Visualization of coronary atherosclerotic plaques in patients using optical coherence tomography: comparison with intravascular ultrasound

OBJECTIVES: The aim of this study was to evaluate the feasibility and the ability of intravascular optical coherence tomography (OCT) to visualize the components of coronary plaques in living patients. BACKGROUND: Disruption of a vulnerable coronary plaque with subsequent thrombosis is currently recognized as the primary mechanism for acute myocardial infarction. Although such plaques are considered to have a thin fibrous cap overlying a lipid pool, imaging modalities in current clinical practice do not have sufficient resolution to identify thin (< 65 microm) fibrous caps. Optical coherence tomography is a new imaging modality capable of obtaining cross-sectional images of coronary vessels at a resolution of approximately 10 microm. METHODS: The OCT images and corresponding histology of 42 coronary plaques were compared to establish OCT criteria for different types of plaques. Atherosclerotic lesions with mild to moderate stenosis were identified on angiograms in 10 patients undergoing cardiac catheterization. Optical coherence tomography and intravascular ultrasound (IVUS) images of these sites were obtained in all patients without complication. RESULTS: Comparison between OCT and histology demonstrated that lipid-rich plaques and fibrous plaques have distinct OCT characteristics. A total of 17 IVUS and OCT image pairs obtained from patients were compared. Axial resolution measured 13 +/- 3 microm with OCT and 98 +/- 19 microm with IVUS. All fibrous plaques, macrocalcifications and echolucent regions identified by IVUS were visualized in corresponding OCT images. Intimal hyperplasia and echolucent regions, which may correspond to lipid pools, were identified more frequently by OCT than by IVUS. CONCLUSIONS: Intracoronary OCT appears to be feasible and safe. Optical coherence tomography identified most architectural features detected by IVUS and may provide additional detailed structural information.     

急性冠状动脉综合征患者不稳定性斑块的血管内超声

目的观察急性冠状动脉综合征患者不稳定性斑块的血管内超声特征.方法 36例急性冠状动脉综合征患者和20例稳定型心绞痛患者进行冠状动脉造影及血管内超声检查.应用血管内超声分别观察比较冠状动脉内斑块的性质,同时测量冠状动脉病变部位及其参考部位的血管外弹力膜面积、管腔面积、斑块面积及管腔面积狭窄率,并计算斑块的偏心指数及血管重构指数.结果急性冠状动脉综合征患者中脂质斑块占77.8%(28/36),其中10例发生斑块破裂及血栓形成;稳定型心绞痛患者主要为纤维性斑块及混合性斑块,脂质斑块仅占10%(2/20),无斑块破裂及血栓形成.两组斑块的特征包括偏心性、外弹力膜面积、斑块面积及管腔面积狭窄率具有显著性差异.不稳定性斑块呈现明显的正性重构,占72.2%(26/36),而稳定性斑块主要表现为负性重构,占75%(15/20).结论血管内超声能够准确地识别动脉粥样硬化不稳定性斑块,为早期临床发现不稳定性斑块并预测斑块破裂奠定了基础.     

Assessment of vulnerable plaques causing acute coronary syndrome using integrated backscatter intravascular ultrasound.

OBJECTIVES: This study aims to define tissue characteristics of vulnerable plaques before acute coronary syndrome (ACS) by use of integrated backscatter intravascular ultrasound (IB-IVUS). BACKGROUND: Tissue characterization of coronary plaques is possible with the use of IB-IVUS. METHODS: The subjects were 140 patients with angina pectoris, and we selected 160 coronary lesions without significant stenosis for evaluation. Ultrasound signals were obtained by an IVUS system using a 40-MHz catheter. RESULTS: At the follow-up (30 +/- 7 months), 12 plaques caused ACS after the initial IVUS examination. Ten of the 12 plaques had IVUS parameters recorded at baseline. These 10 plaques were classified as vulnerable plaques (VP), and the other plaques were classified as stable plaques (SP; n = 143). There was no significant difference of vessel area, lumen area, and plaque area between VP and SP. However, plaque burden (60 +/- 9% vs. 52 +/- 9%; p = 0.014), eccentricity (0.70 +/- 0.10 vs. 0.55 +/- 0.17; p = 0.013), remodeling index (1.30 +/- 0.08 vs. 1.16 +/- 0.16; p = 0.006) and percentage lipid area (72 +/- 10% vs. 50 +/- 16%; p < 0.0001) were greater in VP than in SP. Percentage fibrous area (23 +/- 6% vs. 47 +/- 14%; p < 0.0001) was smaller in VP than in SP. The sensitivities, specificities, and positive predictive values of percentage fibrous area (90%, 96%, and 69%, respectively) and percentage lipid area (80%, 90%, and 42%, respectively) for classifying VP were evaluated. CONCLUSIONS: Tissue characteristics of VP before ACS were different from those of SP. This suggests that VP and SP as classified by IB-IVUS are useful in predicting ACS.     

