed in 187 native coronary lesions treated with each of the 3 strategies. External elastic membrane cross-sectional area (CSA), lumen CSA and plaque CSA were measured. Baseline characteristics were similar. Postprocedural lumen CSA was largest after DCA-stent (11.2+/-2.7 mm2) and DCA (10.8+/-2.5 mm2) than stenting alone (9.0+/-2.9 mm2) (p<0.0005). Follow-up lumen loss was similar. As a result, follow-up lumen CSA was largest after DCA-stent (DCA-stent: 9.1+/-3.4 mm2, DCA: 7.8+/-4.2 mm2, stent: 6.3+/-2.6 mm2, p<0.0005). There was a trend toward a lower rate of restenosis with DCA-stent (DCA-stent, 12.5%; DCA, 18.3%; stent, 18.8%; p=0.57). CONCLUSIONS: DCA-stent is superior to both DCA alone and stent alone in terms of the ability to gain a larger lumen as assessed by IVUS.     

Quantitative angiographic and intravascular ultrasound study >5 years after directional coronary atherectomy

Aggressive and optimal directional coronary atherectomy (DCA) using intravascular ultrasound (IVUS) guidance provides favorable outcomes within 1 year. However, no previous data are available on the changes that occur in target lesions for the long term after stand-alone DCA. This study's aim evaluates, using quantitative angiography and intravascular ultrasonography, the natural history of changes that occur in target lesions between short- (about 6 months) and long-term (>5 years) follow-up angiography after stand-alone DCA. Of 186 patients (221 lesions) with successful stand-alone DCA, 48 patients (53 lesions) underwent revascularization within 6 months, and 14 patients subsequently died, leaving a study population of 124 patients (154 lesions). Complete quantitative coronary angiography (QCA) was obtained in 91 patients (101 lesions) and complete serial IVUS assessment was obtained for 38 lesions before and after intervention and during follow-up. From short- to long-term follow-up angiography, the minimal luminal diameter significantly increased (from 2.12 to 2.56 mm; p <0.0001); lesion subgroups with >30% diameter stenosis at short-term follow-up angiography showed significant late regression as assessed by QCA. Serial IVUS assessment revealed that the vessel cross-sectional area did not change (from 17.3 to 17.4 mm(2); p = NS); however the lumen cross-sectional area significantly increased (from 7.3 to 9.5 mm(2); p <0.0001) due to the reduction of plaque plus media cross-sectional area (from 10.0 to 7.9 mm(2); p <0.0001). The change in lumen cross-sectional area correlated with the change in plaque plus media cross-sectional area (r = -0.686, p <0.0001). Target lesions show late regression due to plaque reduction at >5 years after stand-alone DCA.     

Limitation of angiography to identify the culprit plaque in acute myocardial infarction with coronary total occlusion utility of coronary plaque temperature measurement to identify the culprit plaque.

OBJECTIVES: The purpose of this study was to test the hypothesis that the maximal temperature (Tmax) site, as measured by thermal wire, coincides with the culprit plaque by intravascular ultrasound (IVUS) in patients with acute myocardial infarction (AMI). BACKGROUND: Subsequent thrombosis developing to the proximal region from the site of plaque rupture or erosion can potentially complicate the ability of coronary angiography to identify the accurate culprit plaque in patients with coronary total occlusion. METHODS: In 45 consecutive patients with a first anterior AMI, the Tmax site by thermal wire and the culprit plaque by IVUS were evaluated in the left anterior descending coronary artery (LAD). RESULTS: Twenty-five patients had LAD total occlusion, and the remaining 20 had LAD reperfusion. In both groups of patients, the Tmax site was significantly more distal to the angiographically most stenotic site or occlusive site (reperfusion: mean distance [MD] = 1.1 mm distal, 95% confidence interval [CI] 0.3 to 1.9 mm, p = 0.01; total occlusion: MD = 8.8 mm distal, 95% CI 8.0 to 9.6 mm, p < 0.0001). The culprit plaques by IVUS approximately coincided with those by angiography or thermal wire in patients with reperfusion. However, the angiographic occlusive site was significantly more proximal to the culprit plaque by IVUS (MD = 9.2 mm, 95% CI 7.9 to 10.6 mm, p < 0.0001), but the Tmax site coincided with the culprit plaque by IVUS (MD = 0.3 mm distal, 95% CI 0.3 mm proximal to 1.0 mm distal, p = 0.293) in patients with total occlusion. CONCLUSIONS: Temperature measurement of coronary plaque enables accurate localization of the culprit plaque in AMI with coronary total occlusion.     

Atherosclerotic plaque characterization by quantitative analysis using intravascular ultrasound: correlation with histological and immunohistochemical findings.

