Contribution of inadequate compensatory enlargement to development of human coronary artery stenosis: an in vivo intravascular ultrasound study

Relationship Between Coronary Artery Remodeling and Plaque Composition in Culprit Lesions An Intravascular Ultrasound Radiofrequency Analysis

BACKGROUND

The relationship between coronary artery remodeling and culprit plaque composition in vivo has not been fully evaluated by spectral analysis of intravascular ultrasound (IVUS) radiofrequency (RF) data.

METHODS AND RESULTS

IVUS RF analyses were performed for 56 consecutive de novo culprit lesions of 52 patients undergoing percutaneous coronary intervention. Remodeling of culprit lesions was determined using the remodeling index (RI), calculated as the external elastic membrane area of the minimum lumen area (MLA) site divided by that of the proximal reference site. Positive remodeling was defined as RI >1.05, intermediate remodeling as 0.95< or = RI < or =1.05 and negative remodeling as RI <0.95. Among the 56 lesions, positive remodeling was detected in 24, intermediate remodeling in 16, and negative remodeling in 16. At MLA sites, positive remodeling lesions had a larger percentage of the fibrofatty component than negative remodeling lesions (22.5+/-10.3% vs 10.4+/-6.6%, p=0.0001), whereas the latter contained a larger percentage of the dense calcium component than the former (2.8+/-2.9% vs 8.4+/-7.0%, p=0.016).

CONCLUSIONS

Culprit plaques with positive remodeling have a large lipid burden, whereas those with negative remodeling contain a large amount of calcium.

Oxidized low-density lipoprotein and high-density lipoprotein cholesterol modulate coronary arterial remodeling: an intravascular ultrasound study

BACKGROUND

Oxidized low-density lipoprotein (oxLDL) not only plays an important role in plaque formation, but also impairs the endothelium-dependent relaxation. Constrictive remodeling rather than intimal hyperplasia mainly contributes to restenosis after balloon angioplasty. Probucol (powerful antioxidant) reduced restenosis rate by improving constrictive remodeling. Thus, oxLDL may modulate coronary arterial remodeling.

HYPOTHESIS

The study was designed for using intravascular ultrasound to test the hypothesis that arterial constrictive remodeling (CR) was associated with oxLDL in patients with coronary artery disease.

METHODS

Intravascular ultrasound was performed in 36 patients with de novo atherosclerotic coronary. Remodeling was defined and evaluated as follows: remodeling index (RI) = lesion vessel area (VA)/(proximal reference VA + distal reference VA)/2. Constrictive remodeling (CR) was defined as remodeling index (RI) < 0.9. Neutral and expansive remodeling (NER) was defined as RI > or = 0.9. The level of plasma ox-LDL was measured by sandwich ELISA using the monoclonal antibody (DLH3)-recognized oxidatively modified lipoproteins and the antihuman apoprotein B monoclonal antibody.

RESULTS

Neutral and expansive remodeling was found in 24 lesions, and CR in 12 lesions. Remodeling index was significantly lower in the CR group than in the NER group (0.8 +/- 0.1 vs. 1.0 +/- 0.1, p < 0.001). The level of oxLDL in the CR group was significantly higher than that in the NER group (24.0 +/- 12.1 vs. 16.4 +/- 6.2 U/ml, p < 0.05). The level of high-density lipoprotein-cholesterol (HDL-C) in the CR group was significantly lower than that in the NER group (40.5 +/- 4.8 vs. 46.2 +/- 10.6 mg/ml, p < 0.05). There was a statistically significant correlation between the value of HDL-C/ ox-LDL and the RI (r = -0.48, p < 0.005).

CONCLUSIONS

Oxidized LDL and HDL-C were associated with arterial remodeling in de novo atherosclerotic lesions.

Preintervention arterial remodeling as a predictor of intimal hyperplasia after intracoronary stenting: a serial intravascular ultrasound study

BACKGROUND

The impact of vascular remodeling pattern on intimal hyperplasia (IH) after coronary stenting is unknown.

HYPOTHESIS

The preintervention remodeling pattern of the lesion might be associated with IH after the coronary stenting procedure.

METHODS

Serial (pre-, post-stent implantation, and follow-up) intravascular ultrasound (IVUS) images were obtained in 58 patients with single-stent implantation (GFX stents in 41 and NIR in 17). The matching IVUS image slices at the preintervention lesion site were selected for serial comparisons. The remodeling index (RI) was defined as lesion/proximal reference external elastic membrane cross-sectional area (CSA) at preintervention lesion site. Adequate remodeling was defined as a RI > 0.95 and inadequate remodeling as a RI < or = 0.95. Vessel stretching, percent vessel stretching, and percent IH CSA, as well as pre- and postintervention IVUS variables were evaluated according to the remodeling pattern.

RESULTS

The percent IH CSA was 31% in adequate remodeling (n = 29, mean RI = 1.05) and 41% in inadequate remodeling (n = 29, mean RI = 0.88) (p = 0.049). Percent vessel stretching was 15% in adequate remodeling and 22% in inadequate remodeling (p = 0.007). The RI inversely correlated with percent vessel stretching (r = -0.435, p = 0.001).

CONCLUSIONS

Compared with preintervention adequate remodeling, inadequate remodeling was associated with increased percent IH CSA, which might be related with more vessel stretching.

Prospective comparison of coronary artery remodeling between acute coronary syndrome and stable angina in single-vessel disease: correlation between C-reactive protein and extent of arterial remodeling

BACKGROUND

Retrospective intravascular ultrasound (IVUS) studies showed that positive remodeling of coronary artery was associated with unstable clinical presentation. However, no prospective IVUS study has been performed to demonstrate such relationship. The relationship between C-reactive protein (CRP) and coronary artery remodeling is unknown.

HYPOTHESIS

Positive remodeling might be related with acute coronary syndrome in the prospective IVUS study. C-reactive protein levels might be associated with coronary artery remodeling.

METHODS

Preintervention IVUS images were prospectively obtained in 93 patients with single-vessel disease (30 for acute coronary syndrome and 63 for stable angina). Serum sample for CRP measurement was collected 24 h prior to coronary intervention. The remodeling index was defined as a ratio of (lesion/average reference) external elastic membrane area. Positive remodeling was defined as a remodeling index > 1.05 and negative remodeling as a remodeling index < 0.95.

RESULTS

The remodeling index was 0.99 +/- 0.13 in acute coronary syndrome versus 0.95 +/- 0.12 in stable angina (p = 0.048). Positive remodeling was associated with acute coronary syndrome (43 vs. 19%), whereas negative remodeling was more frequent in stable angina (49 vs. 33%) (p = 0.047). C-reactive protein levels were significantly higher in acute coronary syndrome than in stable angina (1.4 +/- 2.0 vs. 0.5 +/- 0.6 mg/dl, respectively, p = 0.002). However, there was no significant correlation between CRP levels and remodeling index (r = 0.078, p = 0.475).

CONCLUSIONS

Positive remodeling may be related with acute coronary syndrome in the prospective IVUS analysis. C-reactive protein levels may not predict the extent of arterial remodeling.

Elevated homocysteine levels might be associated with coronary artery remodeling in patients with stable angina: an intravascular ultrasound study

BACKGROUND

The relationship between plasma biologic markers and coronary artery remodeling is unknown.

HYPOTHESIS

Plasma biologic markers are associated with coronary artery remodeling.

METHODS

Preintervention intravascular ultrasound images were obtained in 44 patients with chronic stable angina. Plasma samples were collected 24 h before coronary intervention. The biologic markers included total cholesterol, low-density lipoprotein (LDL) cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, lipoprotein(a) [LP(a)], C-reactive protein (CRP), and homocysteine. The remodeling index (RI) was defined as a ratio of the (lesion/proximal reference) external elastic membrane cross-sectional area. Positive remodeling was defined as an RI > 1.05, negative remodeling as an RI <0.95, and intermediate remodeling as an RI between 0.95 and 1.05.

RESULTS

Total cholesterol level (r = 0.092, p = 0.557), LDL cholesterol level (r = 0.123, p = 0.426), triglyceride level (r = 0.020, p = 0.901), HDL cholesterol level (r = 0.042, p = 0.789), LP(a) level (r = 0.062, p = 0.729), and CRP level (r = 0.266, p = 0.089) did not significantly correlate with the RI. However, the plasma homocysteine level positively correlated with the RI (r = 0.398, p = 0.008). The plasma homocysteine level was significantly lower in the lesions with negative remodeling and higher in the lesions with positive remodeling (10.8 +/- 0.7 micromol/l in negative remodeling, 13.1 +/- 0.6 micromol/l in intermediate remodeling, and 18.1 +/- 2.8 micromol/l in positive remodeling, p = 0.021).