Spatial orientation of atherosclerotic plaque in non-branching coronary artery segments

It has been postulated that atherosclerotic plaque deposition is spatially related to regions of low shear in non-branching vessel segments. Intravascular ultrasound (IVUS) allows precise spatial orientation of coronary artery plaque formation in humans. The objective of this study was to test the hypothesis that coronary plaques have a higher prevalence on the myocardial side in regions that encounter low surface shear stress. IVUS allows the determination of the inner versus the outer curve of the vessel based on vascular and perivascular landmarks. We studied 30 consecutive patients pre-intervention using IVUS and measured vessel area, lumen area and plaque area (vessel-lumen area) during a motorized pullback at 1 mm intervals. Vessel segments near a side branch (within two times the diameter of the vessel) were excluded from analysis because of flow disturbances. All plaques were classified as concentric or eccentric and all eccentric plaques were further divided with respect to their spatial orientation in the vessel into quadrants: myocardial (inner curve, lower shear stress), epicardial (outer curve, higher shear stress) and lateral (two quadrants intermediate). A total of 613 cross-sections were analyzed in 14 left anterior descending, six left circumflex, and ten right coronary arteries. Plaque distribution was found to be concentric in 321 (52.4%) and eccentric in 292 (47.6%) cross sections. Of all eccentric plaques, 184 cross sections were oriented toward the myocardial side (62.6%) compared to only 54 toward the epicardial side (17.3%) and 54 in the 2 lateral quadrants (19.5%, P<0.001). No difference in plaque area (6.75+/-2.70 vs. 6.76+/-2.60 mm(2)), vessel area (15.28+/-4.73 vs. 15.35+/-4.40 mm(2)), or plaque thickness (1.26+/-0.37 vs. 1.25+/-0.43 mm) was noted between myocardial or epicardial plaques. These results suggest that atherosclerotic plaques develop more frequently on the myocardial side of the vessel wall, which may relate to lower shear stress. However, plaque size is similar on the epicardial and myocardial side.     

Serial intravascular ultrasound evidence of both plaque stabilization and lesion progression in patients with ruptured coronary plaques: effects of statin therapy on ruptured coronary plaque

Using serial intravascular ultrasound (IVUS), we evaluated the natural evolution of non-culprit/non-target lesion ruptured coronary plaques and assessed the impact of statin therapy. Twenty-eight patients with non-stenotic ruptured plaques underwent baseline and 12-month follow-up IVUS studies; half were treated with statins. Standard IVUS analyses were performed. Complete healing of ruptured plaques was observed in four (29%) statin-treated patients and no non-statin-treated patients (p=0.049). Statin-treated patients had an increase in lumen area of 0.4+/-0.8 mm2 (versus a decrease in lumen area of -0.6+/-1.0 mm2 in non-statin-treated patients, p=0.007) and no change in plaque area (versus an increase in plaque area of 0.6+/-0.9 mm2, p=0.051). During 1-year follow-up, target lesion revascularization was performed in three non-statin-treated patients (21%) and no statin-treated patient (p=0.11). Compared to lesions that did not require revascularization, lesions requiring revascularization had a decrease in lumen area (-1.7+/-1.4 mm2 versus 0.1+/-0.8 mm2, p=0.001) as well as an increase in plaque area (1.6+/-1.0 mm2 versus 0.1+/-0.7 mm2, p=0.002). In conclusion, the current observational follow-up IVUS study showed beneficial effects of statin treatment on reduction of revascularization rates and stabilization of non-culprit/non-target lesion plaque ruptures without significant stenosis. Conversely, healing of non-statin-treated non-culprit/non-target lesion plaque ruptures can be responsible for lesion progression requiring revascularization.     