The aim of this study was to clarify whether atherosclerotic plaque morphology, as defined by quantitative analysis with intravascular ultrasound (IVUS) images, was related to the immunohistochemical findings. Twenty-five coronary lesions in 25 patients who had ultrasound guidance during directional coronary atherectomy (DCA) were enrolled. The lesions retrieved by DCA were analyzed and divided into 3 groups (lesions infiltrated with both macrophages and lymphocytes: group IML; lesions infiltrated with macrophages but not lymphocytes: group IM; and non-infiltrated lesions: group NI). The mean plaque echo level divided by the mean adventitia echo level (MPEL/MAEL) and the heterogeneity of the distribution of plaque echo levels (HDPEL) were calculated. The proportion of patients with acute coronary syndromes was significantly different among the groups: IML (n=14), IM (n=5), and NI (71%, 0% and 17%, respectively; p<0.01). The pre-DCA HDPEL value was highest in group IML and lowest in group NI; however, no significant differences in MPEL/MAEL values were found. The results suggest that plaque morphology, as defined by IVUS images, was related to the immunohistochemical findings. The increase in HDPEL correlated with the presence of immune inflammation.     

Characterization of non-calcified coronary atherosclerotic plaque by multi-detector row CT: comparison to IVUS

Multi-detector row Computed Tomography (MDCT) permits non-invasive visualization of the coronary arteries. The ability to visualize and, with limitations, to characterize non-calcified coronary atherosclerotic plaque has been described. We investigated the CT attenuation of non-calcified plaques as determined by 16-slice MDCT in comparison to intravascular ultrasound (IVUS). METHODS AND RESULTS: Thirty-two patients were investigated by contrast-enhanced 16-slice CT. In addition, IVUS of one coronary artery (motorized pullback) was performed (LM+LAD: 22, LM+LCX: 4, RCA: 6). At 252 sites within the coronary system, in which non-calcified atherosclerotic plaque could be identified both in MDCT and IVUS, the CT attenuation within the plaque was measured using a centrally placed region of interest and correlated to the appearance of the plaque in IVUS at the corresponding location. The mean CT attenuation within plaque that corresponded to hyper-echogenic appearance in IVUS was 121+/-34HU (n=76). The mean CT attenuation within plaque that corresponded to hypo-echogenic appearance was 58+/-43HU (n=176, p<0.001). However, there was substantial overlap of the density values measured by MDCT in the two groups. CONCLUSIONS: A significant difference of the mean CT attenuation within atherosclerotic lesions of hypo-echogenic and hyper-echogenic appearance in IVUS could be observed. However, we observed substantial overlap of attenuation values between plaque types so that the differentiation of "vulnerable" and "stable" plaques based on their CT attenuation is doubtful.     

Role of plaque proliferation in late lumen loss after directional coronary atherectomy.

Previous reports suggest that vessel remodeling is the most important factor in late lumen loss in non-stented lesions, but because results of directional coronary atherectomy (DCA) show that increased plaque area (PA) is also important, the aim of this study was to redefine the mechanism of late lumen loss after DCA. One hundred and twenty lesions that underwent DCA with intravascular ultrasound (IVUS) guidance and serial IVUS analysis were studied, and vessel area (VA), lumen area (LA), PA (VA-LA) and corrected values (each value divided by the value of VA pre procedure to correct the vessel size) were analyzed. During follow-up, corrected VA (cVA) decreased by 0.058 +/- 0.191, whereas corrected PA (cPA) increased by 0.087 +/- 0.159. Though the %PA (PA/VA) after the procedure showed significant negative correlation with the subsequent change in cPA, it did not correlate with the subsequent change in cVA. In conclusions, the mechanism of late lumen loss after DCA consists of both arterial remodeling and plaque proliferation, and the residual %PA after the procedure determines the subsequent lumen loss. With a lower %PA, a change in the PA contributes more to late lumen loss than do changes in VA. With a high %PA, a change in the VA contributes more to late lumen loss.     

Evaluación de la progresión y la regresión de la aterosclerosis coronaria mediante ecografía intravascular. ¿Un nuevo cambio de paradigma?

Intravascular ultrasound (IVUS) has emerged as a powerful imaging modality for the assessment of the arterial wall and it's response to the accumulation of atherosclerotic plaque. The ability to image the coronary arteries on a serial basis provides a unique opportunity for IVUS to monitor the impact that potential anti-atherosclerotic strategies exert on plaque burden. As a result, studies incorporating serial IVUS imaging as the primary endpoint have demonstrated that therapeutic strategies that modify LDL, HDL and blood pressure in patients with established coronary artery disease can have a profound impact on the progression of atherosclerotic plaque. This heralds a paradigm shift that emphasizes plaque regression as a potential target in the development of preventive strategies.     

不稳定型心绞痛患者的血管内超声分析

目的:应用血管内超声(IVUS)探讨不稳定型心绞痛(UAP)患者的斑块形态学特点。方法:经冠状动脉造影和IVUS检查的冠心病患者57例,其中稳定型心绞痛(SAP)21例,UAP 36例,根据斑块回声的强度,将斑块分为软斑块、纤维斑块、钙化斑块、混合斑块和斑块破裂等,分析比较UAP和SAP患者的斑块的形态学特点。结果:IVUS发现软斑块的比例在SAP和UAP患者中分别为47.6%和75.0%,纤维斑块的比例分别为52.4%和25.0%,斑块破裂分别为0和30.6%,钙化斑块分别为52.4%和19.4%(均P<0.05)。结论:IVUS显示UAP的斑块形态学特点主要表现为软斑块和斑块破裂。