CONCLUSIONS

Elevated homocysteine levels might be associated with coronary artery remodeling in patients with stable angina.

Effect of Simvastatin on Coronary Lesion Site Remodeling: A Serial Intravascular Ultrasound Study

BACKGROUND

Direct evidence of coronary artery remodeling can be derived only from serial changes in the external elastic membrane (EEM) and plaque area. The aim of the study was to assess the effect of simvastatin on coronary remodeling in serial intravascular ultrasound (IVUS) studies.

METHODS

In 39 male patients ECG-triggered transducer pullback IVUS was performed at baseline, after 3 months on a lipid-lowering diet (control period), and after another 12 months of simvastatin 40 mg/day. The lesion site was the image slice with maximum plaque burden at 3 months.

RESULTS

Absolute changes in the EEM area correlated significantly with changes in plaque area during the control period [B = 0.966, r = 0.792 (95% CI 0.71-1.22); p < 0.001] and during simvastatin treatment [B = 0.945, r = 0.822 (95% CI 0.73-1.16); p < 0.001], but there was no significant difference in the slope (delta EEM/delta plaque) between the two time intervals. After 12 months of simvastatin, there was a significant reduction in the lesion EEM area of 4.6% (p = 0.006) and in the lesion plaque area of 5.9% (p < 0.001), but there was no change in reference measurements. As a result, the remodeling index was reduced by simvastatin from 1.01 +/- 0.12 to 0.95 +/- 0.09 (p < 0.001).

CONCLUSION

Simvastatin decreases the remodeling index by reducing lesion, but not reference plaque and EEM area. However, simvastatin does not affect direct evidence of remodeling (delta EEM/delta plaque) obtained using serial IVUS studies.

Association of coronary plaque composition and arterial remodelling: a virtual histology analysis by intravascular ultrasound

BACKGROUND

Conflicting data have been reported about the correlation between plaque composition assessed by virtual histology (VH) and remodelling index (RI).

AIM

To evaluate, in a larger patient population, the relationship between plaque morphology obtained by VH and arterial remodelling.

METHODS AND RESULTS

VH intravascular ultrasound was performed on 95 non-bifurcation native significant lesions (>75% stenosis) in 85 patients. Positive remodelling (defined as RI > or =1.05) was present in 28 lesions, whereas intermediate/negative remodelling (RI <1.05) was present in 67 lesions. Compared with intermediate/negative remodelling, positive remodelling was associated with an increased frequency of patients with acute coronary syndrome (n = 13 (52%) vs n = 15 (25%); p = 0.017), and with a greater plaque burden (mean (SD) 78.3 (6.3)% vs 73.2 (6.8)%, p = 0.001). At the minimal lumen site, necrotic core was significantly smaller in lesions with positive remodelling (median (interquartile range) 5.0% (2.2-11.0%)) than in lesions with intermediate/negative remodelling (median (interquartile range) 9.0% (4.0-16.0%); p = 0.048). No differences were observed in the rate of thin-cap fibroatheroma or in the presence of multiple necrotic core layers, and there were no statistical differences for fibrous, fibro fatty and dense calcium percent plaque area at the minimum lumen diameter (MLD), or for the entire lesion length between both groups.

CONCLUSIONS

In vivo VH analysis shows that lesions with positive remodelling have statistically less necrotic core percent area at the MLD site compared with intermediate/negative remodelling lesions.

Static and serial assessments of coronary arterial remodeling are discordant: an intravascular ultrasound analysis from the Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) trial

BACKGROUND

Arterial remodeling is a major determinant of the clinical manifestations of coronary artery disease. Assessment of arterial remodeling with intravascular ultrasound (IVUS) used to rely on comparing the external elastic membrane (EEM) areas of lesion and reference sites at a single time point (static assessment). Recently, performance of serial IVUS provided the opportunity for direct assessment of remodeling. Our aim was to study the concordance of the static and serial methods.

METHODS

We identified 210 focal coronary lesions on the baseline IVUS interrogations of the REVERSAL trial. A follow-up IVUS was performed at 18 months. Static assessment was performed by calculating the remodeling index (RI) (lesion EEM area / reference EEM area) and serial assessment by comparing the changes in atheroma and EEM areas at follow-up.

RESULTS

Using the serial method, there was a 1.24 mm2 increase in EEM area for every 1 mm2 increase in atheroma area at the lesion site, which was indicative of expansive (overcompensatory) remodeling. By using the static method, the RI was paradoxically lower at follow-up (1.062 +/- 0.15 at baseline vs 1.027 +/- 0.14 at follow-up, P < .001), indicating a trend toward constrictive remodeling. The reason for decreased RI at follow-up was the relatively larger expansion of the EEM areas at the reference sites.

CONCLUSIONS

Static and serial assessments of arterial remodeling are discordant. This is due to concomitant remodeling of the reference sites used in the static assessment. Intravascular ultrasound performed at a single point in time does not reflect the dynamic remodeling response.

Remodeling Index Compared to Actual Vascular Remodeling in Atherosclerotic Left Main Coronary Arteries as Assessed With Long-Term (≥12 Months) Serial Intravascular Ultrasound

OBJECTIVES

We present the remodeling index (RI) versus serial intravascular ultrasound (IVUS) data.

BACKGROUND

The RI, derived by comparing lesion external elastic membrane (EEM) cross-sectional area versus the reference at one time point, is used in various IVUS studies as a substitute of true remodeling (change in EEM over time), assuming that it represents true remodeling.

METHODS

We studied 46 non-stenotic left main arteries using serial IVUS (follow-up 18 +/- 8 months). Plaques were divided into subgroups according to the follow-up RI: follow-up RI >1 (n = 27) versus follow-up RI < or =1 (n = 19).

RESULTS

Lesions with a follow-up RI >1 had an increase in lumen despite an increase in plaque because of an increase in EEM. Conversely, lesions with a follow-up RI < or =1 had a reduction in lumen as a result of both a plaque increase and EEM decrease. Overall, the follow-up RI correlated directly with changes in lesion site EEM (baseline-to-follow-up). Although there was no correlation between the follow-up RI and changes in reference EEM area, changes in reference EEM area did correlate directly with changes in lesion EEM area. In nearly 90% of lesions with a follow-up RI >1, there was a previously documented increase in EEM area. Using multivariate linear regression analysis, the follow-up RI was dependent on the baseline RI, the increase in lesion EEM area, and the decrease in reference EEM area. The follow-up RI was not dependent on changes in lesion plaque area.

CONCLUSIONS

The vast majority of left main lesions with a remodeling index >1 had evidence of a previous increase in lesion-site EEM area.

Elevated preprocedural high-sensitivity C-reactive protein levels are associated with neointimal hyperplasia and restenosis development after successful coronary artery stenting

BACKGROUND

Recent data indicate that an elevated serum level of high-sensitivity C-reactive protein (hs-CRP) predicts the risk of recurrent coronary events, and that statin therapy decreases the risk of coronary events. This study assessed the relationship between the pre-procedural hs-CRP level and in-stent neointimal hyperplasia (NIH) after stenting and the effects of statins on the relationship between restenosis after stenting and the serum hs-CRP levels of patients with coronary artery disease.

METHODS AND RESULTS

This study included 100 patients who underwent stent implantation for angiographically significant stenosis. Patients were divided into a normal C-reactive protein (CRP) group (<0.5 mg/dl, n=59) and elevated CRP group (>or=0.5 mg/dl, n=41). All patients underwent angiographic and intravascular ultrasound follow-up at 6 months. The baseline CRP level was 0.29+/-0.08 mg/dl in the normal CRP group and 2.90+/-2.31 mg/dl in the elevated CRP group. The NIH cross-sectional area (CSA) in the minimal lumen CSA at follow-up was significantly larger in the elevated CRP group compared with the normal CRP group (1.9+/-1.3 mm2 vs 3.0+/-1.5 mm2, p=0.001). A significant positive correlation was found between pre-interventional CRP level and NIH area (r=0.52, p<0.001). In patients with normal CRP, an association between statin therapy and restenosis was not observed. However, when the analysis was confined to patients with elevated CRP, statin therapy significantly reduced the restenosis rate (20% vs 37.5%, p=0.031). In the normal CRP group, the intra-stent neointimal area at 6 months was not different between the non-statin and statin groups (2.2+/-1.4 mm2 vs 1.8+/-1.1 mm2). However, in the elevated CRP group, statin therapy significantly decreased the neointimal area at 6-month follow-up (3.6+/-1.7 mm2 vs 2.4+/-1.3 mm2, p<0.001).