Plaque distribution and vascular remodeling of ruptured and nonruptured coronary plaques in the same vessel: an intravascular ultrasound study in vivo

OBJECTIVES: This study was designed to identify potential differences between the intravascular ultrasound (IVUS) characteristics of spontaneously ruptured and nonruptured coronary plaques. BACKGROUND: The identification of vulnerable plaques in vivo may allow targeted prevention of acute coronary events and more effective evaluation of novel therapeutic approaches. METHODS: Intravascular ultrasound was used to identify 29 ruptured plaques in arteries containing another nonruptured plaque in an adjacent segment. Intravascular ultrasound characteristics of these plaques were compared with plaques of computer-matched controls without evidence of plaque rupture. Plaque distribution was assessed by measuring the eccentricity of lumen location (inside the total vessel). Lumen cross-sectional area narrowing was calculated as [1 - (target/reference lumen area)] x 100%. A remodeling index was calculated as lesion/reference arterial area (>1.05 = compensatory enlargement, <0.95 = shrinkage). RESULTS: Among the three groups of plaques, there was no significant difference in quantitative angiographic parameters, IVUS reference dimensions and IVUS lumen cross-sectional area narrowing. There was a difference in plaque distribution; lumen location by IVUS was significantly more eccentric in ruptured than in nonruptured (p = 0.002) and control plaques (p < 0.0001). The arc of disease-free vessel wall was larger in ruptured than in control plaques (p < 0.0001). The remodeling pattern of ruptured and nonruptured plaques differed significantly from that of the control plaques (p = 0.0001 and 0.003); compensatory enlargement was found in 66%, 48%, and 17%, whereas shrinkage was found in 7%, 10% and 48%, respectively. CONCLUSIONS: Intravascular ultrasound assessment of plaque distribution and vascular remodeling may help to classify plaques with the highest probability of spontaneous rupture.     

Role of intravascular ultrasound imaging in identifying vulnerable plaques

A plaque that has a large lipid core and a thin fibrous cap may undergo rupture. Once it ruptures, it may lead to thrombus formation and subsequent vessel occlusion. To identify unstable plaques before they rupture is essential for clinical management and patient's prognosis. Intravascular ultrasound (IVUS) opens a new window for the assessment of plaque morphology to identify vulnerable plaques and plaque rupture. We examined 144 patients with angina and ischemic ECG changes using IVUS. Ruptured plaques, characterized by a plaque cavity and a tear on the thin fibrous cap, were identified in 31 patients (group A) of which 23/31 (74%) clinically presented as unstable angina. Plaque rupture was confirmed by injecting contrast medium filling the plaque cavity during IVUS examination. Of the patients without plaque rupture (group B, n = 108), only 19 (18%) had unstable angina. No significant differences between the 2 groups were found concerning the vessel and plaque areas (p > 0.05). The percent stenosis in group A (56.2 +/- 16.5%) was significantly lower than in group B (67.9 +/- 13.4%) (p < 0.001). Area of the plaque cavity in group A (4.1 +/- 3.2 mm2) was significantly larger than the echolucent zone in group B (1.32 +/- 0.79 mm2) (p < 0.001). The plaque cavity/plaque ratio in group A (38.5 +/- 17.1%) was larger than the echolucent area/plaque ratio in group B (11.2 +/- 8.9%) (p < 0.001). The thickness of the fibrous cap in group A (0.47 +/- 0.20 mm) was significantly thinner than that (0.96 +/- 0.94 mm) in group B (p < 0.001). CONCLUSIONS: Plaques seem to be prone to rupture when the echolucent area is larger than 1 mm2, the echolucent area/plaque ratio greater than 20% and the fibrous cap thinner than 0.7 mm. IVUS has the capacity of identifying plaque rupture and vulnerable plaques. This may have potential influence on patients management and therapy.     

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.     

