Background-Systemic levels of myeloperoxidase predict prognosis in patients with acute coronary syndromes and are considered a marker of plaque vulnerability. It is not known whether myeloperoxidase is associated with different coronary morphologies (ie, rupture or erosion of the culprit lesion) in patients with acute coronary syndrome. Methods and Results-Twenty-five consecutive patients (aged 67Ϯ11 years; 15 men [60%]; 13 [52%] with non-STsegment elevation acute coronary syndrome and 12 [48%] with acute ST-segment elevation myocardial infarction) were enrolled. Optical coherence tomography classified the culprit lesion as ruptured in 18 (72%) or eroded in 7 patients (28%) and detected intraluminal thrombus in 89% of ruptured plaques and 100% of eroded plaques. Baseline systemic levels of serum myeloperoxidase were significantly higher in patients with an eroded plaque than in those with a ruptured plaque (median, 2500 ng/mL; 25th to 75th percentile, 1415 to 2920 versus median, 707 ng/mL; 25th to 75th percentile, 312 to 943; Pϭ0.001), whereas C-reactive protein levels did not differ significantly (median, 11.3 mg/L; 25th to 75th percentile, 1.3 to 28.5 versus median, 3.9 mg/L; 25th to 75th percentile, 1.3 to 17.8; Pϭ0.76, respectively). In addition, the density of myeloperoxidase-positive cells within thrombi overlying plaques in postmortem coronary specimens retrieved from sudden coronary death victims was significantly higher in lesions with erosion (nϭ11) than ruptures (nϭ11) (median, 1584; 25th to 75th percentile, 1088 to 2135 cells/mm 2 versus median, 579; 25th to 75th percentile, 442 to 760 cells/mm

The present registry shows that FD-OCT is a feasible and safe technique for guidance of coronary interventions. Randomised studies will confirm whether the use of FD-OCT will improve the clinical outcome.

Objective-To test the eYcacy of high frequency intravascular ultrasound (IVUS) transducers in identifying lipid/necrotic pools in atherosclerotic plaques. Methods-40 MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary and two carotid arteries, dissected from five diVerent necropsy cases). IVUS acquisition was performed at 0.5 mm/s after ligature of the branching points to generate a closed system. Lipid/necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathological sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm long segments using the most distal recorded IVUS image as the starting reference. Samples were then fixed with 10% buVered formalin, processed for histopathological study, serially cut, and stained using the Movat pentacrome method. Results-122 sections were analysed. Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of these sections (16%; sensitivity 65%, specificity 95%). Conclusions-In vitro assessment of lipid/necrotic pools with high frequency transducers was achieved with good accuracy. This opens new perspectives for future IVUS characterisation of atherosclerotic plaques. (Heart 2001;85:567-570) Keywords: intracoronary ultrasound; atherosclerosis; plaque morphology Coronary intravascular ultrasound (IVUS) provides quantitative information on lumen and vessel dimensions and plaque severity, as well as qualitative information on plaque composition in terms of hard and soft components and calcification. Previous IVUS studies on plaque composition, mainly performed in the early 1990s with 20-30 MHz transducers, showed that the technique defines calcification with high sensitivity and specificity, but is less accurate in assessing soft tissue components. [1][2][3][4][5][6][7][8][9] Thus, although 20 and 30 MHz transducers achieved appropriate definition of plaque morphology, the imaging of details such as the lipid pool and the fibrous cap remained poorly defined. No data are available on the characterisation of plaque morphology with high frequency transducers, which should allow more accurate definition of the soft components of the plaques.In this study we correlated corresponding IVUS and histopathological findings in human arterial specimens obtained at necropsy from patients with atherosclerosis, to determine how accurately 40 MHz IVUS can identify lipid/ necrotic pools. MethodsWe performed in vitro IVUS assessments, using continuous pull back, in arterial segments dissected from necropsy hearts. Arterial samples were serially sectioned in relation to IVUS markers. We then correlated the quantitative and qualitative evaluations of lipid/ necrotic pools obtained from histopathological slides with those obtained from IVUS cross sections. SAMPLE SERIESThe pathological series comprised 12 full length arteries, 10 coronary arteries (one left main, four left anterior...

