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Circulation. 1996;93:924-931

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(Circulation. 1996;93:924-931.)
© 1996 American Heart Association, Inc.

Articles

Limitations of Angiography in the Assessment of Plaque Distribution in Coronary Artery Disease

A Systematic Study of Target Lesion Eccentricity in 1446 Lesions

Gary S. Mintz, MD; Jeffrey J. Popma, MD; Augusto D. Pichard, MD; Kenneth M. Kent, MD, PhD; Lowell F. Satler, MD; Ya Chien Chuang, PhD; Robert A. DeFalco, BS; Martin B. Leon, MD

From the Intravascular Ultrasound Imaging and Cardiac Catheterization Laboratories of the Washington (DC) Hospital Center.

Correspondence to Martin B. Leon, MD, Director of Research, Washington Cardiology Center, 110 Irving St NW (4B-1), Washington, DC 20010.


*    Abstract
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 *Abstract
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Background Plaque distribution (eccentricity) may be a determinant of the success of transcatheter therapy, and certain devices may be better suited to treating severely eccentric lesions than others. However, no study has compared methods for assessing plaque distribution or systematically studied the validity of the angiographic assessment of plaque distribution.

Methods and Results We studied 1446 native vessel target lesions in 1349 patients by intravascular ultrasound and coronary angiography. Angiographic and intravascular ultrasound criteria for lesion eccentricity were compared. Angiography showed that 795 of 1446 (55.0%) of target lesions were eccentric. When intravascular ultrasound was used, only 219 lesions (15.1%) had an arc of normal arterial wall within the lesion (equivalent to the pathological definition of lesion eccentricity). When an eccentricity index of >=3.0 was used, intravascular ultrasound classified 659 lesions (45.6%) as eccentric. The concordance rates of classification were only 47.7% (versus lesions containing an arc of normal arterial wall) and 53.8% (versus lesions with an ultrasound eccentricity index of >=3.0). More eccentric lesions had larger lumen cross-sectional areas, smaller plaque plus media and external elastic membrane cross-sectional areas, and smaller arcs of calcium, suggesting that they may represent less advanced atherosclerotic disease.

Conclusions There was significant discordance between angiography and ultrasound in assessing plaque distribution. Angiography appeared to detect lesion eccentricity more often than intravascular ultrasound. Furthermore, markedly eccentric lesions, in which there is an arc of normal vessel wall, were uncommon.


Key Words: angiography • ultrasonics • coronary disease


*    Introduction
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 up arrowAbstract
 *Introduction
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down arrowResults
down arrowDiscussion
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Coronary angiography is the gold standard for preprocedural risk assessment when coronary artery disease is treated with catheter-based interventions. Angiographic lesion eccentricity has been implicated as a risk factor for reduced short-term procedural results in vivo1 2 3 ; this has been supported by experimental models of coronary angioplasty in vitro.4 5 6 7 8 9 10 In fact, the American Heart Association/American College of Cardiology Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures included angiographic lesion eccentricity as a risk factor for moderate procedural success and moderate complications (type B lesions) even though the standard coronary angiogram is only a "lumenogram" that provides little insight into plaque deposition and pathology. In addition, coronary angiography is the method used most often to guide interventional procedures; it is especially important in guiding those techniques requiring a directional orientation of a device toward the maximum thickness of the atherosclerotic plaque. Thus, the assessment of plaque distribution by angiography goes beyond risk stratification. Its accuracy has important therapeutic and procedural (technical) implications.

The definition of lesion eccentricity depends on the analytical method being used. The pathological definition is the presence of an arc of disease-free arterial wall within the lesion; pathologically, most coronary artery lesions appear to be eccentric.11 12 13 The angiographic definition is a lesion having one of its edges in the outer one quarter of the apparently normal lumen (indicating that there was three times as much plaque on one side of the lesion as on the other); in most angiographic studies, 50% to 60% of lesions appear to be eccentric.14 There is no established intravascular ultrasound definition of lesion eccentricity.

Intravascular ultrasound can be used to measure the maximum and minimum plaque thicknesses and therefore to calculate an eccentricity index. Intravascular ultrasound can also be used to identify an arc of disease-free wall within the lesion (thereby applying the in vitro pathological definition to lesions studied in vivo with intravascular ultrasound). The purposes of this study were (1) to use intravascular ultrasound to evaluate atherosclerotic plaque distribution in vivo, (2) to attempt to develop an intravascular ultrasound classification of lesion eccentricity, (3) to compare the angiographic and intravascular ultrasound classifications of lesion eccentricity, and (4) to determine the accuracy of the angiographic assessment of lesion eccentricity and, in doing so, to identify the determinants of angiographic lesion eccentricity.


*    Methods
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 *Methods
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Patient Population
We studied 1446 target lesions in 1349 patients by intravascular ultrasound and coronary angiography before any intervention. These lesions met the following criteria: native vessel location (thereby excluding vein graft and internal mammary lesions) and the ability to assess target lesion eccentricity by both intravascular ultrasound and coronary angiography (therefore excluding lesions with severe calcification or previous stent placement). There were 1054 men and 295 women 60±11 years of age. Target lesion location was left main artery in 62, left anterior descending coronary artery in 618, left circumflex artery in 224, and right coronary artery in 542; diagonal branches were considered part of the left anterior descending coronary artery, and marginal branches were considered part of the left circumflex artery. No catheter-based intervention was performed in 195 lesions (21 of which were treated with operative revascularization); balloon angioplasty was performed in 138 lesions, directional coronary atherectomy (Devices for Vascular Intervention) in 441, rotational atherectomy (Heart Technology) in 342, extraction atherectomy (InterVentional Technologies) in 5, stent placement (Palmaz and Palmaz-Schatz tubular slotted stents, Johnson & Johnson Interventional Systems; Gianturco-Roubin Flex-Stents, Cook, Inc; and Wiktor coiled stents, Medtronic, Inc) in 213, and excimer laser angioplasty (Advanced Interventional Systems) in 112.