血管内超声与光学相干断层扫描在冠状动脉临界病变中的长期随访对比研究

目的:研究血管内超声(intravenous ultrasound,IVUS)与光学相干断层扫描(optical coher-ence tomography,OCT)在冠状动脉临界病变中的长期随访研究。方法:共入选经过冠状动脉造影(至少4体位造影)证实病变狭窄处于临界病变的患者90例。将入选者按照2∶1随机分为:血管内超声组(IVUS)60例,光学相干断层成像(OCT)组30例。通过血管内超声定量分析最小管腔直径、参考血管直径、最小管腔面积等参数指标;通过光学相干断层扫描分析最小管腔直径、最小管腔面积。同时依据两组检查方法不同特征确定斑块的性质进行定性亚组分析:纤维性斑块、钙化斑块及脂质斑块等,对于高危易损斑块进行冠状动脉介入治疗,术后规律服用药物,观察两组术后住院期间、30d、3个月、9个月、1年和2年的主要心血管事件。采用COX回归模型分析两组2年内免于心血管事件的差异。结果:IVUS和OCT进行亚组软斑块分析,两组测得最小管腔直径分别为[(1.84±0.06)vs.(1.84±0.13)mm,P=0.947]。另外,在最小管腔面积方面两组分别为[(4.7±0.98)vs.(4.8±1.17)mm2,P=0.853]。OCT组通过分析软斑块纤维帽厚度为(94±24.72)μm。通过COX回归模型显示,两组在免于心血管事件的差异无统计学意义(P=0.826)。结论:对于临界病变的患者,采用IVUS或OCT成像系统能够更好的分辨血管内斑块性质,尤其易识别易损斑块。对于临界病变的患者,采用介入影像学方法进行测量分析是安全的、可靠的,能更好指导临床治疗。     

血管内超声与冠状动脉造影在不稳定性心绞痛患者冠状动脉轻度狭窄中的显像特征

目的探讨血管内超声(IVUS)与冠状动脉造影(CAG)在不稳定性心绞痛患者冠状动脉轻度狭窄中的显像特征。方法对经CAG发现冠状动脉轻度狭窄的30例不稳定性心绞痛患者42处病变进行IVUS检查,观察病变斑块性质和血管最大狭窄程度,并对CAG和IVUS两种检查结果进行比较。结果 CAG发现,偏心性狭窄26处,向心性狭窄16处,病变最窄处血管直径狭窄率为(29.06±7.20)%;IVUS发现,偏心性斑块34处,向心性斑块8处,易损斑块28处,病变最窄处血管直径狭窄率为(37.37±6.50)%,面积狭窄率为(41.51±7.50)%。IVUS所测病变最窄处血管直径狭窄率明显高于CAG(P<0.05)。结论 CAG低估血管内病变情况,IVUS可准确地判定冠状动脉的病变性质和狭窄程度,更好地指导临床确定治疗策略。     

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.     

An intravascular ultrasound classification of angiographic coronary artery aneurysms.

The purpose of this study was to use intravascular ultrasound (IVUS) to clarify the morphology of coronary aneurysms diagnosed by angiography. Seventy-seven consecutive patients with an aneurysmal dilatation in a native coronary artery diagnosed by angiography (defined as a lesion lumen diameter 25% larger than reference) were evaluated by IVUS. IVUS true aneurysms were defined as having an intact vessel wall and a maximum lumen area 50% larger than proximal reference. IVUS pseudoaneurysms had a loss of vessel wall integrity and damage to adventitia or perivascular tissue. Complex plaques were lesions with ruptured plaque or spontaneous or unhealed dissection. Aneurysmal dilatation and reference segments were assessed using standard IVUS quantitative techniques. Twenty-one lesions (27%) were classified as true aneurysms, 3 (4%) were classified as pseudoaneurysms, 12 (16%) were complex plaques, and the other 41 (53%) were normal arterial segments adjacent to > or =1 stenosis. The maximum lumen area within the aneurysmal segment was largest for pseudoaneurysm (35.1 +/- 10.4 mm(2)), 22.1 +/- 9.9 mm(2) for true aneurysm, and similar for complex plaques (11.2 +/- 3.5 mm(2)) and normal segments with adjacent stenoses (13.8 +/- 6.4 mm(2)): analysis of variance, p <0.0001. Only one third of angiographically diagnosed aneurysms had the IVUS appearance of a true or pseudoaneurysm. Instead, most angiographically diagnosed aneurysms had the morphology of complex plaques or normal segments with adjacent stenoses.     