CONCLUSION

Measuring the pre-interventional hs-CRP level may help predict the development of restenosis after stenting and statin therapy will significantly reduce the restenosis rate in patients with an elevated hs-CRP.

Association of plaque characterization by intravascular ultrasound virtual histology and arterial remodeling

Positive remodeling is more often observed in lesions of patients who have acute coronary syndromes or vulnerable (rupture-prone) plaques. However, there are few data that correlate plaque morphology, composition, and arterial remodeling in vivo. We evaluated coronary plaque characterization of lesions with positive remodeling using intravascular ultrasound (IVUS) radiofrequency data analysis. Seventy-seven nonbifurcation native coronary lesions (in 50 patients) were imaged in vivo using 30-MHz IVUS transducers. Lesions were classified into 4 plaque types, fibrous, fibrofatty, dense calcium, and necrotic core, by using processing of the radiofrequency signal validated in vitro. The remodeling index was calculated as the lesion external elastic membrane area divided by the proximal reference external elastic membrane area. Lesions were divided into 2 groups: positive remodeling (remodeling index>1.0, 26 lesions) and intermediate/negative remodeling (remodeling index<or=1.0, 51 lesions). Total plaque volume and the volume of each plaque type were averaged over the length of the lesion. Reference segment plaque compositions were similar. Mean lesion fibrofatty plaque area was significantly larger in lesions with positive remodeling than in lesions with intermediate/negative remodeling (1.2+/-0.7 vs 0.8+/-0.4 mm2, p=0.001; 26.3+/-6.6% vs 19.8+/-5.7%, p<0.001, of total plaque volume). The same results were obtained at the minimum lumen site and in the subgroup of patients who had acute coronary syndromes. Further, there was a linear relation between remodeling index and fibrofatty plaque area (r=0.26, p=0.02). In conclusion, in vivo IVUS radiofrequency data analysis demonstrates that positive remodeling occurs in lesions with more fibrofatty plaque.

LDL-cholesterol predicts negative coronary artery remodelling in diabetic patients: an intravascular ultrasound study

AIMS

To investigate the relationship between coronary artery remodelling and glycaemic and lipid profiles in diabetic patients.

METHODS AND RESULTS

Intravascular ultrasound analyses of 131 angiographically non-significant coronary stenoses in 80 diabetic patients were performed. The remodelling index (RI) was calculated as the ratio between total vessel area at target site and total vessel area at proximal reference, and was assessed in two ways: as a continuous variable, and as a binary categorical variable: RI<1 namely, negative remodelling (group I), or RI> or =1 (group II). Percentage cross-sectional narrowing was 57+/-13%. On average, RI was 0.93+/-0.13. Coronary shrinkage was found in 94 (71.7%) lesions. Significant inverse correlations were demonstrated between RI and total cholesterol (r=-0.26, P=0.003), apolipoprotein-B (r=-0.23, P=0.01) and LDL-cholesterol (r=-0.3, P=0.001) levels. Multivariable lineal regression analysis identified LDL-cholesterol as the only independent predictor of RI (P=0.001).

CONCLUSION

Negative remodelling is a frequent finding in diabetics and it is associated with LDL-cholesterol levels. This may contribute to the diffuse coronary artery disease observed in diabetic patients.

Compensatory enlargement of human coronary arteries identified by magnetic resonance imaging

The aim of the present study was to evaluate the role of magnetic resonance imaging (MRI) for the non-invasive detection of coronary abnormalities and specifically the remodeling process in patients with coronary artery disease (CAD). MRI was performed in 10 control healthy subjects and 26 patients with angiographically proven CAD of the right coronary (RCA) or left anterior descending (LAD) artery; 23 patients were within two months of acute coronary syndromes, and 3 had stable angina with a positive test for ischemia. Wall thickness (WT), vessel wall area (VWA), total vessel area (TVA), and luminal area (LA) were measured. There were significant increases in WT (mean +/- SEM, RCA: 2.62 +/- 0.75 vs 0.53 +/- 0.15 mm; LAD: 2.21 +/- 0.69 vs 0.62 +/- 0.24 mm) and in VWA (RCA: 30.96 +/- 17.57 vs 2.1 +/- 1.2 mm(2); LAD: 19.53 +/- 7.25 vs 3.6 +/- 2.0 mm(2)) patients compared to controls (P < 0.001 for each variable). TVA values were also greater in patients compared to controls (RCA: 44.56 +/- 21.87 vs 12.3 +/- 4.2 mm(2); LAD: 31.89 +/- 11.31 vs 17.0 +/- 6.2 mm(2); P < 0.001). In contrast, the LA did not differ between patients and controls for RCA or LAD. When the LA was adjusted for vessel size using the LA/TVA ratio, a significant difference was found: 0.33 +/- 0.16 in patients vs 0.82 +/- 0.09 in controls (RCA) and 0.38 +/- 0.13 vs 0.78 +/- 0.06 (LAD) (P < 0.001). As opposed to normal controls, positive remodeling was present in all patients with CAD, as indicated by larger VWA. We conclude that MRI detected vessel wall abnormalities and was an effective tool for the noninvasive evaluation of the atherosclerotic process and coronary vessel wall modifications, including positive remodeling that frequently occurs in patients with acute coronary syndromes.

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

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

Agents that stabilise atherosclerotic plaque

The concept of plaque stabilisation was developed to explain how medications could decrease adverse coronary events without a substantial reduction in the regression of atherosclerosis. With this concept, a comprehensive view of atherosclerosis is now appreciated. A number of imaging modalities are employed to study atherosclerosis; most identify luminal diameter or stenosis, wall thickness and plaque volume. A number of antiatherosclerotic agents have been studied as well to prove this hypothesis. However, the ultimate goal of medical treatment is to cure or prevent diseases caused by atherosclerosis.

Impact of Preinterventional Arterial Remodeling on In-Stent Neointimal Hyperplasia and In-Stent Restenosis After Coronary Stent Implantation-An Intravascular Ultrasound Study-

BACKGROUND

Patterns of arterial remodeling during the course of plaque development have been shown to play an important role in both the progression of de novo atherosclerosis and in the restenotic process following coronary intervention. The aim of the present prospective study was to evaluate the effect of pre-interventional arterial remodeling on in-stent neointimal hyperplasia (NIH) and in-stent restenosis (ISR) after stenting.

METHODS AND RESULTS

Pre-interventional arterial remodeling was assessed in 85 native coronary lesions by using intravascular ultrasound (IVUS). The remodeling index (RI) was 1.09+/-0.20 in the positive remodeling (PR)/intermediate remodeling (IR) group and 0.84+/-0.12 in the negative remodeling (NR) group. The plaque plus media cross sectional area (P&M CSA) at pre-intervention and NIH CSA at follow-up in the minimal lumen CSA were significantly larger in the PR/IR group (9.2+/-2.9 mm2 vs 6.2+/-1.8 mm2, 3.3+/-1.2 mm2 vs 1.5+/-0.9 mm2; p = 0.001, p = 0.001, respectively). On 3-dimensional analysis of IVUS images at follow-up, the lumen volume was significantly smaller in the PR/IR group than that in the NR group (62+/-15 mm3 vs 75 +/-20 mm3; p = 0.001), and neointima hyperplasia volume was significantly larger in the PR/IR group than that in the NR group (46+/-15 mm3 vs 26+/-10 mm3; p = 0.001). A significant positive correlation was found between pre-interventional RI and follow-up NIH CSA (r = 0.25, p = 0.022). The incidence of ISR and repeat intervention was significantly higher in the PR/IR group (30.8% vs 18.2%, 28.8% vs 15.2%; p = 0.032, 0.035, respectively).

CONCLUSION

Measuring pre-interventional arterial remodeling patterns by IVUS may be helpful to stratify lesions at high-risk of ISR.

Low variation and high reproducibility in plaque volume with intravascular ultrasound

BACKGROUND

Intravascular ultrasound (IVUS) has several advantages compared to angiography when evaluating coronary atherosclerosis in the vessel wall.

METHODS

The accuracy, reproducibility, and short-time spontaneous variation in volume of vessel, plaque and lumen were studied by electrocardiographic-gated three-dimensional (3D) IVUS in 20 male patients with ischaemic heart disease (IHD).