Angiographic Analysis
Preprocedural angiograms were reviewed by a core angiographic laboratory that was blinded to the ultrasound results. Standard qualitative morphological criteria were recorded.14

Lesion length was measured from shoulder to shoulder.

Quantitative angiographic analysis was performed by use of a computer-assisted, automated edge-detection algorithm (ImageComm). With the external diameter of the contrast-filled catheter as the calibration standard, the minimum lumen diameter at end diastole before intervention was measured in multiple projections, and the results from the worst view were recorded.

Angiographic eccentricity was identified as a lesion having one of its edges in the outer one quarter of the apparently normal lumen (suggesting that there was at least three times as much plaque on one side of the lesion as on the other) in any one of the multiple projections obtained before intervention.

Intravascular Ultrasound Analysis
Intravascular ultrasound studies were performed with one of three commercially available systems. The first (InterTherapy, Inc) incorporated a single-element 25-MHz transducer and an angled mirror mounted on the tip of a flexible shaft that was rotated at 1800 rpm within a 3.9F short monorail polyethylene imaging sheath to form planar cross-sectional images in real time; with this system, the transducer was withdrawn automatically at 0.5 mm/s to perform the imaging sequence. The second (Hewlett Packard and Boston Scientific Corporation) incorporated a single-element 30-MHz beveled transducer rotated at 1800 rpm within a 3.5F short monorail imaging catheter; with this system, the catheter was advanced or withdrawn manually with fluoroscopic guidance to perform the imaging sequence. The third (Cardiovascular Imaging Systems Inc) incorporated a single-element 30-MHz beveled transducer within either a 2.9F long monorail imaging catheter having a common distal lumen design (the distal lumen alternatively accommodates the imaging core or the guide wire but not both) or a 3.2F short monorail imaging catheter; with this system, the transducer was withdrawn automatically at 0.5 mm/s to perform the imaging sequence. Intravascular ultrasound studies were recorded on 1/2-in high-resolution super VHS taped for off-line analysis.

All patients were studied after giving informed consent. All intravascular ultrasound imaging protocols have the ongoing approval of the Washington Hospital Center Institutional Review Board.

A single individual performed qualitative (plaque morphology) and quantitative (cross-sectional) analyses of the ultrasound images. The in vitro validation of qualitative and quantitative intravascular ultrasound analyses was reported previously.15 16 17 18 19 20 21 When the atherosclerotic plaque encompassed the catheter, the lumen was assumed to be the size of the imaging catheter. Because media thickness could not be measured accurately, plaque plus media cross-sectional area was used as a measurement of the atherosclerotic plaque; maximum and minimum plaque plus media thicknesses were used as a measure of maximum and minimum wall thicknesses. With computer planimetry, the cross section with the smallest preintervention lumen area containing the largest preintervention plaque burden (percent cross-sectional narrowing) was analyzed, and the following lesion site measurements were made (Fig 1Down): (1) external elastic membrane cross-sectional area (in square millimeters), (2) lumen cross-sectional area (in square millimeters), (3) plaque plus media cross-sectional area (external elastic membrane area minus lumen area, in square millimeters), (4) percent cross-sectional narrowing (plaque plus media cross-sectional area divided by external elastic membrane cross-sectional area), (5) maximum plaque plus media (wall) thickness (in millimeters), and (6) minimum plaque plus media (wall) thickness (in millimeters).



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  		Figure 1. Photograph showing two intravascular ultrasound cross-sectional images. Each is accompanied by a duplicated image in which the external elastic membrane is shown by the heavy, outer black line, and the lumen is shown by the inner black line. The maximum and minimum plaque plus media thicknesses are indicated by the radial white lines. The eccentricity index is calculated as the ratio of the maximum to minimum plaque plus media thicknesses. The lesion in A and B is very eccentric. It contains an arc or normal arterial wall (arrows). The maximum wall thickness measures 2.6 mm, minimum wall thickness measures 0.2 mm, and eccentricity index is calculated to be 5.2. The lesion in C and D is nearly concentric. The maximum wall thickness measures 2.2 mm, minimum wall thickness measures 1.6 mm, and eccentricity index is calculated to be 1.4.

Two intravascular ultrasound definitions of eccentricity were used. First, an eccentricity index (the ratio of maximum to minimum plaque plus media thickness) was calculated (an eccentricity index of 1.0 would have indicated purely concentric target lesion plaque distribution). Next, the presence of an arc of disease-free arterial wall within the lesion was tabulated (this was equivalent to the in vitro pathological definition of lesion eccentricity).11 An arc of disease-free arterial wall was one that had, at worst, a three-layer appearance with an intimal thickness <0.2 mm and a total wall thickness <0.4 mm.22 Because of the possible limitations of target lesion calcification in the measurement of wall thicknesses, the subset of lesions containing no calcium was then analyzed separately.

Because calcium produces bright echoes (brighter than the vessel adventitia) with acoustic shadowing of deeper structures, the measurement of the external elastic membrane cross-sectional area and the maximum and minimum wall thicknesses could sometimes be difficult. To circumvent this, two types of extrapolation were used.23 24 Briefly, because the coronary artery cross section was more or less circular, extrapolation of the circumference of the external elastic membrane was possible, provided that each calcific deposit did not shadow more than 60° of the adventitial circumference. Also, real-time axial movement of the transducer just distal and proximal to a calcific deposit or to find the smallest circumferential arc of calcium within a large calcific deposit unmasked and filled in contiguous parts of the adventitia that were otherwise shadowed by that deposit.