Molecular imaging of plaques in coronary arteries with PET and SPECT

Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lu-men stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increas-ingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography （PET） and single photon emission computed tomography （SPECT） has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging tech-niques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coro-nary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed.     

冠脉斑块稳定性与肿瘤坏死因子相关研究

目的 探讨肿瘤坏死因子(Tumor necrosis fac-tor-alpha,TNF-α)与冠状动脉粥样硬化斑块稳定性的相关性。方法 以血管内超声(Intravascular Ultrasound,IVUS)检出冠状动脉粥样硬化斑块的软硬特性,通过临床是否为急性冠脉综合征患者,将具有软斑块特性,同时急性冠脉综合征者分为不稳定斑块组;而硬斑块特性,且不符合急性冠脉综合征者为稳定斑块组。测定两组间冠状窦及外周血血浆TNF-α浓度,结果与IVUS测定的斑块大小、斑块纤维帽厚度、脂核或无回声带大小、脂核或无回声带/斑块比及面积狭窄率进行相关性分析。结果 不稳定斑块组TNF-α值明显高于稳定斑块组[(o.11o±O.045)ng/mL vs(0.097±0.137)ng/mL,P<0.01和(0.111±0.037)ng/mL vs(0.042±0.022)ng/mL,P<0.05;将测得TNF-α与IVUS所测得纤维帽厚度、脂核或无回声带大小、斑块大小、脂核/斑块、面积狭窄率等进行相关分析,未见明显相关。结论TNF-α与斑块的稳定性有关,同时其在冠状循环与体循环中的量无差异,可望作为冠脉斑块不稳定性的判定指标。     

16排螺旋CT对冠状动脉斑块的诊断价值

目的探讨16排螺旋CT（16-mulddetector spiral computed tomography,16-MDCT）检测和区分冠状动脉斑块的准确性。方法对2005年8月至2006年3月68例拟诊为冠心病的患者先行16-MDCT检查,4天内再行定量冠状动脉造影（QCA）和血管内超声（IVUS）检查,冠状动脉血管腔直径狭窄（DS）≥50％定义为有意义的狭窄,分别测量斑块的CT密度,单位为CT值（Hounsfield units,HU）,根据冠状动脉斑块的CT值区分斑块性质并作出分类：（1）软斑块：CT值为≤50HU;（2）纤维斑块（中等斑块）：CT值为50—119HU;（3）钙化斑块≥120HU。结果在112段16-MDCT和QCA均诊断为冠状动脉狭窄≥50％的病变中,其敏感性为91．8％（112／122）,特异性为97．8％（556／568）,共96段有意义的狭窄病变纳入研究,分别位于左前降支57段,左回旋支17段,右冠状动脉14段,左主干8段。IVUS发现软斑块21个（21．9％）、纤维斑块36个（37．5％）、钙化斑块38个（39．5％）,混合性斑块（纤维钙化斑块）1个（1．1％）,16-MDCT发现软斑块20个,平均CT值（11±36）HU（-27～42HU）、纤维斑块37个,平均CT值（83±20）Hu（58—105HU）、钙化斑块39个,平均CT值（292±80）HU（167—530HU）,差异有统计学意义（P〈0．05）。结论无创性16排螺旋CT冠状动脉成像技术不仅可诊断冠状动脉狭窄病变,同时对区分钙化斑块及非钙化斑块有较高的诊断价值。     

Comparison of ruptured plaques in native coronary arteries and in saphenous vein grafts: an intravascular ultrasound study

Intravascular ultrasound (IVUS) has been used to describe ruptured plaques in saphenous vein grafts (SVGs) and native coronary arteries. We compared clinical, angiographic, and IVUS features of ruptured atherosclerotic plaques in SVGs and native coronary arteries. We identified 95 plaque ruptures in 76 SVGs in 73 patients. These lesions and patients were matched with 95 lesions and patients from a database of 468 native artery ruptures. The matching criterion was IVUS mean reference lumen area. Patients with ruptured SVG plaques were older (68.4 +/- 10.1 vs 65.0 +/- 10.6 years, p = 0.021), more often had hypercholesterolemia (92% vs 74%, p = 0.015) and hypertension (78% vs 62%, p = 0.059), and more often had a history of a remote myocardial infarction (57% vs 32%, p = 0.002). In contrast, anginal symptoms were similar in the 2 groups (70% to 75% of each group had an acute coronary syndrome). Most (90% to 95%) ruptured plaques in each group were classified as angiographically complex. However, ruptured SVG lesions more often had an angiographically visible intimal flap (71% vs 38%, p <0.001). More than 70% of lesions in the 2 groups had positive arterial remodeling by IVUS, but there was a tendency for a higher remodeling index in ruptured plaque SVG lesions (1.18 +/- 0.30 vs 1.11 +/- 0.20, p = 0.085). The site of the initial tear occurred mainly (in approximately 70%) at the plaque shoulders in the 2 groups. In conclusion, although patients with SVG plaque ruptures are older and have more co-morbidities, the clinical presentation and angiographic and IVUS features are remarkably similar to those of native artery plaque ruptures.     