RESULTS

The study lesions were angiographically insignificant, with a length of the analysed segment on 11.4+/-5.9 mm. At baseline the mean minimal lumen diameter was 2.41+/-0.59 mm, minimal lumen area 4.82+/-2.38 mm2, and maximal plaque burden 65.61+/-9.57%. Mean reference diameter was 3.1+/-0.6 mm. No significant changes were observed in volumes of total vessel, lumen or plaque. The coefficient of variation (CV) for two volume measurements at baseline was: vessel 0.8%, plaque 1.3%, and lumen 1.4%. For measurements recorded at baseline and after 12.6+/-1.5 weeks, CV was respectively 3.5%, 3.3% and 6.6%. Reproducibility and interobserver and intraobserver variation showed very high correlations. A linear correlation was present in percent changes over 12.6+/-1.5 weeks between vessel volume and lumen volume (r=0.804; p<0.001) and between percent changes in plaque volume and vessel volume (r=0.581; p=0.007). No correlation was found between changes in plaque volume and lumen volume (r=0.015; p=0.950).

CONCLUSION

ECG-gated 3D IVUS is a highly reproducible method when applied on coronary artery atherosclerosis. CV for lumen volume over 12.6+/-1.5 weeks is twice that of plaque volume indicating the superiority of the 3D IVUS compared to coronary angiography (CAG).

Terrein: a new melanogenesis inhibitor and its mechanism

Terrein is a bioactive fungal metabolite whose effects are almost unknown. In this study, we found for the first time that terrein has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 microM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrein treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrein reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.

Insights into the pathogenesis of vein graft disease: lessons from intravascular ultrasound

The success of coronary artery bypass grafting (CABG) is limited by poor long-term graft patency. Saphenous vein is used in the vast majority of CABG operations, although 15% are occluded at one year with as many as 50% occluded at 10 years due to progressive graft atherosclerosis. Intravascular ultrasound (IVUS) has greatly increased our understanding of this process. IVUS studies have shown that early wall thickening and adaptive remodeling of vein grafts occurs within the first few weeks post implantation, with these changes stabilising in angiographically normal vein grafts after six months. Early changes predispose to later atherosclerosis with occlusive plaque detectable in vein grafts within the first year. Both expansive and constrictive remodelling is present in diseased vein grafts, where the latter contributes significantly to occlusive disease. These findings correlate closely with experimental and clinicopathological studies and help define the windows for prevention, intervention or plaque stabilisation strategies. IVUS is also the natural tool for evaluating the effectiveness of pharmacological and other treatments that may prevent or slow the progression of vein graft disease in clinical trials.

Remodeling of coronary arteries in diabetic patients-an intravascular ultrasound study

BACKGROUND

Coronary artery remodeling is a structural change in the vessel wall and typically in response to atherosclerotic plaque. The nature of coronary remodeling has been described in different clinical situations. However, remodeling characteristics of coronary arteries of diabetic patients have never been studied.

HYPOTHESIS

We tested the hypothesis that positive remodeling of coronary artery in response to atherosclerotic plaque in diabetic patients would be less compared to nondiabetic patients.

METHODS

Coronary intravascular ultrasound analysis of data in 26 consecutive patients (12 diabetic and 14 nondiabetic) was performed. Linear regression analyses of vessel area versus plaque area were carried out to establish a relation between the degree of plaque and the extent of remodeling in diabetic and nondiabetic groups.

RESULTS

The positive remodeling quantified as the slope of the regression line was similar in both the groups (diabetic group 1.32 and nondiabetic group 0.80) when all segments with different plaque areas were considered (P > 0.05). However, the diabetic group had greater positive remodeling in segments with plaque area less than 55%, as the slope for diabetic group was 2.01 and nondiabetic group was 1.40 (P < 0.05).

CONCLUSIONS

Both the diabetic and nondiabetic patients had positive remodeling in response to atherosclerotic plaque formation. Diabetics had greater positive remodeling in the early stages of atherosclerosis compared to nondiabetics, thus providing evidence against our hypothesis. The adverse clinical outcomes in diabetics may not be due to inadequate positive remodeling of coronary arteries as previously thought.

Spectrum of remodeling behavior observed with serial long-term (>/=12 months) follow-up intravascular ultrasound studies in left main coronary arteries

Most intravascular ultrasound (IVUS) studies of arterial remodeling in native coronary arteries reported a remodeling index obtained at a single time point. We analyzed serial IVUS examinations, including the vessel cross-sectional area changes (remodeling behavior), of 60 hemodynamically nonstenotic left main lesions (baseline vs 18.4 +/- 9.4 months follow-up). Lumen reduction resulted from vessel reduction (sometimes despite plaque + media decrease), plaque + media increase (with or without vessel increase), or both. The percent annual changes in lumen area correlated strongly with changes in vessel (r = 0.84), but not with changes in plaque + media area. Plaques were classified as group A lesions, reflecting positive remodeling behavior (vessel changes >0), or group B lesions, reflecting negative (or intermediate) remodeling behavior (vessel changes <==0). Both groups did not differ significantly in demographics, laboratory data, and medications. Group A lesions (n = 40) more often showed plaque + media increase than group B lesions (32 of 40 [80%] vs 9 of 20 [45%]; p = 0.02). Group A lesions had, on average, mild annual lumen increase despite mild plaque + media increase, i.e, overcompensation of remodeling for plaque + media increase (vessel increase greater than plaque + media area increase, 19 of 40 [47%]). Conversely, group B lesions (n = 20) showed a significant lumen area reduction (-2.8 +/- 2.6 mm(2)/year) as a result of a decrease in vessel area only. Thus, serial long-term reduction of lumen size may result from vessel shrinkage (sometimes despite plaque decrease), plaque increase (with or without vessel increase), or both; overall, only the remodeling behavior has a significant relation to lumen changes. More than 30% of lesions show a negative remodeling behavior, which shows no relation to patient characteristics or initial plaque burden.

assessment of coronary remodeling in stenotic and nonstenotic coronary atherosclerotic lesions by multidetector spiral computed tomography

OBJECTIVES

This study was designed to investigate whether contrast-enhanced multidetector spiral CT (MDCT) permits assessment of remodeling in coronary atherosclerotic lesions.

BACKGROUND

With sufficient image quality, MDCT permits noninvasive visualization of the coronary arteries, but its ability to assess remodeling has not been evaluated.

METHODS

Out of 102 patients in whom MDCT (16-slice scanner, intravenous contrast, 0.75-mm collimation, 420 ms rotation) was performed before invasive coronary angiography, 44 patients with high-quality MDCT data sets showing atherosclerotic plaque in a proximal coronary artery segment were chosen for evaluation. In multiplanar reconstructions orthogonal to the coronary artery, the cross-sectional vessel area was measured for the respective lesion and for a reference segment proximal to the lesion. The "Remodeling Index" was calculated by dividing the vessel area in the lesion by the reference segment. Results were correlated to the presence of stenosis (>50% diameter reduction) in invasive angiography. In a subset of 13 patients, MDCT measurements were verified by IVUS.

RESULTS

Reference vessel area was not significantly different between nonstenotic versus stenotic lesions (20 +/- 8 mm(2), n = 23 vs. 22 +/- 8 mm(2), n = 21). The mean Remodeling Index was significantly higher in nonstenotic than in stenotic lesions (1.3 +/- 0.2 vs. 1.0 +/- 0.2, p < 0.001). In five stenotic lesions, "negative remodeling" (Remodeling Index < or = 0.95) was observed. Cross-sectional vessel areas and Remodeling Indices measured by MDCT correlated closely to IVUS (r(2) = 0.77 and r(2) = 0.82, respectively).

CONCLUSIONS

Multidetector spiral CT may permit assessment of remodeling of coronary atherosclerotic lesions in selected data sets of sufficient quality.

Expansive arterial remodeling: location, location, location

The artery is a dynamic organ capable of changing its geometry in response to atherosclerotic plaque formation. Expansion of the vessel diameter retards luminal narrowing and is considered a compensatory response. However, the expansive remodeling response is a "wolf in sheep's clothes," because expansion is associated with the presence of inflammatory cells, proteolysis, and a thrombotic plaque phenotype. The prevalence and clinical presentation of expansively remodeled lesions may differ among vascular beds. However, it is evident that all types of atherosclerotic arterial expansive lesions share the presence of inflammatory cells and subsequent protease activities. The potential role of inflammation and protease activity in the development of the different remodeling modes is discussed.