Plaque morphology was assessed for the presence and extent of calcium.25 Calcium was identified as plaque that was brighter than the reference adventitia with acoustic shadowing of deeper arterial structures. The arc of calcium was then measured with a protractor centered on the lumen.

Statistical Analysis
Statistical analysis was performed by use of StatView 4.02 and BMDP.26 Quantitative data are presented as mean±SD. Qualitative data are presented as frequencies. Categorical variables were assessed with {chi}2 statistics. Continuous variables were compared by use of unpaired Student's t tests and ANOVA as appropriate. Multivariate logistical regression analysis was used to find the angiographic and ultrasound target lesion and reference segment variables that best predicted the classification of angiographic lesion eccentricity (concentric or eccentric). Variables tested included quantitative angiographic reference vessel size and lesion severity (both minimum lumen diameter and diameter stenosis); qualitative angiographic lesion variables such as bend-point lesion location and tortuosity; angiographic lesion length; ultrasound lesion and reference segment eccentricity index, maximum and minimum plaque plus media thicknesses, and external elastic membrane, lumen, and plaque plus media cross-sectional areas; and cross-sectional narrowing. Univariate determinants with a value of P<.2 were entered into the multivariate model. Backward and forward eliminations and maximum likelihood estimation were used to select the independent determinants of angiographic eccentricity.


*    Results
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*Results
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Angiographic Results
The reference segment diameter measured 3.11±0.60 mm, the preintervention minimum lumen diameter measured 1.20±0.69 mm, and the percent diameter stenosis was calculated to be 62±20%. Lesion length measured 8.4±5.5 mm. Morphological angiographic lesion assessment showed that 795 of 1446 target lesions (55.0%) were eccentric.

Intravascular Ultrasound Plaque Distribution
Only 219 of 1446 lesions (15.1%) had an arc of normal or disease-free arterial wall within the target lesion, the intravascular ultrasound equivalent of the pathological definition of eccentricity.

For the entire group, the maximum plaque plus media thickness measured 2.1±0.6 mm, and the minimum plaque plus media thickness measured 0.8±0.4 mm. Fig 2Down shows the frequency distribution of the maximum and minimum plaque plus media thicknesses.



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  		Figure 2. Bar graphs showing the frequency distribution of the intravascular ultrasound maximum and minimum wall thicknesses. The total number of lesions in each group is shown with the percentage of lesions in parentheses. The percentage of lesions that were eccentric by angiography varied with the maximum wall thickness (P=.0023): 50% of lesions with a maximum wall thickness <1.2 mm, 52% with a maximum wall thickness of 1.2 to 2.3 mm, 62% with a maximum wall thickness of 2.4 to 3.5 mm, and 67% with a maximum wall thickness >=3.6 mm were eccentric by angiography. The percentage of lesions that were eccentric by angiography did not vary with the minimum wall thickness: 59% of lesions with a minimum wall thickness <0.4 mm, 56% with a minimum wall thickness of 0.4 to 0.7 mm, 53% with a minimum wall thickness of 0.8 to 1.1 mm, and 53% with a minimum wall thickness >=1.2 mm were eccentric by angiography.

Target lesions were rarely completely concentric. Only 12 of 1446 (<1%) had an eccentricity index of 1.0. The mean eccentricity index was 3.6±2.8; the median eccentricity index was 2.8. Fig 3Down shows the frequency distribution of the intravascular ultrasound eccentricity index. An eccentricity index >=3.0 was selected as the binary ultrasound definition of eccentricity, similar in concept to angiography. With this definition, intravascular ultrasound classified 45.6% of lesions as eccentric (P=.0048 versus angiography).



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  		Figure 3. Bar graph showing the frequency distribution of the intravascular ultrasound eccentricity index. The total number of lesions in each group is shown with the percentage of lesions in parentheses. The percentage of lesions that were eccentric by angiography tended to increase with a larger ultrasound eccentricity index (P=.0023): 53% of lesions with an eccentricity index <3.0, 55% with an eccentricity index of 3.0 to 4.9, 58% with an eccentricity index of 5.0 to 6.9, 58% with an eccentricity index of 7.0 to 8.9, and 77% with an ultrasound eccentricity index >=9.0 were eccentric by angiography.

The subset of 382 noncalcified target lesions was then analyzed separately. On angiography, 225 noncalcified lesions (58.9%) appeared eccentric (P=NS compared with lesions containing calcium). On ultrasound, however, noncalcified lesions tended to be more eccentric than lesions containing even small amounts of calcium. The maximum and minimum plaque plus media thicknesses measured 2.1±0.7 and 0.7±0.4 mm, respectively. Of the 382 lesions, 81 (21.2%) had an arc of normal or disease-free arterial wall within the target lesion. The mean eccentricity index was 4.0±2.9. With a binary definition of an eccentricity index of >=3.0, intravascular ultrasound classified 198 lesions (51.8%) as eccentric; the concordance rate between angiography and ultrasound was still only 44.6%. Table 1Down gives the frequency distribution of eccentricity index, maximum and minimum wall thicknesses, and relationship of angiographic lesion eccentricity to these ultrasound parameters in the 382 noncalcified lesions.


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  		Table 1. Subset Analysis of 382 Noncalcified Calcified Target Lesions

The 1446 lesions were then classified into three groups (Table 2Down): stenoses having an arc of normal or disease-free arterial wall within the lesion (group 1, the most eccentric stenoses), stenoses without an arc of normal or disease-free arterial wall within the lesion but with an eccentricity index >=3.0 (group 2, lesions with moderate eccentricity), and concentric lesions (group 3, those with an eccentricity index <3.0).27 More eccentric lesions (particularly those containing an arc of normal or disease-free arterial wall) had larger ultrasound lumen cross-sectional areas and angiographic minimum lumen diameters, less ultrasound plaque burden (percent cross-sectional narrowing), less severe angiographic diameter stenosis, and smaller ultrasound arcs of calcium compared with more concentric lesions. These findings suggest that eccentric lesions may represent less advanced atherosclerotic disease and concentric lesions may represent more advanced disease.