One-year follow-up after intravascular ultrasound assessment of moderate left main coronary artery disease in patients with ambiguous angiograms.

OBJECTIVES: The purpose of this study was to correlate angiographic and intravascular ultrasound (IVUS) findings in left main coronary artery (LMCA) disease and identify the predictors of coronary events at one year in patients with LMCA stenoses. BACKGROUND: Significant (> or =50% diameter stenosis [DS]) LMCA disease has a poor long-term prognosis. METHODS: One hundred twenty-two patients who underwent angiographic and IVUS assessment of the severity of LMCA disease and who did not have subsequent catheter or surgical intervention were followed for one year. Standard clinical, angiographic and IVUS parameters were collected. RESULTS: The quantitative coronary angiography (QCA) reference diameter (3.91 +/- 0.76 mm, mean +/- 1 SD) correlated moderately with IVUS (4.25 +/- 0.78 mm, r = 0.492, p = 0.0001). The lesion site minimum lumen diameter (MLD) (2.26 +/- 0.82 mm) by QCA correlated less well with IVUS (2.8 +/- 0.82 mm, r = 0.364, p = 0.0005). The QCA DS measured 42 +/- 16%. During the follow-up period, 4 patients died, none had a myocardial infarction, 3 underwent catheter-based LMCA intervention and 11 underwent bypass surgery. Univariate predictors of events (p < 0.05) were diabetes, presence of another lesion whether treated with catheter-based intervention or untreated with DS > 50% and IVUS reference plaque burden and lesion lumen area, maximum lumen diameter, MLD, plaque area and area stenosis. Using logistic regression analysis diabetes mellitus, an untreated vessel (with a DS > 50%) and IVUS MLD were independent predictors of cardiac events. CONCLUSIONS: In selected patients assessed by IVUS, moderate LMCA disease had a one-year event rate of only 14%. Intravascular ultrasound MLD was the most important quantitative predictor of cardiac events. For any given MLD, the event rate was exaggerated in the presence of diabetes or another untreated lesion (>50% DS).     

Screening of ruptured plaques in patients with coronary artery disease by intravascular ultrasound

AIM: To visualise the characteristics of ruptured plaques by intravascular ultrasound (IVUS) and to correlate plaque characteristics with clinical symptoms to establish a quantitative index of plaque vulnerability. METHODS: 144 consecutive patients with angina were examined using IVUS. Ruptured plaques, characterised by a plaque cavity and a tear on the thin fibrous cap, were identified in 31 patients (group A), of whom 23 (74%) presented with unstable angina. Plaque rupture was confirmed by injecting contrast medium filling the plaque cavity during IVUS examination. Of the patients without plaque rupture (group B, n = 108), only 19 (18%) had unstable angina. RESULTS: No significant differences were found between groups A and B in relation to plaque and vessel area (p > 0.05). Mean (SD) per cent stenosis in group A was less than in group B, at 56.2 (16.5)% v 67.9 (13.4)%; p < 0.001. Area of the emptied plaque cavity in group A (4.1 (3.2) mm2) was larger than the echolucent zone in group B (1.32 (0.79) mm2) (p < 0.001). The plaque cavity to plaque ratio in group A (38.5 (17.1)%) was larger than the echolucent area to plaque ratio in group B (11.2 (8.9)%) (p < 0.001). The thickness of the fibrous cap in group A was less than in group B, at 0.47 (0.20) mm v 0.96 (0.94) mm; p < 0.001. CONCLUSIONS: Plaques seem to be prone to rupture when the echolucent area is larger than 4.1 (3.2) mm2, when the echolucent area to plaque ratio is greater than 38.5 (17.1)%, and when the fibrous cap is thinner than 0.7 mm. IVUS can identify plaque rupture and vulnerable plaques. This may influence patient management and treatment.     