Classification of arterial plaque by spectral analysis in remodelled human atherosclerotic coronary arteries

We aimed to characterise and to identify the predominant plaque type in vivo using unprocessed radiofrequency (RF) intravascular ultrasound (US) backscatter, in remodelled segments of human atherosclerotic coronary arteries. A total of 16 remodelled segments were identified using a 30-MHz intravascular ultrasound (IVUS) scanner in vivo. Of these, 9 segments were classified as positively remodelled (>1.05 of the total vessel area in comparison with the proximal and distal reference segments) and 7 as negatively remodelled (<0.95 of reference segment area). Spectral parameters (maximum power, mean power, minimum power and power at 30 MHz) were determined and plaque type was defined as mixed fibrous, calcified or lipid-rich. Positively remodelled segments had a larger total vessel area (16.5 +/- 1.1 mm2 vs. 8.7 +/- 0.9 mm2, p<0.01) and plaque area (7.3 +/- 1.1 mm2 vs. 4.4 +/- 0.8 mm2, p=0.05) than negatively remodelled segments. Both positively and negatively remodelled segments had a greater percentage of fibrous plaque (p<0.01) than calcified or lipid-rich plaque. Comparing positively and negatively remodelled segments, there was no significant difference between the proportion of fibrous, calcified or lipid-rich plaque. We have been able to characterise and to identify plaque composition in vivo in human atherosclerotic coronary arteries. Our data suggest that remodelled segments are predominantly composed of fibrous plaque, as identified by RF analysis, although plaque composition is similar, irrespective of the remodelling type.

Plaque Volume Measurement by Magnetic Resonance Imaging as an Index of Remodeling of Middle Cerebral Artery: Correlation with Transcranial Color Doppler and Magnetic Resonance Angiography

BACKGROUND

The feasibility of a noninvasive evaluation of remodeling of the middle cerebral artery (MCA) by magnetic resonance imaging (MRI) was assessed. The results were correlated with magnetic resonance angiography (MRA) and transcranial color Doppler (TCD) findings.

METHODS

26 patients (13 male and 13 female, age ranged from 46 to 82 years) who presented with symptoms of cerebrovascular accidents had TCD, MRA and MRI assessment of the MCA. The TCD and MRA findings of 40 MCAs accessible by TCD were correlated with the ratio of cross-sectional area of the vessel (VA), luminal area of the vessel (LA) and plaque load (PL).

RESULTS

The VA ratio and LA showed no correlation with TCD or MRA results. PL however was shown to be associated with both TCD and MRA.

CONCLUSIONS

MRI could be used to assess remodeling in MCAs. PL was found to be associated with TCD and MRA findings.

Impact of preinterventional arterial remodeling on neointimal hyperplasia after implantation of (non-polymer-encapsulated) paclitaxel-coated stents: a serial volumetric intravascular ultrasound analysis from the ASian Paclitaxel-Eluting Stent Clinical Trial (ASPECT)

BACKGROUND

This study used serial volumetric intravascular ultrasound (IVUS) to evaluate the effect of preinterventional arterial remodeling on in-stent intimal hyperplasia (IH) after implantation of non-polymer-encapsulated paclitaxel-coated stents.

METHODS AND RESULTS

Patients were randomized to placebo or one of two doses of paclitaxel (low dose, 1.28 microg/mm2; high dose, 3.10 microg/mm2). Complete preinterventional, post-stent implantation, and follow-up IVUS were available in 18 low-dose and 21 high-dose patients. IH volumes were similar in low-dose and high-dose patients: 17.6+/-15.1 mm3 in low-dose patients and 13.1+/-13.3 mm3 in high-dose patients (P=0.3). Therefore, IVUS findings in low- and high-dose patients were combined. Preinterventional remodeling was assessed by comparing lesion site to proximal and distal reference arterial area: positive remodeling (lesion>proximal reference, n=13), intermediate remodeling (distal reference<lesion<proximal reference, n=13), and negative remodeling (lesion<distal reference, n=13). During follow-up, there was a decrease in lumen volume in positive remodeling lesions (from 106+/-30 to 90+/-27 mm3; P=0.0067) and in intermediate remodeling lesions (from 97+/-28 to 76+/-31 mm3; P=0.0004), but not in negative remodeling lesions (99+/-27 versus 92+/-32 mm3; P=0.15). The follow-up IH volume was lower in negative remodeling lesions (5+/-7 mm3) compared with positive remodeling (20+/-14 mm3; P=0.0051) and intermediate remodeling lesions (20+/-15 mm3; P=0.0043); however, IH volume was virtually identical in positive and intermediate remodeling lesions. Multivariate linear regression analysis determined that remodeling and inflation pressure were independent predictors of IH volume; variables tested in the model included diabetes, acute coronary syndromes, dose, remodeling, and preinterventional plaque burden.

CONCLUSIONS

Preinterventional arterial remodeling, especially negative remodeling, influences neointimal hyperplasia suppression after implantation of non-polymer-encapsulated paclitaxel-coated stents.

Intravascular ultrasound assessment of patterns of arterial remodeling in the absence of significant reference segment plaque burden in patients with coronary artery disease

OBJECTIVES

We evaluated the impact of reference vessel segment plaque burden on lesion remodeling. Intravascular ultrasound (IVUS) assessment of lesion remodeling compares lesions to reference segments. However, reference segments are rarely disease-free and, therefore, have also undergone remodeling changes.

METHODS

Pre-intervention IVUS was obtained in 274 patients with right coronary artery lesions selected because the right coronary artery has less tapering and fewer side branches than the left anterior descending or left circumflex artery. Standard IVUS definitions were used. Patients were divided according to reference vessel segment plaque burden: group A (minimal reference disease, n = 91), both proximal and distal reference plaque burden <20%; group B (n = 91), either proximal or distal reference plaque burden 20% to 40% but both < or =40%; and group C (n = 92), either proximal or distal reference plaque burden >40%.

RESULTS

The remodeling index measured 0.98 +/- 0.16 in group A (range, 0.68 to 1.47), 1.04 +/- 0.18 in group B (range, 0.67 to 1.91), and 1.04 +/- 0.15 in group C (range, 0.74 to 1.70), analysis of variance p = 0.0208 (p = 0.0234 group A vs. group B and p = 0.0012 group A vs. group C, but p = 0.8 group B vs. group C). Positive, intermediate, and negative remodeling were observed in 24 (26%), 24 (26%), and 43 lesions (48%) in group A; 36 (40%), 28 (30%), and 27 lesions (30%) in group B; and 34 (37%), 39 (42%), and 19 lesions (21%) in group C, respectively (p = 0.0022).

CONCLUSIONS

Negative remodeling occurs commonly in coronary lesions with minimal reference segment disease. Negative remodeling is not just an "artifact" introduced by comparing lesions to diseased reference segments.

Coronary arterial remodeling in differing clinical presentations of unstable angina pectoris--an intravascular ultrasound study

BACKGROUND

Coronary arterial remodeling influences the clinical presentation of ischemic heart disease; however, there is little information on the relationship between coronary arterial remodeling and the type of angina pectoris that patients manifest.

HYPOTHESIS

The study was undertaken to determine the difference of coronary arterial remodeling in patients with different types of angina pectoris.

METHODS

We analyzed 100 patients with ischemic heart disease using intravascular ultrasound (IVUS). Intracoronary IVUS images of proximal reference (PR), distal reference (DR), and target lesion were recorded, and intraluminal area (LA) and external elastic membrane (EEM) were measured. We defined a remodeling index as 100 x (lesion EEM - [PR-EEM + DR-EEM]/2) / ([PR-EEM + DR-EEM]/2). Cases were classified into three groups according to the clinical history (Group 1a: de novo unstable angina pectoris, Group 1b: accelerating unstable angina pectoris, and Group 2; stable angina pectoris).

RESULTS

The remodeling index in Group 1a was significantly larger than that in Groups 1b and 2 (18.6 +/- 28.5 vs. 5.3 +/- 27.1 and 18.6 +/- 28.5 vs. -2.7 +/- 17.6, p = 0.0347 and p = 0.0005, respectively), but there was no statistical difference in remodeling index between Groups 1b and 2.

CONCLUSIONS

Our results indicate that positive coronary arterial remodeling is more prevalent in patients with new onset of angina pectoris. The specific type of coronary arterial remodeling may affect the clinical presentation of patients with coronary artery disease.