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  		Table 2. Comparison of Target Lesions According to Severity of IVUS Eccentricity

Correlation of Angiographic, Intravascular Ultrasound, and Pathological Definitions of Lesion Eccentricity
Angiographically eccentric lesions had a larger intravascular ultrasound eccentricity index than concentric lesions. This was the result of an increased maximum plaque plus media thickness (2.2±0.6 versus 2.0±0.6 mm, P=.0001) rather than a decreased minimum plaque plus media thickness (0.8±0.4 versus 0.8±0.4 mm, P=.0573). Angiographically eccentric lesions more often had an arc of normal arterial wall within the lesion (15.8% versus 14.2%, P=.029). Table 3Down compares the angiographic, intravascular ultrasound, and pathological definitions of lesion eccentricity.


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  		Table 3. Comparison of Pathological Equivalent, Angiographic, and Ultrasound Eccentricity

However, when the binary ultrasound definition of lesion eccentricity (eccentricity index >=3.0) was used, the concordance rate of classification (angiography versus ultrasound, concentric versus eccentric) was only 53.8% ({kappa}=0.086). Similarly, using the pathological definition of lesion eccentricity (an arc of normal arterial wall within the lesion) gave a concordance rate of classification (angiography versus pathology, concentric versus eccentric) of only 47.7%.

Determinants of Angiographic Eccentricity
Through multivariate logistic regression analysis, the strongest determinant of angiographic lesion eccentricity was angiographic lesion length (P=.0005). Other determinants included the maximum and minimum plaque plus media thicknesses (P=.05 and P=.0073, respectively), but not the intravascular ultrasound eccentricity index.

To assess the interrelationship of lesion length and plaque distribution, lesions were grouped according to their length (Table 4Down). Longer lesions were associated with increased maximum and minimum plaque plus media thicknesses and a reduced frequency of an arc of normal arterial wall within the lesion. The eccentricity index did not vary with lesion length.


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  		Table 4. Impact of Angiographic Lesion Length on IVUS Plaque Distribution


*    Discussion
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*Discussion
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Atherosclerosis is a diffuse process, with plaque accumulation varying in involvement over the length of the coronary artery tree. The standard coronary angiogram is, in reality, a lumenogram providing useful information about lumen diameter but yielding little insight into plaque composition or lesion pathology.14 Nevertheless, a number of morphological characteristics identified have provided prognostic information in patients undergoing coronary angioplasty.28 29 As a result, coronary angiography has become the gold standard for the preprocedural lesion-based risk assessment of percutaneous transluminal coronary angioplasty (PTCA).30 The American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Subcommittee on Coronary Angioplasty)31 developed a risk stratification schema that has since been validated twice.28 32 This schema included lesion eccentricity as a risk factor for moderate success and moderate risk (type B lesions). The reduced procedural success in the treatment of angiographically eccentric lesions has been attributed to greater degrees of elastic recoil and larger residual percentage diameter stenosis.1 2 3 33 34 35 36 The importance of lesion eccentricity in coronary angioplasty has been confirmed in vitro,4 but in vitro pathological models of lesion eccentricity may have little relevance to angiographically concentric or eccentric stenoses. Not all clinical studies have confirmed the deleterious effect of angiographic lesion eccentricity on procedural outcome after balloon angioplasty.28 29 These discrepancies may be explained in part by the significant interobserver variability in the angiographic classification of lesion complexity (even by skilled operators); eg, the interobserver agreement in classifying lesion eccentricity was only 72%.28 37 The present study suggests one alternative explanation: that the angiographic appearance of a lesion does not reliably reflect actual plaque distribution. This questions the accuracy (and therefore the usefulness) of the angiographic assessment of lesion eccentricity.

The present study compared intravascular ultrasound and angiography to evaluate plaque distribution in vivo with three definitions of lesion eccentricity. The findings can be summarized as follows. First, angiography classified 55% of lesions as eccentric. Second, an arc of disease-free arterial wall within the lesion (the pathological definition of eccentricity) was present in 15% of lesions studied in vivo: in 16% of the angiographically eccentric and 14% of the angiographically concentric lesions. Comparing the angiographic and pathological definitions of lesion eccentricity, we see a concordance rate of 48%. Third, by use of a binary definition of eccentricity (maximum to minimum plaque plus media thickness >=3.0), intravascular ultrasound classified 46% of lesions as eccentric. An ultrasound eccentricity index >=3.0 was found in 49% of angiographically eccentric and 41% of angiographically concentric lesions. Comparing the angiographic and binary intravascular ultrasound definitions of lesion eccentricity gives a concordance rate of only 54%.

Pathological Analysis of Eccentricity
The pathological definition of an eccentric stenosis is an atherosclerotic plaque that fails to involve the entire coronary artery circumference, leaving an arc of disease-free arterial wall.11 12 13 The percentage of stenoses that fit this definition of eccentricity has been reported to be as high as 70%11 13 ; the arc of disease-free wall in these studies averaged {approx}15% to 20% of the total arterial circumference.12 13 However, our intravascular ultrasound findings agreed more with the pathological observations of Baroldi,27 who found that only 30% of lesions contained an arc of normal arterial wall, another 24% were eccentric, but the lumen was completely encircled by plaque.

Pathological studies have suggested that balloon angioplasty of lesions containing an arc of normal arterial wall may result in the asymmetric expansion of the normal vessel wall with little change to the atherosclerotic plaque, leading to frequent acute recoil, and dissection at the margin of plaque and normal wall.4 5 6 7 8 9 10 The current study found a disease-free segment of coronary artery wall in only 15% of the {approx}1500 lesions analyzed; thus, it suggests that the above-mentioned mechanisms of balloon angioplasty, acute recoil, and vasospasm (all of which depend on the presence of a normal arc of arterial wall) may also be uncommon.