Relation of myocardial perfusion defects and nonsignificant coronary lesions by angiography with insights from intravascular ultrasound and coronary pressure measurements

Several studies have demonstrated a correlation between myocardial ischemia and severity of coronary lesions as determined by intravascular ultrasound (IVUS) and fractional flow reserve (FFR) measurements. However, their value for the assessment of mild coronary stenoses that are associated with myocardial perfusion abnormalities has not been well studied. The objective of this study was to prospectively compare the results of myocardial perfusion as determined by exercise/dipyridamole myocardial single-photon emission computed tomography with IVUS and FFR measurements in patients who had angiographically mild coronary stenosis (< 50% diameter stenosis by quantitative coronary angiography). Forty-eight patients who had stable coronary disease (61 +/- 11 years of age; 6 women) were included. All had mild coronary stenosis in the proximal/middle segment of > or = 1 coronary artery and had undergone maximal exercise myocardial technetium-99m tetrofosmin single-photon emission computed tomography within 48 hours before coronary angiography. IVUS measurements included lesion lumen area, external elastic membrane area, lesion plaque burden (calculated as external elastic membrane minus lumen area, divided by external elastic membrane, and multiplied by 100), and lumen area stenosis (calculated as reference lumen area minus lesion lumen area, divided by reference lumen area, multiplied by 100). Fifty-three coronary lesions were studied, with a mean percent diameter stenosis of 34.9 +/- 7.9% on angiography. Myocardial perfusion defects were demonstrated by single-photon emission computed tomography in 11 patients (12 myocardial regions) with no differences in lesion percent diameter stenosis compared with those without perfusion defects. The presence of reversible perfusion defects was associated with a higher lesion plaque burden as evaluated by IVUS (67.4 +/- 8.1% vs 60.2 +/- 9.3%, p = 0.01). FFR values did not differ in the presence or absence of perfusion defects (0.90 +/- 0.06 vs 0.92 +/- 0.07, respectively; p = NS). In conclusion, plaque burden as determined by IVUS may partly explain the presence of myocardial perfusion defects in cases of angiographically nonsignificant coronary lesions. However, the high FFR values associated with these lesions suggest that other mechanisms, such as endothelial/microvascular dysfunction, might also account for perfusion abnormalities in these patients.     

Intravascular ultrasonic study of gender differences in ruptured coronary plaque morphology and its associated clinical presentation

Coronary plaque rupture is a phenomenon underlying most acute coronary events. Although gender is an important determinant of the incidence and clinical course of coronary atherosclerosis, its relation to plaque rupture is unknown. Therefore, we assessed gender differences in native artery plaque rupture characteristics and their related clinical presentations. There were 468 intravascular ultrasound (IVUS) preintervention images of ruptured plaques retrospectively identified. There were 328 men (81.6%) with 387 plaque ruptures and 74 women (18.4%) with 81 plaque ruptures. Patient demographics, angiographic characteristics, and qualitative and quantitative IVUS analyses of ruptured plaques were assessed. On average women were older than men (67.6 +/- 11.8 vs 62.6 +/- 11.4 years, p = 0.001) and more often presented with an acute coronary syndrome (89.2% vs 72.9%, p = 0.003). Older women had smaller vessel areas at the rupture site (p = 0.001), minimum lumen site (p = 0.002), and reference segments (p = 0.002) and smaller lumen areas at the rupture site (p = 0.026) and reference segments (p = 0.03). Ruptured plaques in older women were more often associated with IVUS-evident thrombus (48.1% vs 34.6%, p = 0.022). Independent predictors of acute clinical presentation were female gender (p = 0.006), smoking (p = 0.013), and presence of thrombus (p = 0.049). Independent predictors of the presence of thrombus were female gender (p = 0.025), smaller lumen area (p = 0.023) and larger plaque area (p = 0.008) at the rupture site, longer plaque ruptures (p = 0.016), and smoking (p = 0.045). In conclusion, coronary plaque ruptures are more often associated with thrombus and acute presentations in women than in men.