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

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

Impact of moderate lesion calcium on mechanisms of coronary stenting as assessed with three-dimensional intravascular ultrasound in vivo

Axial plaque redistribution is an important mechanism of lumen enlargement after stenting of noncalcified lesions. To assess effects of lesion calcification on mechanisms of coronary stenting, we analyzed 55 lesions with noncircumferential calcification with 3-dimensional intravascular ultrasound (IVUS) (standard qualitative and quantitative analyses) before and after implantation of balloon-expandable stents. Thirty-two plaques (58%) showed arcs of calcium <120 degrees of vessel circumference (group A), whereas 23 lesions (42%) contained arcs of calcium > or =120 degrees of vessel circumference (group B). In the entire cohort of 55 lesions, as well as groups A and B, which were studied separately, both single-slice IVUS analysis (performed at minimum lumen site before intervention) and mean stented segment IVUS analysis showed an increase in lumen and vessel area and a decrease in plaque area (p <0.001). The magnitude of lumen and vessel increase and of plaque decrease was similar in both groups. Group A lesions showed significant plaque extrusion into the distal reference segment that was not observed in group B (increase in plaque area of 1.3 +/- 1.9 vs 0.1 +/- 2.0 mm(2), p <0.04). Stenting did not alter plaque area of the proximal reference segment in either group. In addition, there was an increase in vessel area of the distal reference of both groups, indicating that stent-induced vessel expansion observed within the lesion also affected the distal reference. Thus, longitudinal plaque redistribution and vessel expansion contribute to increased lumen dimensions during stenting of lesions with varying amounts of calcium; however, marked plaque extrusion was found only in lesions with a calcium arc of <120 degrees.

Impact of diabetes mellitus on angiographically silent coronary atherosclerosis

Constrictive remodeling occurs in significant atherosclerotic lesions of the diabetic patient, but the impact of diabetes mellitus (DM) on the angiographically normal coronary artery is still unclear. Morphometric analysis using intravascular ultrasound (IVUS) prior to intervention evaluated 54 sites in 33 DM patients and 106 in 62 non-diabetic patients. Vessel area (VA) and lumen area (LA) were measured at angiographically normal sites in the vessel. Plaque area (PA) was calculated as VA - LA. Percentage plaque area (%PA) was calculated as PA VA. Even in the angiographically normal site, mild coronary atherosclerosis was detected by IVUS in both groups. In the patients with DM, VA and LA were significantly smaller than in the non-diabetic patient (15.5 vs 17.8 mm(2), p<0.01; and 10.1 vs 12.2 mm(2), p<0.01 respectively), whereas % PA was similar (34.5 vs 31.6%). At angiographically normal sites where mild coronary atherosclerosis is detected by IVUS, the coronary artery of diabetic patients is smaller than that of the non-diabetic. These results suggest impaired compensatory enlargement or some other constrictive mechanism has already occurred in the early stages of coronary atherosclerosis in patients with DM.

Intravascular ultrasound imaging of myocardial-infarction-related arteries after percutaneous transluminal coronary angioplasty reveals significant plaque burden and compensatory enlargement

We studied patients with acute myocardial infarction (MI) by intravascular ultrasound (IVUS) to elucidate the controversy as to the amount and severity of the atherosclerotic disease at the culprit lesion site in acute MI, as discrepancies exist between angiographic and pathological reports. Twenty-five consecutive patients (age 56 3 10.5 years), with acute MI, underwent IVUS study of the MI-related artery immediately following successful PTCA to the culprit lesion. The IVUS images were analyzed quantitatively and qualitatively and were compared with the angiography of the same arteries. At the PTCA site, 64% of the lesions had an area stenosis of 50-70% and the plaque cross-sectional area (CSA) averaged 0.5 3 0.18 of the arterial CSA. IVUS-defined atherosclerosis was found also in 72% of the segments proximal and distal to the culprit lesion with a plaque/artery CSA ratio of 0.25 3 0.2. The angiogram revealed only 30% of these segments to be abnormal (P 3 0.001). Sixty-nine per cent of all the plaques were defined as 'soft' (low echo-genecity) versus 31% 'hard' (high echo-genecity). The hard plaques were larger than the soft plaques (0.5 3 1.6 versus 0.37 3 0.19 CSA index, respectively, P 3 0.01). With the increase in plaque area there was a significant increase in arterial cross-sectional area. This was demonstrated for all the diseased segments with a correlation coefficient of 0.49 (P 3 0.0001) and for the diseased reference sites a similar correlation coefficient of 0.49 (P 3 0.003) was found. Contrary to coronary angiographic-based reports, this IVUS study revealed a significant atheromatous plaque burden at the culprit lesion of MI-related arteries as well as diffuse atherosclerosis in the reference segments proximal and distal to the lesion. The detection of compensatory enlargement may explain the discrepancies between the histopathological and the angiographic studies.

Intravascular ultrasound observations of atherosclerotic lesion formation and restenosis in patients with diabetes mellitus

Coronary artery disease is more aggressive in diabetic patients than in nondiabetics; they have more diffuse disease, higher mortality rates and worse clinical outcomes after coronary interventions. Intravascular ultrasound (IVUS) produces transmural tomographic images of the coronary arteries in vivo. Recent IVUS studies have provided new insights into the mechanisms of stenosis formation and restenosis in both nondiabetic and diabetic patients. Arterial remodeling is defined as a change in arterial area. During atherogenesis, an increase in arterial area usually accompanies plaque accumulation to delay lumen compromise. Stenosis formation is related to: (a) the rate of plaque accumulation versus the rate of positive remodeling; and (b) the limits and ultimate failure of positive remodeling. However, there is a marked variability in remodeling. IVUS studies have suggested that remodeling may be impaired in some diabetic patients during atherogenesis. Following non-stent catheter-based interventions, serial (post-intervention and follow-up) IVUS studies have shown that the change in lumen area correlates better with the change in arterial area (remodeling) than with the change in plaque area (neointimal hyperplasia). In some patients, a positive remodeling response mitigates against the increase in plaque area to limit late lumen loss and restenosis. Neointimal hyperplasia is exaggerated in diabetic patients. Despite this, there is a reduced frequency of positive remodeling, potentially similar to the impaired positive remodeling in some diabetic patients during atherogenesis. Failed or inadequate arterial remodeling may contribute to the pathogenesis and natural history of atherosclerotic coronary artery disease in diabetic patients.

Impact of deep vessel wall injury on acute response and remodeling of coronary artery segments after cutting balloon angioplasty

Deep vessel wall injury is believed to affect vessel dimension following coronary intervention. The cutting balloon is designed to treat coronary artery stenoses with dilatation and surgical incisions, thereby reducing excess vessel injury. This study examines the effect of deep vessel wall injury on acute and late coronary arterial response after cutting balloon angioplasty. Serial volumetric intravascular ultrasound (IVUS) analyses were performed in 63 lesions treated with cutting balloon angioplasty alone. Before intervention, the longitudinal range of the lesion segment that included the smallest lumen area (LA) was determined as LA <4 mm(2) and/or LA stenosis >60%. The exact corresponding site at postintervention and follow-up was aligned using peri- and intravascular landmarks. Average vessel area (VA), plaque area (PA), and LA were measured. Lesion segments were categorized as with or without deep vessel wall injury, which was defined as the presence of plaque/vessel wall fracture extending to the sonolucent (medial) layer. Before intervention, the lesion vessel size of deep injury group was smaller than that of the nondeep injury group (p <0.05 for average VA and PA), whereas average lesion LA, lesion length, and reference vessel size did not differ. Immediately after cutting balloon angioplasty, the deep injury group showed a significant increase in VA (p <0.0001) and a lesser decrease in PA (p <0.01) compared with the nondeep injury group. During follow-up, the increase of VA tended to be greater in the deep injury group than in the nondeep injury group (p = 0.06), whereas the change of PA did not differ. Consequently, LA decrease was less in the deep injury group than in the nondeep injury group (p <0.05). From these results, it is suggested that deep vessel wall injury tends to occur in lesions with relatively small size and such lesions show favorable vessel response after cutting balloon angioplasty.

Estabilización de la placa de ateroma: un nuevo concepto basado en la biología dinámica de la aterosclerosis

As it is well-known, a thrombus evolving into a disrupted/eroded atherosclerotic plaque causes most acute coronary syndromes. Plaque stabilization via reduction of the lipid core and/or thickening of the fibrous cap is one of the possible mechanisms accounted for the clinical benefits displayed by different anti-atherosclerotic strategies. The concept of plaque stabilization was developed to explain how lipid-lowering agents could decrease adverse coronary events without substantial modifications of the atherosclerotic lesion. A number of imaging modalities (vascular ultrasound, MRI, and coronary computed tomography) are used for non-invasive assessment of atherosclerosis; most of them can identify luminal stenosis, wall thickness and plaque volume and composition, and can even characterize the rupture-prone vulnerable plaques. Several classes of drugs, including statins, ACE inhibitors, -blockers, and antithrombotics, are able to reduce the plaque burden and the incidence of cardiovascular events; this may be attibutable, at least in part, to plaque-stabilizing effects and the improvement of endothelial dysfunction.