Angiographic Eccentricity
Overall, 55% of the 1446 lesions (and 59% of the noncalcified lesions) were classified as eccentric. While this might seem high, 60% of lesions in patients enrolled in the Stent Restenosis Study were eccentric (66% in the stent arm and 54% in the PTCA arm).38 Similarly, 52% of lesions in patients enrolled in the Belgian Netherlands Stent Study were eccentric (50% in the stent arm and 54% in the PTCA arm).39 Furthermore, 49% of the 2233 native vessel lesions in the multidevice (including PTCA) New Approaches to Coronary Intervention database were eccentric (J.J.P., unpublished observations), and 56% of lesions in the balloon angioplasty study reported by Ellis et al28 were eccentric.

An angiographic eccentric lesion appearance did not predict the presence of an arc of normal arterial wall within a lesion. In experimental models of balloon angioplasty, the junction of atherosclerotic plaque and an arc of normal or disease-free wall within the lesion is a frequent site of dissection. Therefore, identification of an arc of normal arterial wall within a lesion may be important in avoiding angioplasty-induced dissections favoring the use of new angioplasty devices. Similarly, identification of the presence and orientation of an arc of normal arterial wall within the lesions may be important in avoiding other complications such as perforation with some new angioplasty devices (eg, directional coronary atherectomy or excimer laser angioplasty).

An angiographic eccentric lesion did not predict significantly eccentric plaque distribution (defined as an intravascular ultrasound eccentricity index >=3.0). The concordance rate between angiography and ultrasound was only 50%. Rather, angiographic lesion eccentricity indicated lesions with a greater plaque burden as evidenced by a larger preintervention percent cross-sectional narrowing. The angiographic classification of lesion eccentricity was dependent on the lesion length and the maximum and minimum plaque plus media thicknesses. Long lesions were classified more often as eccentric. However, intravascular ultrasound imaging did not find that longer lesions were more eccentric; in fact, longer lesions less often had an arc of normal arterial wall within the lesion. Because angiographic morphological lesion assessment required visual interpolation of the course of the coronary artery and lumen, interpolation was obviously more difficult in longer lesions than in shorter lesions. The angiographic assessment of lesion eccentricity and the angiographic measurement of lesion length appear to be interrelated; this is substantiated by the fact that angiographic lesion length, not the ultrasound lesion length, was selected by the discriminant model. Thus, lesion length affected the angiographic assessment of eccentricity but was not related to actual plaque distribution. This may explain why visual assessment of angiographic lesion eccentricity may be less predictive of procedural outcome than a computer-generated eccentricity index.34

Angiography is usually used to guide interventional procedures. The optimal performance of some interventional procedures is dependent on correct assessment of plaque distribution. Notable among these is directional coronary atherectomy in which the atherectomy device window must be oriented toward the plaque. It is conventionally taught that when the plaque has extremely eccentric morphology, the window should be oriented toward the eccentric plaque with cuts made over a 180° arc; when the plaque is mildly or moderately eccentric or concentric, cuts should be made in a 360° arc.40 However, this study clearly shows that the angiographic assessment of lesion eccentricity does not predict plaque distribution. Thus, the use of the angiographic assessment of plaque distribution in guiding the directional atherectomy procedure may be misleading. Furthermore, we have observed in the laboratory that the angiogram may suggest that the thickest plaque is located in one direction, while the ultrasound study may show it to lie in the opposite direction. However, there is no absolute anterior, posterior, left, right, superior, or inferior during ultrasound imaging. Branches can be used as spatial markers for comparisons of angiography and ultrasound.41 Alternatively, a reference cut during a directional atherectomy procedure could be used to confirm plaque distribution.42

Intravascular Ultrasound Classification of Lesion Eccentricity
The advent of smaller intravascular ultrasound imaging catheters makes routine preintervention imaging feasible in most lesions (>90%). This allows routine preintervention assessment of ultrasound lesion morphological characteristics, including plaque distribution. By intravascular ultrasound, the maximum and minimum plaque plus media thicknesses were rarely equal; thus, all lesions appeared somewhat eccentric. Plaque distribution, as assessed with an intravascular ultrasound eccentricity index, was a continuous variable; in this study, it ranged from 1.0 (completely concentric) to 22.0. Therefore, the classification of lesions as concentric versus eccentric depended on the specific binary definition used. For example, a binary ultrasound definition of maximum and minimum plaque plus media thickness >=2.0 would have classified 74% of the lesions as eccentric; however, the concordance rate with angiography still would have been poor (56%). A binary definition of maximum and minimum plaque plus media thickness >=4.0 would have classified 30% of the lesions as eccentric, but the concordance rate with angiography would have been similar (52%). The binary definitions used in this study were selected to be most similar to the angiographic and pathological definitions of lesion eccentricity, including the upper limits of the ultrasound definition of normal arterial wall.22

Clinical Correlations
Eccentric lesions in this study may have represented less advanced disease or "younger" narrowings compared with concentric lesions. Eccentric lesions (particularly those containing an arc of normal or disease-free vessel wall) had larger lumen cross-sectional areas, smaller plaque plus media and external elastic membrane cross-sectional areas, and smaller percent cross-sectional narrowings. This indicated a smaller plaque burden and less global compensatory arterial remodeling in eccentric compared with concentric lesions. Compensatory remodeling is a time-dependent process that is especially important in the adaptive phase of atherosclerosis.43 Furthermore, eccentric lesions in this study had less calcium; calcium may be a marker of more advanced atherosclerosis.44