Background-The aim of this study was to evaluate the relationship between residual plaque burden after coronary stent implantation and the development of late in-stent neointimal proliferation. Methods and Results-Between January 1996 and May 1997, 50 patients underwent intravascular ultrasound (IVUS) interrogation at 6Ϯ1.2 months after coronary stent implantation in native coronary arteries. IVUS images were acquired with a motorized pullback, and cross-sectional measurements were performed within the stents at 1-mm intervals. The following measurements were obtained: (1) lumen area (LA), (2) stent area (SA), (3) area delimited by the external elastic membrane (EEMA), (4) percent neointimal area calculated as (SAϪLA/SA)ϫ100, and (5) percent residual plaque area calculated as (EEMAϪSA)/EEMAϫ100. Volume measurements within the stented segments were calculated by applying Simpson's rule. In the pooled data analysis of 876 cross sections, linear regression showed a significant positive correlation between percent residual plaque area and percent neointimal area (rϭ0.50, yϭ 45.03ϩ0.29x, PϽ0.01). There was significant incremental increase in mean percent neointimal area for stepwise increase in percent residual plaque area. Mean percent neointimal area was 16.3Ϯ10.3% for lesions with a percent residual plaque area of Ͻ50% and 27.7Ϯ11% for lesions with a percent residual plaque area of Ն50% (PϽ0.001). The volumetric analysis showed that the percent residual plaque volume was significantly greater in restenotic lesions compared with nonrestenotic lesions (58.7Ϯ4.3% versus 51.4Ϯ5.7%, respectively; PϽ0.01). Conclusions-Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.

Intravascular ultrasound (IVUS), which depicts both lumen and plaque, offers the potential to improve on the limitations of angiography for the assessment of the natural history of atherosclerosis and progression or regression of the disease. To facilitate measuremenk and increase the reproducibility of quantitative IVUS analyses, a computerized contour detection system was developed that detects both the luminal and external vessel boundaries in 3dimensional sets of IVUS images. To validate this system, atherosclerotic human coronary segments (n = 13) with an area obstruction ~~40% (40% to 61%) were studied in vitro by IVUS. The computerized IVUS measurements (areas and volumes) of the lumen, total vessel, plaque-media complex, and percent obstruction were compared with findings by manual tracing of the NUS images and of the corresponding histologic cross sections obtained at 2-mm increments (n = 100). Both area and volume measurements by the contour detection system agreed well with the results obtained by manual tracing, showing low mean betweenmethod differences (-3.7% to 0.3%) with SDS not exceeding 6% and high correlation coeffrcienk (r = 0.97 to 0.99). Measurements of the lumen, total vessel, plaque-media complex, and percent obstruction by the contour detection system correlated well with histomorphometry of areas (r = 0.94,0.88,0.80, and 0.88) and volumes (r = 0.98,0.91,0.83, and 0.91). Systematic dii ferences between the resulk by the contour detection system and histomotphometry (29%, 13%, -%, and -22%, respectively) were found, most likely resulting born shrinkage during tissue fixation. The resulk of this study indicate that this computerized tVUS analysis sys tern is reliable for the assessment of coronary atherosclerosis in vivo. 0 7 996 by Excerpta Medica, Inc. (Am J Cardiol 1996;78: 1202-1209 Th e natural history and progression or regression of coronary atherosclerosis after pharmacologic and nonpharmacologic interventions have most often been assessed by quantitative coronary angiographyk3 However, the quantitative angiographic approach permits only the assessment of the luminal silhouette4 and indirect estimation of plaque burden. As a result of vessel remodeling, early atherosclerosis remains angiographically undetected until luminal encroachment starts and plaque occupies approximately 40% of the internal elastic membrane area.5 Intravascular ultrasound (IVUS) depicts both coronary lumen and vessel wall; measurements can be obtained by manually tracing the luminal and ex- ternal vascular boundaries.6-8 To reduce the time and subjectivity of manual tracing,' automated systems for quantitative analysis in 3-dimensional IVUS image sets have been developed.'0-14 As the available systems detect only the lumen, we developed a contour detection algorithm that detects both the luminal and external vascular boundaries of atherosclerotic coronar sets.'591 2 arteries in 3-dimensional IVUS image This approach allows the quantification of all IVUS images and permits even volumetric assessment which ha...