Atherosclerotic expansive remodeled plaques: a wolf in sheep's clothing

Geometric arterial remodeling is an important determinant of luminal narrowing in atherosclerotic disease. Expansive remodeling retards while constrictive remodeling accelerates luminal narrowing by plaque formation. Cross-sectional as well as follow-up studies revealed that expansive remodeling is associated with adverse cardiovascular events and a vulnerable plaque phenotype. Although the relation between expansive remodeling and plaque vulnerability is associative rather than causal, expansively remodeled plaques should be considered as a wolf in sheep's clothes. Further understanding of the processes that regulate arterial remodeling and plaque rupture may lead to new strategies to responsibly manipulate these processes for the benefit of patient outcomes.

Infectious agents in coronary atheromas: a possible role in the pathogenesis of plaque rupture and acute myocardial infarction

In this review we report our recent findings of histopathological features of plaque instability and the association with Mycoplasma pneumoniae (MP) and Chlamydia pneumoniae (CP) infection, studying thrombosed coronary artery segments (CAS) of patients who died due to acute myocardial infarction. Vulnerable plaques are known to be associated with fat atheromas and inflammation of the plaque. Here we demonstrated that vulnerability is also related with focal positive vessel remodeling that maintains relatively well preserved lumen even in the presence of large atheromatous plaques. This phenomena may explain why the cinecoronariography may not detect large and dangerous vulnerable plaques. Greater amount of these bacteria in vulnerable plaques is associated with adventitial inflammation and positive vessel remodeling: the mean numbers of lymphocytes were significantly higher in adventitia than in the plaque, good direct correlation was obtained between numbers of CD20 B cells and numbers of CP infected cells in adventitia, and between % area of MP-DNA in the plaque and cross sectional area of the vessel, suggesting a cause-effect relationship. Mycoplasma is a bacterium that needs cholesterol for proliferation and may increase virulence of other infectious agents. In conclusion, co-infection by Mycoplasma pneumoniae and Chlamydia pneumoniae may represent an important co-factor for plaque instability, leading to coronary plaque thrombosis and acute myocardial infarction, since larger amount of these bacteria strongly correlated with histological signs of more vulnerability of the plaque. The search of CMV and Helicobacter pilori in these tissues resulted negative.

Relationship between coronary artery remodeling and plaque vulnerability

BACKGROUND

In vivo studies with intravascular ultrasound have shown that complex plaque anatomy and plaque rupture are more frequent in the presence of marked outward remodeling. A large lipid core and a high macrophage count are recognized histological markers for plaque vulnerability. The link between plaque vulnerability in terms of these markers and remodeling in coronary arteries has not been explored.

METHODS AND RESULTS

In 88 male subjects who died suddenly with coronary artery disease, 108 plaques were studied. The percent remodeling was calculated. Lesions with remodeling > or = 0% were considered to have positive remodeling, and those in which remodeling was < 0% were considered to have negative remodeling. Percent lipid core and macrophage count at the plaque were assessed. Of 108 plaque sites, 64 (59.2%) had undergone no remodeling or positive remodeling, and 44 (40.7%) had negative remodeling (vessel shrinkage). Lesions with positive remodeling, compared with lesions with vessel shrinkage, had a larger lipid core (percent mean lipid core was 39.0 +/- 21.0% versus 22.3 +/- 23.1%, respectively; P < 0.0001) and a higher macrophage count (mean macrophage count was 15.6 +/- 12.3 versus 8.9 +/- 11.6, respectively; P = 0.005).

CONCLUSIONS

We have shown that coronary artery plaques with positive remodeling have a higher lipid content and macrophage count, both markers of plaque vulnerability. These results may explain why plaque rupture is often apparent at sites with only modest luminal stenoses (but marked positive remodeling).

Factors predicting compensatory vascular remodelling of the carotid artery affected by atherosclerosis

OBJECTIVE

To investigate factors predicting the development of outward remodelling of the carotid artery in patients with atherosclerosis.

DESIGN

130 patients with carotid artery stenosis (15-85% of the vessel diameter) were divided into two groups, based on the presence or absence of outward remodelling of the sclerotic carotid segment on high resolution ultrasonography. Logistic regression analysis was used to evaluate the contribution of haemodynamic, laboratory, and clinical measurements on the development of remodelling, including age, sex, type of stenosis, extent of plaque, per cent diameter stenosis, underlying disease, selected drug treatment, and plasma concentrations of total cholesterol, high density lipoprotein cholesterol, triglyceride, and uric acid.

RESULTS

64 patients (49%) had outward remodelling. Multivariate regression analysis showed that hypertension, the type of plaque, the thickness of the plaque, and the extent of stenosis were independent factors predicting remodelling. The odds ratios of hypertension, unstable shape of plaque, thickness of plaque, and the extent of the stenosis were 6.70, 3.02, 2.04, and 1.05, respectively. Other measurements did not contribute significantly to the estimation of remodelling.

CONCLUSIONS

Compensatory enlargement of the vessel occurs in about 50% of carotid artery segments with a diameter stenosis of 15-85%. Hypertension and the shape of the plaque are major determinants of the development of outward remodelling.

Impact of pre-interventional arterial remodeling on subsequent vessel behavior after balloon angioplasty: a serial intravascular ultrasound study

OBJECTIVES

The purpose of this study was to assess the impact of pre-intervention arterial remodeling on subsequent vessel behavior following balloon angioplasty.

BACKGROUND

Positive arterial remodeling before intervention has been shown to have a negative impact on the clinical outcome after nonstented coronary interventional procedures. However, the mechanism of interventions in coronary vessel geometry over time is less well characterized.

METHODS

Serial (pre-, post- and follow-up) intravascular ultrasound analysis was performed in 46 native coronary lesions. Positive remodeling (PR) was defined as vessel area (VA) at the target lesion greater than that of average reference segments. Intermediate or negative remodeling (IR/NR) was defined as VA at the target lesion less than or equal to that of average reference segment. Remodeling index was defined as VA at the target lesion site divided by that of average references.

RESULTS

Pre-interventional PR and IR/NR were present in 21 (46%) and 25 (54%) of 46 patients, respectively. At follow-up, the change in plaque area was similar between the two groups (1.3 +/- 2.1 vs. 1.2 +/- 2.1 mm(2), p = 0.840). Lesions with PR showed a significantly smaller change in VA than those with IR/NR (-0.2 +/- 2.5 vs. 1.4 +/- 2.3 mm(2), p = 0.03). As a result, late lumen loss was significantly larger in lesions whose pre-intervention configuration exhibited PR (-1.5 +/- 1.8 vs. 0.2 +/- 1.6 mm(2), p = 0.002).

CONCLUSIONS

Lesions with PR appear to have less capacity to compensate for further plaque growth after balloon angioplasty and thus show a proportional increase in late lumen loss. This may in part explain the less favorable clinical outcomes of positively remodeled lesions.

Increased intimal apoptosis in coronary atherosclerotic vessel segments lacking compensatory enlargement

OBJECTIVES

In a histopathologic study, we assessed the balance of cell proliferation and apoptosis by counting the number of apoptotic and proliferating cell nuclear antigen-positive cells in freshly harvested atherectomy specimens from 34 patients.

BACKGROUND

Remodeling of human coronary arteries is an adaptive process that alters vascular lumen size.

METHODS

Intravascular ultrasound was performed prior to atherectomy. Total vessel area (area within the external elastic lamina [EEL]), lumen area and plaque area were measured at the region of interest (ROI), and at a proximal and distal reference segment, utilizing the formula Delta(%)=100x(ROI-reference segment)/reference segment. Positive arterial remodeling (R+) resulting in luminal expansion was defined as DeltaEEL >10%. Absence of remodeling (0 < DeltaEEL <10%) and constrictive arterial remodeling (DeltaEEL <0) were considered as neutral remodeling (R0) and negative remodeling (R-), respectively.

RESULTS

In R- lesions, apoptotic indices (APO) were significantly elevated (17.17 +/- 2.19%) compared with R+ lesions (4.89 +/- 1.7%; p = 0.0007). In a rabbit iliac percutaneous transluminal coronary angioplasty model intimal apoptosis was increased four weeks after balloon angioplasty injury (APO 8.8 +/- 0.03%) compared with contralateral untreated segments (APO 3.0 +/- 0.04%, n = 6). Lesions with an EEL/intimal area <3.0 showed significantly more intimal apoptosis than untreated lesions (p = 0.02).