Other authors have suggested a relationship between lesion eccentricity and rapid progression of atherosclerosis.45 46 Thus, another explanation for the differences in lumen, plaque plus media, and external elastic membrane cross-sectional areas in eccentric versus concentric lesions may be rapid progression. Emerging evidence suggests that rapid progression of atherosclerosis follows minor fissuring of atheromatous plaques with subsequent thrombus formation and fibrotic organization; in this scenario, there is insufficient time for adaptive remodeling.46 47 48 49

Limitations
Plaque distribution (and therefore lesion eccentricity) may vary over the length of a target lesion. We chose to analyze the anatomic section with the smallest lumen cross-sectional area containing the largest plaque burden for two reasons. First, transcatheter device therapy is directed primarily at the smallest lumen. Second, we and others have shown that the maximum residual plaque burden (percent cross-sectional narrowing) is a strong predictor of restenosis and subsequent events50 ; and it is our experience that the anatomic section with the most residual plaque burden also generally is the anatomic section with the smallest preintervention lumen cross-sectional area containing the largest preintervention plaque burden.

The ultrasound definitions used were arbitrary; however, they were selected to allow comparison with other analytical techniques. Ultimately, the best definition of lesion eccentricity is the one that correctly predicts short-term or late procedural outcomes.

Two factors may affect the extrapolation of this data to the general angioplasty community. First, the lesions and patients in this study were mostly referred for and treated with new device angioplasty. It is the bias of our interventional program to use new angioplasty devices rather than balloons whenever possible. Second, this study included only lesion images before intervention, thus excluding lesions that could not be imaged before intervention. These factors may have affected the percentage of lesions classified as eccentric (versus concentric) and may limit the application of our results to a more conventional (type A/B1) lesion population.

The assessment of the eccentricity index requires identification or extrapolation of the external elastic membrane behind lesion calcium. This was not possible in some lesions. Three-dimensional reconstruction of the ultrasound images with contour detection techniques may improve the reliability of interpolation of the external elastic membrane behind lesion calcium.

Conclusions
The prognostic value of plaque distribution in coronary artery disease remains uncertain. Two factors may explain the inconsistent importance of angiographic eccentricity as a predictor of short-term and long-term results after coronary angioplasty. First, marked lesion eccentricity may be less common in significant coronary artery stenoses than suggested by angiography. Second, the angiographic classification of lesions as eccentric versus concentric may depend only partly on plaque distribution; therefore, angiography may not be an adequate standard for assessing plaque distribution. Nevertheless, the optimum performance of certain interventional techniques, notably directional coronary atherectomy, relies on the correct assessment of plaque distribution. In this, angiography may often be misleading.

By providing transmural images of the coronary arteries, intravascular ultrasound can measure wall thickness directly and determine plaque distribution in vivo. Thus, intravascular ultrasound should become the gold standard for determining target lesion plaque distribution.


*    Acknowledgments
 
This study was supported in part by The Cardiology Research Foundation and Medlantic Research Institute, Washington, DC.

Received July 10, 1995; revision received September 27, 1995; accepted October 6, 1995.