CONCLUSIONS

The data indicate that constrictive remodeling of atherosclerotic coronary lesions is associated with increased apoptosis of intimal cells. We speculate that increased apoptosis is due to extensive plaque healing after episodes of symptomatic or asymptomatic plaque rupture.

Plaque burden, arterial remodeling and plaque vulnerability: determined by systemic factors?

OBJECTIVES

This study was designed to determine whether arterial remodeling and plaque vulnerability are influenced by systemic factors.

BACKGROUND

Atherosclerotic luminal narrowing is caused by gradual plaque growth and arterial remodeling. In the acute phase, luminal narrowing may be accelerated by acute thrombus formation, usually precipitated by rupture of a vulnerable plaque.

METHODS

Femoral arteries were obtained from elderly individuals at autopsy. Pairs of atherosclerotic femoral arteries from 42 individuals were examined. The arteries were divided in 1-cm intervals. Plaque size, the mode of arterial remodeling and histopathologic characteristics of plaque vulnerability (lipid-rich core and plaque inflammation) were compared between right and left femoral arteries obtained from the same individual. A role for systemic factors was assumed if a phenomenon was equally present in both arteries.

RESULTS

There was concordance in average plaque size (r(2) = 0.5, p < 0.001), expansive remodeling (kappa = 0.42, p = 0.007) and occurrence of plaques containing a large lipid-rich core (kappa = 0.60, p = 0.001), but no concordance in plaque inflammation (kappa = 0.067, p = 0.61) between right and left arteries.

CONCLUSIONS

These results suggest that not only the amount of atherosclerosis, but also arterial remodeling and lipid deposition in plaques, are influenced by systemic factors. The nonhomogeneous distribution of inflammation in atherosclerotic arteries supports the hypothesis that plaque inflammation is locally affected.

Relation between coronary artery remodelling (compensatory dilatation) and stenosis in human native coronary arteries

OBJECTIVES

To investigate the contribution of plaque size and vessel remodelling to coronary artery stenosis and to assess the role of vessel shrinkage (negative remodelling) across a wide range of lesions.

DESIGN

Postmortem study of coronary remodelling in perfusion fixed hearts.

SUBJECTS

24 men and 24 women who died suddenly with coronary artery disease.

MAIN OUTCOME MEASURES

Percentage stenosis, percentage plaque burden, percentage remodelling, and arc of normal vessel were measured and related to age, sex, smoking status, and history of hypertension.

RESULTS

There was a positive relation between percentage stenosis and percentage plaque burden (r = 0.6, p < 0.0001) and an inverse relation between percentage stenosis and percentage remodelling (r = -0.4, p < 0.0001). Multilinear regression modelling showed that luminal stenosis = 1.0 (plaque burden) - 0.4 (vessel remodelling). Remodelling was greater in lesions that would not have been significant at angiography (</= 25% stenosis) than in the remaining lesions (25.9 (26)% v 10.0 (21.1)%, p < 0.0001, respectively) and was reduced in segments with circumferential plaques (12.7 (24.5)% v 20.7 (24.3)% in eccentric plaques, p = 0.001). Remodelling did not correlate with age, sex, or smoking. Negative remodelling was present in 62 lesions with a stenosis > 25% versus 10 lesions with </= 25% stenosis (p < 0.0001). Lesions with negative remodelling had greater plaque burden and luminal stenosis and a reduced arc of normal segment.

CONCLUSION

Outward arterial remodelling negates the stenosing effect of increasing plaque size. Significant coronary stenoses arise from a failure of this outward remodelling in the face of a large plaque burden. Coronary arterial remodelling is unrelated to sex or smoking and is plaque specific.

Relation between coronary artery remodelling (compensatory dilatation) and stenosis in human native coronary arteries

OBJECTIVES

To investigate the contribution of plaque size and vessel remodelling to coronary artery stenosis and to assess the role of vessel shrinkage (negative remodelling) across a wide range of lesions.

DESIGN

Postmortem study of coronary remodelling in perfusion fixed hearts.

SUBJECTS

24 men and 24 women who died suddenly with coronary artery disease.

MAIN OUTCOME MEASURES

Percentage stenosis, percentage plaque burden, percentage remodelling, and arc of normal vessel were measured and related to age, sex, smoking status, and history of hypertension.

RESULTS

There was a positive relation between percentage stenosis and percentage plaque burden (r = 0.6, p < 0.0001) and an inverse relation between percentage stenosis and percentage remodelling (r = –0.4, p < 0.0001). Multilinear regression modelling showed that luminal stenosis = 1.0 (plaque burden) − 0.4 (vessel remodelling). Remodelling was greater in lesions that would not have been significant at angiography (⩽ 25% stenosis) than in the remaining lesions (25.9 (26)% v10.0 (21.1)%, p < 0.0001, respectively) and was reduced in segments with circumferential plaques (12.7 (24.5)% v20.7 (24.3)% in eccentric plaques, p = 0.001). Remodelling did not correlate with age, sex, or smoking. Negative remodelling was present in 62 lesions with a stenosis > 25% versus 10 lesions with ⩽ 25% stenosis (p < 0.0001). Lesions with negative remodelling had greater plaque burden and luminal stenosis and a reduced arc of normal segment.

CONCLUSION

Outward arterial remodelling negates the stenosing effect of increasing plaque size. Significant coronary stenoses arise from a failure of this outward remodelling in the face of a large plaque burden. Coronary arterial remodelling is unrelated to sex or smoking and is plaque specific.

Arterial remodeling and coronary artery disease: the concept of "dilated" versus "obstructive" coronary atherosclerosis

Traditionally, the development of coronary artery disease (CAD) was described as a gradual growth of plaques within the intima of the vessel. The outer boundaries of the intima, the media and the external elastic membrane (EEM), were thought to be fixed in size. In this model plaque growth would always lead to luminal narrowing and the number and severity of angiographic stenoses would reflect the extent of coronary disease. However, histologic studies demonstrated that certain plaques do not reduce luminal size, presumably because of expansion of the media and EEM during atheroma development. This phenomenon of "arterial remodeling" was confirmed in necropsy specimens of human coronary arteries. More recently, the development of contemporary imaging technology, particularly intravascular ultrasound, has allowed the study of arterial remodeling in vivo. These new imaging modalities have confirmed that plaque progression and regression are not closely related to luminal size. In this review, we will analyze the role of remodeling in the progression and regression of native CAD, as well as its impact on restenosis after coronary intervention.

Atheromas that cause fatal thrombosis are usually large and frequently accompanied by vessel enlargement

Several lines of clinical evidence show that AMI frequently occurs at sites with mild to moderate degree of coronary stenosis. The degree of luminal stenosis depends on plaque deposition and degree of vessel remodeling, features poorly assessed by coronary angiography. This postmortem study tested the hypothesis that the size of coronary atheroma and the type of remodeling distinguish culprit lesion responsible for fatal AMI from equi-stenotic nonculprit lesion in the same coronary tree. The main coronary branches from 36 consecutive patients with fatal AMI were studied. The culprit lesion (Group 1) and an equi-stenotic nonculprit segment (Group 2) obtained in measurements of another coronary branch from the same patient were compared. Morphometry and plaque composition was assessed in both groups. Compared to Group 2, Group 1 had larger areas of: plaque 9.6 vs. 4.7 mm(2), vessel 12.7 vs. 7.4 mm(2) and lumen 1.7 vs. 1.2 mm(2); (P< .01). Positive remodeling was more frequent in Group 1 than Group 2: 21/30 (70%) vs. 8/26 (31%). Plaque area correlated positively with lipid core and macrophages and negatively with fibrosis and smooth muscle cells. Atherosclerotic plaques that cause fatal thrombosis are more frequently positively remodeled and tend to be larger than nonculprit plaques with the same degree of cross-sectional stenosis. We tested whether arterial remodeling and plaque size vary between segments containing a fatal thrombosed plaque versus an equi-stenotic nonculprit plaque. Culprit vessel segments had higher cross-sectional areas of intimal plaque and of vessel wall than equi-stenotic nonculprit plaques. The cross-sectional area of the vessel correlated positively with both the lipid core area and CD68(+) macrophage content, and negatively with fibrosis area and smooth muscle cell content. These results add elements explaining limitations of angiography in identifying plaques and provide new insights into the role of remodeling in plaque instability.

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.