*    References
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*References
 

  1. Simpfendorfer C, Belardi J, Bellamy G, Galan K, Franco I, Hollman J. Frequency, management and follow-up of patients with acute coronary occlusions after percutaneous transluminal coronary angioplasty. Am J Cardiol. 1987;59:267-269. [Medline] [Order article via Infotrieve]
  2. Meier B, Gruentzig AR, Hollman J, Ischinger T, Bradford JM. Does the length or eccentricity of coronary stenoses influence the outcome of transluminal dilatation? Circulation. 1983;65:497-499.
  3. Cowley MJ, Dorros G, Kelsey SF, Van Raden M, Detre KM. Acute coronary events associated with percutaneous transluminal coronary angioplasty. Am J Cardiol. 1984;53:12C-16C. [Medline] [Order article via Infotrieve]
  4. Waller BF. `Crackers, breakers, stretchers, drillers, scrapers, shavers, burners, welders, and melters': the future treatment of atherosclerotic coronary artery disease? A clinical-morphologic assessment. J Am Coll Cardiol. 1989;13:969-987. [Abstract]
  5. Honye J, Mahon DJ, Jain A, White CJ, Ramee SR, Wallis JB, Al-Zarka A, Tobis JM. Morphological effects of coronary balloon angioplasty in vivo assessed by intravascular ultrasound imaging. Circulation. 1992;85:1012-1025. [Abstract/Free Full Text]
  6. Waller BF, Orr CM, Pinkerton CA, Van Tassel J, Peters T, Slack JD. Coronary balloon angioplasty dissections: `the good, the bad, and the ugly.' J Am Coll Cardiol. 1992;20:701-706. [Medline] [Order article via Infotrieve]
  7. Castaneda-Zuniga WR, Formanek A, Tadavarthy M, Vlodaver Z, Edwards JE, Zolikofer C, Amplatz K. The mechanism of balloon angioplasty. Radiology. 1980;135:565-571. [Abstract/Free Full Text]
  8. Lee G, Ikeda RM, Joye JA, Bogren HG, DeMaria AN, Mason DT. Evaluation of transluminal angioplasty of chronic coronary artery stenosis. Circulation. 1980;61:77-83. [Abstract/Free Full Text]
  9. Block PC, Myler RK, Stertzer S, Fallon JT. Morphology after transluminal angioplasty in human beings. N Engl J Med. 1981;305:382-385. [Medline] [Order article via Infotrieve]
  10. Tobis JM, Mallery JA, Gessert J, Griffith J, Mahon D, Bessen M, Moriuchi M, McLeay L, McRae M, Henry WL. Intravascular ultrasound cross-sectional arterial imaging before and after balloon angioplasty in vitro. Circulation. 1989;80:873-882. [Abstract/Free Full Text]
  11. Vlodaver Z, Edwards JE. Pathology of coronary atherosclerosis. Prog Cardiovasc Dis. 1971;14:256-274. [Medline] [Order article via Infotrieve]
  12. Saner HE, Gobel FL, Salomonowitz E, Erlien DA, Edwards JE. The disease-free wall in coronary atherosclerosis: its relation to degree of obstruction. J Am Coll Cardiol. 1985;6:1096-1099. [Abstract]
  13. Waller BF. The eccentric coronary atherosclerotic plaque: morphologic observations and clinical relevance. Clin Cardiol. 1989;12:14-20. [Medline] [Order article via Infotrieve]
  14. Popma JJ, Bashore TD. Qualitative and quantitative angiography. In: Topol E, ed. Textbook of Interventional Cardiology. Philadelphia, Pa: WB Saunders; 1994:1052-1068.
  15. Hodgson JM, Graham SP, Sarakus AD, Dame SG, Stephens DN, Dhillon PS, Brands D, Sheehan H, Eberle MJ. Clinical percutaneous imaging of coronary anatomy using an over-the-wire ultrasound catheter system. J Cardiac Imaging. 1989;4:186-193.
  16. Gussenhoven EJ, Essed CE, Lancee CT, Mastik F, Frietman P, van Egmond FC, Reiber J, Bosch H, van Urk H, Roelandt J, Bom N. Arterial wall characteristics determined by intravascular ultrasound imaging: an in vitro study. J Am Coll Cardiol. 1989;14:947-952. [Abstract]
  17. Nishimura RA, Edwards WD, Warnes CA, Reeder GS, Holmes DR Jr, Tajik AJ, Yock PG. Intravascular ultrasound imaging: in vitro validation and pathologic correlation. J Am Coll Cardiol. 1990;16:145-154. [Abstract]
  18. Potkin BN, Bartorelli AL, Gessert JM, Neville RF, Almagor Y, Roberts WC, Leon MB. Coronary artery imaging with intravascular high-frequency ultrasound. Circulation. 1990;81:1575-1585. [Abstract/Free Full Text]
  19. Nissen SE, Grines CL, Gurley JC, Sublett K, Haynie D, Diaz C, Booth DC, DeMaria AN. Application of a new phased-array ultrasound imaging catheter in the assessment of vascular dimensions: in vivo comparison to cineangiography. Circulation. 1990;81:660-666. [Abstract/Free Full Text]
  20. Tobis JM, Mallery J, Mahon D, Lehmann K, Zalesky P, Griffith J, Gessert J, Moriuchi M, McRae M, Dwyer ML, Greep N, Henry WL. Intravascular ultrasound imaging of human coronary arteries in vivo: analysis of tissue characterizations with comparison to in vitro histological specimens. Circulation. 1991;83:913-926. [Abstract/Free Full Text]
  21. Nissen SE, Gurley JC, Grines CL, Booth DC, McClure R, Berk M, Fischer C, DeMaria AN. Intravascular ultrasound assessment of lumen size and wall morphology in normal subjects and patients with coronary artery disease. Circulation. 1991;84:1087-1099. [Abstract/Free Full Text]
  22. Fitzgerald PJ, St. Goar FG, Connolly AJ, Pinto FJ, Billingham ME, Popp RL, Yock PG. Intravascular ultrasound imaging of coronary arteries: is three layers the norm? Circulation. 1992;86:154-158. [Abstract/Free Full Text]
  23. Mintz GS, Potkin BN, Keren G, Satler LF, Pichard AD, Kent KM, Popma JJ, Leon MB. Intravascular ultrasound evaluation of the effect of rotational atherectomy in obstructive atherosclerotic coronary artery disease. Circulation. 1992;86:1383-1393. [Abstract/Free Full Text]
  24. Kovach JA, Mintz GS, Pichard AD, Kent KM, Popma JJ, Satler LF, Leon MB. Sequential intravascular ultrasound characterization of the mechanisms of rotational atherectomy and adjunct balloon angioplasty. J Am Coll Cardiol. 1993;22:1024-1032. [Abstract]
  25. Mintz GS, Douek P, Pichard AD, Kent KM, Satler LF, Popma JJ, Leon MB. Target lesion calcification in coronary artery disease: an intravascular ultrasound study. J Am Coll Cardiol. 1992;20:1149-1155. [Abstract]
  26. Dixon WJ, Brown MB, Engelman L. BMDP Statistical Software Manual. Berkley, Calif: University of California Press; 1990.
  27. Baroldi G. Diseases of the coronary arteries. In: Silver MD, ed. Cardiovascular Pathology. New York, NY: Churchill Livingstone; 1983:341-342.
  28. Ellis SG, Vandormael MG, Cowley MJ, DiSciascio G, Deligonul U, Topol EJ, Bulle TM. Coronary morphologic and clinical determinants of procedural outcome with angioplasty for multivessel coronary disease. Circulation. 1990;82:1193-1202. [Abstract/Free Full Text]
  29. Savage MP, Goldberg S, Hirschfeld JW, Bass TA, MacDonald RG, Margolis JR, Taussig AS, Vetrovec G, Whitworth HB, Zalewski A, Hill JA, Cowley M, Jugo R, Pepine CJ. Clinical and angiographic determinants of primary coronary angioplasty success. J Am Coll Cardiol. 1991;17:22-28. [Abstract]
  30. Ellis SG. Elective coronary angioplasty: technique and complications. In: Topol EJ, ed. Textbook of Interventional Cardiology. Philadelphia, Pa: WB Saunders Co; 1994:186-206.
  31. Ryan TJ, Bauman WB, Kennedy W, Kereiakes DJ, King SB III, McCallister BD, Smith CS, Ullyot DJ. Guidelines for percutaneous transluminal coronary angioplasty: a report of the American Heart Association/American College of Cardiology Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Committee on Percutaneous Transluminal Coronary Angioplasty). Circulation. 1993;88:2987-3007. [Free Full Text]
  32. Cragg DR, Friedman HZ, Almany SL, Gangadharan V, Ramos RG, Levine AB, LeBeau TA, O'Neill WW. Early hospital discharge after percutaneous transluminal coronary angioplasty. Am J Cardiol. 1989;64:1270-1274. [Medline] [Order article via Infotrieve]
  33. Satler LF, Warth D. Dissections after high speed rotational atherectomy: frequency, predictive factors, and clinical consequences. Circulation. 1992;86(suppl I):I-785. Abstract.
  34. Ghazzal ZMB, Hearn JA, Litvack F, Goldenberg T, Kent KM, Eigler N, Douglas JS, King SB III. Morphologic predictors of acute complications after percutaneous excimer laser coronary angioplasty: results of a comprehensive angiographic analysis: importance of the eccentricity index. Circulation. 1992;86:820-827. [Abstract/Free Full Text]
  35. Bittl JA, Sanborn TA. Excimer laser-facilitated coronary angioplasty: relative risk analysis of acute and follow-up results in 200 patients. Circulation. 1992;86:71-80. [Abstract/Free Full Text]
  36. Ghazzal ZMB, Shefer A, Litvack F, Holmes D, Rothbaum DA, Pichard AD, Goldenberg T, King SB III. The new directional laser catheter (DLC): early results from a multicenter experience. Circulation. 1992;86(suppl I):I-654. Abstract.
  37. Kleiman NS, Rodriguez AR, Raizner AE. Interobserver variability in grading of coronary arterial narrowings using the American College of Cardiology/American Heart Association grading criteria. Am J Cardiol. 1992;69:413-415.[Medline] [Order article via Infotrieve]
  38. Fischman DL, Leon MB, Baim DS, Schatz RA, Savage MP, Penn I, Detre K, Veltri L, Ricci D, Nobuyoshi N, Cleman M, Heuser R, Almond D, Teirstein PS, Fish RD, Colombo A, Brinker J, Moses J, Shaknovitch A, Hirshfeld J, Bailey S, Ellis S, Rake R, Goldberg S. A randomized comparison of coronary stent placement and balloon angiopasty in the treatment of coronary artery disease. N Engl J Med. 1994;331:496-501. [Abstract/Free Full Text]
  39. Serruys P, De Jaegere P, Kiemeneij F, Macaya C, Rutsch W, Heyndrickx G, Emanuelsson H, Marco J, Legrand V, Materne P, Belardi J, Sigwart U, Colombo A, Goy JJ, van den Heuvel P, Delcan J, Morel M-A. A comparison of balloon-expandable-stent implantation with balloon angioplasty in patients with coronary artery disease. N Engl J Med. 1994;331:490-495.
  40. Hinohara T, Robertson GC, Simpson JB. Directional coronary atherectomy. In: Topol EJ, ed. Textbook of Interventional Cardiology. Philadelphia, Pa: WB Saunders Co; 1994:641-658.
  41. Kimura BJ, Fitzgerald PJ, Sudhir K, Amidon TM, Strunk BL, Yock PG. Guidance of directed coronary atherectomy by intracoronary ultrasound imaging. Am Heart J. 1992;124:1365-1369. [Medline] [Order article via Infotrieve]
  42. Bauman RP, Morris KG, Krucoff MW, Annex BH, Brott BC, Mullen WL, Yock PG. Maximizing plaque removal with directional coronary atherectomy: a new method using ultrasound guidance. J Am Coll Cardiol. 1994;23:386A. Abstract.
  43. Glagov S, Weisenberg E, Zarins CK, Stankunacicius K, Kolettis GJ. Compensatory enlargement of various human atherosclerotic arteries. N Engl J Med. 1987;316:1371-1375. [Abstract]
  44. Frink RJ, Achor RWP, Braun AL Jr, Kincaid OW, Brandenburg RO. Significance of calcification of the coronary arteries. Am J Cardiol. 1970;26:241-247. [Medline] [Order article via Infotrieve]
  45. Waller BF, Pinkerton CA. `Cutters, scoopers, shavers and scrapers': the importance of atherectomy devices and clinical relevance of tissue removed. J Am Coll Cardiol. 1990;15:426-428. [Medline] [Order article via Infotrieve]
  46. Fuster V, Badimon L, Badimon JJ, Chesbro JH. The pathogenesis of coronary artery disease and the acute coronary syndromes. N Engl J Med. 1992;326:242-250, 310-318. [Medline] [Order article via Infotrieve]
  47. Ambrose JA, Winters SL, Arora RR, Haft JI, Goldstein J, Rentrop KP. Coronary angiographic morphology in myocardial infarction: a link between the pathogenesis of unstable angina and myocardial infarction. J Am Coll Cardiol. 1985;6:1233-1238. [Abstract]
  48. Ambrose JA, Winters SL, Stern A, Eng A, Teichholz LE, Gorlin R. Angiographic morphology and the pathogenesis of unstable angina pectoris. J Am Coll Cardiol. 1985;5:609-616. [Abstract]
  49. Ambrose JA, Tannenbaum MA, Alexopoulos D, Hjemdahl-Monsen CE, Leavy J, Weiss M, Borrico S, Gorlin R, Fuster V. Angiographic progression of coronary artery disease and the development of myocardial infarction. J Am Coll Cardiol. 1988;12:56-62. [Abstract]
  50. Mintz GS, Chuang YC, Popma JJ, Pichard AD, Kent KM, Satler LF, Bucher TA, Griffin J, Leon MB. The final % cross-sectional narrowing (residual plaque burden) is the strongest intravascular ultrasound predictor of angiographic restenosis. J Am Coll Cardiol. 1995;25:35A. Abstract.



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